UNSTABLE SLOPE MANAGEMENT 

PROGRAM FOR FEDERAL LAND 

MANAGEMENT AGENCIES

Publication No. FHWA-FLH-19-002 January 2019
FOREWORD

The Federal Lands Highway Division (FLH) of the Federal Highway Administration (FHWA)

promotes development and deployment of applied research and technology applicable to solving 

transportation related issues on federal lands and with our state transportation partners. The FLH 

provides technology delivery, innovative solutions, recommended best practices, and related 

information and knowledge sharing to federal agencies, tribal governments, and other offices 

within the FHWA.

The objective of this study was to provide rapid geotechnical assessment, evaluation, and 

management methodologies to assist Federal Land Management Agencies (FLMAs) and lower 

annual daily traffic transportation departments and agencies among our state transportation 

partners to manage their unstable rock and soil slopes. Management tools include condition 

assessments that consist of hazard and risk evaluation, digital field data collection applications 

and an Internet-based searchable database, examples of performance measures, and scalable and 

flexible cost/benefit and quantitative risk assessment prioritization techniques as part of this 

research and development project.

_____________________________________

Timothy G. Hess, P.E.

Associate Administrator for Federal Lands

Federal Highway Administration

Federal Lands Highway

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 

in the interest of information exchange. The U.S. Government assumes no liability for the use of 

the information contained in this document. This report does not constitute a standard, 

specification, or regulation.

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers' names appear in this report only because they are considered essential to the 

objective of the document.

Quality Assurance Statement

The FHWA provides high-quality information to serve Government, industry, and the public in a 

manner that promotes public understanding. Standards and policies are used to ensure and 

maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically 

reviews quality issues and adjusts its programs and processes to ensure continuous quality 

improvement.
Technical Report Documentation Page

1. Report No.

FHWA-FLH-19-002

2. Government Accession No. 3. Recipient's Catalog No.

4. Title and Subtitle

Unstable Slope Management Program for Federal Land 

Management Agencies

5. Report Date

January 2019

6. Performing Organization Code

7. Author(s)

Darren Beckstrand, David Stanley, Paul Thompson, Eric 

Bilderback, Mike Wittie, Upulee Kanewala, Eli Cuelho, and 

Douglas A. Anderson

8. Performing Organization Report No.

9. Performing Organization Name and Address

Western Transportation Institute

PO Box 174250

Bozeman, Montana 59717-4250

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

Federal Highway Administration

610 East 5th Street

Vancouver, WA 98661

13. Type of Report and Period Covered

 Final Report

14. Sponsoring Agency Code

 

15. Supplementary Notes

This project was funded under several programs. Phase I was funded under the FHWA Federal Lands 

Highway Coordinated Technology Implementation Program (CTIP). Phase II was funded by Federal Lands 

Planning and Programming (FLPP), Geohazards, Extreme Weather Events and Climate Change, Technical 

Transfer Funds from the FHWA Resource Center – Office of Technical Services, the National Park Service 

Geologic Resources Division, the Oregon and Washington Region of the Bureau of Land Management, and 

by Region 6/10 of the United States Forest Service.

16. Abstract

 The primary objective of this research project was to develop an unstable slope management program (USMP) 

based on transportation asset management (TAM) for use by multiple federal land management agencies (FLMAs)

and lower traffic volume transportation departments and agencies among our state transportation partners to

manage their unstable rock and soil slopes. TAM uses economic and engineering analysis to create a process for 

maintaining, preserving, rehabilitating, and replacing assets to maintain them in a state of good repair over their 

life cycle and for the minimum practical cost. The USMP was also founded on performance management and risk 

management principles. The objective was in accordance with generally accepted transportation asset management 

principles and with recent federal highway legislation (MAP-21 and FAST Act) and their supporting regulations.

 The scope of work for this phase of the USMP project included the development of a standardized rating tool, 

a database with searching and reporting capabilities, and a GIS-based map to display unstable slopes and rockfalls 

along transportation corridors. As part of the development process, examples of performance metrics for 

geotechnical assets were established, an assortment of scalable and flexible benefit/cost analysis procedures for 

differing levels of available information were developed for prioritizing slope work, and a quantitative risk analysis 

procedure was developed to support further risk assessment needs for some transportation partners. In addition, 

the research plan included tasks to create maintenance tracking forms, forms for recording new geotechnical events, 

and mobile software applications to conduct rapid field inventory and inspection work using hand-held devices. 

Final tasks associated with the project centered on the creation of various training tools and educational materials 

for classroom and field training sessions at several locations around the U.S.

17. Key Words

unstable slope management, geotechnical asset 

management, rock slopes, soil slopes, geotechnical 

engineering, quantitative risk analysis

18. Distribution Statement

 No restriction. This document is available to the 

 public from the sponsoring agency at the website 

 http://www.fhwa.dot.gov/engineering/geotech

19. Security Classification. (of this report)

Unclassified

20. Security Classification (of this page)

Unclassified

21. No. of Pages

177

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
ii

SI* (MODERN METRIC) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol 

LENGTH

in inches 25.4 millimeters mm 

ft feet 0.305 meters m 

yd yards 0.914 meters m 

mi miles 1.61 kilometers km

AREA

in2 square inches 645.2 square millimeters mm2 

ft2 square feet 0.093 square meters m2

yd2 square yard 0.836 square meters m2 

ac acres 0.405 hectares ha 

mi2 square miles 2.59 square kilometers km2

VOLUME

fl oz fluid ounces 29.57 milliliters mL 

gal gallons 3.785 liters L 

ft3 cubic feet 0.028 cubic meters m3

yd3 cubic yards 0.765 cubic meters m3

NOTE: volumes greater than 1000 L shall be shown in m3

MASS oz ounces 28.35 grams g 

lb pounds 0.454 kilograms kg 

T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t")

TEMPERATURE (exact degrees)

°F Fahrenheit 5 (F-32)/9 Celsius °C

or (F-32)/1.8

ILLUMINATION 

fc foot-candles 10.76 lux lx 

fl foot-Lamberts 3.426 candela/m2 cd/m2

FORCE and PRESSURE or STRESS 

lbf poundforce 4.45 newtons N 

lbf/in2 poundforce per square 6.89 kilopascals kPa

APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH mm millimeters 0.039 inches in 

m meters 3.28 feet ft 

m meters 1.09 yards yd 

km kilometers 0.621 miles mi 

AREA mm2 square millimeters 0.0016 square inches in2

m2 square meters 10.764 square feet ft2

m2 square meters 1.195 square yards yd2

ha hectares 2.47 acres ac 

km2 square kilometers 0.386 square miles mi2 

VOLUME

mL milliliters 0.034 fluid ounces fl oz 

L liters 0.264 gallons gal 

m3 cubic meters 35.314 cubic feet ft3

m3 cubic meters 1.307 cubic yards yd3

MASS

g grams 0.035 ounces oz 

kg kilograms 2.202 pounds lb

Mg (or "t") megagrams (or "metric 1.103 short tons (2000 lb) T 

TEMPERATURE (exact degrees) °C Celsius 1.8C+32 Fahrenheit °F

ILLUMINATION

lx lux 0.0929 foot-candles fc 

cd/m2 candela/m2 0.2919 foot-Lamberts fl 

FORCE and PRESSURE or STRESS

N newtons 0.225 poundforce lbf 

kPa kilopascals 0.145 poundforce per square inch lbf/in2
iii

TABLE OF CONTENTS

Chapter 1. Introduction ............................................................................................................... 1

Report Organization.................................................................................................................... 4

Chapter 2. Statement of Work..................................................................................................... 5

Background................................................................................................................................. 5

Research Plan.............................................................................................................................. 7

Chapter 3. Unstable Slope Management Program for FLMAs.............................................. 12

Geotechnical Asset Management.............................................................................................. 12

Defining Geotechnical Assets................................................................................................... 13

Steps to Managing Unstable Slopes.......................................................................................... 14

Chapter 4. How to Conduct Field Ratings................................................................................ 27

Unstable Slope Rating Category Descriptions.......................................................................... 27

Personnel to Perform Ratings................................................................................................... 28

Equipment List.......................................................................................................................... 28

Planning .................................................................................................................................... 29

USMP Website and Mobile Applications................................................................................. 31

Chapter 5. How to Set and Use Performance Measures ......................................................... 33

Importance of Tracking Geotechnical Events .......................................................................... 34

Setting Agency-Specific Performance Goals ........................................................................... 35

Slope Condition Rating and Performance Measures................................................................ 37

Example of Performance Monitoring for U.S. Forest Service ................................................. 38

Chapter 6. How to Use Benefit/Cost Approaches.................................................................... 40

Various Approaches to Benefit/Cost Calculations ................................................................... 40

Selecting the Appropriate Approach......................................................................................... 44

Cost Estimation......................................................................................................................... 44

Examples from Gifford Pinchot National Forest...................................................................... 45

Chapter 7. How To Conduct Quantitative Risk Assessment.................................................. 49

QRA Analysis Factors.............................................................................................................. 50

Estimated chance of an Incident ............................................................................................... 53

Risk Reduction Benefit/Cost Analysis ..................................................................................... 53

References.................................................................................................................................... 54

Appendix A. USMP Rating Form Detailed Descriptions....................................................... 57

Appendix B. USMP Rating Forms............................................................................................ 96

Appendix C. Detailed Instructions for USMP Website and Mobile Applications.............. 103

Appendix D. Benefit/Cost Approach for Rock and Soil Slopes............................................ 114

Appendix E. Gifford Pinchot National Forest Cost Estimation ........................................... 140
iv

Appendix F. Unstable Slope Performance Measures for FLMAs Using USMP Ratings... 151

Appendix G. Qualitative Risk Analysis Online Form and Usage......................................... 164

List of Figures

Figure 1. GAM Process (Thompson, 2016).................................................................................. 15

Figure 2: FLMA GAM Process Roadmap.................................................................................... 16

Figure 3. Navigation Bar for USMP Website and Mobile Applications. ..................................... 31

Figure 4. USMP Searching and Reporting Interface .................................................................... 32

Figure 5. Virginia DOT Performance Dashboard (VDOT website – accessed 

December 16, 2016)............................................................................................................... 33

Figure 6. BLM Transportation System Modes............................................................................. 36

Figure 7. Landslide on a BLM road, southwest Oregon............................................................... 36

List of Tables

Table 1. Good, Fair, and Poor Classifications for USMP Slopes................................................. 38

Table 2. Example Performance Measure Table for U.S. Forest Service (bold text 

indicates examples filled in). ................................................................................................. 39

Table 3. Sites used in benefit/cost calculations with selected site information............................ 46

Table 4. Calculating Benefit/Cost ratios or Priority Indexes for Gifford Pinchot 

National Forest sample sites. The USMP sites have also been ranked under each 

analysis alternative................................................................................................................. 47

Table 5. Priority index for Gifford-Pinchot sites calculated using Alternative 3, and 

organized from highest to lowest index score (note that rockfall and landslide 

hazards have been analyzed separately in the rankings). ...................................................... 48
1

CHAPTER 1. INTRODUCTION

Transportation corridors for roads and trails in our Federal lands contain numerous unstable 

slopes, both natural and constructed (cut slopes and embankments), all subject to some form of 

failure – from slow creep failures to sudden rockfall. These slope failures may be simple 

maintenance nuisances that require an out of ordinary expenditure of public funds, but 

sometimes they are serious incidents that cause loss of life, injury, and property damage; block 

use of roads or trails; and cost into the millions of dollars.

Federal engineering geology and geotechnical staff recognized that geotechnical asset 

management (GAM) could be adaptable to Federal lands agency use and initiated this research

and development effort using the Coordinated Technology Implementation Program (CTIP)

program. The Alaska Department of Transportation and Public Facilities (AKDOT&PF) was 

selected as the contractor for Phase I, because the agency had already begun an extensive 

research project to create a pioneering GAM program addressing slopes and other geotechnical 

assets. Following the initial project, additional non-CTIP funding through Federal Lands 

Planning and Performance Management (FLPP), Climate Change, and Unstable Slope Hazards 

was allocated for a second phase, and the primary contractor became Western Transportation 

Institute (WTI) at Montana State University. Subconsultants Landslide Technology, Paul D. 

Thompson and DA Stanley Consulting, all of whom worked on the AKDOT&PF GAM research

projects and Phase I of this project, were also retained for Phase II.

Recently, with the growing acceptance of Transportation Asset Management (TAM) and impetus 

from the Federal legislation, agencies have begun to develop systems to manage a wide range of

geotechnical assets using TAM principles. Modern, proactive asset management-based 

programs are based on maintaining assets in a state of good repair, meeting a required level of 

service in the most transparent and cost-effective manner, and considering economics and life 

cycle costs for the transportation network as a whole, rather than focusing on single assets, one at 

a time. Performance management adds in the element of setting and meeting appropriate 

performance levels and goals established by the agencies. Risk management is also considered 

part of the process in the modern systems approach to assess risk cost as an integral part of 

economic analysis. These principles formed the basis of the Unstable Slope Management 

Program (USMP) for Federal Land Management Agencies (FLMAs).

Following completion of the Phase I work, further research and development was initiated 

through 17 tasks, outlined in Chapter 2. The research plan for the USMP Phase I and II projects

included: developing standardized rating categories, establishing examples for asset management 

performance measures, developing a database and integrating it with an open-source GIS-based

platform, creating scalable and flexible benefit/cost analysis procedures for differing levels of 

available information to prioritize unstable slope work, and developing a quantitative risk 

analysis procedure to support further risk assessment needs for some transportation partners. In 

addition, the research plan included tasks to create maintenance tracking forms, forms for 

recording new geotechnical events, and mobile software applications to conduct rapid field 

inventory and inspection work using hand-held devices. Final tasks associated with the project 
2

centered on the creation of various training tools and educational materials for classroom and 

field training sessions at several locations around the U.S.

The primary objectives under Phase I was to establish a standardized set of rating criteria for all 

FLMAs, to develop a standardized rating form that included hazard and risks associated with 

unstable slopes, to test the standardized rating form in a project demonstration on the Gifford 

Pinchot National Forest in southwest Washington State, and to develop a brief video about the 

USMP and its value to managing slope assets and meeting the Moving Ahead for Progress in the 

21st Century Act (MAP-21) policies. To build on the Phase I work, four major objectives were 

set as part of Phase II to accomplish the work outlined within this project: 1) establish a 

standardized evaluation system to rate and track unstable slopes through the development of a 

searchable database with a GIS-based platform, 2) provide examples for performance measures, 

3) create scalable and flexible benefit/cost approaches for differing levels of available 

information, and 4) develop a quantitative risk analysis tool. Each of these major tasks is briefly 

summarized below.

A stakeholder group consisting of members from the National Park Service (NPS), the Bureau of 

Land Management (BLM), and the United States Forest Service (USFS) was established to help 

guide and verify the various developments associated with this project. The USMP is thought to 

be relevant and useful to several other state and federal agencies, including but not limited to, the 

Bureau of Indian Affairs (BIA), the U.S. Army Corps of Engineers (USACE), the U.S. Bureau of 

Reclamation (USBR), the U.S. Fish and Wildlife Service (USFWS), and state and county 

departments of transportation, including urban Metro Park departments.

Activities related to the primary objectives of Phase II include the following:

• Standardized Unstable Slope Evaluation and Tracking System with a Database on a GISbased Platform. A standardized relative-rating evaluation system for unstable soil and 

rock slopes customized for low-volume roads and trails typically found on FLMA lands 

was developed during Phase I. A two-page standardized rating form was created to 

rapidly conduct field ratings of unstable rock and soil slopes on both roads and trails. 

This evaluation system includes hazard and risks associated with unstable slopes and is 

the cornerstone of the Unstable Slope Management Program for FLMAs. Three asset and 

performance management supporting forms were also developed to: 1) track the 

occurrence of new unstable slope events to alert transportation managers, 2) document 

maintenance activities related to unstable slopes to track deterioration of unstable slopes, 

and 3) record pertinent cost estimate data for various risk reduction and full mitigation 

alternatives for highly rated unstable slopes within a given corridor or high use area.

• Performance Measures. An FLMA-focused Performance Management (PM) framework 

was developed for select geotechnical assets to measure progress toward agency goals. 

Performance measures are indicators of work performed and results achieved. 

Performance measures are also the quantitative indicators of the service provided by the 

agency’s transportation system to the user. Performance measures range from high level 
3

generalized agency-wide aspirational “management” goals to asset-specific “condition” 

goals. Using the road network management approach developed by the USDA Forest 

Service, the research team developed sample Performance Measures that can be used as a 

guide by other FLMAs to develop their own agency-specific Performance Measures 

based on their agency mission, land management approach, and policy goals.

• Benefit/Cost Analysis Approach. The benefit/cost analysis process assists FLMAs as they 

seek to prioritize slope assets in order to maintain a state of good repair or improve their 

status. It is necessary to set priorities and make decisions about agency resource 

allocation to ensure limited funds are used in the most efficient way possible. In TAM 

practice, the fundamental framework for setting priorities and allocating resources is 

based on benefit/cost comparisons. The research team (led by Paul Thompson for this 

task) created a simple yet flexible approach to set priorities and allocate resources, based 

on varying levels of available information. The different approaches provide an objective 

and consistent means of summarizing the degree to which each project may contribute to 

agency objectives while minimizing long-term cost and risk.

• Quantitative Risk Analysis. An independent quantitative risk analysis (QRA) module was 

also created as part of this project. It was designed to augment the unstable slope ratings 

as a risk-based prioritization tool or separately to analyze unstable rock or soil slope risk 

to individuals or public land users in areas where corridors have not been rated with the 

USMP evaluation system. The output from this analytical tool can be compared to other 

common societal risks (such as worldwide landslide fatalities, earthquakes, health issues, 

and vehicular accidents). To achieve a greater degree of transparency, reproducibility, 

and comparability in risk assessment, the NPS-Geologic Resources Division (GRD) has 

been using a QRA method that relies on empirical, modeled, or estimated probabilities. 

This useful method was adapted for use within the USMP tool. The graphical user 

interface developed for FLMA managers as part of this project allows for expeditious use 

of the QRA.

Databases were set up for the storage, searching and calculation of unstable slope rating data. 

An associated GIS-based map interface was also created to display this data spatially. Paper 

forms are also available to collect field data, which can be input manually into the database 

through the USMP website. In addition, to optimize efficiency, field data collection applications

were developed for Android and iOS mobile devices to automatically store, calculate, and upload

field data. USMP data can be exported or connected from the USMP website interface for use in 

previously developed FLMA-specific databases and compatible GIS systems.

Project information was disseminated through two-day training courses teaching how to rate 

unstable rock and soil slopes at three locations in 2017: 1) Great Smoky Mountains National 

Park in Gatlinburg, Tennessee, 2) Denver Service Center for the National Park Service in 

Lakewood, Colorado, and 3) Western Federal Land Highway Division (WFL) Offices in 

Vancouver, Washington. Training courses were free of charge and spanned two days; one 

classroom day and one field day.
4

REPORT ORGANIZATION

This manual is intended to introduce the reader to the background of asset and performance 

based management as it is applied to unstable slopes (soil and rock) along transportation 

corridors, and to outline the process of establishing, employing, and managing a USMP within 

your agency. It begins by outlining the background and essential parts of the unstable slope 

management program as it relates to geotechnical asset management strategies (Chapter 3). 

Chapter 4 describes how to rate unstable slopes in the field. A detailed description of each 

section of the rating form, along with its various calculations, is included in Appendix A. The 

rating forms themselves are provided in Appendix B, and can be printed out for use in the field. 

Use of the mobile applications is also described in Chapter 4, and detailed instructions on how to 

download and use the mobile applications is included in Appendix C. Chapter 0 describes 

examples on how to use and set performance measures, using the U.S. Forest Service’s road 

maintenance levels as the management framework. A detailed description of the performance 

measures concept is included in Appendix F. Chapter 6 describes how to conduct a benefit/cost 

analysis for the USMP, and includes a general description of benefit/cost approaches having

different levels of available data for rock and soil slopes (refer to Appendix D). Finally, Chapter 

7 outlines the quantitative risk analysis and how it can be used to understand and manage risk by 

your agency as it relates to an USMP. Examples describing the use of the QRA are included in 

Appendix G.
5

CHAPTER 2. STATEMENT OF WORK

Transportation corridors consisting mainly of roads and trails within our federally managed lands

contain numerous unstable and potentially unstable slopes and slope failures. A variety of

unstable slopes, including natural and constructed rock slopes, soil cut slopes and embankments,

are all subject to failures occurring as rockfall, landslides, debris flows, creep, and settlement. 

These instabilities range in severity from maintenance nuisances that generally go unnoticed by 

the traveling public, to those that can block traffic or trail usage, or to those that cause injury 

and/or property damage. Although slope failures that cause significant property loss or loss of 

life are not most common, unstable slopes along a transportation corridor are a problem for the 

agency responsible for providing and maintaining safe and efficient transportation for people and 

goods. Consistent with the Federal efforts for overall disaster preparedness and risk reduction, 

many state transportation agencies are moving towards proactive risk management strategies to 

help mitigate unstable slopes; however, there has been little information to guide FLMAs, tribes, 

and state agencies (such as state, county, cities, state parks, and metropolitan parks) with low to 

very low traffic volumes and various levels of trail usage on how to manage slopes using asset 

and performance management principles. This project was created to provide guidance to

manage geotechnical assets by developing and implementing an unstable slope management 

program (USMP) for FLMAs, tribes, and other local or state agencies with similar assets and 

infrastructure assessment needs.

BACKGROUND

Under the first phase of this project, two primary road corridors with known unstable slopes were 

identified for use in the field demonstration of the USMP. The road corridors were in the 

Gifford Pinchot National Forest (in southwest Washington State) on Forest Service Roads 25 and 

99. The primary task of this first phase included identifying stakeholders in partnering agencies, 

and providing, developing, and presenting geotechnical asset management materials to educate 

the team about unstable slope asset and performance management. Input from the stakeholders 

was used to refine the AKDOT&PF’s unstable slope rating criteria for FLMAs with very low to 

low volume roads and significant trail network usage. FLMAs also requested development of a 

brief video about development of the USMP and its value to managing slope assets and meeting 

the Moving Ahead for Progress in the 21st Century Act (MAP-21) requirements. A draft USMP 

rating form, calculations, and rating criteria definitions were produced prior to demonstrating the 

field inventory and condition survey at approximately 20 unstable slopes consisting of both soil 

and rock unstable slopes of varying condition and severity. Following the field demonstration 

with the partnering agencies (NPS, USFS, BLM, BIA, and WFL of FHWA), the standardized 

unstable slope rating forms, calculations, and rating criteria definitions were finalized and 

presented in a report that included maps of the demonstration corridors with completed rating 

forms, site photographs, and a ranked list of the unstable slopes with their slope ratings.

Inventorying and assessing the condition of unstable slopes is the first step in managing them; 

however, understanding the magnitude of the problems associated with unstable slopes requires 

more information and analysis. Successful management also includes an understanding of the 
6

costs associated with maintaining, fixing, and replacing such assets. Asset management is being 

used with increasing frequency as a means of reducing overall life-cycle costs. Geotechnical 

Asset Management (GAM) is in its infancy within most public agencies, and specifically within 

FLMAs, while assets such as pavements, bridges, and some larger culverts are usually more 

commonly inventoried and managed. Geotechnical assets (such as unstable slopes, retaining 

walls, and material sources) are typically handled using a reactive approach when a slope failure 

closes a trail or roadway. Emergency funds, often from other road and trail maintenance funds, 

are used to mitigate unstable slopes, thereby shortchanging the intended use of those funds for 

other programmed maintenance needs. GAM tools such as the USMP provide a proactive 

approach to inventorying, assessing, prioritizing, and requesting dedicated funds for mitigation 

efforts. In addition, asset management under the MAP-21 Act, and now the Fixing America’s 

Surface Transportation (FAST) Act, mandates that asset and performance management tools be 

developed and utilized to manage bridge and pavements, provide transparency to the public, and 

determine strategic infrastructure needs to most efficiently use the limited and uncertain funding 

sources for these types of preservation and safety improvement projects. Proactive management 

of ancillary assets is encouraged, with regulatory flexibility provided for agencies to enact 

customized or incrementally implemented management plans for assets such as soil and rock 

unstable slopes.

The value of asset and performance management is to base decision-making on a proactive, 

strategic approach that takes a long view of performance and cost using analytical tools to allow 

for alternative comparisons. Accurate and effective asset management is founded on a database 

of relevant information collected during routine or periodic inventories and condition 

assessments. Agency performance goals and standards are needed to evaluate the asset and to 

determine whether to abandon, repair, or replace the asset in a strategic manner.

The USMP is innovative and unique because of its application of the principles of asset and 

performance management to geotechnical assets. As part of the implementation process, the 

USMP will provide guidance on setting and validating performance goals and standards for 

unstable slope assets. This work will benefit all partnering agencies by providing them 

significant cost saving through applying asset and performance management principles for 

unstable slopes. The program will also provide policy statement examples about safety and 

service life goals for managing unstable slope assets.

One significant method of incorporating asset and performance management principles and 

meeting the MAP-21 and FAST Act forward-looking requirements is to implement an USMP in 

FLMAs. Asset management for unstable slope assets covers four general areas: 1) building an 

inventory of unstable slope assets that includes their condition, 2) establishing performance 

standards and service life criteria, 3) identifying and developing risk reduction corrective actions, 

and 4) prioritizing and taking risk reduction corrective actions.

The second phase of this project was to develop, verify, and demonstrate a database for unstable 

slopes that could be populated using a web-based electronic form or via iOS-based and Androidbased applications that function off-line and upload when back online. Data generated from 
7

USMP ratings is displayed graphically on a map to facilitate simple and quick visual 

assessments. Additional development under this phase also included creating a form to 

document new unstable slopes that occur, a maintenance form to track deterioration of unstable 

slopes to stage risk reduction work or mitigation, and a search and reporting tool that allows 

users to harvest the data and analyze it as they see fit. The quantitative risk analysis (QRA) tool 

is included in the USMP work to provide risk assessments for unstable slopes that may not have 

data in an USMP already, or it can be used to help quantify the risk associated with a given 

unstable slope as it relates to comparisons with other societal risks, such as auto accidents

fatalities, lightning strikes, or being a victim of violent crime. All accomplishments from this 

second phase are documented in this manual for users, and three free two-day seminars were

held around the U.S. to train potential users of the program. The following tasks were 

undertaken as part of the second phase of this project to develop and execute a robust and useful 

USMP for FLMAs.

RESEARCH PLAN

The tasks outlined below address the objectives of this phase (Phase II). Tasks 1, 4, 5, 6, 8 were 

led by Landslide Technology of Portland, Oregon with significant assistance from subconsultants 

DA Stanley Consulting and Paul D. Thompson. Tasks 2, 3, 7, 10, 11, 12, 13, and 14 were led

by the Western Transportation Institute (WTI) and the Computer Science department at Montana 

State University in Bozeman, Montana. Tasks 9 and 15 had shared responsibility between

Landslide Technology, Inc. and WTI. This phase of research was coordinated by WTI through a 

contract with WFLHD.

Task 1 – Develop Examples of Performance Measures

Task 1 was to develop performance measures for the USMP based on the system used by the 

United States Forest Service (USFS), which manages its roadway system by utilizing five 

distinct Maintenance Levels, each with their own usage goals and objectives (refer to Chapter 5). 

Performance Measures were divided into two general categories, Condition Performance 

Measures and Management Performance Measures. The Performance measurements based on 

condition followed and expanded upon examples outlined in an FHWA Office of Transportation 

Performance Management fact sheet describing a Notice of Proposed Rulemaking (NPRM) for 

pavements and bridges (Federal Highway Administration, 2015). Performance measures based 

on management are intended to track how well the Agency is proactively managing and 

improving their unstable slope assets over time using data obtained during the slope rating 

procedures, and tracking of maintenance records for road-closing unstable slope events, as well 

as mitigation and risk reduction projects.

Task 2 – Database Development

Task 2 was to develop a searchable database based on open-source technologies (such as

Postgres and MySQL) that is appropriate for USMP management needs. The database accepts 

input from field ratings and measurement using web forms, or direct input through an application 

programming interface (API). The database is integrated with the GIS-based platform developed 
8

in Task 3, described below. Stored data is available to future applications of USMP data through 

read-only SQL queries (Task 10). Complementary mobile device applications, based on Android

and iOS platforms, were developed for field use as part of Task 13 to expedite data gathering, 

uploading, and saving in the database.

Task 3 – GIS Platform Development

Task 3 was to develop a map-based GIS platform that presents the information from the USMP 

database. It provides users with a graphical method for data query and content creation. Stored 

USMP data can be displayed on an interactive map through interactive, color-coded icons and 

callouts. Content creation is supported through web forms available to field operators, or 

through an API. The web forms also support uploading of scanned documents and photographs 

to be associated with the rated unstable slopes.

Task 4 – Input Phase I Unstable Slope Inventory Data

Task 4 was to test the USMP database with the map-based GIS platform using the Phase I

unstable slope inventory condition information and the US Forest Service’s preliminary service 

life estimates for slopes, and to set performance standards based on service life (based on Task 1) 

to determine what slopes are identified for possible risk reduction corrective action. Ten slopes 

were prioritized for conceptual design and cost estimating in the field.

Task 5 – Site Visits

Task 5 was to rate ten additional unstable slopes in the field within the demonstration corridor to 

test the field data collection and GIS-based platform developed under Task 2 and 3, and to 

further test the USMP database and the map-based GIS platform. The 10 unstable slopes used to 

assess conceptual design alternatives and cost estimating were used to develop the benefit-cost 

alternatives under Task 6.

Task 6 – Cost-Benefit Formulation

Task 6 was to write a summary document to synthesize a series of alternative approaches for 

benefit/cost prioritization of slope preservation, mitigation, and reconstruction. The alternative 

approaches focused on differing levels of available agency data to feed the benefit cost 

formulations. All the approaches were based on widely-accepted principles of risk management 

and asset management, with varying levels of data requirements. The approaches are meant to 

provide an objective and consistent means of summarizing the degree to which each project may 

contribute to agency objectives while minimizing long-term cost and risk. An accompanying 

spreadsheet program was included to provide the necessary benefit factors for use in the 

formulas, and to demonstrate their use.

Task 7 – Database and GIS Map Integration

Task 7 was to create a single platform to deliver a fully functional open source database, web 

form, and map-based GIS platform based on the work accomplished in Tasks 2 and 3. The 
9

database and GIS-based map will be available for use on desktop computers, iOS, and Android 

applications (Task 13).

Task 8 – Development of Field Manuals

Task 8 was to produce a brief and simple manual to outline the procedure for planning and rating 

unstable slopes and to describe the use of the database and associated map-based GIS platform.

Task 9 – Produce a Training Video on How to Rate Unstable Slopes

Task 9 was to produce a video training tool to aid deployment of the USMP to FLMAs. The 

training tool focuses on planning field work and rating unstable slopes.

Task 10 – Develop a Searching and Reporting Tool for the USMP Database

Task 10 was to develop a front-end web form to allow searching the contents of the USMP 

database by multiple categories and allow refined searches in at least three sub-categories. 

Reporting of the tabular data resulting from the searches can be presented in a spreadsheet-type 

format containing the categories and search ranges used for the search criteria and the resulting 

data. The “search and report” web form is linked to the USMP web-based GIS platform 

developed in Task 7 to illustrate the results of the search criteria geographically.

Task 11 – Maintenance Tracking Form

Task 11 was to develop a web form that can be used in the field by maintenance crews (even in 

the absence of an internet connection). Off-line data can be automatically downloaded into the 

USMP database upon reconnecting to the internet. This tracking form was intended to be used 

for normal, scheduled maintenance activities associated with known unstable slopes. The form 

can be used to capture the level of effort and associated costs required to maintain the roadway 

or trail, re-open the road or trail, or preserve the integrity of the roadway through specialized 

maintenance projects.

Task 12 – New Slope Event Form

Task 12 was to develop a web form that can be used in the field by FLMA personnel (even in the 

absence of an internet connection). Off-line data can be automatically downloaded into the 

USMP database upon reconnecting to the internet. This form is intended for new unstable slopes 

not already in the USMP inventory. In the future, an email function could be added to this form 

to automatically alert designated FLMA agency officials to trigger a possible field visit and/or 

full unstable slope rating when information from a new unstable slope form is added to the 

USMP database.

Task 13 – iOS and Android Application Development

Task 13 was to develop iOS-based and Android-based applications as supplemental alternatives 

to the PC platform developed as part of Tasks 2, 3, 7, 10, 11 and 12 described above. 
10

Application platform choices will encourage more usage by FLMA agency users and are less 

costly for FLMAs to implement.

Task 14 – Develop Quantitative Risk Analysis Module

Task 14 was to develop a Quantitative Risk Analysis (QRA) module as a graphical user interface 

implementation of the four factor QRA equation used by NPS-GRD. Probability factors and 

items affecting probability factors such as rock size and number of boulders for rockfall, speed of 

traversing the hazard area, and stopping distance required to avoid the hazard were used to 

generate an annual or daily individual risk of death or injury. Risk probability could then be 

compared with other societal risks in an output comparison graph. Risk of death or injury 

occurrence and societal costs could also be estimated through input of the number of people 

exposed to the risk and an implementation of the U.S. Department of Transportation’s 

(USDOT’s) Value of Statistical Life guidance.

Task 15 –USMP Technology Deployment and Training Course

Task 15 was to develop and deliver up to four two-day training courses across the United States 

to educate potential users how to use the USMP rating tools and associated software. This 

training helped facilitate implementation of the USMP for FLMAs. Training consisted of oneday of office level instruction and one-day of field training. Students learned how to prepare for 

rating slopes, input data into the various web forms, interact between the USMP database and 

map-based GIS platform, and download the collected field data from the software applications 

when returning to the office.

Task 16 – Present USMP to FHWA Performance Management Team and FLMA 

Leadership

Task 16 was to present the USMP to the FHWA Performance Management Team and the FLMA 

Performance Management Leadership Team. This helped inform upper management of the 

unstable slope management program and its potential benefits to many FLMAs.

Task 17 – Provide Marketing Materials for Technology Deployment and Training Courses

Task 17 was to develop an electronic brochure describing the benefits of unstable slope asset 

management available through the free training course offered as part of Task 15. The brochure 

described how the training course will prepare an attendee to collect and manage data collection 

and analysis in the USMP database and GIS map-based platform. The electronic brochure 

targeted FLMA personnel, road managers, trail managers, Federal geotechnical consultants, 

municipalities, counties or metro parks personnel, and consultants.

The value of asset and performance management is utilizing a proactive, strategic approach to 

make decisions that take a long view of performance and cost, and are based on accurate 

information using analytical tools to allow for alternative comparisons. Asset and performance 

management is founded on accurate data in asset inventories and condition assessments. 

Agencies employing this system can set performance standards to determine the optimal 
11

approach once the service life of the asset is understood. This work will benefit all partnering 

agencies by providing them significant cost savings through applying asset management 

principles for geotechnical assets. It can also result in providing policy statements about safety 

and service-life goals for managing geotechnical assets, such as unstable slopes.

The third phase of this project, which is currently unfunded, entails providing a stable, long-term 

information technology environment for the USMP database. This includes the following 

proposed Information Technology (IT) solutions:

• Locating a cost-effective location(s) to house the USMP data for all FMLAs (for 

example, with the Roadside Inventory Program (RIP), Guardwall Inventory Program 

(GIP), and Wall Inventory Program (WIP) databases located and managed by Eastern 

Federal Lands and Headquarters of FHWA; or at each participating agency).

• Updating the operation and maintenance of the database and web-based map platform to 

ensure the platform is stable and functional.

• Establishing data quality control and assurance to ensure database integrity.

• Performing database cleanup and IT projects to ensure compatibility and connectivity 

with other FMLA corporate databases.

• Ensuring data are available in a timely fashion to provide more transparent decision 

making that translates to more effective and efficient management of FLMA roads and 

trail networks.

Overall, the third phase of the project seeks to provide longevity for this USMP asset and 

performance management program decision support tool by performing regular maintenance and 

providing operational support from IT staff so that the data remains available, error-free, and 

centralized for continued use by FLMA personnel.
12

CHAPTER 3. UNSTABLE SLOPE MANAGEMENT PROGRAM FOR FLMAS

Federal Land Management Agencies (FLMA) are taking part in the national and international 

trend toward better management of public assets through the concepts of Transportation Asset 

Management (TAM). It is commonly understood that transportation infrastructure is aging faster 

than national, state and local governments can manage with traditional methods. TAM is a 

strategic and systematic process of maintaining and managing infrastructure assets throughout 

their life cycle, focusing on business and engineering practices for resource allocation and 

utilization. It uses data and analysis to improve decision making, with the objective of providing 

the required level of service in the most cost effective manner (Gordon, et al., 2011). Simply 

put, TAM and associated system management programs provide a better than traditional means 

for designing, building, operating, maintaining and replacing transportation works.

Most transportation agencies have generally reacted to geotechnical problems as they arose, 

whether the issue was a landslide, a failed embankment or road closures due to rockfall events. 

Recently, however, there has been a move toward applying asset management principles and 

processes to geotechnical assets. More recently, a greater understanding of and an appreciation 

for the role these “dirt” assets in transportation systems, and Geotechnical Asset Management 

(GAM) is increasingly recognized as an integral part of transportation asset management.

FLMAs, through the Federal Highway Administration’s WFL office, have undertaken a research 

and development project to explore use of GAM principles in developing an unstable slope 

management program tailored to the needs of FLMA transportation systems. The USMP project 

is broadly discussed in the preceding chapters. This chapter summarizes the major components 

of the USMP, and outlines the steps taken to develop and implement it.

GEOTECHNICAL ASSET MANAGEMENT

Transportation agencies spend a significant portion of their funds on geotechnical assets, the 

value of which may be on a par with or exceed the value of the agency’s “primary assets,” which 

are usually considered to be pavement and bridges. For instance, the combined replacement 

value for Alaska’s inventoried geotechnical assets (retaining walls, rock slopes, unstable soil 

slopes) was three times the replacement cost of the state’s bridge assets (Thompson, et al., 2016). 

By applying the same types of systems management techniques to geotechnical assets as are 

applied to bridges and pavement, FLMAs can reasonably expect improvements in condition and 

performance of geotechnical transportation assets along with reductions in life cycle costs.

Geotechnical assets are generally different from bridges and other “bricks and mortar” 

transportation assets. Some geotechnical assets, such as retaining walls, may be managed in very 

similar means. However, other geotechnical assets, like embankments and constructed soil 

slopes, are very different in character because they are built of non-homogeneous materials such 

as soil and rock, or constructed of combinations of soil, rock, geotextiles and more traditional 

steel and concrete. The taxonomy of geotechnical assets is not yet settled, but the concepts have 

recently been proposed (Anderson, et al., 2016). 
13

As geotechnical assets deteriorate during their life cycle, most transportation agencies resort to a 

short term “worst-first” approach in determining when or whether to ignore, repair, rehabilitate, 

or replace the asset. For example, rockfall inventory programs in many states rank rockfall sites 

so that the most dangerous in the transportation system receives attention first. However, 

expending limited funds on worst-first short-term problem fixes(Pierson & Van Vickle, 1993)

results in steadily declining conditions for transportation systems. This result is inevitable since 

agencies do not have the resources to address all problems. Ignoring most assets to fix only 

those in the worst condition means missing opportunities to make lower cost repairs that extend 

the life of assets, which is not cost-effective (Sanford Bernhardt, et al., 2003). Asset 

management facilitates spending to gain the most long-term, positive effects to get the most 

“bang for the buck.”

DEFINING GEOTECHNICAL ASSETS

The literature of Geotechnical Asset Management offers significant guidance on which assets are 

considered geotechnical assets. The earliest publications on GAM in the U.S. are from the early 

2000s. About ten years later, GAM development took a leap forward, and there are now 

numerous publications, webinars, conference presentations, and related resources that address 

program development. Many of these documents address the issue of what assets should be 

included in a GAM program.

More recently, the emphasis in development has changed to looking forward and determining 

how to implement these programs. With that change has come a need to understand what assets 

should be included in GAM programs, how they are characterized, and how relevant terminology 

should be defined. Where possible, GAM practitioners will use the same terminology already in 

use in transportation asset management (Anderson, et al., 2016; Sanford Bernhardt, et al., 2003; 

Vessely, 2013).

Below is a list of geotechnical assets that could be managed using GAM principles. Only a 

handful of these would be expected to apply to the FLMA USMP and no program is likely to 

manage all or even most of the assets listed here. However, it may be useful to FLMAs to look 

ahead to more mature GAM/TAM programs that could include the assets included in the list 

below (Anderson, et al., 2016; Sanford Bernhardt, et al., 2003):

• Rock slopes.

• Rockfall mitigation elements including barriers, wire and cable mesh, rock bolts, and 

anchors, as separate, independent assets.

• Embankments and constructed cut slopes.

• Landslides and rockfall sites.

• Earth retaining structures/retaining walls (retaining walls, reinforced soil slopes, and 

earth and rock buttresses).

• Culverts and drainage channels.

• Horizontal drains.
14

• Pavement subgrade.

• Foundations.

• Buried structural components.

• Bridge foundations.

• Tunnels.

• Materials sites (borrow, pit, and quarry sites).

• Subgrade and land within right-of-way.

• Buried reinforcing elements, rock bolts, tieback anchors, and other buried structural 

elements.

• Instruments: slope indicators, piezometers and standpipes, and thermistors.

• Geotechnical data (slope movement survey data, lab testing, temperature data, slope 

indicator data).

STEPS TO MANAGING UNSTABLE SLOPES 

There are many state transportation agencies in the U.S. that have some form of management 

system for unstable slopes. Most of these programs have inventory and rating systems, but have 

not taken steps to integrate slope programs with the broader transportation asset management or 

performance management programs. A few agencies have taken steps to address unstable slopes 

from the standpoint of risk management.

The steps required to initiate and maintain an unstable slope management program for FLMAs

will vary from agency to agency because there can be considerable differences in the asset mix

and goals and objectives between, for example, the USFS and the NPS. USFS has a high 

proportion of roads versus managed acreage to provide access to timber cutting areas. These 

roads may receive heavy use for a few years, and then be placed in “storage” for perhaps 

decades, until another timber cutting area is opened along the route. USFS has other low service 

roads that are not maintained for standard vehicle travel. NPS has numerous roads in national 

parks that generally are kept open continuously to allow public access; however, the road miles

crossing NPS land are limited in comparison to those crossing USFS lands in order to preserve 

the condition and character of the landscape.

The same road-closing unstable slope event might have a low impact on USFS forest lands, but a 

major impact on national park land. Thus, the strategies are different between agencies for 

maintaining slopes or other geotechnical assets that can potentially close a corridor. 

Performance measures to set targets for agencies to keep roads open will be different. Another 

similar issue arises in developing management techniques for low volume, low speed roads or 

trails versus high speed, high volume roads. There will be much less urgency for remediation of 

failed slopes for low volume roads or trails than for major arteries crossing public lands.

At the time of the creation of this manual there were no standardized Federal guidelines for 

implementing a comprehensive GAM program, though the transportation departments of Alaska 

and Montana are well on their way to developing their own programs for various geotechnical 
15

assets. However, there is no widely accepted set of steps to develop, execute and maintain a 

GAM program. GAM researchers generally agree that the steps should mirror the accepted steps 

for the transportation asset management process, adapted as needed for the differences in the 

asset types. The AKDOT&PF program has illustrated the GAM process as shown in Figure 1.

©2016 Thompson

Figure 1. GAM Process (Thompson, 2016)

This comprehensive process ensures that AKDOT&PF will continuously measure the 

performance of its geotechnical assets, and that its investments are cost-effective in improving 

performance. The figure shows there is a clear relationship between decision-making for 

geotechnical assets and agency objectives. The process includes consideration of alternatives 

based on benefit/cost calculations and feeds data to short-term and long-term planning to support 

budget allocations. A somewhat simpler, though consistent, roadmap for the FLMA USMP 

programs is proposed in Figure 2. The FLMA process, with its focus on slopes, need not address 

a variety of dissimilar assets, but must be flexible enough to account for inter-agency differences 

in asset types, performance goals, objectives, and policies, as discussed above.

The FLMA roadmap is general, as it must be to address the needs of several agencies. However, 

it leads to the specific steps necessary to execute a GAM-based USMP program, to create 

performance measures consistent with agency goals and objectives, and to conduct the economic 

analysis each agency needs to support decision-making for the agency.

With these basics in mind, what are the steps in creating performance measures and metrics? An 

axiom for transportation asset management is that performance measures must be “S-M-A-R-T” 

(specific, measurable, achievable, relevant and time bound) (Cambridge Systematics, 2002). In 

setting performance measures for FLMAs, these factors must be considered for each measure or 

key performance indicator.

Goals and policies

Asset inventory

Condition assessment and performance modeling

Alternatives evaluation and program optimization

Short and long-range plans, programs, and targets

Program implementation

Performance monitoring and feedback

Budget, resource 

allocation

Forecasting

models
16

Figure 2: FLMA GAM Process Roadmap

Step 1 – Identify applicable high-level agency performance goals and objectives. Begin with 

an outlined GAM Plan that includes reference to documents that set out agency performance 

measures that address transportation assets and corridors, and especially maintenance and 

operations metrics. Performance measures proposed here may take advantage of metrics that do 

not expressly address slopes but address similar assets, and management concepts that will fit 

slopes. As noted above, review of agency documents shows agency will likely have very 

complete high-level goals, objectives, and policies, which will apply to the USMP. Many of the 

agencies may have specific performance measures already in place to address slope issues. It is 

expected that adaptation of existing performance measures and development of new performance 

measures will be needed to meet the needs of the FLMAs. Agency staff will be best positioned 

to develop performance measures that both reflect high level agency goals, objectives and 

policies and the lower level needs of agency sections and subsections to effectively manage the 

asset for which they have responsibility.

Step 2 – Identify agency-specific programmatic guidance. Examples include the 

“Maintenance Level” scheme of the USFS and the “Maintenance Intensities” system of the 

Bureau of Land Management (BLM). Select the key candidate goals and objectives guidance 

that apply most directly to slope management. Review the results and select a small group of 

key asset characteristics or features that, taken together, will best represent both the condition of 

the slope assets and the efficacy of management activities that apply to the slopes. Examples: 

USFS examples (see Chapter 5 [Setting Agency Specific Performance Goals] for additional

detail):

• Slope condition ratings

• Road closure extent and frequency

• Average time to clear incident and reopen road

Potential BLM Performance Measures:

, QRA
17

• System-wide (or region- or state-wide) aggregated slope condition ratings

• Number of lane-miles of roads with slopes in fair or better condition

• Condition of slopes at recreation sites

• Condition of unstable slopes adjacent to high-traffic trails and facilities

Make connection with management and especially planning groups to determine what 

information they need to incorporate knowledge of condition and performance of slopes and that 

will be useful for managing the agency’s performance.

Step 3 – Conduct desk-based inventory/survey of slope assets. Documents and information 

may be found in agency design and construction records, maintenance and operations records, 

and using Google Earth, Google Street View, and aerial photography, among other sources. 

Prioritize slopes, road segments, corridors and other geographical units following agency 

policies and directives (e.g. lumping together similar maintenance level or use roads and trails as 

a first cut).

Step 4 – Initiate development of database to collect inventory and condition-rating data 

and information. Initiate development of GIS-based mapping scheme to communicate 

performance measures and condition rating data and information. Conduct development with 

full cooperation of IT staff to avoid later problems and conflicts with software, hardware and 

applications for data collection that may be incompatible with the agency computing system. 

Plan data collection and display in consultation with management, maintenance, and operations 

sections and especially planning groups to affirm the utility of the USMP as a decision-support 

tool. This USMP program includes the database scheme for agency adoption on multiple 

platforms.

Step 5 – Conduct field inventory and survey following priorities set in Step 3. Extensive 

inventories may require multiple years to collect and catalogue sites to the practical limit. 

Following a priority scheme will likely require overlap in inventory and condition rating 

activities. Provide flexibility in the program to conduct both tasks simultaneously to limit field 

work in low priority geographic areas. Load inventory data into the database and maps. This 

step may be combined with Step 6, below.

Step 6 – Conduct condition ratings for slopes following priority scheme. Utilize newly 

developed inventory with portable devices and application software to simplify and expedite 

field work. Expect detailed ratings of extensive portfolio of assets and large geographic areas to 

take multiple years (such as an entire agency or region). Geographically-limited condition 

assessments, such as at a single Park in the NPS system, may take only one season.

Step 7 – Analyze initial condition ratings and assess utility of system. Based upon an early 

initial period, assess the condition rating program. Consider ease of use, sufficiency of hardware 

and apps for the collection process, completeness and quality of collected data, ability to collect 

data in a timely manner sufficient to complete ratings to meet goals and objectives for the 

agency’s USMP, and any other agency-specific factors. Determine if changes to the data 
18

collection program are warranted and make the changes. Determine if changes are needed to the 

database and interfaces and make those changes.

Step 8 – Continue condition ratings with reassessed database system, hardware and 

applications, and mapping software. Continue data collection until first round of data for all 

prioritized assets are complete. Repeat condition ratings at regular intervals. Conduct condition 

ratings as needed to meet requirements of adverse unstable slope events. Load data as it is 

collected into the database. Recent statewide geotechnical asset management programs in 

Alaska and Montana have recommended 5-year rating intervals (Beckstrand et al., 2017a; 

Beckstrand et al., 2017b). Extreme weather events may also trigger emergency assessments on 

an as needed basis to help prioritize response activities. Each FLMA will need to weigh its 

policies, goals, business practices, corridor importance, and other factors in setting its re-rate 

interval.

Step 9 – Track performance trends over time, assess performance results, re-assess USMP

for needed changes to process. Assess the change trends in performance, based upon the 

measures and indicators developed earlier. Communicate with management, maintenance and 

operations and planning units to determine their “customer” view of the program. Make changes 

to the program to improve utility to users. Changes may include revisions to rating system to 

change which attributes are rated; agency may find some are not useful and that new attributes 

may be needed. Note that changes to the forms and database fields may impact the ability to 

share maintenance and IT support through a multi-agency (IT) maintenance agreement. Other 

changes may include priority for asset ratings, changes to database, map format and content, and 

webpage and other communication methods, or changes to frequency of rating events. 

Coordinate with economic analysts to determine whether the decision-support aspects of the 

USMP have utility for the overall program.

Step 10 – Communicate the Results. Consider various means to communicate the results of the 

condition rating and performance monitoring both internally to management, maintenance and 

operations and planning, and externally through annual reports, performance dashboards and online project stories, social media and other means. Tailor your message to stakeholders, the 

public, legislators and funding groups, and other key audiences.(NCHRP, 2009).

Performance Goals and Objectives

Performance Management is a means for transportation agencies to measure progress toward a 

goal. Performance measures are indicators of work performed and results achieved(NCHRP, 

2006). Performance Management is an integral part of Transportation Asset Management 

programs and is used by transportation agencies to measure progress toward Federal, State, and 

agency goals and objectives, often set in legislation or acts.

For FLMAs, the statutes and agency goals and objectives supporting USMPs may include broad 

goals of safety, infrastructure condition, congestion reduction, and system reliability resilience,

as well as agency-specific goals depending on the types of assets concerned and the difference 
19

between agencies(Landslide Technology, 2015). Guidance on these goals and objectives may be 

found in a variety of agency long-range transportation plans or other asset management plans. 

These goals, objectives, and policies provide the basis for appropriate investment decisions based 

in part on system performance and condition. Chapter 5 in this report describes examples on 

how to use and set performance measures, using the U.S. Forest Service’s road maintenance 

levels as the management framework.

Performance measures are the quantitative indicators of the service provided by the agency’s 

transportation system to the user.(Gordon, et al., 2011). The performance measures (and more 

specific key performance indicators) range from high level generalized agency-wide aspirational 

“management” goals to asset-specific “condition” goals. Examples of the former could include 

reducing the number of traffic fatalities and reducing cost of maintenance or reducing the 

number of structurally deficient bridges as measured by deck area. Condition goals could 

include improving the condition of rock slopes on a specific road corridor from poor to fair as 

expressed in percent of slopes reaching a specific level in a condition-rating scheme.

For FLMA USMP, “management” performance measures track how well the agency is 

managing and improving its unstable slopes over time. Using data from slope rating and 

maintenance activities, an agency can track the expected decrease of repairs, road closures, etc. 

over time. Agencies should expect that many years can pass before observing a marked decrease 

in maintenance and other costs and a related increase in system resiliency and performance 

improvements. 

The performance measures and monitoring provide a method to develop an optimal investment 

plan and measure progress in moving toward strategic system goals. Agency adherence to 

performance measures derived from goals, objectives and policies lead to improved 

performance, reduced cost, improved safety, and other benefits.

Corridor Selection

Developing and implementing a USMP program within an agency does not necessarily begin 

with a comprehensive, system-wide inventory and condition assessment. The program’s initial 

goals and focus may concentrate on certain corridors or management areas that have particular 

significance to the FLMA. These corridor selection criteria can focus on factors such as existing 

road classifications, mobility and safety risk factors, roadway modernization corridors, or other 

economic factors.

Existing Road Classification

Many FLMAs and DOTs currently subdivide their road systems with unique classifications, 

typically based on their intended function. The Forest Service utilizes a Maintenance Level scale 

subdivided into five levels(US Forest Service, 2009). State highway departments typically have

two systems, a Functional Classification (Interstates, Primary or Secondary Arterial, Local 

Routes, etc.) and a Highway System Designation (National Highway Systems, State Highway 

System, etc.). FLMAs can use the existing classifications, which have already been designed to 
20

fit with the agencies’ goals and objectives. For instance, the Forest Service may opt to first 

inventory slopes on a road classified as Maintenance Level 5, its highest expectation of 

performance. State highway systems may opt to inventory Interstate and Primary Arterials on 

the National Highway System as the first set.

Mobility and Safety Risk Factors

These risk factors can be primarily tied to the frequency that people are susceptible to the hazard 

posed by the slope, which is roughly equivalent to average annual daily traffic. If the FLMA 

tracks traffic volumes, a cut off volume can be established where corridors above the determined 

volume are assessed and those below are deferred. Existing policies of the FLMA or percentile 

volumes (e.g. 75% of network volume is carried on 10% of the road network) offer a reasonable 

basis to develop cut off volumes.

Mobility and safety risks resulting from slope failures will be present where unstable slopes 

exist. Even though the FLMA has not carried out a comprehensive assessment at this early 

stage, experienced maintenance and geotechnical personnel are still likely to have a good mental 

map of where these issues exist. This experiential-based assessment of “known” unstable slopes 

can serve as a good ‘common-sense’ starting point for a focused inventory and condition 

assessment.

Mobility risk factors are also tied to the availability of alternate routes in the event of a road 

closure. The presence of a short detour (for example, less than 15 minutes added to travel time) 

will reduce mobility risk factors, while long detours or routes where detours are not available 

will increase risk costs. The FLMA can analyze or judge its road network for locations where 

these routes may exist.

Roadway Improvement Corridors

Roadway projects focused on improving safety and roadway geometry take years to develop and 

design. It is critical to provide geotechnical input in the early stages of these major improvement 

projects. For example, it is useful to focus inventory and condition evaluations in these study

corridors so proper environmental clearances can be obtained early in the process. This action

will permit improvement of the poorly performing assets where additional right-of-way or 

impact areas can be identified and addressed. Slope evaluations will provide credibility that they 

pose a risk to the FLMA and public and warrant inclusion in the project, just as corridor 

improvement projects often correct known bridge defects. Another advantage is to prioritize the 

highly rated unstable slopes and conduct a cost/benefit analysis and/or QRA to support selection 

of some unstable slopes for risk reduction in a given improvement corridor when funding levels 

are not available for immediate implementation but a plan for future investment is needed for 

proactive funding requests and managing the unstable slope assets.

Inventory/Desk Study

A well-planned and executed desk inventory or desk study helps the FLMA focus resources and 

saves time in the field. The desk study should focus on a particular asset type (such as retaining 
21

walls or unstable slopes); cover previously selected regions, routes, or corridors; and work 

towards compiling all available data on the chosen geotechnical asset type in the area. 

The information used in the desk study comes from a variety of sources. This includes available 

as-built information, road- or trail-view data (either internally maintained by the department or 

accessible through Google Street View or similar), intelligent mining of maintenance cost 

records or other data sets that reflect events, and, if possible, surveys of relevant maintenance 

personnel to locate maintenance “hot spots,” and reviewing environmental, cultural, and right-ofway maps with the appropriate specialists to locate potential habitat, cultural, or adjacent 

property owner concerns in the transportation corridors that will be rated.

Final products of the desk study should include, at a minimum, a summary of what is known 

about current assets and a geo-database with initial asset location information. The data 

summary for the desk study assets will probably include information that cannot be obtained in 

the field, such as year of asset construction. During desk study design and work, bear in mind 

that the final dataset should be easily appended to the field assessment data, so that all asset data 

is ultimately located in a single file. This makes relevant data easy to find, and prevents 

accidental loss of data when the final asset data set is transferred within the agency or shared 

with other agencies.

Field Assessments

Although a desk study provides valuable information, the core of an unstable slope management 

program is the field assessments. The work done in the field is used to verify the desk study, and 

is then incorporated into the performance measures used by agencies to manage their assets. 

Typical information collected in the field includes asset location, linear extents, and ratings over 

a variety of risk and hazard categories. Some of these hazard categories may be specific to a 

given failure type, while others may be general and applied to both rock and soil slopes.

The USMP field rating system is best utilized by engineering geologists and geotechnical 

engineers, but this system has been designed to be utilized by physical science educated 

personnel with a wide range of experience levels and should return total scores generally within 

a 10-20% range of each other. FLMAs may opt to utilize temporary positions staffed by 

geologic or engineering interns to populate the initial database for economic and/or educational 

purposes under the responsible charge of experienced geotechnical personnel for accuracy and 

reasonableness. If an unstable slope event causes injury and litigation follows, some of the legal 

benefits may not be realized if the work is not checked and verified by experienced geotechnical 

staff. Using ‘cutoff’ scores and the preliminary score ranges can serve as useful indicators for 

review by more experienced personnel. See Chapter 4 (Personnel to Perform Ratings) for 

additional discussion of personnel performing the ratings.

In the initial phase of USMP development, field assessments may require multiple weeks of 

work in a single season. In an established USMP program, field assessments should be 

conducted on a regular schedule, for example, every three to five years, to help capture corridor 

condition changes. Within an established program, additional ratings could be conducted on an 
22

ad hoc basis to capture site-specific changes resulting from asset deterioration or risk reduction 

mitigation work, or new failures as a result of a significant event, such as an earthquake or 

prolonged storm event.

Field assessment work should be planned and personnel trained in conducting field ratings prior 

to going out to the field. Once in the field, inventory and rating data should be collected as 

comprehensively as possible. At every site, the rater should be able to conduct an initial rating 

with initial scores for all relevant categories, even if these initial scores are revised based on later 

interviews with maintenance personnel. The ratings and information should be incorporated into 

the existing desk study, and shared within the agency through a geospatially referenced file and 

dataset. These datasets can be mined for the data required to determine the performance 

measures used to guide programmatic-level planning and budgeting.

The slope ratings can be carried out prior to or following the commencement and collection of 

new slope events and maintenance tracking activities. There is a benefit in implementing these 

two tracking activities for a year or two to begin collecting uniform history information for 

informing the relevant slope rating categories, such as rockfall history. Once the slope ratings 

commence and site IDs are created, the slope events and maintenance tracking forms can be 

linked to the unique site IDs for assigning specific events and activities to each feature (similar to 

bridge numbers) for asset tracking and improved cost estimation.

Once the scope of asset inventorying and condition assessment is determined following the 

guidelines above, Chapter 4 provides thorough guidelines for setting up, preparing, and 

conducting the ratings. The rating category descriptions are listed in Appendix A and the rating 

forms are contained in Appendix B. Appendix C provides instructions on utilizing the digital 

forms on a desktop computer’s web browser or using iOS or Android mobile devices.

Tracking Performance-Related Events 

Performance management systems for geotechnical assets require data to operate. Some of the 

data needed for the FLMA USMP have been collected in the past by the respective FLMA 

agencies and are stored in databases and paper archives. New data on present condition, and 

future data to support the USMP process, will be derived from three types of occurrences: 1) 

initial inventory and condition surveys, and tracking forms for 2) “geotechnical events” and, 3) 

“maintenance events.” The initial inventory and condition surveys have their own standardized 

procedures and forms for FLMA agencies discussed elsewhere in this report. 

For purposes of the tracking forms, a “geotechnical event” is typically considered a process 

resulting in a slope failure that is not the result of close proximity, in time or distance, 

construction or maintenance activities. This type of event represents an opportunity to collect 

data about the effect of these processes affecting slope assets and the current condition of an 

agency’s geotechnical assets. A “maintenance event” is an activity initiated by an agency, either 

planned and scheduled or arising because of a situation or condition that requires an unplanned 

response. The maintenance event provides a chance to collect detailed data about the 

performance of a slope asset and costs of operating and maintaining a slope. Both types of 
23

events give rise to data useful for performance management programs when it is readily available 

in an agency database. 

The objective of using forms and standardized procedures for recording data about geotechnical 

events and maintenance activities is to ensure success in collecting and analyzing complete and 

accurate data sets so the information is most useful in supporting decision-making processes for 

agencies. The location, occurrence dates, and severity of events will help agencies pinpoint 

areas of concern. The area of concern may be a specific site that has a high risk to users or it 

may be a broader area that is causing higher than expected maintenance costs. Also, the data 

from tracking maintenance costs is the basis for computing the life cycle cost of slope assets over 

time. The collected condition data can be analyzed to determine trends in the deterioration rate 

of slopes and appurtenances such as rockfall barriers, in order to make the best decisions about 

priority setting and resource allocation for maintenance, repair and eventual reconstruction 

and/or road realignment of slope assets. Collection of data over time about these events provides 

a baseline of data about size and cause of events, condition of slopes, frequency of occurrence,

and other factors that can be utilized to make forecasts about future condition, cost to maintain 

and repair, and other planning needs. The ability to forecast future costs and conditions will be a 

significant aid to agency decision-making about priority setting and resource allocation.

Tracking New Geotechnical Events

Geotechnical events are recorded in the “New Slope Event” form. A geotechnical event is an

event such as a landslide or a rockfall that may range in severity from a nuisance (such as filling 

a ditch with soil, rock or other debris, but leaving roadway or trail open) to a catastrophic failure 

that closes a road or trail for a lengthy period before the damage can be repaired and the hazard 

mitigated. The event may be triggered solely from natural processes such as a heavy rainfall 

event or earthquake. These events may also be caused in part by human activity such as creating 

over-steepened cut slopes, construction activity altering drainage patterns, or simply the presence 

of the roadway embankment loading a marginally stable landslide. Whatever the source, these 

events are the primary target of the FLMA USMP. The collective FLMA agencies have goals to 

reduce risk, reduce cost and improve performance of their transportation systems. For the 

USMP, this means identifying slopes, analyzing their physical characteristics, and assessing 

slope life cycle cost and other economic factors (both benefits and costs), followed by planning 

maintenance, repair and replacement activities, all based on data collected for geotechnical 

events and for maintenance activities. The data are needed by agencies to achieve a transparent 

decision support tool for the decision-making process for maintenance, repair and replacement of 

slope assets. 

The “New Slope Event” form was developed to provide guidance for data collection methods 

and procedures, along with data collection forms for this project. This form can be used to 

collect data about geotechnical events including rockfall, landslides, and snow avalanches. It

provides for a slope identification tag, location information (both GIS identifiers and a point on a 

GIS map), route ID, type of event, and photographs. The form then provides check boxes for 

specific information on size and volume, description of the event, possible causes, and injuries or 
24

damage from the event. Data from the forms are intended to be promptly uploaded to the 

agency’s database – either in the field at the time of collection through an internet connection or 

from a desktop computer once the recorder/observer has returned from the field. Android and 

iOS applications facilitate data collection and storage. Management, geotechnical staff and 

planning staff will then have up-to-date data and information about agency-managed slopes. If 

preferred, a paper version of the form is contained in Appendix B.

Tracking Maintenance Activities

As noted above, the performance management system for the FLMA USMP requires data to 

support decision-making. Maintenance data are a key part of the data that supports decisions 

about maintaining, repairing and, eventually, reducing the risk or mitigating the risk of unstable 

slopes. Often, transportation field personnel across the country record data by hand to diaries or 

journals, including the types of problems, location, crew hours and equipment hours needed to 

address issues. These records are not always complete and generally do not yield the kind of 

data needed for thorough support of a USMP. Sometimes these handwritten records are 

transcribed and entered into a Maintenance Management System (MMS), but not always. 

Additionally, the records are rarely detailed enough to provide much of the information needed 

to support analysis for performance management. Typical transportation agencies collect little 

direct data about slope assets. Some MMS databases have one or two job activity codes that 

relate to rockfall or slope stability problems, but the personnel often collect several different 

kinds of activity under one code, making it difficult to separate out specific actions. For 

example, maintenance forces may record hours for “clearing debris from the road” that includes 

hauling away rocks that fell from a slope, trees that fell on the road, animal carcasses, and 

garbage. Much of this data is useless in terms of managing performance for slopes. Where 

existing MMSs are in place, they can be revised to include more specific codes to effectively 

characterize maintenance costs.

A better means of supporting the USMP is to employ an easy-to-use “Maintenance Tracking

Form” accessible through the USMP website or on a mobile application. This form is intended 

to be a simple-to-use form that records data about agency-initiated maintenance activities. 

Maintenance events might be a routine planned activity, such as ditch cleaning, or an unplanned 

mitigation/repair of a slope that is about to or has already failed. These events may occur either 

in concert with planned, periodic maintenance activities or as an ad hoc activity occasioned by

events such as failures due to a significant weather event. Whatever the nature of the activity, it 

is an opportunity for the agency to collect inventory and condition data about the site or sites and 

enter the data into the USMP system to support analysis and decision-making.

The data in the Maintenance Tracking Form include agency-specific location data about land 

unit designation, route or trail number (usually with mile markers), and type of event and cost 

data for personnel and equipment charges from a menu of activity types for hauling debris, 

bringing in patching materials, and other items such as gravel and asphalt patching material, 

rockfall barrier parts or draped netting. The total estimated cost of the maintenance activity is 

recorded along with the cost of each aspect of the maintenance event as a percentage of the total 
25

work associated with a specific maintenance activity. The reporter/observer should also note 

whether agency forces are in use or contractors or both, among other information. This data can 

be recorded on paper forms or using the iOS and Android applications. Data from the paper 

forms are intended to be promptly uploaded to the agency’s database – either in the field at the 

time of collection through an internet connection or from a desktop computer once the 

recorder/observer has returned from the field. If preferred, a paper version of the form is 

provided in Appendix B.

The maintenance tracking form data can be shared with an existing agency database through a 

correlating window on the form named, “Facility Index Code Relationship/Job Code Tracking 

(Optional).” This allows the data to be uploaded to an existing agency maintenance database 

once the fields have been created in the agency database to accommodate the USMP 

maintenance tracking form information. 

Quantitative Risk Analysis

Quantitative risk analysis (QRA) is another decision-support tool inside the larger USMP. In the 

context of unstable slopes, QRA uses measured or estimated numeric factors contributing to risk 

to assess risk probability and compare assessed risk with other societal risks. The purpose of the 

QRA is to compare estimated risk at any unstable slope site with other societal risks. This is 

useful if USMP ratings have not been done adjacent to the slope in question to provide a risk 

estimate independent from other USMP ratings, or as a prioritization tool on a subset of rated 

slopes to help prioritize them and put them in a “perceived” societal hazard context. In any 

discussion of risk, it is important to note the different meanings of the terms hazard and risk. 

Hazard is defined as something that poses a theoretical risk of harm to life, health, property or 

environment. Risk, on the other hand, takes into account the probability of occurrence and the 

consequence if the hazard is realized (Holmes, et al., 2012). Slope ratings use hazard and risk 

components to develop a numeric rating, but the QRA focuses specifically on estimating risk 

probability using factors about the hazard and the consequence that can be measured or 

estimated. 

The value of using a quantitative estimate, such as the QRA, is that the assessed risk can be put 

in context with other societal risks. Such risk statistics are compiled by agencies such as the 

National Oceanic and Atmospheric Administration (NOAA), the Centers for Disease Control and 

Prevention (CDC), insurance agencies, and various FLMAs. A quantitative risk estimate is only 

as accurate as the factors that go into the estimate and other parts of the USMP can greatly 

inform a QRA, especially the ability to systematically track frequency of unstable slope events. 

Conducting a QRA can support benefit/cost analysis or help differentiate similarly rated slopes 

by focusing on exposure to the hazard. 

Benefit/Cost Calculations

The final step in implementing the USMP is the application of benefit/cost analysis in the longterm planning process. These analyses integrate the data collected in previous steps (such as 

asset condition and corridor importance) into a single metric allowing straightforward and 
26

defensible project prioritization. The need for this prioritization arises from funding limitations 

faced by every agency, where the total cost of all deserving projects almost always exceeds the 

available funds. Benefit/cost calculations enable planners to consistently determine the 

maximum benefit achievable for a given amount of funding based, of course, on the quality and 

comprehensiveness of data in the asset management database. In a final list of projects, the 

projects that provide maximum benefit for minimum funding will be prioritized when allocating 

budget resources. The general form of the benefit/cost priority formula is:

BBBBBBBBBBBBBB

CCCCCC = [LL cccccccc aaaa bb ] + [RR RR rr rrrr bb ][PP PP cc ]

The life-cycle agency benefit is a combination of the life-cycle benefit, the recovery benefit and 

the environmental benefit of addressing geotechnical instabilities at a given site. The life-cycle 

benefit is a function of condition state and slope size since slope maintenance and eventual 

replacement generally becomes more expensive with size and over the passage of time. The 

recovery benefit represents the savings to the department or agency in decreased 

maintenance/event response costs. The environmental benefit assigns a monetary value to 

additional non-transportation benefits, such as reducing siltation in sensitive streams or 

preventing damage to culturally sensitive sites due to rockfall or landslides. The user benefit is a 

combination of the mobility and safety benefits. Both user benefits are tied to risk, and are 

frequently presented as the annual likelihood of an adverse event and the probable impacts of 

that event. Potential user mobility impacts include increased travel distances and time, or the 

complete inability of travelers to reach their desired destinations. The safety impact term 

estimates damages from accidents, typically providing a per-accident average cost that includes 

both injury and non-injury accidents. 

When these cost and benefit concepts are quantified and applied in an objective and consistent 

manner, the agency will be provided with a relatively simple tool for use in multiple aspects of 

decision support. When making funding decisions, however, the agency should document any 

assumptions or estimates made when calculating benefits and costs. Initial costs and benefits 

should be refined by more detailed studies during the planning process, which may lead to 

funding allocation adjustments. 

The benefit/cost approach to decision making is discussed in detail in Appendix D and in 

Chapter 6, which summarize the current state of practice, basic principles, and factors for 

consideration. Four alternative methods for calculating cost/benefit ratios have also been 

developed for integration in the FLMA program, and the advantages and disadvantages of each 

alternative are discussed. When making network-wide decisions, an FLMA should utilize only 

one approach that best suits its data availability, to ensure consistency. On a more limited basis 

(such as selecting between only four slopes or selecting slopes in a specific corridor) alternative

benefit/cost options may be utilized depending on data. Using these alternatives, ten example 

sites from the Gifford-Pinchot National Forest in southwest Washington State are prioritized for 

mitigation using a cost benefit approach. Appendix E contains detailed information on these 

approaches for these sites.
27

CHAPTER 4. HOW TO CONDUCT FIELD RATINGS

To obtain high quality data for use in geotechnical asset management work, field ratings must be 

performed by qualified and/or trained personnel using repeatable methods. The following 

sections describe the basic guidelines needed to conduct field ratings of unstable slopes. 

Detailed category descriptions for each rating field are contained in Appendix A. All forms for 

rating slopes, tracking unstable slope “geotechnical” events, their related maintenance activities, 

and a sample conceptual design and cost estimation form are contained in Appendix B.

UNSTABLE SLOPE RATING CATEGORY DESCRIPTIONS

The unstable slope rating category descriptions fall into three groups: preliminary rating 

categories, detailed hazard rating categories, and detailed risk rating categories. All sites 

identified for potential inclusion in the FLMA unstable slopes database receive a preliminary 

rating. If a site’s preliminary rating score falls above the given agency cutoff, then the site will 

also receive detailed hazard and risk ratings. Cutoff scores may vary between agencies, based on 

internal practices and public expectations.

The detailed hazard ratings seek to assess the general likelihood of an adverse event occurring at 

a given site. In general, the larger and more active a site is, the more likely it is to require 

unplanned and potentially extensive maintenance attention. For both rockfalls and landslides, 

slopes are scored over nine hazard categories, for a total possible hazard rating of 767 points. 

Three hazard rating categories are the same for soil and rock slope assets: slope drainage, annual 

rainfall, and slope height/axial length. However, due to the different failure types for rock slopes 

and soil slopes, the remaining six rating categories differ between the two asset types. For 

landslides and erosion failures, the remaining hazard categories describe the roadway or trail 

width affected, landslide/erosion effects, roadway or trail length affected, thaw stability, 

instability related maintenance frequency, and movement history. For rockfalls, the remaining 

hazard categories describe ditch effectiveness, rockfall history, rockfall event size, rockfall 

related maintenance frequency, and geologic character.

The detailed risk ratings seek to describe the potential impacts of an adverse event on the 

travelling public, the agency, and the environment if an adverse event should occur. There are 

nine detailed risk rating categories, for a total possible score of 805. The risk rating categories 

are the same for all unstable slope types.

Brief rating category descriptions are provided on the paper and digital rating forms. However, 

these descriptions are for quick reference only, and do not replace the detailed rating category 

descriptions provided in Appendix A. Those performing the assessments are encouraged to 

review the detailed rating category descriptions and review the “How to Rate an Unstable Slope” 

video prior to the start of fieldwork, so that any potential sources of confusion are identified and

addressed. If possible, a copy of the detailed rating categories should be included in the field 

equipment for reference.
28

PERSONNEL TO PERFORM RATINGS

The field ratings should ideally be conducted by experienced engineering geologists or 

geotechnical engineers. Raters with expertise in these fields are best able to assess probable 

failure mechanisms, event volumes, and event frequencies based on field observations. 

However, some agencies have found success training geology, geotechnical engineering, or 

applied physical sciences university students for ratings, with experienced personnel supervising 

condition assessments and under their responsible charge. Ideally, ratings will be conducted by a 

two-person team. Use of a team simplifies measurements and increases safety working around 

potentially unstable slopes. Furthermore, a more experienced rater can train someone less 

experienced during the field rating work. Field ratings can be completed by agency personnel, or 

by an outside professional if other constraints prevent a FLMA from conducting field 

assessments internally. While conducting site assessments, personnel should be physically able 

to stand for extended periods of time and to navigate the irregular surfaces potentially created by 

unstable slope events, while being situationally aware of safety hazards posed by slopes, narrow 

shoulders, and potentially inattentive drivers. Safety precautions set by each agency should be 

strictly followed at all times.

EQUIPMENT LIST

Rating personnel should pack the following items when conducting field assessments:

• All relevant safety gear. At a minimum, this should include a high-visibility, reflective

safety vest for any work conducted along roadways. It may also be prudent to wear a 

hardhat in areas prone to active rockfall or falling tree limbs on a landslide. Along hightraffic routes, traffic control and/or temporary signing may be required.

• A camera, preferably GPS-enabled, for taking site photographs.

• A handheld GPS unit for recording slope beginning and endpoints.

• Laser range-finder for quickly measuring slope heights, ditch dimensions, and related 

characteristics.

• A measuring tape for obtaining dimensions of blocks in the roadside rockfall catchment 

ditch, offsets along cracks in asphalt, and other measurements.

• A measuring wheel for obtaining slope lengths and site distances (back up equipment to a 

range finder).

• Laptop computer, tablet, or other device capable of running the appropriate software for 

field data collection.

• Paper field rating forms, even if for backup only. Binding the forms will help keep them 

organized and help prevent loss. Water-resistant paper will also be useful in inclement 

weather.

• A calculator for completing the rating equations in the paper field forms. This is 

automated in the software applications.
29

• A copy of the Detailed Unstable Slope Rating Category Descriptions (Appendix A), for 

use as a reference in the field. Again, water-resistant paper will also be useful in 

inclement weather.

Additional items that may be helpful during rating work are wet-weather gear, spare batteries, 

and maps of the area. These are not required to conduct field ratings, but help speed and 

simplify rating work. Certain items, such as the device capable of running geo-database software 

may not be included in the final field equipment list, at the FLMA’s discretion. However, if the 

goal is to create a geospatially referenced dataset, creating this geospatial file as a back up to the 

field rating work is highly recommended, both to improve project efficiency and to help prevent 

possible location errors.

PLANNING

Safety

Personnel safety during field rating work is a concern that should be incorporated into the 

planning process from the beginning. Safety requirements may vary depending on where rating 

activities are to take place, and modifications to safety precautions may be required over the 

course of field assessment work, as raters move between corridors. Because safety precautions 

can vary extensively based on where the evaluated assets are located, reasonable safety 

procedures should be developed on a corridor-specific basis as field inventory work begins and 

adaptability of these safety procedures need to consider traffic volumes changing seasonally on 

federal land transportation routes. 

Corridor Selection

Selection of corridors prior to the start of field assessment work allows the agency to focus

scarce dollars on areas of particular concern. Selecting corridors in advance also enables field 

raters to obtain required external data, such as economic or recreational importance of the 

corridor, prior to starting field assessment work. Possible criteria to assist in selecting corridors 

are described in Chapter 3 (Steps/Corridor Selection) above, but additional criteria may be 

generated for each FLMA or by a regional entity within the FLMA. Once chosen, obtain maps 

of the corridors, then develop an informal database, such as a spreadsheet, to track corridors 

selected for asset inventory work and those where evaluation will either be deferred or not 

completed.

IT Database Procedures

Asset management is only useful if sufficient data are available to agency planners. To meet this 

need and others, the data collected during field rating work should be incorporated into a 

database that is easily accessible by agency personnel. The database developed as part of this 

program is exportable into an open format (comma separated values, .csv) that permits data to be 

incorporated into a variety of text and geo-database formats. The FLMA USMP database is

searchable so that planners can look for unstable slopes under a variety of criteria, such as 
30

location, failure type, condition state, or by scores in specific rating categories. The database and 

its searching and reporting functions are described in Appendix C.

All new data, whether collected using paper forms or entered directly into a field database,

should undergo a QA/QC process upon returning to the office, and then the new data should be 

imported into the master database. An agency may wish to designate a single individual as the 

contact responsible for overseeing the addition of new data to the database, and for assisting in 

global changes to data (such as new traffic or trail counts) in the system, the generation of 

reports, or extraction of other information.

Using Forms

When conducting fieldwork, raters can use either paper or digital forms. Both types have 

distinct strengths and weaknesses, as discussed below.

Well-designed paper field rating forms are easy to use and work well under a variety of 

conditions. They are easy to transport and, if printed on appropriate paper, useable under all 

weather conditions. If multiple sites are being evaluated, the paper forms should be bound into a 

booklet, to avoid the loss of any single sheet. If the corridor to be evaluated is known in 

advance, external data, such as annual daily traffic counts, can be added to the paper sheets 

before leaving for the field. During fieldwork, the rater should bring a calculator for evaluating 

those rating categories that are directly measured and scored. Calculating scores in the field is 

recommended to verify field measurements and to evaluate the need for additional site checks 

before departing a site.

The central weakness of the paper forms is that the rater is required to manually enter calculated 

category scores and data from external sources. Manually entering this data onto the paper form 

and later manually entering it in the database increases the risk of transcription errors and is less 

efficient. However, this problem is addressed through implementing a QA/QC program that 

double checks field notes and electronic transcription. Ideally, completed paper forms should be 

scanned and uploaded to a central location once rating work is repeated, so that they can easily 

be accessed and referred to as necessary.

Use of digital forms simplifies many data input issues, but requires that field raters have access 

to a laptop or handheld device during field work. Outdoor screen brightness settings and GPS 

usage can drain device batteries. The user should learn and implement battery preservation 

methods, such as dimming the screen; screen timeouts; and turning off Wi-Fi, Bluetooth®, and 

cellular network connectivity when without an expectation of connection. Connecting to vehicle 

power sources and/or spare battery packs will likely be required for prolonged field use. Digital 

forms have been designed such that the layout is as similar as possible to the paper forms, so that 

raters can alternate between the two formats as project locations dictate. All forms are contained

in Appendix B of this manual.
31

USMP WEBSITE AND MOBILE APPLICATIONS

The USMP website and mobile applications provide an interface to add information into the 

USMP database, as well as to search and retrieve information from the USMP database. Access 

to the USMP website (https://usmp.info/) requires a username and password, for security 

purposes. The user will see the navigation bar shown in Figure 3 after logging in.

A new slope rating form can be started by clicking on “Slope Rating Form” in the navigation bar. 

Information about the slope can be input using various entry methods (dropdown menus, radial 

buttons and open dialogue boxes). Information is stored in the database by clicking the “Submit” 

button near the bottom of the page. Submitted information is saved in the USMP database. A 

similar process is used to submit data on the “New Slope Event” and “Maintenance Form,” both 

of which are also found in the navigation bar.

Source: FHWA

Figure 3. Navigation Bar for USMP Website and Mobile Applications.

The USMP website also provides an interface to search and retrieve information from the USMP 

database. The search functionality can be accessed by clicking on “Map” in the navigation bar. 

A dropdown menu is located at the top of the page, just above the map. Searches can be made in 

any of the datasets associated with one of three information sources shown in Figure 4. Once 

one of these is selected, the user will have the option to select from three main search criteria to 

narrow the search. Results from the search are shown graphically on the map and/or exported to 

a comma-separated values (.CSV) file. Step-by-step instructions for creating/submitting forms

and for performing a search can be found in Appendix C.
32

Source: FHWA

Figure 4. USMP Searching and Reporting Interface

Mobile applications were also developed for iOS and Android platforms. Login information is 

the same between the website and the mobile applications. Apps provide similar functionalities 

as those available in the USMP website, but are more convenient to use on smaller tablets and 

handheld devices in the field.

Users can create new sites while they are offline by creating new forms accessible via the 

navigation bar, similar to the process on the USMP website. Information entered in these forms 

will be stored in the mobile device when the user is offline and then can be submitted (one at a 

time) to the USMP database when the user returns to connectivity with Internet service. 

Additional information about the use of the mobile applications is in Appendix C.
33

CHAPTER 5. HOW TO SET AND USE PERFORMANCE MEASURES

Performance management is a way for transportation agencies to measure progress toward a 

goal. Performance measures are indicators of work performed and results achieved(NCHRP, 

2006). Performance management is an integral part of Transportation Asset Management 

programs and is used by transportation agencies to measure progress toward Federal, State, and 

department or agency goals, as well as objectives set in legislation or acts. In the current Federal 

rules, agencies have significant flexibility in how they implement performance management for 

assets other than bridges and pavements. This flexibility will permit testing and refinement of 

performance measures as agencies gain experience with implementing the USMP system, 

thereby providing a stronger footing for eventual inclusion in agency-wide TAM plans. The 

summary below is expanded upon in Appendix F.

Performance measures (PMs) are a critical component of asset management for slopes. PMs are 

the means by which transportation related agencies measure their progress toward goals and 

objectives. Performance measures come in a variety of forms. The first unstable slope PMs 

were developed as part of the AKDOT&PF GAM program and were tied to Levels of Service as 

targets (Stanley & Pierson, 2011; Stanley & Pierson, 2012). These initial PMs were qualitative 

targets and measures. Measures developed for the FLMAs have further advanced GAM 

principles and have moved the PMs to a more quantitative format.

Key high-level performance measures, such as number of fatalities, bridge condition and 

congestion goals, are often shared with stakeholders and the public through public reports and 

web pages. A frequently-used method for web reporting is the PM “dashboard” which gives a 

pictorial view of the agency’s performance, 

as shown in Figure 5. More detailed, and 

specific PMs, such as those needed for 

programs like the USMP for FLMAs, may be 

internal to the agency staff or may be shared 

by grouping many PM results into a few or

even a single performance measure for public 

sharing. It may be useful for agency officials, 

legislators, the public, and stakeholders such 

as user groups to know that 80% of the 

agency’s slopes statewide or region-wide are 

in “good” condition, or that only 8% of a 

region’s bridges are “structurally deficient.” 

However, much more detail is needed for 

agency staff to adequately manage a diverse 

group of assets across large geographic areas 

with highly variable conditions, topography, 

climate, geology, and nature of their use. The 

following sections provide guidance in how 

© VDOT

Figure 5. Virginia DOT Performance 

Dashboard (VDOT website – accessed 

December 16, 2016)
34

to create and execute a PM system to fit specific agency needs.

By inventorying and assessing all unstable slopes within a selected agency (or subset thereof),

small, incremental improvements to the entire inventory can be tracked when maintenance is 

performed (such as ditch cleaning for rock slopes improving ditch effectiveness, which reduces 

the USMP score) or more significant improvements are made. For example, consider the 

hypothetical situation where an agency has 2 million square feet of ‘Poor’ condition rock slopes 

out of a total inventory of 10 million square feet. Five million square feet are in ‘Fair’ condition 

and the remaining area is in ‘Good’ condition. resulting in a 30/50/20 split between 

Good/Fair/Poor categories, respectively. A five-year plan has a combination of scaling and ditch 

improvements planned for 200,000 square feet of ‘Poor’ rock slopes to improve their condition 

to ‘Fair’. In this scenario, an additional 300,000 square feet of ‘Fair’ slopes will be improved to 

‘Good’ through an associated road realignment by significantly improving ditch effectiveness 

and utilizing the nearby rock slopes as an embankment fill material source. Ignoring the 

deterioration of untouched slopes, the final proportions of Good/Fair/Poor will be 33/49/18 after 

this five-year plan is carried out. This approach is very similar to how network pavement quality 

is tracked and reported through time.

IMPORTANCE OF TRACKING GEOTECHNICAL EVENTS

Performance management systems require fuel to operate, and the fuel is data. For FLMA 

slopes, data are often a result of a “geotechnical event.” The occurrence of geotechnical events 

represents an opportunity to collect data useful for performance management programs. A 

geotechnical event may be defined as a slope failure event such as a rainfall-caused landslide or a 

rockfall. Record these event types in the New Slope Event Form described in Chapter 3 

(Tracking Performance Related Events) and in Appendix B. 

The event might be an agency-initiated planned event, like ditch maintenance, or an unplanned 

maintenance and operations repair of a slope failure and would be recorded in the Maintenance 

Tracking Form described in Chapter 3 (Tracking Performance Related Events) and Appendix B. 

The event may also be a sequence of slope rating activities such as conducting USMP inventory 

and condition assessments, either in a planned periodic sequence or as an ad hoc activity 

stimulated by a significant weather event, which would be tracked by the individual agency. 

Whatever the nature of the activity, it is an opportunity for the agency to collect inventory and 

condition data about the site or sites and enter the data into the USMP system.

Asset management depends on data, and managing data requires a database. The USMP for 

FLMAs includes database tools, forms and mobile device applications for collecting data in the 

field and storing the data in the “agency” databases. Each agency has unique IT requirements 

and configurations, along with an agency-specific firewall and other security requirements and 

specifications for acceptable software and hardware. The individual agencies will control those 

details, but the important point is that a database is necessary along with an efficient means of 

collecting and storing data, then winnowing it down to extract information usable for managing 

slopes. 
35

To date, the most useful platform for geotechnical asset management databases is web-based 

mapping tools that provide the end user with a scalable visual picture of the location and 

condition of individual assets, groups of assets of a type, and groups of differing assets. This 

type of deliverable also allows instant connection to backup information such as slope rating 

forms, spreadsheets and other tabular data, photos, drawings, incident reports, maintenance 

repair cost reports, geotechnical reports on a site or a corridor, condition ratings, benefit/cost 

calculations, mitigation strategy reports, and forecasts of condition and cost. 

However, the mere amount of data collected can create problems over time if not carefully 

managed. It is critical for successful asset management programs to collect only the data needed 

to conduct management activities. Collecting the right data for the right asset at the right time 

reduces the amount of IT work necessary to populate and maintain a geotechnical database for 

asset management purposes. It is likely that valuable asset management data can be mined from 

existing agency databases. These issues can be addressed by keeping a data roadmap in mind. 

One recent summary classifies geotechnical data for asset management as consisting of road 

sections, corridors, elements (individual asset types) and past actions (history of construction and 

maintenance activities) (Thompson, et al., 2014). To accommodate the daunting array and 

quantity of data that can be generated in a performance-monitoring program, it is very desirable 

to develop a “data business plan” or “data governance plan” to address as many issues as 

possible at the outset of launching an asset management program. Guidance on this issue is 

available, starting with the TAM Guide in Section 8.4.2(Gordon, et al., 2011).

SETTING AGENCY-SPECIFIC PERFORMANCE GOALS

Chapter 3 (Steps/Performance Goals and Objectives) and Appendix F of this document discuss 

sample performance measures (PMs) for a USMP for the U.S. Forest Service. Development of 

the PMs for the USFS built on a well-developed set of USFS guiding principles, goals and 

objectives to develop the program’s performance measures and key performance indicators. A 

critical factor in the utility of USFS’s plan is the agency’s established five-level “Maintenance 

Level” system. Level ML-1 is the lowest level and designated for roads that have been placed in 

“storage” and for which only minimal maintenance is conducted to prevent unplanned 

deterioration. Level ML-5 is the highest level and is used for roads that provide a high degree of 

user comfort and convenience. Most transportation corridors within Region 6 of the USFS are 

paved double lane roads expected to be passable by passenger cars. The research team created a 

set of PMs for a USFS USMP based on agency goals and objectives and the Maintenance Level 

system. The PMs include both management and condition performance measures and key 

performance indicators (refer to Appendix F for a detailed discussion on this topic).
36

The Bureau of Land Management, one of 

the collaborating agencies on this project, 

has already developed an asset 

management plan (Bureau of Land 

Management, 2009) and an inventory and 

condition assessment manual for roads 

(Bureau of Land Management, 2011).

The 2009 Asset Management Plan divides 

the BLM’s transportation system into 

three modes: roads, primitive roads, and 

trails, as shown in Figure 6. The plan 

contains the key elements of a typical 

transportation asset management plan that 

can lead directly to creation of PMs for 

slopes along the transportation 

infrastructure. This document (H-9113-2)

does not provide specific guidelines for 

rating unstable slopes, but USMP 

condition ratings could be incorporated 

into this preexisting framework. This 

would increase the speed of USMP rating 

adoption.

Additional backup documents include the 

BLM Manual, which has enumerated 

“Maintenance Intensities” very similar in 

nature to the USFS Maintenance Levels (see Section MS 9113-Roads of the BLM Manual). 

There is also a BLM Strategic Plan for Oregon and Washington that includes a priority for 

improving processes and 

functions with a subtopic for 

“Program Investment for Travel 

and Transportation/Road 

Infrastructure.” Additionally, 

BLM has already developed 

decision support tools to prioritize 

spending, including the Asset 

Priority Index (API), Facility 

Condition Index (FCI) and 

Current Replacement Value 

(CRV), used in conjunction to 

develop a business plan for asset 

planning along with a deferred 

maintenance and a capital 

Source: BLM 

Source: BLM

Figure 6. BLM Transportation System Modes

Figure 7. Landslide on a BLM road, southwest 

Oregon.
37

improvement program. These taken together comprise a mature and extensive system for 

addressing asset management. BLM has an extensive set of performance measures already in 

place to track the progress of the asset management plan and business plan; one of which directly 

applies to the USMP. “Maintenance: Number of lane miles of roads maintained in adequate 

condition” applies to slopes such as shown in Figure 7, which can be assessed to determine if the 

roads are in an adequate condition or if unstable slopes pose a risk to mobility and maintenance

(Bureau of Land Management, 2009).

In summary, for those FLMA agencies with strategic goals and organized, comprehensive 

programs to address the current and future condition, cost, and performance of their respective 

asset portfolios, it is possible to create a useful USMP program integrated in the agency’s 

existing asset management plan. Where goals and objectives are already in place it is possible to 

devise appropriate performance measures and metrics for tracking progress over time that are 

readily included in the existing agency management framework.

SLOPE CONDITION RATING AND PERFORMANCE MEASURES

Chapter 4 of this report and Appendix F discuss slope ratings in detail. For the FLMA USMP, 

performance measures (PMs) connect the agency objectives, goals and policies with the 

performance metrics based on the slope condition rating system. PMs and key performance 

indicators (KPI) relate to an agency’s progress, as measured by the condition ratings, to improve

the overall condition of an agency’s slopes. Large scale PMs may refer to an entire 

transportation system, a regional system, or in the case of the USFS, a national forest 

management unit such as the Gifford Pinchot National Forest. Small scale PMs or KPIs may 

refer to corridors within a national forest management unit, road segments of a corridor, or even 

individual slopes.

Performance measures, as noted above, may be “management” metrics or “condition” metrics. 

Management metrics tend to be less technical in nature and may include levels-of-service 

measures that reflect customer expectations about non-technical issues such as clarity of signage, 

extent of congestion, and could include, for example, perceived safety of travel past rock slopes 

in poor condition. These issues can be represented numerically, even though they are generally 

observational in nature.

Condition metrics may be more technical in nature, for example pavement rating systems that 

rely on measured characteristics of roughness and extent of cracking. For unstable slopes the 

condition rating is the heart of the USMP. Slope rating systems usually combine measurements 

of physical attributes, such as height of slope, width of ditch, sight distance and reports on traffic 

volume, as well as geotechnical measurements and observations of discontinuities, rock type, 

and degree of weathering. The individual scores are summed to make a combined score for an 

individual slope. The total preliminary score can be categorized in groups and can be expressed 

in a Good/Fair/Poor condition (Table 1), as is common in TAM systems. As repeated cycles of 

slope ratings are conducted, either on a schedule (i.e., every five years) or ad hoc rating periods 
38

(such as after increased debris flows due to heavy rainfall), the originally assessed condition may 

change.

The Good/Fair/Poor system is adopted in FHWA funding legislation and accompanying 

regulations. The primary objectives for adopting a Good/Fair/Poor system are to define a 

consistent and reliable method for assessing infrastructure health and to help develop tools that 

will allow transportation agencies to get a better and more complete view of infrastructure 

health. Good/Fair/Poor classifications are defined based on the preliminary ratings as follows for 

the USMP, modeled after definitions for bridges and pavements (Guerre, et al., 2012).

Table 1. Good, Fair, and Poor Classifications for USMP Slopes.

Good Condition Slope Asset is free of significant defects, and has a condition that does not 

adversely affect its performance. This level of condition typically only requires 

preventive maintenance activities such as routine, occasional ditch cleaning. 

USMP Preliminary Scores are typically 15 to 21 points.

Fair Condition Slope Asset has minor deterioration, erosion/raveling of cut slope, rockslides or 

rockfall, or infrequent subsidence of the embankment slope. This level of condition 

typically could be addressed through maintenance or risk reduction mitigation 

efforts, such as installation of barriers at road level and draped mesh to direct rock 

to the ditch or occasional subgrade improvement/strengthening with asphalt

patching and/or drainage improvements. USMP Preliminary Scores are typically 

22 to 161 points.

Poor Condition Slope Asset exhibits advanced deterioration and conditions that impact ability of 

slope to remain intact. This level of condition typically requires narrowing the 

roadway, risk reduction slope repair, rehabilitation, reconstruction or replacement. 

Potential mitigation may include robust barriers, draped or anchored wire mesh, 

landslide stabilization techniques such as horizontal drains or buttresses, or cable 

net to hold rock on slope or direct it to ditches. USMP Preliminary Scores are 

typically >161 points.

EXAMPLE OF PERFORMANCE MONITORING FOR U.S. FOREST SERVICE 

Performance measures (PMs) were prepared as part of this project based on how well one of the 

participating FLMAs was maintaining its unstable slope assets and their contribution to the 

continued function of the road network. PMs were prepared using information from the US 

Forest Service based on its five-tier Maintenance Level road classification system. 

An excellent example of a set of FLMA goals and objectives can be found in the document, 

“U.S. Forest Service Accomplishments FY2013 Federal Lands Transportation Program.” 

Additional information is found in the Forest Service Road Maintenance Management System

(U.S. Forest Service, 2009). The goals and objectives are summarized below. These strategic 

priorities imply transportation objectives of safety, mobility, and protection of natural resources:

• Overall goals and objectives from investment strategy – maintain, preserve and, if 

possible, improve access to high priority areas.

• Specific goals and objectives:
39

o Ensure safe access.

o Reduce bridge deficiencies.

o Focus on high priority roads for maintenance and improvement.

• USFS strategic plan goals and priorities:

o Facilitate outdoor recreation opportunities.

o Enhance social, health, economic, etc. opportunities and experiences for visitors.

o Provide seamless transportation access from public roads to USFS destinations.

o Implement forest plans.

o Improve rural economic opportunities.

o Manage transportation to protect natural resources.

The draft Performance Measures prepared for the Forest Service utilize the USMP scoring 

system, geotechnical event trackers, and unstable slope maintenance trackers to assist with the 

documentation, analysis and determination of deteriorating, stagnant, or improving conditions on 

its road network. These performance measures are contained in Appendix F, with an example 

table filled in below with hypothetical performance data (Table 2).

Table 2. Example Performance Measure Table for U.S. Forest Service (bold text indicates 

examples filled in).

Performance Measure. Maintain slope condition to applicable goodfair-poor service levels, as measured by road closing events. Where 

no unstable slopes exist, the slope ratings would be considered 

“Good”. 

Prev. Period Closure Freq.& DensityCurrent Period Closure Freq.& DensityPerformance TargetTrend

ML-3: Roads are open to standard passenger vehicles and shall 

remain open with application of normal maintenance routine. 

Occasional partial or full closures may result due to slope instability 

caused by deterioration and/or unusual conditions (e.g., heavy rainfall 

causing slope failures) that may require repair prioritization behind 

higher priority roads. Preventative maintenance is performed to 

reduce impacts over time. Likelihood expressed as a per mile annual 

occurrence of closure.

2 

closures 

over 17 

miles 

2005-

2010 

(2.3%)

5 

closures 

over 17 

miles 

2010-

2015 

(5.9%)

<1 per 3 

years per 

10 miles

(3.3%)

Worse, 

Met 

Target, 

then 

worseened

ML-4: Roads are open to standard passenger vehicles and shall 

remain open with application of normal maintenance routine. 

Occasional partial or full closures may result due to slope instability 

caused by deterioration and/or unusual conditions (e.g., heavy rainfall 

causing slope failures) that may require repair prioritization behind 

higher priority roads. Preventative maintenance is performed to 

reduce impacts over time.

1 closure 

over 9 

miles 

2005-

2010 

(2.2%)

1 closure 

over 9

miles 

2010-

2017

(1.6%)

<1 per 3 

years per 

15 miles

(2.2%)

Better, 

Met 

Target & 

more 

improvement

ML-5: Highest priority roadways. Rare partial or full closures may

result due to slope instability caused by deterioration and/or unusual 

conditions (e.g., heavy rainfall causing slope failures). Preventative 

maintenance is prioritized and performed to reduce impacts over 

time.

3

closures 

over 30

miles 

2002-

2010 

(1.3%)

2 

closures 

over 30

miles 

2010-

2015 

(1.3%)

<1 per 5 

years per 

20 miles

(1%)

No 

change. 

Does not 

meet 

Target
40

CHAPTER 6. HOW TO USE BENEFIT/COST APPROACHES

The benefit/cost approaches formulated for this project present a series of alternative analyses for 

prioritization of slope preservation, risk reduction mitigation, and reconstruction. All of the 

approaches are based on widely accepted principles of risk management and asset management, 

with varying levels of data requirements. The approaches provide an objective and consistent 

means of summarizing the degree to which each project may contribute to agency objectives 

while minimizing long-term cost and risk. A full description of how to implement these 

techniques is summarized in Appendix D.

For agencies and asset classes that lack a history of data collection and sophisticated tools, the 

appropriate methods for geotechnical assets are much simpler than those that are commonly used 

for pavements and bridges. Nonetheless, the adoption of certain basic well-structured practices, 

relying on a systematic inventory and condition survey, can substantially enhance the 

consistency and objectivity of priority setting and resource allocation. This can reduce long-term 

costs and establish the groundwork for continuous improvement over time.

The need for prioritization and resource allocation arises because of limitations on funding. The 

list of attractive projects that need to be completed is usually costlier than can be accomplished 

with available funds. If two projects are expected to have the same benefit, then in principle the 

one with lower cost is given more priority. If two projects have the same cost, the one with 

higher benefit is given more priority. A list of projects sorted by benefit/cost ratio provides a 

consistent way to determine the maximum benefit that is achievable for any given amount of 

funding, and selects the list of projects that can achieve this high level of benefits.

To support the FLMAs in these management functions, four approaches were developed to assist 

in prioritizing and selecting projects to advance, using both national (i.e., encouraging the use of 

asset management principles on non-pavement and bridge assets to reduce long-term costs and 

improve system performance) and Forest Service-specific goals and objectives. Each approach 

is summarized below and detailed in Appendix D.

VARIOUS APPROACHES TO BENEFIT/COST CALCULATIONS

As part of this manual, multiple methods have been developed for calculating benefit/cost ratios, 

based on the level of data available to the agency. In their purest form, benefit cost calculations 

incorporate life cycle costs, risk analyses, and site-specific risk reduction mitigation costs. 

Depending on data availability and desired level of detail, the basic formula can be simplified in 

a variety of ways. These options are summarized in the following subsections, and are described 

in detail in Appendix D. To illustrate how these various approaches can be applied to an existing 

data set, they are applied to a set of sites from the Gifford Pinchot National Forest later in this 

chapter.
41

Alternative 1: Computed Benefits and Costs

If sufficient data are available for a given slope, the most precise estimate of benefit/cost ratio 

would fully utilize the formulas in Appendix D. Combining the life-cycle cost and risk 

components, the basic ratio would be:

BB

CC = LL CC BBBBBBBBBBBBBB + LL h ×CCCC CC CC

II CCCCCC

The detailed equation in Appendix D allows any term to be replaced if more detailed information

is available, such as an actual risk reduction mitigation cost estimate. The unit costs presented in 

Appendix D are initial order-of-magnitude estimates and can be improved over time through 

additional research, interviews, data mining of existing maintenance records, and tracking of 

future maintenance, risk reduction mitigation, and accident costs. The constants in the 

consequence equation are derived from AASHTO guidelines and can similarly be replaced if 

better estimates are available from analysis or judgment (AASHTO, 2010).

Data requirements for Alternative 1:

• Average daily traffic (for low-traffic critical roads, a minimum ADT could be assigned, 

or an ADT computed for the busiest months applied to capture seasonal traffic).

• Condition state (derived from USMP preliminary score).

• Detour length in miles.

• Detour time in hours, or detour speed in miles per hour (where no detour information is 

available, the analyst can make a rough estimate of average user costs in terms of dollars 

per vehicle, through a process described in Appendix D).

• Estimate of environmental cost of slope failure. Since there is no established 

methodology to compute this, it would generally be omitted unless a study has been done 

to quantify it; however, environmental costs are very important to the mission of many of 

the FLMAs.

• Height of slope (for rock slopes).

• Length of slope along the road (for both slope types).

Advantages of Alternative 1:

• Offers the most precise estimate of benefits and costs.

• Recognizes the life cycle benefit of preservation, which may save money in the long 

term.

• Uses all available data.

• Contains the most reliable approach for defending programming decisions.

Disadvantage of Alternative 1:

• Requires more data than any alternate method.
42

Alternative 2: Priority Index

For sites where the level of detail required by Alternative 1 is not available, a simplified 

expression can be used to develop a priority index, which is shown below: 

BB

CC = SS SS ×AA $ + LL h ×(18AAAAAA + SS SS ×RR $)SS SS ×CCCCCC $

In this index, detour information has been omitted, with the assumption that detour distances 

between the evaluated sites are relatively consistent or that the detour distances are immaterial to 

the affected roadway users. Since no detour information is included, it is best applied to sites 

within a single transportation corridor, and not used to compare sites where detour distance or 

overall availability vary widely. Other simplifications are listed below.

• Mobility benefits are directly correlated with safety impacts, with both dependent on the 

traffic volume and likelihood of service disruption based on site condition.

• The environmental benefits have been eliminated.

• Benefits and costs are no longer explicitly addressed.

• Dollar values of additional project impacts cannot be incorporated into the numerator or 

denominator.

• This simpler formula is not valid if no traffic exists on the road (for example, USFS 

Maintenance Level 1).

Data requirements for Alternative 2:

• Length of slope along the road.

• Height of slope (for rock slopes).

• Average daily traffic.

• Maintenance level.

• Condition state (derived from USMP preliminary score).

Advantages of Alternative 2:

• Simpler than computed costs and benefits.

• Moderate data requirements.

• Recognizes the life cycle benefit of preservation.

Disadvantages of Alternative 2:

• Does not account for sites with long detour routes, which may be problematic if these 

routes also have heavy traffic.

• Not able to incorporate additional site-specific information, such as an actual cost 

estimate.
43

Alternative 3: USMP Score Priority Index

For sites with no economic data, a priority index can be developed based on total site rating, size,

and average daily traffic. A higher USMP score indicates poorer slope condition and increased 

likelihood of service disruption. Greater slope size implies greater mitigation costs. Higher 

traffic volumes imply higher mobility and safety risk costs, as well as general importance of the 

corridor to the agency. The relationship of these three variables is captured in the following 

formula: 

PP ii = UU UU SS ×

AAAAAA

SS SS

where: size = slope size (approximated area for rock slopes or length of the road affected for 

landslides), and ADT = average daily traffic.

This alternative is known as a “worst-first” indicator because it does not consider life cycle costs. 

It is not able to assign a benefit to preservation actions. For critical roads with very low ADT, a 

minimum ADT value may be assigned. Similarly, for seasonal traffic, the index may be 

computed using average ADT for the busiest months.

Data requirements for Alternative 3:

• Length of slope along the road.

• Height and length of slope (for rock slopes).

• Average daily traffic.

• USMP total score.

Advantage of Alternative 3:

• Smallest additional data requirements.

Disadvantages of Alternative 3:

• Cannot consider preservation actions, ultimately producing more expensive programs.

• Does not account for maintenance and recovery costs.

• Does not account for sites with long detour routes, which may be problematic if these 

routes also have heavy traffic.

• Inability to incorporate additional site-specific information.

• Not compatible between asset classes.

• Unsuitable for resource allocation or computation of fiscally-constrained performance 

targets.

• More difficult to communicate results to users outside the geotechnical expertise area.

Alternative 4: Hybrid of Alternatives 1 and 2

Alternatives 1 and 2 are mutually compatible because both use the same factors for scaling the 

benefit/cost ratio. Where the detailed mobility and environmental impact data required for 
44

Alternative 1 (e.g., detour length, slowdown duration) are not available for all sites, but sufficient 

data are available to follow Alternative 2, both equations can be used within the same priority 

list. This is especially useful for agencies that have only partial coverage of some of the data 

items in the inventory. Alternative 1 would be used whenever possible, falling back on 

Alternative 2 when necessary.

Advantages of Alternative 4:

• Applicable to a partially completed database.

• Maximum soundness from an engineering and economic perspective.

• Most amenable to scenario analysis, such as considering fiscal alternatives and 

performance targets, because more of the inventory can be covered than in Alternative 1 

alone.

• The approximate analysis using Alternative 2 can be used to prioritize additional data 

gathering for use in Alternative 1.

Disadvantages of Alternative 4:

• Comparing Alternative 1 to Alternative 2 sites may be problematic if sites have long 

detours.

• See disadvantages of Alternative 2.

SELECTING THE APPROPRIATE APPROACH

The alternative that best suits a given data set is determined using the quality of the data 

available. Although site condition must be established with a field visit and associated rating, 

additional data, such as ADT and detour length, is obtained from other sources, and can be added 

or edited in the office. If risk reduction mitigation cost estimates are available for some sites, but 

potential mobility impacts are not, the missing data can be estimated using publicly available 

mapping software or agency sources. 

Once the decision is made on how much to improve the data set before conducting cost/benefit 

analysis, the appropriate approach is the most detailed alternative for which all required data are 

available. If data are available for a computed cost/benefit analysis (Alternative 1), then 

presenting a USMP Score-Based Priority Index does a disservice to high-level planners seeking 

to allocate resources as effectively as possible. The various cost/benefits approaches are applied 

to a sample data set from the Gifford Pinchot National Forest in the last section of this chapter.

COST ESTIMATION

Initial conceptual designs and cost estimates should be developed by experienced geotechnical 

engineers or engineering geologists during a field reconnaissance of the site. Because the 

development of a site-specific cost estimate requires more time than the typical 15-minute fieldrating visit, sites should be selected for conceptual mitigation based on the ranked slope ratings 

by some set of criteria prior to heading out to conduct the field reconnaissance. Potential criteria 

include using a minimum USMP score or ADT count as a cutoff value, focusing on a specific 
45

corridor and linking the extent of conceptual design and cost estimates to the overall corridor 

level of service set by the agency. Agencies may combine various selection criteria to best suits 

their needs.

An alternative programmatic approach would be to assign cost estimation that correlates to size 

and condition of the slope rather than conducting a site-specific conceptual design with cost 

estimates. The accuracy of the cost estimate is a controlling factor for data quality. Agencies 

may opt to generate network-wide estimates of improvement costs without expending the effort 

to gather site-specific cost estimates for hundreds of slopes. This approach has been used in 

some recent research projects (Beckstrand et al., 2017a; Beckstrand et al., 2017b) with cost 

estimates prepared from large data sets (Beckstrand et al., 2016; Pierson et al., 2005; Washington 

State Department of Transportation, 2010). These generalized estimates are very useful for long 

range programmatic level planning and have helped state DOTs better understand the value of 

their geotechnical assets. As described above, as additional or higher quality information 

becomes available, it can be replaced in many of the alternatives detailed in Appendix D.

When performing site-specific cost estimates, the conceptual designs themselves should be 

performed by experienced personnel who are capable of quickly and efficiently conducting a 

field reconnaissance. These estimators should have sufficient experience in risk reduction 

mitigation projects to be able to estimate likely costs for the various components selected to 

improve a given site. Because required mitigation work will become more extensive as slopes 

degrade, cost estimates should also be revisited at regular intervals of 5 to 10 years, similar to 

whatever interval the agency is applying to site inspections to review USMP ratings. Appendix 

B contains a form to help practitioners conceptualize designs and estimate costs. 

EXAMPLES FROM GIFFORD PINCHOT NATIONAL FOREST

Ten sites within the Gifford Pinchot National Forest were selected for initial cost estimate work. 

Instead of incorporating specific filtering criteria, a broad range of sites were intentionally 

selected for the conceptual mitigation work, with an equal number of rockfall and landslide sites. 

A two-person team composed of an engineering geologist and a geotechnical engineer visited 

each site, conducted a field reconnaissance, developed a conceptual mitigation design and 

associated quantities, and estimated project costs based on past experience and expert judgment. 

These cost estimates were then used in example applications of the various cost/benefit 

approaches, as described in the following section. Specific conceptual designs and cost 

estimates with USMP site ratings are contained in Appendix E.

In September 2014, Landslide Technology evaluated 126 sites along paved routes in Gifford 

Pinchot National Forest. Conceptual mitigation designs and costs were developed for 10 of these 

sites in June 2015. Ranked USMP site ratings for the 2014 work were submitted as part of the 

Task 1 memorandum. The site-specific USMP ratings and risk reduction mitigation estimates 

for the 10 sites used as cost/benefit examples are also compiled in Appendix E for review. An 

overview of the example sites and USMP site information used in the various benefit cost 

analyses alternatives is provided in Table 3 below. 
46

Table 3. Sites used in benefit/cost calculations with selected site information.

Site Hazard 

Type

ADT Size 

(approx.)

USMP 

Score

Site 

Condition

Estimated 

Mitigation 

Cost

Est. 

Detour 

(mi.)*

Est. 

Detour 

Time 

(minutes)*

FS 25 MP 29.44 Landslide 450 260 ft 371 Poor $ 235,650 44.1 25

FS 25 MP 24.70 Landslide 450 125 ft 286 Poor $ 50,250 44.1 25

FS 25 MP 24.45 Landslide 450 168 ft 416 Poor $ 57,250 44.1 25

FS 25 MP 25.15 Landslide 450 175 ft 492 Poor $ 373,500 44.1 25

FS 25 MP 28.33 Landslide 450 115 ft 336 Poor $ 25,050 44.1 25

FS 25 MP 21.71 Rockfall 450 28,000 sf 251 Fair $ 55,000 44.1 25

FS 25 MP 24.63 Rockfall 450 32,000 sf 465 Poor $ 318,125 44.1 25

FS 25 MP 28.36 Rockfall 450 9,000 sf 401 Poor $ 395,800 44.1 25

FS 90 MP 13.26 Rockfall 1500 34,000 sf 446 Poor $ 315,000 44.1 25

FS 25 MP 25.11 Rockfall 450 47,000 sf 354 Poor $ 162,600 44.1 25

* The detour distance is calculated based on the assumed diversion to the assumed destination. In this example, it was

assumed that Woodland, WA was the diversion point and the destination was Windy Ridge Lookout, which has a 44.1 

mile longer route travelling through Randle, WA rather than through Cougar, WA. Due to the higher travel speeds on

SR 12 and I-5 versus SR 503, the added 44 miles only takes an extra 25 minutes.

Although most data used in this cost-benefit work was taken directly from the 2014 data set, 

several assumptions were made to obtain Average Annual Daily Traffic (ADT) and detour 

information. ADT is required for all benefit/cost calculations, but it was not available for sites 

on FS 25. As a work-around, an ADT count was approximated based on the score selected for 

the “AADT / Usage / Economic or Recreational Importance Category.” All sites on FS 25 were 

given a score of 27 in this category, which is defined as “AADT 450 / Frequently used / 

Moderate Economic or recreational importance.” Based on this definition, an ADT of 450 was 

used for all sites on FS25. For detour length and time calculations, it was assumed that most of

the travelers on FS 25 and the site on FS 90 were visitors heading to Windy Ridge on FS 99, and 

that most of these visitors started their trip somewhere before Woodland, Washington. In the 

event of a road closure, these visitors would detour and approach Windy Ridge from the north, 

passing through Randle, Washington. Detour lengths and times were calculated as the difference 

between the two routes. The detour/time assumptions may not be true for the FS 90 site, since 

that route has significantly higher ADT and provides access to the Mt. Adams area. No 

environmental benefit estimates were made during cost estimations; incorporation of these 

benefits could also change the calculated ratios in Alternatives 1 and 2.

Working with the site-specific data and with the cost estimates, the sample group was evaluated 

using the three cost/benefit evaluation alternatives. The cost/benefit ratio or priority index score 

for each site under the various approaches, along with the USMP site rank under each approach, 

is presented in Table 4. Note that under Alternatives 1 and 2, all asset types can be evaluated 

together, but under Alternative 3, separate priority lists must be developed for each asset type.
47

Table 4. Calculating Benefit/Cost ratios or Priority Indexes for Gifford Pinchot National 

Forest sample sites. The USMP sites have also been ranked under each analysis 

alternative.

Site Name

Hazard 

Type

Alternative 1 Alternative 2 Alternative 3

Benefit/Cost 

Ratio Rank

Priority 

Index Rank

USMP 

Score 

Priority 

Index Rank*

FS 25 MP 28.33 Landslide 2.48 1 0.11 5 1313.53 1

FS 25 MP 24.45 Landslide 1.37 2 0.10 7 1114.96 3

FS 25 MP 24.7 Landslide 1.30 3 0.11 5 1029.46 4

FS 25 MP 25.11 Rockfall 0.61 4 0.14 4 3.41 5

FS 25 MP 29.44 Landslide 0.45 5 0.10 7 641.88 5

FS 25 MP 21.71 Rockfall 0.27 6 0.21 1 3.99 4

FS 25 MP 24.63 Rockfall 0.24 7 0.15 3 6.54 3

FS 25 MP 25.15 Landslide 0.22 8 0.10 7 1265.50 2

FS 25 MP 28.36 Rockfall 0.10 9 0.20 2 19.26 2

FS 90 MP 13.26 Rockfall 0.10 9 0.07 10 19.45 1

* NOTE: Rockfall and landslide sites were ranked separately for Alternative 3.

In Alternative 1, the only option to incorporate specific risk reduction mitigation costs, the three 

sites with the highest benefit/cost ratios are landslides. The site with the highest benefit in this 

alternative is a landslide at Mile Post 28.33 on FS 25. The site on FS 90 has the lowest 

benefit/cost ratio, but this could change if the detour distance is updated to reflect more people 

using the road to travel to alternative locations.

In Alternative 2, the specific risk reduction mitigation cost estimates were replaced with an 

estimated unit cost based on asset type. As a group, rockfall sites moved up in the priority index 

relative to the benefit/cost calculation approach in Alternative 1. The landslide with the highest 

calculated benefit/cost ratio is now number five on the priority index. This may indicate 

something about the underlying geology of the rated corridor and an associated discrepancy from 

projected agency-wide unit costs.

Because of the difference in size calculations between landslides and rockfalls, Alternative 3 

cannot be used to make a single priority list including all asset types. For improved clarity in 

discussion of this alternative, the assets are presented in separate groups in Table 5.
48

Table 5. Priority index for Gifford-Pinchot sites calculated using Alternative 3, and 

organized from highest to lowest index score (note that rockfall and landslide hazards have 

been analyzed separately in the rankings).

Site Name

Alternative 3 

Priority Index - Rockfall Site Name

Alternative 3

Priority Index - Landslide

FS 90 MP 13.26 19.45 FS 25 MP 28.33 1313.53

FS 25 MP 28.36 19.26 FS 25 MP 25.15 1265.50

FS 25 MP 24.63 6.54 FS 25 MP 24.45 1114.96

FS 25 MP 21.71 3.99 FS 25 MP 24.70 1029.46

FS 25 MP 25.11 3.41 FS 25 MP 29.44 641.88

Unlike Alternatives 1 and 2, the priority index does not directly incorporate any costs, not even 

typical unit costs. Instead, it links high-scoring sites, which are generally in worse condition, to 

ADT (a relative measure of route importance and safety risk) and site size (a relative measure of 

mitigation cost). On FS 25, where the same ADT has been assumed for all sites, this priority 

index becomes a comparison of the site total score/size ratio in the corridor. Speaking broadly, 

the largest sites in a corridor become the lowest priority to address because they impose the 

greatest risk reduction mitigation costs. This approach will lead to lower overall risk reduction 

in the corridor. Note that the rockfall site on FS 90, which was at the bottom of the indexes in 

Alternatives 1 and 2, is now the highest priority site in the rockfall index because the ADT for 

that site is more than three times higher than that estimated for the FS 25 sites.

Alternative 4 is designed to bridge the gap between Alternatives 1 and 2, making it possible for 

agencies to incorporate sites into their long-term planning goals, even if the data set is 

incomplete. However, the different equations used in these two alternatives generate numbers

that are not comparable between the two approaches. In the Gifford Pinchot National Forest 

example USMP sites, benefit/cost ratios calculated in Alternative 1 were much higher than the 

ratios calculated using the Alternative 2 priority index. The most extreme example of this was 

the landslide on FS 25 MP 28.33, where the calculated benefit/cost ratio was 21 times higher in 

Alternative 1 than in Alternative 2. If an Agency is unaware that it is basing decisions on a

mixed data set, where Alternative 2 is being applied to some sites, these sites will be passed over 

for funding due to the low benefit/cost ratios. To address this, Alternative 4 should be used as 

part of a two-part system. The Alternative 2 priority index is applied to all sites in the agency 

data set. The results of this analysis can then be used to help focus efforts on specific corridors 

or corridor segments for further study. The computed benefit/cost analysis of Alternative 1 

would then be applied to this subset, helping to generate information that will be easily 

understood by high-level planners and applied when allocating budget resources.
49

CHAPTER 7. HOW TO CONDUCT QUANTITATIVE RISK ASSESSMENT

Risk analysis for the USMP that considers natural hazards that affect transportation corridors

(roads and trails), such as landslides or rockfall, should be transparent, reproducible and

comparable with similar analysis about other hazards that pose a risk to facilities or people. The 

methods that constitute the current standard for risk analysis in NPS, for example, include 

probability-impact graphs or risk matrices. While these methods are simple and quick to apply,

they use qualitative language that is prone to differing interpretations, and they are not inherently

transparent in the factors used to assess risk. Furthermore, the current methods do not allow easy 

quantitative risk comparisons with other common hazards. To achieve a greater degree of 

transparency, reproducibility and comparability in risk assessment, the NPS Geologic Resources 

Division (GRD) has been using a quantitative risk analysis (QRA) method adopted from the 

Australian Geomechanics Society (Australian Geomechanics Society, 2007) and work

following the 2010-2011 devastating earthquake that induced rockfall in Christchurch, New

Zealand (Massey, et al., 2012; Massey, et al., 2014). The QRA relies on empirical, modeled, or

estimated probabilities, but it is possible that with some simple guidance and a graphical user

interface, as opposed to a spreadsheet, FLMA geotechnical specialists and managers outside of 

NPS-GRD could make expeditious use of the QRA.

The currently used QRA consists of a straightforward four factor probability equation and a list 

of annually, or biennially, updated societal risks for comparison. Since the QRA used by

GRD has been developed for, and applied to, rockfall and landslide hazards, it makes sense that a

USMP would incorporate the QRA as an additional decision support tool for individual slopes or 

as part of a prioritization process within similar prioritized transportation corridors. While risk

is already estimated as part of the USMP slope rating, a QRA that can be directly related to other 

societal risks has utility for greater context and as a tool to use if decisions about risk reduction 

mitigating actions or corridor closures need to be made rapidly. For an example of how the QRA 

can help further prioritize rated unstable slopes see Capps et al., (2017). In this example from 

Denali National Park in Alaska, the top ten USMP rated slopes on a newly rated priority corridor 

of 141 unstable slopes were analyzed with the QRA to help refine priorities among the top 10 

rated slopes and provide context to park managers about the risk associated with each unstable 

slope evaluated.

The QRA module or tool is a graphical user interface implementation of the four factor QRA

equation used by GRD and accessed from the USMP website interface. Users can enter in 

probability factors and items affecting probability factors such as rock size and number of

boulders for rockfalls, or speed limit in a hazard zone, to generate annual or daily individual risk

of damage, death, or injury. This risk probability may then be compared with other societal risks

in an output comparison graph. Risk of death or injury occurrence and societal costs may also be

estimated through input of the number of people exposed to the risk using the USDOT’s Value of 

Statistical Live (VSL) guidance. A step-by-step description is provided in Appendix G for using 

the USMP QRA form. 
50

QRA ANALYSIS FACTORS

At least four factors need to be estimated or determined to estimate annual risk to an individual 

using facilities exposed to an unstable slope hazard: 1) the annual probability of an unstable 

slope event; 2) the probability of a person being present in the path of a falling rock or a 

landslide; 3) the time a person spends in the hazard zone; and 4) the vulnerability or consequence 

of being caught in an unstable slope event. These four factors can be expressed within the 

general risk equation:

R(AIR) = P(occ) × P(loc) × P(pres) × P(vul)

where:

• R(AIR) is the annual individual fatality or injury risk or the risk of damage to facilities.

• P(occ) is the annual probability of an unstable slope event affecting the hazard zone, the 

probability of occurrence.

• P(loc) is the probability of a person, if present in the hazard zone, being in the path of an 

unstable soil slope event in the full length of the hazard zone, or in the case of rockfall, 

one or more rocks at a given location, where the entire hazard zone is not necessarily 

affected by every event.

• P(pres) is the occupancy rate or rate of presence, the amount of time spent by an individual 

in the affected area.

• P(vul) is the vulnerability, or probability of a person being killed or injured by the event. 

The four probability factors used in the USMP QRA are similar to factors used in other 

quantitative risk assessments such as the Australian Geomechanics Society(Australian 

Geomechanics Society, 2007), and a rockfall QRA used to evaluate rockfall risk following the 

2010 and 2011 Christchurch, New Zealand earthquakes(Massey, et al., 2012; Massey, et al., 

2014).

Probability of Occurrence, P(occ)

The first factor to estimate risk requires data that indicate the occurrence probability or frequency 

of an unstable slope event. Tracking the occurrence of unstable slope events with the USMP 

through periodic ratings or through new slope event forms provides baseline data for occurrence 

probability. In addition, scientific methods for dating unstable slope events can yield data for 

occurrence probability. In the absence of some basic tracking of events at a slope or scientific

data, the future probability of the unstable slope event would need to be estimated. 

If small numbers of unstable slope events at a site have been tracked over many years or large 

numbers of events have been tracked over several years, the recurrence probability (P) of event x

can be estimated using a “simple” recurrence equation, x events in n observations:

P(x) = x/n
51

If an event occurs and there is no, or very little, record of unstable slope events at a site, it is 

reasonable to assume that some slope condition changed or reached a threshold to allow for slope 

instability, and that this slope condition is still in effect. In this “prior” case, the period of 

observation under the current slope event generating conditions is limited, but it is still 

conservative to assume that there is some real chance of slope events in the future. This is an 

assumption based on an uninformative, yet objective prior, infrequent events over a small 

observation period. Rather than assuming a single or small number of events in a single or small 

number of observation periods is informative, the prior condition mentioned above is not very 

informative and equal probability should not automatically be assumed for either an unstable 

slope event occurring or not occurring in a given observation period. So, in this “uninformative 

prior” case the recurrence probability (P) of event x can be estimated using a statistical 

formulation for events that have occurred without a strong historical record, x times in n

observations:

P(x) = (x +1)/(n + 2)

When using either the “simple” recurrence or the “uninformative prior” recurrence estimate, the 

estimates should be adjusted as further observations are recorded and the QRA refined.

In addition to environmental unstable slope event triggering factors, any risk assessment for a 

surface geologic process must incorporate the risk of earthquake. A close proximity magnitude 

5.5 or greater earthquake would likely cause significant rockfall (Mackey & Quigley, 2014; 

Massey, et al., 2014). Earthquake ground motion can also trigger a significant number of 

landslides (e.g., Huang and Fan, 2013). Earthquake probabilities or peak ground acceleration 

probabilities are estimated by the USGS, and these values can be used when performing the 

QRA. 

Probability of Location, P(loc)

For landslide unstable slope events, the QRA assumes that the most likely landslide affects the 

entire hazard zone, and the probability of a person in the hazard zone being affected by the 

unstable slope event is 100%. For rockfall scenarios the following equation is used to estimate 

the probability that a person, if present in the hazard zone, will be in the path of one rock at a 

given location:

P1(loc) = (2D+d)/L

Where D is the estimated diameter of the rock, d is the diameter of the threatened object, such as 

a person, and L is the length of the hazard zone. Since people are the potential victim, the 

Americans with Disabilities Act minimum doorway width of 81.5 cm (32 inches) is used for the

diameter (d). 

During a rockfall, the probability of hitting the same location multiple times increases with the 

number of rocks generated by the rockfall event, such that if N rocks are randomly distributed 

across the slope:
52

P(loc) = 1-(1- P1(loc))

N

Once probability of occurrence and probability of location are assessed or estimated, there are 

two remaining risk factors that need attention.

Probability of Occupancy, P(pres)

The occupancy rate is the amount of time (measured as percent of time per year) an individual 

spends in the hazard zone. For transportation corridors, this is dependent on the length of the 

hazard zone and the speed a person travels through the hazard zone. The exposure of 

maintenance personnel in this hazard zone should also be considered. 

Probability of Vulnerability, P(vul)

Vulnerability is a consequence and must be estimated or based on previous unstable slope 

events. The estimated consequence could range in severity from damage to destruction of 

infrastructure, or injury to death for people impacted by unstable slope events. The two 

following empirical examples show how consequence may be estimated based on previous 

events:

• For landslides, the widely reported and researched landslide in Oso, Washington on

March 22, 2014 killed about 74% of the people that were in its path.

• For rockfall , Grant et al. (2017) found a strong power-law correlation between modeled 

kinetic energy (KE), measured in kilojoules from impact on timber framed house walls,

and runout distance (m) into and through the structure (0.064KE0.75), and area (m2

) 

directly impacted within a structure (0.023KE0.97). This work also observed that a 

rockfall event energy threshold may exist at approximately 10 kJ (~3.7 ft-tons). Below 

about 10 kJ, very small portions of each structure within the study were affected, but 

above 10 kJ significant consequences are possible. Based on this work, it is likely that 

above approximately 10 kJ (~3.7 ft-tons), rockfall striking people would likely result in 

a fatality.

Even with some empirical examples, judgment is likely to be required to determine the 

probability of a fatality from rockfall or landslide because the specific components of each 

scenario may differ. Specific aspects could include the size of the probable rock striking the 

person and the likelihood of striking vital portions of the body. If the unstable slope event is a 

rockfall, and the energy of the rockfall is potentially higher during an earthquake triggered event, 

because of larger boulder sizes or some other factor, the probability vulnerability will be higher 

for an earthquake triggered event. Estimating the probability of injury or damage to a facility 

may involve less uncertainty as any unstable slope event that strikes a person or facility very 

likely causes injury or damage. 
53

ESTIMATED CHANCE OF AN INCIDENT

Once annual individual risk is estimated, it is possible to estimate the annual chance of an 

incident by multiplying the annual individual risk by the annual number of individuals exposed 

to the hazard.

RISK REDUCTION BENEFIT/COST ANALYSIS

Once a life/safety risk has been estimated, the benefit of mitigating the risk can be assigned a 

monetary value using the concept of a Value of a Statistical Life (VSL) for people at risk and/or 

the value of infrastructure at risk. VSL is the estimated cost of mitigating the risk of a fatality. 

The US Department of Transportation Value of a Statistical Life is about $9.6 million in 2017 

dollars(US Department of Transportation, 2013). This figure, multiplied by the estimated risk 

and the number of people at risk, provides an estimate for the value of mitigating the risk. Since 

it is not always possible to completely mitigate risk, the QRA benefit/cost analysis assumes a 

target natural hazard annual individual fatality risk probability of one in a million (1×10-6). This 

risk level would be the goal for full mitigation or significant risk reduction and would bring the 

unstable slope event risk down into the range of other natural hazard risks.
54

REFERENCES

AASHTO. (2010). User and Non-User Benefit Analysis for Highways. American Association of 

State Highway and Transportation Officials.

Anderson, S., Schaefer, V., & Nichols, S. (2016). Taxonomy for Geotechnical Assets, Elements, 

and Features.

Australian Geomechanics Society. (2007). Practice note guidelines for landslide risk 

management. Journal and News of the Australian Geomechanics Society, 42(1), 63-114.

Beckstrand, D., Black, B., Mines, A., Stanley, D., Thompson, P., Jackson, J., Helm, S., Boundy, 

B. (2017a) Montana’s Rock Slope Asset Management Program (RAMP), 68th Highway 

Geology Symposium, Marietta, GA, May 2017.

Beckstrand, D., Mines, A., Pierson, L., Thompson, P., Kimmerling, R., Benko, B., Stanley, D. 

(2017b) Alaska’s Geotechnical Asset Management Program, Third North American 

Symposium on Landslides, Roanoke, VA, June 4 - 8 2017.

Beckstrand, D., Mines, A., Thompson, P., & Benko, B. (2016). Development of Mitigation Cost 

Estimates for Unstable Soil and Rock Slopes Based on Slope Condition. The 2016 

Annual Meeting Compendium of Papers. Transportation Research Board.

Bureau of Land Management. (2009). Asset Management Plan. Retrieved from 

http://www.blm.gov/style/medialib/blm/wo/Business_and_Fiscal_Resources/asset_mana

gement_plan.Par.66677.File.dat/2009AssetManagementPlan.pdf

Bureau of Land Management. (2011). Roads National Inventory and Condition Assessment 

Guidance & Instructions Handbook. Retrieved from 

http://www.blm.gov/style/medialib/blm/wo/Information_Resources_Management/policy/

blm_handbook.Par.85371.File.dat/H-9113-2.pdf

Cambridge Systematics. (2002). Asset Management Guidance for Transportation Agencies.

FHWA, NCHRP Project 20-24(11), Washington, DC.

Capps, D.M, Rosenberg, R., Collins, A., Hooper, S., Rogers, H., Anderson, D.A., and

Bilderback, E. (2017) Geohazards Risk Assessment of the Denali National Park Road, In 

De Graff, J.V. and Shakoor, A. (eds.), Landslides: Putting Experience, Knowledge and 

Emerging Technologies into Practice, AEG Special Publication No. 27, p. 840-850.

Federal Highway Administration. (2015, January 5). NRPM: National Performance Management 

Measures; Assessing Pavement Condition for the National Highway Performance 

Program and Bridge Condition for the National Highway Performance Program. Notice 

of Proposed Rulemaking, FHWA. Retrieved from http://www.gpo.gov/fdsys/pkg/FR2015-01-05/pdf/FR-2015-01-05.pdf

Gordon, M. G., Smith, G. J., Thompson, P. D., Park, H., Harrison, H., & Elston, B. (2011). 

AASHTO Transportation Asset Management Guide Volume 2: A Focus On 
55

Implementation. Washington DC: American Association of State Highway and 

Transportation Officials.

Grant, A., Wartman, J., Massey, C. I., Olsen, M. J., O’Banion, M., & Motley, M. (2017). The 

impact of rockfalls on dwellings during the 2011 Christchurch, New Zealand 

earthquakes. Landslides, https://doi.org/10.1007/s10346-017-0855-2.

Guerre, J., Groeger, J., Van Hecke, S., Simpson, A., Gonzalo, R., & Visintine, B. (2012). 

Improving FHWA’s Ability to Assess Highway Infrastructure Health Pilot Study Report.

Washington DC: Federal Hihgway Administration. Retrieved from 

http://www.fhwa.dot.gov/asset/pubs/hif12049/hif12049.pdf

Holmes, R.R., Jones, L.M., Eidenshink, J.C., Godt, J.W., Kirby, S.H., Love, J.J., Neal, C.A., 

Plant, N.G., Plunkett, M.L., Weaver, C.S., Wein, A. & Perry, S.C. (2012), U.S. 

Geological Survey natural hazards science strategy - Promoting the safety, security, and 

economic well-being of the Nation, Circular 1383-F, 1383-F, U.S. Geological Survey.

Huang, R. & Fan, X. (2013) The landslide story. Nature Geoscience, 6(5), pp. 325-326.

Landslide Technology. (2015). Rockfall Hazard Process Assessment: Task 1 Report Literature 

Search and Information Technology Review. Retrieved from 

http://www.mdt.mt.gov/research/projects/geotech/rockfall.shtml

Mackey, B. H., & Quigley, M. C. (2014). Strong proximal earthquakes revealed by cosmogenic 

3He dating of prehistoric rockfalls, Christchurch, New Zealand. Geology, 42(11), 975-

978.

Massey, C. I., McSaveney, M. J., Heron, D., & Lukovic, B. (2012). Canterbury Earthquakes 

2010/11 Port Hills slope stability: Pilot study for assessing life-safety risk from rockfalls 

(boulder rolls). GNS Science Consultancy Report 2011/311.

Massey, C.I., McSaveney, M.J., Taig, T., Richards, L., Litchfield, N.J., Rhoades, D.A., 

McVerry, G.H., Heron, D.W., Ries, W. & Van Dissen, R.J. 2014, Determining rockfall 

risk in Christchurch using rockfalls triggered by the 2010–2011 Canterbury earthquake 

sequence, New Zealand., Earthquake Spectra, 30, pp. 155-181

NCHRP. (2006). Performance Measures and Targets for Transportation Asset Management.

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NCHRP. (2009). Communication Matters - Communicating the Value of Transportation 

Research. Washington DC: Transportation Research Board. Retrieved from 

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Pierson, L., & Van Vickle, R. (1993). Rockfall Hazard Rating Program - Participants' Manual.

Washington DC: FHWA.

Pierson, L., Beckstrand, D., Black, B. (2005). Rockfall Hazard Classification and Mitigation 

System.: Montana Department of Transportation. Report No. FHWA/MT-05-011/8174.
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Sanford Bernhardt, K., Loehr, J. E., & Huaco, D. (2003). Asset Management Framework for 

Geotechnical Infrastructure. Journal of Infrastructure Systems.

Stanley, D. A., & Pierson, L. A. (2011). Geotechnical Asset Management Performance Measures 

for an Unstable Slope Management Program. Proceedings 62nd Highway Geology 

Symposium. Lexington, KY.

Stanley, D. A., & Pierson, L. A. (2012). Performance Measures for Rock Slopes and 

Appurtenances. In E. F. Eberhardt (Ed.), Landslides and Engineered Slopes: Protecting 

Society through Improved Understanding, Proceedings of the 11th International and 2nd 

North American Symposium on Landslides and Engineered Slopes, Vol. 2, (pp. 1113-

1118). Banff, Alberta, Canada.

Thompson, P. D. (2016). Geotechnical Asset Management Plan - Technical Report, Report No. 

STP000S(802)(B).

Thompson, P. D., Pierson, L. A., & Beckstrand, D. L. (2014, March/April). Condition Indices, 

Performance Measures, and Managing Performance Data for Geotechnical Asset 

Management – Don’t Get Buried! GEOSTRATA. Retrieved from 

http://geostrata.geoinstitute.org/article/2014-03-04p26-30/

US Department of Transportation. (2013). Guidance on Treatment of the Economic Value of a 

Statistical Life in U.S. Department of Transportation Analyses. US Department of 

Transportation. Retrieved from 

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US Forest Service. (2009). Road System Operations and Maintenance Handbook: Chapter 60 -

Road Maintenance. Retrieved from Road System Operations and Maintenance 

Handbook: Chapter 60 - Road Maintenance

Vessely, M. (2013). Geotechnical Asset Management, Implementation Concepts and Strategies.

Central Federal Lands Highway Division.
 

57

APPENDIX A. USMP RATING FORM DETAILED DESCRIPTIONS

UNSTABLE SLOPE MANAGEMENT

PROGRAM FOR FEDERAL LAND

MANAGEMENT AGENCIES –

RATING CATEGORY 

DESCRIPTIONS

Landslide Technology, WFLHD, NPS,

USFS, BLM, and Bureau of Indian Affairs (BIA)
 

58

TABLE OF CONTENTS

SITE INFORMATION ...................................................................................59

PRELIMINARY RATINGS .............................................................................65

DETAILED HAZARD RATINGS ......................................................................76

DETAILED RISK RATINGS (ROCKFALL AND LANDSLIDES).............................88

REFERENCES FOR APPENDIX A ...................................................................95
59

SITE INFORMATION

The top of the field data collection sheet contains fields for the collection of location and site 

information. These fields record location information and field measurements critical for later 

rating criteria. Many of the fields should be self-evident to the geological or engineering 

personnel who will be providing training, overseeing, and possibly performing the ratings, but 

some of the fields are explained in more detail below. Heading order follows the rating form

(see sample slope rating form in Appendix B).

Management Area

Federal Land Management Agency (FLMA) management area, specific for each FLMA. 

Examples include the region and four letter 

Park/Area code for the NPS, state and field 

office for the BLM, or region and forest for 

the US Forest Service. The “Other” category 

should be used when the transportation asset 

does not occur on land managed by NPS, 

BLM, or USFS. Select the State and County 

for the corresponding dropdowns in the 

“Other” category. These are standardized on 

the electronic forms.

Hazard Type

The section is divided into two unstable 

slope hazard types, rockfall and landslides. 

Rockfall failure types include classic failure 

mechanisms (planar, wedge, and toppling),

raveling rock slopes (such as talus slopes)

(Hoek & Bray, 1981), rock avalanche, 

differential erosion (interlayered weak and 

stronger rock), and indeterminate rock 

failures. See Figure 1 for simplified 

schematic drawings of each rock failure 

type. Note that the ‘Indeterminate Rock 

Failure’ classification is primarily for sites 

where the rockfall mechanism is a complex 

interaction between multiple joints such that 

the straightforward planar, wedge, or 

toppling models are insufficient to describe 

the failure mechanism. This classification 

may be quite common in steep, hard, jointed 

rock cuts. Marking multiple selections is

permissible.

Figure 1. Simplified rock slope failure types 

(planar, wedge, and toppling adapted from 

Hoek & Bray, 1981).
60

Landslides can be generally classified by both 

their location relative to the route in question and 

by broad failure mode. Translational slides are 

typically composed of intact blocks that are 

moving on a flat or inclined discrete failure plane 

weaker than the surrounding geologic material. 

Rotational slides are typically formed by a 

circular failure surface, often on steep slopes. 

Debris flows are sudden, fast moving flows 

comprised of rock, soil, water and woody debris. 

Shallow slumps are common on transportation 

systems where the shoulder or outside lane are 

failing within the fill material or from debris 

above the road. Erosional failures are typical 

where the river system or culvert outfall is 

eroding the embankment or slope below the road 

which currently or may threaten the route in the 

future. See Figure 2 for simplified schematic 

drawings of each soil failure type, some 

modified from Cruden and Varnes, 1996 or 

Cornforth, 2005.

Road/Trail No. and Classification

Use the standard road numbering or naming 

approach for the FLMA’s road system. Note the 

road or trail’s classification (abbreviated as 

‘class’ on the form) according to the Agency’s 

road maintenance or use level 

classification/designation schema. 

Length of Affected Road/Trail

This is measured as the length of the road or trail 

adjacent to the hazard. For rockfall, it is 

measured from the start to the end of the cut 

slope or outcrop, not just where the highest level 

of rockfall activity is present. For landslides, it 

is measured from the beginning to the end of the 

slide where it is affecting the road or trail. For 

roadways, the affected length measurement 

includes both the paved road surface and the 

embankment on which the road is founded. For 

slides above the road, the affected length is 

measured as the distance over which the slide is 

Figure 2. Simplified landslide failure types 

(Cruden & Varnes, 1996; Cornforth, 

2005).
61

likely to impact the road or trail, from one end to the other. This measure is used in rating 

calculations.

Beginning and Ending Mile Markers

Use the posted mile markers and an offset with two decimal places. Ancillary vehicle devices 

(such as distance measuring devices) are helpful, but not required. Third-party mobile device 

odometer applications may also provide sufficiently accurate offsets. When markers are not 

posted, or used, a distance with direction from a main intersection may be sufficient to note in 

the comments section on the form. However, based on USMP practitioner feedback, it is 

strongly suggested that latitude and longitude locations be used as the primary locater because 

mile markers (when present) can change over time with realignments and administrative changes 

to road mileage. 

Side of the Road

Side of the road or trail is either left or right while travelling up mile point. When an unstable 

slope impacts both sides of the route, like a deep-seated landslide, note the upslope direction for 

side of the road or trail. Use cardinal directions when the route does not have mile markers 

posted.

Datum

Record the datum of the coordinate system. Note that WGS 84 is required for proper entry into 

the online mapping system so coordinates may need to be converted to WGS 84 if collected in 

another format.

Slope Height/Axial Length

This is measured as the maximum vertical 

height of the rock slope or the maximum axial 

length (slope distance) of a landslide feature. 

On short embankments where it appears that a 

fill failure is at fault, this measure is typically 

the axial length from the top to the base of fill; 

in other cases, engineering judgment may be 

needed. For debris flows, the axial length 

measurement could be in the thousands of feet 

due to the channel length (or axial length) being 

quite long. For safety and expediency, often 

times the axial length of the track of the debris 

flow can be measured through recent 

orthophotography or widely available electronic 

imaging available on the internet (see note 1 in 

Category K below). This measure is used in 

Figure 3. Examples of measuring vertical slope 

height on a rock slope and axial length on a 

landslide.
62

rating calculations. See Figure 3 for an example of evaluating slope height for rock slopes or 

landslides.

Slope angle

This is the average or representative angle of the rock cut slope/outcrop or the angle of the 

failing embankment or soil slope. This measure is not used in rating calculations.

Sight Distance

Sight distance is measured as the length of roadway from when a two-foot object is first seen 

from a driving position (3.5 feet from the road surface) until the object is reached. Sight distance 

is typically hindered by narrow shoulders, poor ditch vegetation control, and vertical and 

horizontal roadway curvature. The location’s sight distance should be measured in the lane 

direction with the worst visibility. This measure is used in rating calculations.

Roadway/Trail Width

This is measured as the available paved width of the roadway or trail, including paved shoulders 

as it exists at the time of rating. If the slope is rated while the road is partially closed due to 

debris or damage, repair of damage to the full width would require a new or updated rating to 

document the improvement to this unstable slope section. On unpaved routes, such as aggregate 

or native surface roads or trails, it would be the measured as the drivable or navigable width. 

Where width changes within a section, it should be taken at the narrowest part of the section. 

This measure is used in rating calculations.

Speed Limit

Record the speed limit in effect at the unstable slope. If lower advisory speeds are posted, those 

supersede the regular, posted speed limit. This measure is used in rating calculations.
63

Ditch Width/Depth/Foreslope

For rockfall areas, the roadside catchment 

ditch is an important rockfall risk reduction 

mitigation measure. A clean, wide ditch 

with a well-maintained foreslope is one of 

the most common risk reduction mitigation 

measures on transportation systems. Provide 

a measure of the range of ditch widths and 

depths and a representative foreslope angle. 

If needed, provide a note on the cleanliness 

of the ditch in the comments area of the 

form. This measure is not used in rating 

calculations.

Block Size/Volume

For rockfall only. Enter a reasonable value for the largest rock size (in feet) that could enter the 

roadway. This can be estimated by observation of rocks in the ditch, rocks that appear loose on 

the slope, or interviews with maintenance personnel (preferred). If a volumetric event is the 

dominant failure mechanism, enter the number of cubic yards that have or reasonably could enter 

the roadway. Again, interviewing maintenance personnel is very important to collect this 

historical information. This measure is used in rating calculations.

Annual Rainfall

Enter the average annual rainfall for the location. This measure is used in rating calculations. If 

a range is not available, then use the average rainfall for both ends of the minimum-maximum 

range. Precipitation maps are typically available on a statewide basis from Regional Climate 

Centers (such as the Western Regional Climate Center (http://www.wrcc.dri.edu/) or the state’s 

weather service. This measure is used in rating calculations.

Sole Access Route

If there are no alternative routes or detours in the event of a road closure, select “Yes”, otherwise 

select “No”. When seasonal closures create a sole access route condition, select “Yes”. This 

measure is not used in rating calculations.

Mitigation (Fixes) Present

If mitigation measures have been undertaken to halt or slow down a landslide, stabilize the rock 

slope, prevent rocks from reaching the roadway, etc., check the appropriate box. Typically, 

asphalt patches do not offer any appreciable stabilization effect on landslides and eventually can 

accelerate movement, so do not include patching or crack sealing as mitigation for landslides. 

On the paper field form, this field is listed as ‘Fixes Present’ due to space constraints. This 

Figure 4. Simple schematic of rock slope 

ditch.
64

measure is not used in rating calculations but provides a searchable field for uploading past 

unstable slope work documents and photos.

Photo/Documents Upload

Take (GPS-located) site photos and upload with your preferred hand-held device using the 

USMP Android or iOS application (recommended). Note that the size of photos and documents 

will be automatically reduced to 1600 by 1600 pixels to conserve space. Downloaded 

documents are limited to 10 Mb in size. For the paper forms, record the photo number range for 

the photos taken at the site, such as DSC005891.JPG to DSC005898.JPG, to help stay organized. 

These are often viewable on the digital camera’s image review screen.
65

PRELIMINARY RATINGS

The preliminary ratings are a select subset of the comprehensive rating categories. This subset is 

intended to provide guidance on whether to continue the rating assessment and can be used to 

include or exclude a candidate unstable slope location from the final database. If a site falls 

below the suggested score cutoffs, an agency may opt to completely exclude the site from the 

unstable slope database. If a site later becomes more of an issue, it should be assumed that the 

site has degraded from an acceptable to an unacceptable condition. If the site’s Preliminary 

Rating is above the suggested cutoff score of 21 (all scores of ‘3,’ with allowance of one ‘9’), the 

full field rating should be completed.

Note that all calculated category scores max out at 100 points.

When evaluating categories that are not calculated and have a max score of 81 points, it is not 

uncommon to determine that you are between two rating categories, for example, between 9 and 

27. When in doubt, it is advisable to select the higher rating value, and be consistent in your 

usage of this rule-of-thumb. When programmatic decisions are made for scoring cutoffs, you 

will want to make sure a seasoned geotechnical specialist will have an opportunity to review 

these unstable slopes that may be on the cusp of the cutoff score. As part of the conceptual 

design work, the geotechnical specialist will review the USMP rating and adjust it as needed. In 

some cases, this will lower some of the total scores below the cut line and they will not be further 

considered for conceptual design at this stage of the process. Selecting lower scores in some 

situations could result in missing some unstable slopes that deserved to be in the cutoff for 

further evaluation. This discussion will become clearer as you use the USMP process more and 

more.

Landslide-Specific Preliminary Hazard Ratings

Letters used in subsection headings correspond to specific fields in the slope rating forms (see 

Appendix B.)

A. Roadway Width Affected

When a part of the roadway or trail is lost, or blocked the following can occur: collision with the 

debris, driving off a scarp, attempting an evasive maneuver where the driver goes off the road or 

into oncoming traffic, or a hiker is forced into a hazardous situation that can lead to an accident. 

The hazard is related to the percentage of the roadway or trail affected.
66

Table 1. Preliminary Landslide Slope Rating – Roadway Impedance Category Narratives

3 points 0-5 percent The travel lanes are generally not affected by the landslide feature, but the 

available paved surface is reduced. A detour or traffic control (flagging) is typically not 

required except during maintenance activities. Trails typically are only slightly affected.

9 points 6-25 percent Events affect up to 25% of the travel lanes. Adequate paved surface is 

available to maneuver around the event. A detour is typically not required but traffic 

control may need to be utilized until the roadway is reestablished. A visual cue for 

tripping hazards may be needed on trails.

27 points 26-50 percent Events affect up to half of the surface dedicated to travel lanes. 

Maneuvering actions may still be possible by using paved or unpaved shoulders, if 

available. A detour or complete vehicle stoppage may be required. A visual cue for 

tripping hazards may be needed on trails and maintenance may be considered.

81 points 51-100 percent Events affect more than half of the road with limited paved surface 

available to maneuver around the event. A detour or stopping traffic flow is required. 

Trails may be closed and maintenance may be required to keep the trail open.

Example of roadways affected by landslide or settlement-related displacement are presented in 

Figures 5 and 6 below. As shown in Figure 5, the affected roadway width can vary throughout 

the site extents. The score should be based on the largest percentage observed at the site or 

reasonably predicted to occur in the event of landslide movement.

Figure 5. Embankment failure affecting up to 25 percent of the roadway. Forest Service 

Road 25, Milepost 30.
67

Figure 6. Embankment failure affecting entire roadway. Forest Service Road 25, Milepost 

25.

B. Slide/Erosion Effects

Unanticipated condition changes in a travel 

lane, such as those shown in Figure 7 at 

right, can result in unsafe maneuvers or loss 

of vehicle control. Larger obstructions 

increase the likelihood of an accident and 

require more maintenance effort and cost to 

repair. The category is scored by following 

the rating category narratives in the table 

below. Offsets indicated in the table below 

can be either horizontal or vertical.

Note: For trails, the slower driving speed 

indicated in the table below may be 

reflected in increased tripping hazards 

rather than lower speed limits.

Figure 7: Roadway deformation caused by 

embankment failure. Forest Service Road 90, 

Milepost 11.5.
68

Table 2. Preliminary Landslide Slope Rating – Slide/Erosion Effects Category Narratives

3 points Visible crack or slight deposit of material on road/minor erosion. For paved routes, slight 

pavement cracking or heaving, or a thin deposit of slide debris has occurred but they are small 

enough not to disturb traffic flow or require evasive maneuvers. Scheduled roadway maintenance 

is required. 

For thaw unstable slopes and/or unpaved routes, normal roadway speeds and driving behavior is 

maintained throughout the affected section. 

For trails, public activity is not affected.

9 points 1 inch offset, or 6-inch deposit of material on road/major erosion will affect travel in <5 years. For 

paved routes, a noticeable drop or heave in the pavement or a deposit of slide debris has occurred 

that requires lower speeds to traverse. Maintenance attention is required. 

For thaw unstable slopes and/or unpaved routes, a notable vertical movement is felt when 

traversing the affected roadway section at the speed limit.

For trails, public activity is not affected, but movement is noticeable.

27 points 2-inch offset or 12-inch deposit of material on road/moderate erosion impacting travel annually. 

For paved routes, a large drop or heave in the pavement or a deposit of slide debris has occurred 

that requires significantly lower speeds to traverse and may elicit unsafe driver reactions. 

Immediate maintenance attention is required.

For thaw unstable slopes and/or unpaved routes, breaking or evasive maneuvering is required when 

travelling the speed limit.

For trails, public activity is affected, prompting some to avoid the trail or turn back.

81 points 4-inch offset or 24-inch deposit of material on road/severe erosion impacting traffic consistently. A 

major drop or heave in the pavement or deposit of slide debris has occurred that cannot be 

traversed. Unsafe driver reactions are likely and immediate maintenance attention is required to 

reestablish safe traffic flow.

For thaw unstable slopes and/or unpaved routes, these sections have been marked by maintenance 

crews with warning signs, cones, or a temporary reduction of the speed limit.

For trails, the trail is periodically closed due to slide activity or the public needs to carefully 

traverse a severe offset.

C. Roadway Length Affected

The length of the roadway (or trail) affected by a landslide poses a hazard to the travelling public 

by increasing the likelihood of encountering the hazard, diverting into an adjacent lane, or 

increasing the distance or length of time the hazard will need to be avoided. To the agency, the 

length is proportional to the maintenance required and the costs associated with treatment. 

Longer slides will also require longer (both time duration and spatial length) lane closures during 

maintenance or repair activities. 

The length of roadway affected by landslide deformation is measured in the field, and the score 

is directly calculated from these field measurements, using the equation below. A graph of this 

equation is also provided for reference in Figure 8, as well as a table showing sample category 

scores, Table 3. 

SS = 3xx (max 100); = � h rr rrrr aa

25 ( )

Equation 1. Length of Roadway Affected Score
69

Figure 8. Chart illustrating the relationship between the length of roadway affected and the 

category score. The category score maxes out at an affected roadway length of about 440 

feet.

Table 3. Preliminary Landslide Slope Rating – Roadway Length Affected Sample 

Calculated Scores

3 points 25 feet

9 points 100 feet

27 points 225 feet

81 points 400 feet

Rockfall-Specific Preliminary Hazard Ratings

D. Ditch Effectiveness

The effectiveness of a ditch or catchment is measured by its ability to restrict falling rock from 

reaching the paved roadway, including any paved shoulder. The risk associated with a particular 

rock slope section is dependent on how well the ditch is performing in capturing rockfall. When 

little rock reaches the roadway, no matter how much rockfall is released from the slope, the 

danger to the public is low and the category score assessed is low. Conversely, if rockfall events 

are rare occurrences but the ditch is nonexistent, the resulting hazard is greater and a higher score 

is assigned to this category. Many factors must be considered in evaluating this category. The 

reliability of the result depends heavily on the rater's experience. Ditch Effectiveness is a 

subjective category. Figure 9 presents a graphic diagram of ditch effectiveness for guidance.

0

25

50

75

100

0 50 100 150 200 250 300 350 400 450

Roadway Length Category Score

Roadway Length Affected (ft.)
70

Figure 9. Ditch effectiveness explanatory diagram.

A wide fallout area does not necessarily guarantee that rockfall will be restricted from the 

highway. In estimating the ditch effectiveness, the rater should consider several factors, such as: 

1) slope height and angle; 2) ditch width, depth and shape; 3) anticipated rockfall event volume 

or rock size; and 4) impact of slope irregularities (launch features) on falling rocks. Evaluating 

the effect of slope irregularities is especially important because they can completely negate the 

benefits expected from a fallout area. Valuable information on past ditch performance can be 

obtained from maintenance personnel.

Table 4. Preliminary Rock Slope Rating – Ditch Effectiveness Category Narratives

3 points Good Catchment. All or nearly all falling rocks are retained in the catch ditch.

9 points Moderate Catchment. Falling rocks occasionally reach the roadway.

27 points Limited Catchment. Falling rocks frequently reach the roadway.

81 points No Catchment. No ditch, or ditch is totally ineffective. All or nearly all falling rocks 

reach the road.

E. Rockfall History

The rockfall history directly represents the known rockfall activity at the site. This information 

is an important check on the potential for future rockfalls. This information is best obtained 

from the maintenance personnel responsible for the slope. There may be no history available at 

newly constructed sites or where documentation practices are poor. The maintenance costs 

associated with a site may be the only information that reflects the rockfall activity. 
71

If the score a rater assigns to a section is determined not to correspond well with the rockfall 

history, a review of the rating is advisable.

Table 5. Preliminary Rock Slope Rating – Rockfall History Category Narratives

3 points Few Falls. Rockfalls occur only a few times a year (or less), or only during severe storms. 

This category is also used if no rockfall history data is available and evidence of rockfall 

is absent.

9 points Occasional Falls. Rockfall occurs regularly. Rockfall can be expected several times per 

year and during most storms.

27 points Many Falls. Typically, rockfall occurs frequently during a certain season, such as the 

winter or spring wet period, or the winter freeze/thaw, etc. This category is for sites where 

frequent rockfalls occur during a certain season but are not a significant problem during 

the rest of the year. This category may also be used where severe rockfall events have 

occurred.

81 points Constant Falls. Rockfalls occur frequently throughout the year. This category is also for 

sites where severe rockfall events are common.

F. Block Size or Volume per Event

Larger blocks or volumes of falling rock produce more total kinetic energy and greater impact 

force than smaller events. In addition, the larger events obstruct more of the roadway, reducing 

the possibility of safely avoiding the rock(s), and result in higher cleanup costs for the managing 

agency. In essence, the larger the blocks or event volume; the greater the hazard created; thus 

the higher the assigned score in this category.

This measurement should be representative of the type of rockfall event most likely to occur. As 

shown in Figure 10, debris currently contained in the roadside ditch can help generate a 

reasonable estimate. If individual blocks are typical of the rockfall at a site, as at the site in

Figure 10, then block size should be used for scoring. If a mass of blocks tends to be the 

dominant type of rockfall, volume per event should be used. A decision on which to use can be 

determined from the maintenance history, or estimated from observed conditions when no 

history is available. This measurement will also be beneficial in determining remedial measures.
72

Figure 10. Rockfall debris in the roadside ditch can be used to help assess both block 

size/event volume and failure type. Forest Service Rd 25, Milepost 25.

The category score is calculated according to the following equations. If the rater is uncertain, or 

both block size and volumetric events are present/feasible, rate the site using both equations and

record the higher of the two scores. If values for block size and volume are both are 

present/feasible and entered into the USMP electronic form under the block size/volume in Site 

Information, the larger of the two calculations will be recorded in this category. A pair of charts 

showing the exponential relationship between block size/event volume and category score is also 

presented in Figure 11 for reference, as are sample calculated category scores in Table 6.

BB SS SS SS = 3xx (max 100) ; = bb ( )

VV VV SS SS SS = 3xx (max 100) ; = �

3

3 �

Equation 2. Block Size and Volume Size Score
73

Figure 11. Chart pair illustrating the relationship between the block size and the category 

score and between the event volume and the category score. Note that the category score 

for block size maxes out for block sizes greater than 4 feet, while the category score for 

event volume maxes out for events over 12 cubic yards.

Table 6. Preliminary Rock Slope Rating – Block Size or Volume Size Sample Calculated 

Scores

Block Size Volume Size

3 points 1 foot 3 cubic yards

9 points 2 feet 6 cubic yards

27 points 3 feet 9 cubic yards

81 points 4 feet 12 cubic yards

Common Preliminary Slope Risk Ratings (Rockfall and Landslides)

G. Impact on Use 

Impacts on the transportation system due to a failure can be minimized if the expected impacts 

would be minimal, or if a detour around the site is available. The scoring should take into 

account a probable worst-case scenario, rockfall history, and geologic conditions when judging 

the impacts on traffic.

0

25

50

75

100

0 1 2 3 4 5

Block Size Category Score

Block Size (feet)

0

25

50

75

100

0 3 6 9 12 15

Event Volumne Category Score

Event Volume (cubic yds)
74

Table 7. Common Preliminary Rating – Traffic Impacts Category Narratives

3 points Full use continues with minor delay. A wide shoulder is available for traffic diversion for 

large slide events; small rockfall events contained in the ditch; nearby detours are 

available.

9 points Partial use remains. Use modification required, short (<3mile/30min.) detour available. 

Traffic control for a lane closure or detour is required for maintenance or clean-up. 

Detours are less than 3 miles or under 30 minutes in length for up to 1 day.

27 points Use is blocked – long (>30 min) detour available or less than 1 day closure for up to 1 

week. 

81 points Use is blocked – no detour available or closure longer than 1 week. Major reconstruction 

efforts with weeks or months closure with no detour.

H. Annual Average Daily Traffic (AADT) or Usage/Economic/Recreational Importance

This category is designed to capture route or trail importance and can be assessed using either 

quantitative or qualitative data. The AADT of a roadway provides a rough quantitative indicator 

of its impact on the regional economy and mobility of people, goods, and services. High traffic 

corridors will receive a higher risk score. The AADT score is based on the following equation:

SS = 3xx (max 100) ; = �AAAAAAAA

50

Equation 3. Annual Average Daily Traffic Score

Figure 12. Chart illustrating the relationship between AADT and the category score. The 

category score maxes out at an AADT of approximately 880 vehicles.

0

25

50

75

100

0 100 200 300 400 500 600 700 800 900

AADT Category Score

Annual Average Daily Traffic (AADT)
75

For those roads or trails where AADT information is not available (uncheck the “Use AADT in 

Calculation” box on the electronic form), a qualitative score relating to usage and relative 

economic/recreational importance is applied, as shown in Table 8. 

Table 8. Common Preliminary Rating – AADT Sample Calculated Scores

AADT Score* Qualitative Usage/Economic/Recreational Importance Score*

3 points 50 Rarely used. Insignificant economic and/or recreational importance

9 points 200 Occasionally used. Minor economic and/or recreational importance

27 points 450 Frequently used. Moderate economic and/or recreational importance

81 points 800 Constantly used. Significant economic and/or recreational importance

*The highest rating of the two category narratives is applied

For a site where both quantitative (AADT) and qualitative (i.e., relative importance) data is 

available, both categories should be evaluated, and the highest resulting score given to the site. 

For example, a roadway that is the only route to a popular trail may be of moderate recreational 

importance (27 pts), but the AADT is only 200 (9 pts). For this site, the higher score of 27 

would be used.

Preliminary Rating Score

Following the completion of the Preliminary Ratings, the slopes can be categorized into one of 

three categories of ‘Good’, ‘Fair’, or ‘Poor.’ This language is consistent with Federal legislation 

for bridge and pavement asset management regulations. Depending on your agency’s approach 

to conducting ratings, ‘Good’ slopes may not require further assessment. If a slope is 

categorized as ‘Fair’ or ‘Poor,’ this may trigger further evaluation and completion of the Hazard 

and Risk Categories. At a minimum, Fair and Poor sites should have the full detailed ratings 

performed.

Table 9. Good, Fair, and Poor Score Ranges.

Descriptor Preliminary Score Range

Good 15-21

Fair 22-161

Poor >161
76

DETAILED HAZARD RATINGS

The Detailed Ratings complete the suite of possible rating categories. Depending on an agency’s 

rating approach, these categories will be evaluated if the Preliminary Rating is above a cutoff 

score, proposed as 21 in this manual, but official policy or documented decisions regarding the 

rational for adjusting these cutoff scores between good, fair, and poor slopes are left to the 

discretion of each participating agency or department.

Common Hazard Ratings (Rockfall and Landslides)

I. Slope Drainage

In conjunction with rainfall quantity, the ability of the slope materials to be free draining and the 

presence of seeps and/or springs (indicating a relatively constant water source) provides 

information on the ability of the slope to cope with rainfall and freeze-thaw events. This 

subcategory is based on subjective evaluations. Note that rating this category at different times 

of the year may produce different results as creeks and springs may dry up during late summer 

months. For guidance in field evaluations, Figure 13 is provided below, and rating category 

narratives are provided in Table 10.

Figure 13. Guidance figure for evaluating slope drainage.
77

Table 10. Common Hazard Rating - Slope Drainage Category Narratives

3 points Well Drained. Slope appears dry or well drained; surface runoff well controlled; slope is 

dry hours after rain events; or a functioning drainage system is installed.

9 points Moderately Well Drained. Water is intermittently on slope; moderately well drained; 

surface runoff moderately controlled; slope is dry days after rain events.

27 points Moderately Poorly Drained. Water usually on slope; poorly drained; surface runoff 

poorly controlled; slope is still wet a week or two following rain events, but may dry 

during prolonged dry spells.

81 points Poorly Drained. Water always on slope; very poorly drained; or surface water runoff 

control not present.

J. Annual Rainfall

In conjunction with slope drainage, the amount of annual rainfall at a site is a rough indicator of 

the frequency and potential for high pore-water pressures to accumulate. Areas with frequent, 

intense storms typically have more unstable rock and soil slopes. 

This subcategory is rated based on rainfall ranges. A rock slope in an area with 12 inches of 

average annual rainfall and a rock slope in an area with 29 inches of average annual rainfall 

should both receive a score of 9 points in this category. Because annual rainfall cannot be 

estimated during a site visit, annual rainfall data must be obtained from an appropriate regional 

or local source before starting field work.

Table 11. Common Hazard Rating – Annual Rainfall

3 points 0-10 inches of rain annually

9 points 10-30 inches of rain annually

27 points 30-60 inches of rain annually

81 points 60+ inches of rain annually
78

K. Slope Height or Axial Length of Slide

This category evaluates the risk 

associated with the height of a rock slope 

or axial length of a landslide or debris 

flow. The slope height measurement is to 

the highest point from which rockfall is 

expected or the axial length (slope 

distance) of a landslide, as shown in the 

adjacent figure. The Site Information 

portion of the form should already 

contain these measurements.

If rockfall is generated from the natural 

slope above the cut slope, the slope height 

measurement should include both the cut 

height and the additional vertical height 

on the natural slope to the rockfall source. 

On a landslide, the distance from scarp to 

toe should be measured. For debris flows 

the approximate axial or channel distance 

from the roadway to the source area 

should be entered.1

In cold climates, thaw instability can affect roadway embankments that run over relatively flat 

ground. In those cases, the axial length of the slide is assumed to be equal to the axial length of 

the embankment fill prism. Although thaw instability can affect an embankment over many 

hundreds of feet, which is captured in the Roadway Length Affected in Category C, the 

maximum slump or settlement caused by thawing soils cannot exceed the height of the roadway 

embankment.

This category is directly measured and scored using the equation presented below. A chart 

relating slope height/axial length and category score is presented for reference, as is a table 

containing sample calculated category scores.

SS = 3xx (max 100) ; = ss h h aa aa h

25

Equation 4: Slope Height or Axial Length Score

 

1 Note: Channel length measurements for debris flows do not need to be precise, as the rating category score maxes 

out at a slope height/axial length of approximately 105 ft. An estimated channel length of 1,000 feet or of one mile 

has the same net effect: maxing out the rating score for this category. 

Figure 14. Examples of measuring vertical slope 

height on a rock slope and axial length on a 

landslide.
79

Figure 15. Chart illustrating the relationship between the slope height or axial length and 

the category score. The category score maxes out at height/axial length of approximately 

105 feet

Table 12. Common Hazard Rating - Slope Height or Axial Length of Slide Sample 

Calculated Scores

3 points 25 feet

9 points 50 feet

27 points 75 feet

81 points 100 feet

Landslide-Specific Hazards 

L. Thaw Stability (Cold Climates)

Roads and embankments founded on melting permafrost become unstable, creating a rough and 

wavy driving surface along with other roadway hazards. Melting slopes above the road become 

unstable and have the potential to impact the roadway. Depending on the gradation, soils 

containing frozen water pose maintenance problems if the ice thaws. The magnitude and 

likelihood of related problems are higher for finer-grained soils that contain large amounts of ice 

or ice layers. Where the ice-bearing layers are not visible, base the thaw stability on the relative 

performance of the roadway.

While performing field ratings, the subsurface condition described below can be estimated by the 

surficial expressions of thaw instability. For instance, thaw instability is often expressed by 

wavy pavements. Low amplitude ‘waves’ that developed over a long period of time represent 

greater thaw stability than higher amplitudes that develop quickly or need frequent repair. 

0

25

50

75

100

0 10 20 30 40 50 60 70 80 90 100 110

Height/Axial Length Category Score

Slope Height or Axial Length (ft)
80

Examination of nearby outcrops or cuts may expose ice conditions. A review of local geology 

and geomorphic features indicating ice (patterned ground, palsas, pingos, etc.) assists with 

interpreting subsurface ice conditions.

Table 13. Detailed Landslide Slope Rating – Thaw Stability Category Narratives

3 points Unfrozen / Thaw Stable. Soil may be coarse- or fine-grained. No ice is visible with the 

naked eye, but if present, it does not occupy space in excess of the original voids. These 

soils are usually thaw-stable. No thaw unstable slopes should be rated in this category

9 points Slightly Thaw Unstable. Soil is coarse-grained. Ice occupies space equal to, or in excess 

of, the original voids. It is present as crystals or lenses visible with the naked eye. These 

soils may be thaw-unstable depending on soil density. Few thaw unstable slopes should be 

rated in this subcategory.

27 points Moderately Thaw Unstable. Soil is fine-grained. Ice occupies space equal to, or in excess 

of the original voids and is present as crystals or lenses visible with the naked eye. These 

soils are typically thaw-unstable. Most thaw unstable slopes are rated in this category 

based on relative performance of the roadway.

81 points Highly Thaw Unstable. Soil layers contain significant quantities of ice well in excess of 

the original void space. The ice is readily visible with the naked eye and is present as 

large lenses or as separate ice layers. These materials are highly thaw-unstable. Any 

embankment sections with characteristics indicating a likelihood or history of rapid failure 

or severe displacement due to the presence of thaw unstable materials should be rated in 

this subcategory.

M. Instability-Related Maintenance Frequency

As instability-related movement progresses, 

trail or roadway deformation begins to hamper 

performance, and maintenance attention is 

required to ensure that the site remains 

passable. Slide maintenance puts staff and 

equipment in, or near the road, which may 

impede traffic and exposes both maintenance 

personnel and the general public to potential 

hazards. The more often maintenance activity 

is required, the greater the hazards posed to the 

public and maintenance staff, and the greater 

the maintenance cost.

Maintenance frequency should be determined 

through an interview with maintenance 

personnel, but it can be initially estimated by 

the rater based on field observation, and refined in interviews with maintenance personnel

following field work. This category is rated subjectively based on the rating category narratives 

in Table 14 below.

Figure 16. Instability requiring repeated 

maintenance attention. Forest Service Road 

25, Milepost 25.
81

Table 14. Detailed Landslide Slope Rating – Maintenance Frequency Category Narratives

3 points Every 10 years. Events requiring maintenance intervention are relatively rare or 

nonrecurring and/or the repair activities can typically be completed using standard 

equipment with minimal impacts to traffic flow.

9 points Every 5 years. Maintenance intervention is required occasionally and/or the repair 

activities can usually be completed in less than a day using standard equipment, but traffic 

flow is reduced and flagging is required.

27 points Every 2 years. Maintenance action is routinely required and/or the repair activities require 

non-standard equipment or more than one day to complete; or the traffic flow is 

significantly impeded for more than a day and flagging is required.

81 points Every year. Maintenance is required one or more times per year or wherever major events 

have occurred requiring several days to restore traffic. This category also applies if an 

outside contractor is required.

N. Movement History

The rate of slide movement per event and the frequency of events relate to public hazard and 

maintenance requirements. Higher rates of movement are more likely to create unanticipated 

roadway conditions that require immediate, unscheduled maintenance. This category should be 

rated based on input from maintenance personnel, since it is difficult to accurately assess an 

annual rate of movement from a single site visit. Movement magnitudes focus on paved 

roadways. For trails and unpaved roads, evaluate the impacts of movement according to the 

descriptions in Table 15.

Table 15. Detailed Landslide Slope Rating – Movement History Category Narratives

3 points Minor movement or sporadic creep. The rate of movement is low and non-continuous. 

Pavement disturbance is minor on an annual basis and maintenance requirements are 

minimal and carried out as a scheduled activity. 

9 points Up to 1 inch annually or steady annual creep. The rate of movement is low but 

continuous. Corridor maintenance is routinely required to avoid closures but maintenance 

action can generally be conducted on a scheduled basis.

27 points Up to 3 inches per event, one event per year. The rate of movement is moderately high. 

Events occurring more than twice a year that require immediate and unscheduled 

maintenance are a persistent maintenance problem.

81 points >3 inches per event, >6 inches annually, or more than 1 event per year (includes all 

debris flows). The rate of movement is high with significant travel disturbance 

developing quickly. Aggressive, unscheduled maintenance intervention is required to 

maintain traffic flow and correct unsafe conditions.

Rockfall-Specific Hazards

O. Rockfall Related Maintenance Frequency

The required frequency of maintenance is an indicator of both rockfall activity and long-term 

cost to the agency. When there is little to no maintenance required and only scheduled ditch 
82

cleaning required, both maintenance staff and the travelling public are typically not exposed to 

risk and little cost to the agency is required. As rockfall activity increases at a site, additional 

surveillance activities specifically checking for rockfall activity may be warranted after storm 

events and rockfall clean-up activities increase. An example of a rock slope requiring almost

daily maintenance attention is shown in the figure below.

Figure 17. Constant rockfalls occur at this rock slope on the Glenn Highway in Alaska. 

Maintenance personnel stockpile the daily debris in this pullout for regular removal. This 

rock cut received a category score of 81.

Maintenance frequency should be determined through an interview with maintenance personnel, 

but it can be initially estimated from conditions observed at the site, as in the figure above, but 

category ratings should be confirmed through discussions with maintenance personnel following 

field work.

Table 16. Detailed Rock Slope Rating – Rockfall-Related Maintenance Frequency Category 

Narratives

3 points Normal, scheduled ditch maintenance. Only routine, scheduled ditch maintenance is 

required on an infrequent (3-5 year) basis. Few, if any rocks accumulate in ditch between 

maintenance intervals.

9 points Road Patrols conducted after storm events. Maintenance staff only actively search for

rock within the ditch or roadway after extreme storm events. Ditch cleanout of rock 

debris is infrequently required beyond scheduled ditch cleaning.

27 points Routine seasonal road patrols. Maintenance staff routinely patrol for rock during typically 

high rockfall seasons (fall, winter, spring). Ditch cleanout of rock debris is occasionally 

required beyond scheduled ditch cleaning.

81 points Year-round road patrols. Maintenance staff routinely patrol for rock year round. Ditch 

cleanout of rock debris is frequently required beyond scheduled ditch cleaning.
83

Geologic Character

The geologic conditions of the rockfall section are evaluated with these categories. Since the 

conditions that cause rockfall generally fit into two categories, Case 1 and Case 2 rating criteria 

have been developed. Case 1 is for slopes where joints, bedding planes, or other discontinuities 

are the dominant structural features that lead to rockfall. Case 2 is for slopes where differential 

erosion or oversteepening is the dominant condition that controls rockfall. 

Raters should use the case that best fits the slope for the rating. If both situations are present, and 

it is unclear which dominates, both can be scored, but only the worst case (highest score) is used 

in the rating. 

Case 1

Rockfall from Case One slopes occurs as a 

result of movement along discontinuities. 

The word “joint” as applied here, which 

represents all possible types of 

discontinuities, including bedding planes, 

foliations, fractures, and faults. The term 

“continuous” refers to joints that are greater 

than 10 feet in length. The term “adverse” 

applies not only to the joint's spatial 

relationship to the slope, but also to such 

things as rock friction angle, joint infilling, 

and the effects of water on slope stability, if 

present. An example of a rock slope in 

geologic Case 1 is shown in Figure 18.

P. Case 1 - Structural Condition

Jointed rock is typically more prone to rockfall than massive rock. Movement occurs along these 

joints where the resistance to movement is significantly less than the intact strength of the rock 

itself. When the joints are orientated adversely to the slope, the potential for rockfall is greater. 

Adverse joints are those that singularly, or in combination with other joints, make planar, 

circular, block, wedge or toppling failures kinematically possible.

Figure 18. Rock cut where failure is 

controlled by interaction between geologic 

structure and rock friction. Forest Service 

Road 90, Milepost 13.
84

Table 17. Detailed Rock Slope Rating – Case 1 Structural Condition Category Narratives

3 points Joints with favorable orientations. Slope contains jointed rock with no or very few 

adversely oriented joints.

9 points Random (both favorable and unfavorable) orientations. Slope contains randomly oriented 

joints creating a variable pattern. The slope is likely to have some scattered blocks with 

adversely oriented joints, but no dominant adverse pattern is present.

27 points Discontinuous joints with adverse orientations. Rock slope exhibits a prominent joint 

pattern with an adverse orientation. These features have less than 10 feet of continuous 

length.

81 points Continuous joints with adverse orientations. Rock slope exhibits a dominant joint pattern 

with an adverse orientation and a length greater than 10 feet.

Q. Case 1 - Rock Friction

The potential for rockfall caused by movement along discontinuities is controlled by the 

condition of the joints. The condition of the joints is described in terms of micro and macro 

roughness. The Joint Roughness Coefficient (JRC) (Barton & Choubey, 1977) can be used as a

guide for approximating roughness.

This parameter directly affects the potential for a block to move relative to another. Friction 

along a joint, bedding plane, or other discontinuity is governed by the macro and micro 

roughness of the surfaces. Macro roughness is the degree of undulation of the joint relative to 

the direction of possible movement. Micro roughness is the texture of the surface. Rockfall 

potential is greater on slopes where the joints contain hydrothermally altered or weathered 

material, movement has occurred causing slickensides or fault gouge to form, or the joints are 

open or filled with water. 

Table 18. Detailed Rock Slope Rating – Case 1 Rock Friction Category Narratives

3 points Rough. Irregular. The surface of the joints is rough and the joint planes are irregular 

enough to cause interlocking.

9 points Undulating. Rough but without the interlocking ability, judged on the macro scale.

27 points Planar. Macro smooth and micro rough joint surfaces. Friction is derived strictly from the 

roughness of the rock surface.

81 points Clay Infilling, Open, or Slickensides. Low friction materials separate the rock surfaces, 

negating any micro or macro roughness of the joint surfaces. Slickensided joints also 

have a lower friction angle because joint surfaces have been smoothed by movement, 

whether related to slope stability or tectonic movement.
85

Figure 19. Joint Roughness Coefficient (JRC) guide, modified here as dimensionless. Low 

JRC values for macro roughness (large planar joints) joints would equate to a higher score. 

Rough, irregular joints (high JRC), both in macro and micro scale, score low.

27

.

.

.

.

.

.

.

9

.

.

.

.

.

.

.

3 

Approximate 

rating progression 

using the JRC as a 

guide.
86

Case 2

This case is used for slopes where differential 

erosion or oversteepening is the dominant 

condition that leads to rockfall. Erosion features 

include oversteepened slopes, unsupported rock 

units (overhangs), or exposed resistant rocks on a 

slope, which may eventually lead to a rockfall 

event. An example of this geologic case is shown 

in Figure 20.

R. Case 2 - Structural Condition

Rockfall is commonly caused by erosion that 

leads to a loss of support, either locally or 

throughout a slope. The types of slopes that may 

be susceptible to this condition are: layered 

geologic units containing more easily erodible 

units that undermine more durable rock; talus 

slopes; highly variable geologic units, such as 

conglomerates, and mudflows, that weather 

differentially, allowing resistant rocks and blocks 

to fail, and rock/soil slopes that weather allowing 

rocks to fall as the soil matrix material is eroded.

Table 19. Detailed Rock Slope Rating – Case 2 Structural Category Narratives

3 points Few Differential Erosion Features. Minor differential erosion features that are not 

distributed throughout the slope.

9 points Occasional Differential Erosion Features. Minor differential erosion features that are 

widely distributed throughout the slope.

27 points Many Differential Erosion Features. Differential erosion features that are large and 

numerous throughout the slope.

81 points Major Differential Erosion Features. Severe cases, such as dangerous erosion-created 

overhangs, or significantly oversteepened soil/rock slopes or talus slopes.

S. Case 2 - Differential Erosion Rate

The materials comprised in a slope can have markedly different characteristics that control how 

rapidly weathering and erosion occur. As erosion progresses, resulting in portions of the slope 

becoming unsupported, the likelihood of a rockfall event increases. 

Figure 20. Rock cut where differential erosion 

is the dominant cause of failure. Forest Service 

Road 25, Milepost 30.
87

The rate of erosion on a Case 2 slope directly relates to the potential for a future rockfall event. 

As erosion progresses, unsupported or oversteepened slope conditions develop. The impact of 

the common physical and chemical erosion processes, as well as the effects of human actions, 

should be considered. The degree of hazard caused by erosion and thus the score given this 

category, should reflect the rate at which erosion is occurring; the size of rocks, blocks, or units 

being exposed; the frequency of rockfall events; and the amount of material released during an 

event.

Table 20. Detailed Rock Slope Rating – Case 2 Differential Erosion Rate Category 

Narratives

3 points Small Difference. Erosion features take many years to develop. Slopes that are near 

equilibrium with their environment are covered by this category.

9 points Moderate Difference. The difference in erosion rates allows erosion features to develop 

over a period of a few years.

27 points Large Difference. The difference in erosion rates allows noticeable changes in the slope 

to develop annually.

81 points Extreme Difference. The difference in erosion rates allows rapid and continuous 

development of erosion features.
88

DETAILED RISK RATINGS (ROCKFALL AND LANDSLIDES)

V. Route Width or Trail Width

The roadway or trail width is measured perpendicular to the centerline. This category measures 

the available maneuvering width of the road or trail, and captures the ability of a traveler to 

navigate around unforeseen roadway or trail hazards. For example, if a traveler notices rocks in 

the road, or rocks falling, it is possible for the driver or hiker to react and take evasive action to 

avoid them. The more room there is for this maneuver on a roadway, the greater the likelihood 

the driver will successfully miss the rock without hitting some other roadside hazard or 

oncoming vehicle. For a trail, greater room for maneuvering reduces the likelihood that a user 

will trip or be compelled to exit the trail in order to avoid the obstacle.

Roadway width is measured as the available paved width of the roadway or trail, including 

paved shoulders as it exists at the time of rating. If paved, the edges of pavement define the 

roadway. It is difficult to get uniform estimates among different raters about what is unpaved 

shoulder and what is an unmaneuverable side slope. For that reason, the unpaved shoulders are 

not included in the measurement. On unpaved routes, such as aggregate or native surface roads 

or trails, it would be the measured as the drivable or navigable width. Where width changes 

within a section, it should be taken at the narrowest part of the section. On divided roadways, 

only the portion of the roadway available to the driver for maneuvering should be measured. If 

the slope is rated while the road is partially closed due to debris or damage, repair of damage to 

the full width would require a new or updated rating to document the improvement to this 

unstable slope section. 

This category score is based on direct measurements according to the equations below. Graphs 

of the category scores for roads and for trails are also provided for reference in 

Figure , and sample calculation results are provided in Table .

SS = 3xx (max 100); where

= 44 − RR h ( )

8 for vehicles, = 18 − h ( )

4 for trail traffic

Equation 5. Roadway Width Score
89

Figure 21. Chart pair illustrating the relationship between the paved roadway with and the 

category score and between the trail width and the category score. Note that the category 

score for paved roadway width maxes out at a width of 10 feet, while the category score for 

trail width maxes out at a width of 1 foot.

Table 21. Risk Rating – Roadway Width Sample Calculated Scores

Roadway Width Trail Width

3 points 36 feet 14 feet

9 points 28 feet 10 feet

27 points 20 feet 6 feet

81 points 12 feet 2 feet

W. Human Exposure Factor

The Human Exposure Factor evaluates the potential for a roadway or trail user to be involved in 

an unstable slope event. This risk is associated with the percentage of time a route user is 

present in the evaluated section. The percentage is obtained by using the formula based on slope 

length, average annual daily traffic (AADT), and the posted or advisory speed limit (or average 

walking speed, 2.7 mph(Knoblauch, et al., 1996) at the site. If a different walking speed is 

entered, note study and/or rationale in the comment field.

A rating of 100% means that, on average, a user will be within the defined unstable section 

100% of the time. Where high AADTs or longer slope lengths exist, calculated values can be 

greater than 100%, meaning that at any particular time, more than one user is present within the 

measured section. The result also reflects the significance of the route.

This category is scored using direct measurements following the equation below.

0

25

50

75

100

10 20 30 40 50

Route Width Category Score

Paved Roadway Width (feet)

0

25

50

75

100

0 5 10 15 20

Trail Width Category Score

Trail Width (feet)
90

SS = 3xx (max 100) ; =

�

AAAAAAAA

24 × ss h ( ) ×100

ss ss �

12.5

Equation 6. Human Exposure Factor Score

Table 22. Risk Rating – Human Exposure Factor Sample Calculated Scores

3 points Human Exposure 12.5% of the time

9 points Human Exposure 25% of the time

27 points Human Exposure 37.5% of the time

81 points Human Exposure 50% of the time

X. Percent Decision Sight Distance (PDSD) or Avoidance Ability on Trails

The Percent Decision Sight Distance (PDSD) category compares the amount of sight distance 

available through an unstable slope section to the optimal sight distance for a 

speed/path/direction change. 

For roadways, sight distance is measured as the length of roadway from when a two-foot object 

is first seen from a driving position (3.5 feet above the road surface) until the object is reached. 

Decision sight distance (DSD) is the length of roadway, in feet, required by a driver to perceive a 

problem and then bring a vehicle to a stop. The required DSD increases with increased vehicle 

speed and this distance is critical when obstacles in the road surface are difficult to see, or when 

unexpected or unusual maneuvers are required. Decision sight distances prescribed by 

AASHTO for rural roads for typical posted speeds are presented in Table 23 below.

Table 23. AASHTO Recommended Minimum Decision Sight Distance for selected speed 

limits

Posted Speed 

Limit (mph)

AASHTO Recommended 

Minimum Decision Sight Distance 

(ft)

25 375

30 450

35 525

40 600

45 675

50 750

55 875

60 1,000

65 1,050
91

The DSD is critical when obstacles on the road are difficult to see, or when unexpected or 

unusual maneuvers are required. Throughout an unstable slope section, the sight distance can 

change appreciably. Horizontal and vertical highway curves along with obstructions such as 

rock outcrops and vegetation can severely limit a driver’s ability to notice and react to a rock in 

the road. In calculating this category score, the sight distance is determined in both travel 

directions, and the most restricted sight distance should be used. Both horizontal and vertical 

sight distances are evaluated.

The measurement, generally made with a roller tape or laser range finder, is the distance required 

for a two-foot object positioned on the fog line (or on the edge of pavement if there is no fog

line) to disappear from view at an eye height of 3.5 feet above the road surface. The posted, or 

advisory speed limit throughout the rockfall section is used because unstable slopes are often 

located within highway curves, where the posted advisory speed limit is lower than the highway 

design speed. Formally, AASHTO standards require placing the object in the travel lanes and 

measuring it from a driver’s position near the centerline; however, ratings are typically 

performed under live traffic and this would be an unsafe practice for both the rater and the 

public. 

For roadways, this category is scored based on direct measurements using the equation below.

SS = 3xx; =

120 − � SS h

AAAA AAAAAA RR SS h × 100�

20

Equation 7. Percent Decision Sight Distance Score

Avoidance ability on trails should be estimated qualitatively based on observations at the time of 

rating. Since comparable design standards for trails do not exist, the rater should judge the 

ability of a hiker to avoid a sudden rockfall, broken down into easily, moderately, difficult, or 

very difficult to avoid. For example, a hiker traversing a trail through a flat grassy area would 

easily avoid sudden hazards by leaving the trail into predictable surroundings; on a trail next to a 

shallow stream without a drop off it may be moderately difficult to avoid a hazard; on a 

boardwalk trail with handrails and a five foot drop to wetlands below it may be difficult to avoid 

a sudden hazard; and on a narrow trail with a tall cliff below and loose rocks it may be very 

difficult to avoid a sudden hazard. Below, Table 24 provides the qualitative descriptions and 

scoring breakdowns for trails, and the calculated value breakdown for roadways based on 

Equation 7 above. 

Table 24. Risk Rating – Percent Decision Sight Distance Sample Calculated Scores

Roadways Trails

3 points Adequate, 100% of design value Hazards easily avoided

9 points Moderate, 80% of design value Hazards moderately difficult to avoid

27 points Limited, 60% of design value Hazards difficult to avoid

81 points Very Limited, 40% of design value Hazards very difficult to avoid
92

Y. Right of Way Impacts if Left Unattended

Adjacent land owners may be impacted by unstable slopes retrogressing to property boundaries 

and beyond. If structures or other transportation systems are potentially impacted by unstable 

slopes, then the risk to the agency increases. Maps displaying right of way (ROW) are helpful 

when performing evaluations. 

To offer additional flexibility in this rating category for other agency or department facility 

assets beside roads and trails, raters may opt to use this category to evaluate the impact of 

landslides or rockfall on their built infrastructure. For instance, where no facilities are in harm’s 

way, 3 points would be scored. Minor, easily replaceable facilities, such as benches or railings 

could be 9 points. Retaining walls, bear boxes, or drinking fountains could be 27 points, and 81 

points could be assigned to significant structures such as ranger stations, restrooms, or other 

occupied structures.

Table 25. Risk Rating – Right of Way Impacts Category Narratives

3 points No ROW implications. Unstable slopes very unlikely to extend beyond agency ROW. 

9 points Minor effects beyond ROW. Retrogressing unstable slopes impacting non-agency ROW, 

but adjoining landowner indifferent to minor impacts. Minor impacts include overburden 

slumping, minor drainage changes, or rock slope crest retrogression.

27 points Private property, no structures affected. Unstable slopes actively retrogressing into 

private property but not impacting or likely to threaten structures. ROW acquisition of 

private lands may be a remote option.

81 points Structures, roads, RR, utilities, or parks affected. Retrogressing unstable slopes actively 

threatening adjacent structures, transportation systems, or Federal or State Park lands. In 

this score range, ROW acquisition of private lands may be a viable option. Coordination 

of mitigation approaches with outside agency landowner(s) will likely be required.

Z. Environmental/Cultural Impacts if Left Unattended

If the unstable slope is left unattended, impacts to the environment or cultural resources may 

occur. These impacts can include siltation of streams, culvert plugging, subsequent fish passage 

blocking, habitat impacts, or damage to historic features or sites. Due to the highly variable 

nature of potential environmental impacts, a range of environmental and cultural descriptions are 

used for this category. The rater should select the category containing the highest environmental

or cultural impact if left unattended. If these impacts are anticipated, a review by environmental 

and/or cultural resource professionals may be recommended. 

Preservation of paleontological resources, which is mandated by law, should also be considered

in this category and separated similarly to the rating categories provided for environmental and 

cultural impacts presented in Table 26.
93

Table 26. Risk Rating – Environmental/Cultural Impacts Category Narratives

3 points None/No potential to cause effects. No known sensitive environmental issues are present 

or anticipated if a probable worst-case scenario occurs. Hazard does not have the potential 

to cause effects on historic properties, assuming such historic properties are present (36 

CFR 800.3(a)(1)).

9 points Likely to affect/No historical property affected. If a probable or historically common 

failure occurs or the slope retrogresses, minor environmental impacts are anticipated, but 

adverse impacts are not anticipated. Historic properties are present but the hazard will 

have no effect upon them (36 CFR 800.4(d)(1))

27 points Likely to Adversely Affect/Finding of No Adverse Effect. If a probable or historically 

common failure occurs or the slope retrogresses adverse impacts are anticipated. Historic 

properties are present but the hazard will require modification or conditions imposed 

should the hazard continue untreated (36 CFR 800.5(a)(2)(vii)(b)).

81 points Current adverse effects/Adverse Effect. Current conditions are causing adverse 

environmental effects. An adverse effect is found when an undertaking may alter, directly 

or indirectly, any of the characteristics of a historic property (36 CFR 800.5(a)(1)).

AA. Maintenance Complexity

Complexity of maintenance following routine and/or a probable worst case scenario rockfall or 

landslide event is indicative of the maintenance costs and associated hazards. Maintenance could 

be as simple as cleaning rocks off the road during routine road patrols or as complex as the 

maintenance of unstable slope remediation systems, such as rockfall attenuator fences or 

construction of mechanically stabilized earth (MSE) walls to remediate an embankment 

landslide. This information should be gathered during the interview of maintenance personnel, 

specifically what the personnel capabilities and equipment is available to the agency to perform 

maintenance activities in the rating corridors.

Table 27. Risk Rating – Maintenance Complexity Category Narratives

3 points Routine effort/in-house. Maintenance staff typically deal with unstable slopes with roadgoing equipment such as a pickup with a blade, particularly effective with rockfall 

incidences. Trails require typical maintenance activities.

9 points In-house maintenance/special project. Maintenance of the site requires mobilization of 

specialized equipment such as a backhoe, excavator, paver, or guardrail post driver. Trails 

may require blasting and/or geotextile fabrics with existing surface materials to maintain 

the trail route and width. 

27 points Specialized equipment/contract. Maintenance requires specialized equipment to be 

mobilized a significant distance or requires assistance from an outside contractor. More 

involved maintenance may require basic engineering efforts (such as subgrade design or 

asphalt mixes). This would be similar for trails, such as renting a trail excavator and small 

dump to haul materials and may require basic engineering efforts (such as short retaining

walls or realignments of trail sections).

81 points Complex or dangerous effort/location/contract. Specialty contractor is required to 

perform maintenance activities (such as maintaining rockfall attenuator fences); more 

complex maintenance designs (such as subgrade reinforcement, tall MSE walls, or 

rockfall mitigation) requiring geotechnical design efforts; or difficult/dangerous access 

(rope access, spider hoe) is required.
94

BB. Event Cost

The estimated, or actual cost if available, to maintain or repair a probable worst-case scenario or 

a historically bad failure should be considered. The costs should be considered at comparable 

private-sector equipment rental and operator rates. If an extreme event requires outside 

assistance (planning, design, and/or construction) the costs should include both those outside 

costs and the agency contracting and supervisory costs. These rating categories are based on 

typical spending and contractual authorities in Federal agencies and departments. Again, 

interviewing maintenance personnel to determine the previous expenditures for similar unstable 

slope work proposed can be very helpful when teamed with a brief field review of the unstable 

slope sites to determine the likely, and appropriate rating for this category. 

Table 28. Risk Rating – Event Costs Category Narratives

3 points $0-2k. Maintenance efforts and costs involve only agency maintenance staff using 

existing equipment. No design work required.

9 points $2-25k. Event cost and response is more involved and may include input from agency 

engineering staff. 

27 points $25-100k. Costs indicate extensive, multi-day efforts and likely input from engineering 

staff. Costs may include outside contractors and engineering costs.

81 points $ >100k. Large contract with significant outside contractor and engineering costs.
95

REFERENCES FOR APPENDIX A

Barton, N. & Choubey, V., 1977. The Shear Strength of Rock Joints in Theory and Practice. 

Rock Mechanics and Rock Engineering, 10(1), pp.1-54.

Cornforth, D., 2005. Landslides in Practice. Wiley & Sons.

Cruden, D.M. & Varnes, D.J., 1996. Landslide Types and Processes. In A.K. Turner & R.L. 

Schuster, eds. Landslides: Investigation and Mitigation. Washington D.C.: 

Transportation Research Board, National Research Council. pp.36-75.

Hoek, E. & Bray, J.D., 1981. Rock Slope Engineering: Third Edition. London and New York: 

Institute of Mining and Metallurgy.

Knoblauch, R.L., Pietrucha, M.T. & Nitzburg, M., 1996. Field Studies of Pedestrian Walking 

Speed and Start-Up Time. Transportation Research Record: Journal of the 

Transportation Research Board, pp.27-38.

Transportation Research Board, 1996. Landslides: Investigation and Mitigation: Special Report 

247. Special Report 247. National Research Council.
96

APPENDIX B. USMP RATING FORMS

This Appendix contains four forms developed for this project:

• Slope Rating Form

• New Slope Event Form

• Maintenance Form

• Conceptual Design and Cost Estimate Form
FLMA - Unstable Slope Management Program Field Rating Form Rev 1.09 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

SLOPE RATING FORM – SITE INFORMATION

Management Area: Date:

Hazard Type (select all 

that apply within one 

of the categories):

Rockfall Planar | Wedge | Toppling |

Raveling/Undermining | Rock Avalanche |

Indeterminate Rock Failures | Differential Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow |

Shallow Slump | Erosional Failure

Road/Trail No.: ⃝ Trail Road/Trail Class: Rater: ⃝ Road 

Beginning Mile Marker: Ending Marker: Side: Weather:

Begin 

Coord.:

Lat. (xx.xxxxx): End 

Coord.:

Lat. (xx.xxxxx): Datum: AADT: Long. (-xxx.xxxxx): Long. (-xxx.xxxxx):

Length of Affected Road/Trail (ft): Slope Height (rock) /Axial Length (slide) (ft): Slope Angle (°):

Sight Distance (ft): Usable Roadway/Trail Width (ft): Speed Limit (mph):

Ditch Width (ft): RANGE ROCKFALLDitch Depth (ft): RANGE ROCKFALLDitch Slope (H:V): RANGE ROCKFALLBlk Size (ft)/Volume (cy): ROCKFALL

Annual Rainfall (in): RANGE Sole Access Route □ Yes □ No Fixes Present □ Yes □ No Photo # Range:

Comments:

PRELIMINARY RATING

Category Rating 3 9 27 81 Score

A. Landslide – Roadway Width 

Affected 0-5 Percent 6-25 Percent 26-50 Percent 51-100 Percent

B. Landslide – Slide/Erosion Effects

Visible crack or 

slight deposit of 

material /

minor erosion

1 inch offset, or 6-

inch deposit of 

material / major 

erosion will affect 

travel in < 5 yrs

2-inch offset or 

12-inch deposit/ 

mod. erosion 

impacting travel 

annually

4-inch offset or 24-

inch deposit/ severe 

erosion impacting 

travel consistently

C. Landslide – Roadway Length 

Affected 25 ft 100 ft 225 ft 400 ft CALC

D. Rockfall – Ditch Effectiveness 

(consider launch features) Good Moderate Limited No Catchment

E. Rockfall – Rockfall History Few Falls Occasional Falls Many Falls Constant Falls

F. Rockfall – Block Size or Volume 

per Event

1 ft

or

3 yd3 

2 ft

or

6 yd3 

3 ft

or

9 yd3 

4 ft

or

12 yd3 

CALC

G. All – Impact on Use

Full use continues 

with minor delay

Partial use remains

Use modification 

required, short (3 

mi/30 min.) detour 

available 

Use is blocked –

long (>30 min) 

detour available 

or less than 1 day 

closure

Use is blocked – no 

detour available or 

closure longer than 1 

week

H. All – AADT / Usage / Economic 

or Recreational Importance 

(highest rating applies)

50

Rarely Used 

Insignificant 

economic / rec. 

importance

200

Occasionally used 

Minor economic / 

rec. importance

450

Frequently used 

Moderate 

economic / rec. 

importance

800

Constantly used 

Significant economic 

/ rec. importance

CALC 

FOR 

AADT 

ONLY

LANDSLIDES TOTAL (A+B+C+G+H) CALC

ROCKFALL TOTAL (D+E+F+G+H) CALC

Preliminary Rating Good (15-21 pts) | Fair (22-161 pts) | Poor (>161 pts)

Sites rated as Fair or Poor receive detailed evaluation (complete back page)

ITALICIZED DATA CATEGORIES REQUIRED FOR FULL RATING
FLMA - Unstable Slope Management Program Field Rating Form Rev 1.09 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

SLOPE RATING FORM – DETAILED SLOPE HAZARD RATING

Category Rating 3 9 27 81 Score

I. All – Slope Drainage

Slope appears dry 

or well drained; 

surface runoff well 

controlled

Intermittent water 

on slope; mod. well 

drained; or surface 

runoff moderately 

controlled

Water usually on 

slope; poorly 

drained; or 

surface runoff 

poorly controlled

Water always on 

slope; very poorly 

drained; or surface 

water runoff control 

not present

J. All – Annual Rainfall 0-10” 10-30” 30-60” 60”+

K. All – Slope Height (rockfall) / 

Axial length of slide (landslide) 25 ft 50 ft 75 ft 100 ft CALC Select One Unstable Slope Type Landslides/ Erosion (add A, B, C)

L. Thaw Stability (cold 

climates)

Unfrozen/Thaw 

Stable

Slightly Thaw 

Unstable

Moderately Thaw 

Unstable

Highly Thaw 

Unstable

M. Instability-Related 

Maint. Frequency Every 10 years Every 5 years Every 2 years Every year

N. Movement History Minor movement 

or sporadic creep 

Up to 1 inch 

annually or steady 

annual creep 

Up to 3 inches per 

event, one event 

per year

>3” per event, >6” 

annually, more than 

1 event per year 

(includes all debris 

flows)

Rockfalls

(add D, E, F)

O. Rockfall-Related 

Maint. Frequency

Normal, scheduled 

maintenance

Patrols after every 

storm event

Routine seasonal 

patrols Year-round patrols

Geologic Character

Case 1

P. Structural 

Condition Favorable Random Adverse 

Discontinuous

Adverse 

Continuous

Q. Rock 

Friction

Rough/

Irregular Undulating Planar Clay infilled/ Slickensided

Case 2

R. Structural 

Condition

Few differential 

erosion features

Occasional 

differential erosion 

features

Many differential 

erosion features

Major differential 

erosion features

S. Diff. in 

Erosion Rates Small difference Moderate 

difference Large difference Extreme difference 

T. LANDSLIDE HAZARD TOTAL (A+B+C+I+J+K+L+M+N) CALC

U. ROCKFALL HAZARD TOTAL (D+E+F+I+J+K+O+(greatest of P+Q or R+S)) CALC

DETAILED RISK RATING

V. Route Width or 

Trail Width

36 ft

14 ft

28 ft

10 ft

20 ft

6 ft

12 ft

2 ft CALC

W. Human Exposure Factor 12.5% of the time 25% of the time 37.5% of the time 50% of the time CALC if 

AADT avail

X. % of Decision Sight Distance 

(Judge avoidance ability on trails)

Adequate, 100% of 

low design value

Moderate, 80% of 

low design value

Limited, 60% of 

low design value

Very Limited, 40% of 

low design value

CALC for 

roads

Y. Right of Way (R/W) Impacts (If 

Left Unattended)

No R/W 

implications

Minor effects 

beyond R/W

Private property, 

no structures 

affected

Structures, roads, RR, 

utilities, or Parks 

affected

Z. Environmental/Cultural Impacts 

if Left Unattended

None/No potential 

to cause effects

Likely to effect/No 

hist. prop. affected

Likely to adversely 

affect/Finding of 

no adverse effect

Current adverse 

effects/Adverse 

effect

AA. Maintenance Complexity Routine effort/InHouse

In-House Maint./

Special project

Specialized 

equip./contract

Complex/Dangerous 

effort/location/

contract

BB. Event Cost $0-2k $2-25k $25-100k >$100k

CC. RISK TOTALS: (G+H+V+W+X+Y+Z+AA+BB) CALC

TOTAL USMP SCORE: LANDSLIDES (T+CC) OR ROCKFALL (U+CC) CALC

Total USMP Score Good (< 200 pts) | Fair (200 - 400 pts) | Poor (> 400 pts)
FLMA - Unstable Slope Management Program Field Rating Form Rev 1.09 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

For the directly measurable categories, use the following formulas to calculate the exponent value (x) for the 

scoring formula y = 3x

. This will allow the calculation of a precise score for the category measurement and 

development of category scoring tables.

C. Length of roadway affected exponent:

= � h aa

25

F. Block size or the volume exponent formula:

bb = bb

vv = �

3

3 �

H. AADT exponent formula:

= �AAAAAAAA

50

K. Slope height/axial slide length exponent formula:

= ss h h

25

V. Width exponent formula:

= 44 − RR h ( )

8 for vehicles, = 18 − h ( )

4 for trail traffic

W. Human exposure factor exponent formula for roads and trails: 

=

�

AAAA

24 × ss h ( ) ×100

ss ss �

12.5

X. Percent decision sight exponent formula:

=

120 − � h

AAAA AAAAAA h ×100�

20
FLMA - Unstable Slope Management Program New Slope Event Form Rev 1.03 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

NEW SLOPE EVENT FORM – OBSERVER INFORMATION

Observer Name: Today’s Date:

Phone No.: Email:

Date of Event: About Date of Event (circle one): Known, Approximate, Unknown

Observer Comments/Sketch:

EVENT INFORMATION

Road/Trail No.: ⃝ Trail State: ⃝ Road

Hazard Type (select all that apply): Rockfall | Landslide/Erosion | Debris Flow | Snow Avalanche

Beginning Mile Marker: Ending Mile Marker: Photo # Range:

Event 

Coord.

Latitude (xx.xxxxx): Datum: Length of Affected Road/Trail (ft): (1m = 3 ft):

Longitude (-xxx.xxxxx):

Road/Trail Conditions after Failure: Blocked | Blocked/Detours exist around failure | Partially blocked but passable |

Ditch full of debris | Route threatened by unstable slope

Size of Largest Fallen Rock: No. of Rocks: Estimated Volume of Debris:

⃝ Less than 3 inches (< 8 cm) - baseball size or smaller

⃝ Less than 1 foot (< 30 cm) - basketball size or smaller

⃝ 1 to 3 feet (30 - 100 cm) - fits through standard doorway

⃝ Greater than 3 feet (> 1 m) thousands of pounds

⃝ 1

⃝ 2

⃝ 3 - 5

⃝ 5 - 10

⃝ 10+

⃝ < 5 ft3 (< 0.15 m3 ) – wheelbarrow or less

⃝ < 2.5 yd3 (< 2 m3 ) – pickup truck or less

⃝ < 10 yd3 (< 8 m3 ) – dump truck or less

⃝ > 10 yd3 (> 8 m3 ) – several dump trucks

Description of Event Location (select all that apply): Possible Cause of Event (select all that apply):

⃝ Above road/trail

⃝ Below road/trail

⃝ At a culvert

⃝ Above river

⃝ Above coast

⃝ Burned area

⃝ Deforested slope

⃝ Urban

⃝ Mine

⃝ Retaining wall

⃝ Natural slope

⃝ Engineered slope

⃝ Unknown

⃝ Other (Please describe in Observer Comments)

⃝ Rain

⃝ Thunderstorm/downpour

⃝ Continuous rain (> than 24 

hours)

⃝ Hurricane/cyclone

⃝ Flooding

⃝ Snowfall/snowmelt

⃝ Prolonged freezing

⃝ High temperatures

⃝ Other (Please describe in 

Observer Comments)

⃝ Long-term creep/poor soil cond.

⃝ Earthquake

⃝ Volcanic activity

⃝ Leaking pipe

⃝ Mining

⃝ Construction

⃝ Dam embankment collapse

⃝ No obvious cause

⃝ Unknown cause

Did deaths, injuries, or damages coincide with the landslide/rockfall?

⃝ Yes

⃝ No

If yes, please describe:
FLMA - Unstable Slope Management Program New Maintenance Event Form Rev 1.03 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

MAINTENANCE FORM – SITE INFORMATION

Facility Index Code Relationship/Job Code Tracking (Optional): Maintenance Type:

o New Maintenance

Beginning Mile Marker: Ending Mile Marker: o Repeat Maintenance (within 5 years)

Maintenance Event 

Coordinates: Latitude (xx.xxxxx): Longitude: (-xxx.xxxxx):

Road or Trail Number: Site ID: Date(s) of Maintenance:

Type of Event:

o Recent Unstable Slope Event

o Routine Maintenance

o Slope Mitigation/Repair

Agency Information: Notes:

Description of Events/Activities:

Estimated total cost of the maintenance activity: $

Action Cost (%)

Design, PS&E:

Removing debris from the road ditch and/or maintaining other drainage features:

Removing debris from the roadway or trail:

Re-leveling roadway (aggregate):

Re-leveling roadway (asphalt patch):

Constructing a drainage improvement:

Constructing a deep patch:

Hauling debris away from the site:

Scaling of unstable rock slopes:

Minor shifting of roadway/trail alignment:

Repair of rockfall barrier:

Repair of rockfall netting (on-slope):

Sealing cracks in pavement:

Installing, maintaining, or replacing guardrail:

Cleaning and/or maintaining horizontal drains and associated subsurface drainage:

Flagging and signing:

Other (enter description):

Other (enter description):

Other (enter description):

Other (enter description):

Running total of the cost percentages:
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.02 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Date:

Road/Trail No.: ⃝ Trail Created By: ⃝ Road 

Beginning MP: Ending MP: Side: Weather:

Hazard Type (select all 

that apply within one 

of the categories):

Rockfall Planar | Wedge | Toppling |

Raveling/Undermining | Rock Avalanche | 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow |

Shallow slump | Erosional Failure

Previous Total Rating: Previous Rating Agency: Previous Rating Date:

Current Rating (if re-rated): Photo # Range:

Problem Statement:

Proposed Correction:

ESTIMATING FACTORS

Item Unit Amount 

Required Unit Cost Total Cost

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $0.00
103

APPENDIX C. DETAILED INSTRUCTIONS FOR USMP WEBSITE

AND MOBILE APPLICATIONS

This appendix details how to use the USMP website and the USMP iOS/Android mobile 

applications. The first section describes how to use the USMP website, including step-by-step 

instructions on how to create, edit, and save slope rating forms, new slope event forms, and 

maintenance forms. The second section describes how to use the USMP iOS/Android apps for 

the similar tasks.

USING THE USMP WEBSITE

To login to the USMP website, visit https://usmp.info/ and input your username and password. 

New users will need to obtain a username and password to begin from the appropriate agency 

manager. There are several options listed in the task bar near the top of the website. Each of 

these options (Map, Slope Rating Form, New Slope Event Form, Maintenance Form, QRA, 

Account, and Logout) link you to specific functions within the USMP website, which are 

described in greater detail below. Information on the USMP project including links to training 

videos, presentations, forms and the field manual can be accessed through the “About” link on 

the USMP homepage. 

Map

GoogleTM maps is the platform that is used to graph the information collected in the USMP. It is 

also where information can be searched and downloaded from the database (search process is 

described below). Also, new forms can be added based on location by clicking on the area of 

interest as described below.

Slope Rating Form

To begin a new rating form for a site, click on ‘Slope Rating Form’ on the navigation bar at the 

top of the webpage. Doing this will open a new slope rating form, as illustrated in Figure 1.

Figure 1. Top of Slope Rating Form on USMP website.
104

Fill in all the text and number fields, radio buttons, drop down options with related information 

as part of the rating process. If any required field is left empty or is filled with invalid 

information, an error message will automatically appear, and incorrect fields will be highlighted

red, as shown in Figure 2. A list of required fields and their value restrictions are as follows:

• Management Area must be specified by selecting Agency from the drop down, then 

State/Region/Territory, then Local/County/Territory

• Date must be specified in either 'YYYY-MM-DD' or 'YYYY-MM-DD HH:MM:SS' 

formats. The date is auto-filled at the time the form is loaded, but may be modified to 

reflect the date of a field rating.

• Either Rockfall or Landslide must be selected.

• Hazard Type must have a value, or multiple values selected from the multi-select list. The 

list is populated based on the Rockfall/Landslide selection.

• Road/Trail No. cannot be empty and must be shorter than 30 characters.

• Road/Trail must be selected.

• Road/Trail Class cannot be empty and must be shorter than 30 characters.

• Rater cannot be empty and must be shorter than 30 characters.

• Beginning Mile Marker and Ending Mile Marker must have a non-negative decimal 

value.

• Side must be selected.

• Weather must be selected.

• Beginning and Ending Coordinates Latitude must be floating point values.

• Beginning and Ending Coordinates Longitude must be floating point values.

• AADT must have a non-negative integer value

• Length of Affected Road/Trail must have a non-negative decimal value.

• Slope Height (rock)/Axial Length (slide) must have a non-negative decimal value.

• Slope Angle must have an integer value between 0 and 90 degrees.

• Sight Distance must have a non-negative decimal value.

• Roadway/Trail width must have a non-negative decimal value.

• Speed Limit must have a non-negative integer value.

• Ditch Width minimum and maximum must have non-negative decimal values.

• Ditch Depth minimum and maximum must have non-negative decimal values.

• Ditch Slope beginning and ending horizontal and vertical cells must all have nonnegative decimal values.

• Block Size or Volume must have a non-negative decimal value.

• Volume must have a decimal value.

• Annual Rainfall minimum and maximum must have non-negative decimal values.

• Sole Access Route must be selected.

• Mitigation Present must be selected.
105

Figure2. Example error message and highlighted cell on New Slope Form on the USMP 

website.

Users can upload single or multiple images and/or documents associated with a particular slope 

rating by selecting “Browse” in the Photo/Documents section of the form. Image file format 

must be "jpeg", "jpg", or "png". Documents can be any format, but sizes are restricted to 10 Mb 

per file. Photos will be automatically downsized to 1600 by 1600 pixels.

Information can be submitted to the database by clicking on the “Submit” button on the bottom 

of the form. If there are any empty required fields or fields that contain data in an incorrect 

format, a popup window with an error message will open during the submission process, as 

shown in Figure 3. If the form entries are correct and complete, a popup message indicating that 

the information for that site was successfully added to the database will appear, as shown in 

Figure 4.

Figure 3. Example error message during submission process.
106

Figure 4. Example success message during submission process.

To view or edit an existing site on the USMP website, begin by clicking on “Map” in the 

navigation bar. Be patient as the site loads all the unstable slope information, which can take up 

to 10 seconds or more for the icons to appear. Rated sites will appear on the map as a rockfall or 

landslide icon in one of three colors (green, yellow or red) depending on the rating score. A popup window containing selected information about a particular site can be opened by simply 

clicking on the icon of interest. Several hyperlinks are included in each pop-up window. The 

existing slope rating form can be opened by clicking on the hyperlink, and users can view and/or 

edit the fields of the opened slope rating form. Clicking on the “Submit” button will save any 

new changes made to the form and generate a new edit record that will show up in the popup the 

next time it is opened. After submitting the data, you will need to have administrative rights to 

make changes to the data later.

New Slope Event Form

A new slope event form can be created using one of two methods. One method is to select ‘New 

Slope Event Form’ on the navigation bar. An alternate method is to navigate to the Map page 

and create a new slope event using geographic information. First, the map must be set to display 

only new slope event information. To do this, select “New Slope Event Information Search” 

from the first dropdown menu. The next step is to right click on the desired location in the map 

to create a location pin. Left clicking on this pin will open a pop-up that contains a hyperlink 

with the text “Add New Slope Event.” Click on this hyperlink to create a New Slope Event 

associated with that location. Fill in the text fields, radio buttons, check boxes, and drop down 

options with relevant information in the new slope event form, and click the “Submit” button at 

the bottom of the form when finished. As with the rating form, if any of the required fields are 

empty or filled with incorrectly formatted information, an error message will be displayed and 

incorrect fields will be highlighted red. If the form entries are properly filled in, a message will 

be displayed indicating that the information was successfully added.

Required fields:

• About Date of Event must be selected.

• Date must be selected using the calendar select popup.
107

• One or more hazard types must be selected.

• Latitude and Longitude must have floating point values.

• Road/Trail must be selected.

Maintenance Form

Creating a New Maintenance Form for an Existing Site

To add a New Maintenance Form for an existing site (i.e., a site that has already been rated), 

click on the icon of the desired unstable slope site on the map. A pop-up window will open 

which includes a hyperlink labeled “Add new maintenance form” (see illustration in Figure 5. 

Clicking on this hyperlink will open a New Maintenance Form. If a particular site is desired, the 

“Select Search and Reporting Option” dropdown tool in the upper left of the “Map” page can be 

used to find a specific site ID or other distinguishing feature. Once found, the Maintenance form 

can be completed. Maintenance forms that are associated with an existing (rated) site are shown 

as blue pins.

Figure 5. Illustration of access to New Maintenance Form through pop-up associated with 

existing site.

Click the Submit button at the bottom of the form when the form is complete. If any of the 

required fields are empty or filled with incorrectly formatted data, an error message will be 

displayed under the submit button, and all affected fields will be highlighted red. If the form 

entries are correct then a message indicating successful saving to the database will appear. After 

clicking on the OK button, it will automatically redirect the Maintenance Form page back to the 

Map page.

Required fields:

• Select Agency must be selected.

• Select State/Region must be selected.

• Select Local/County must be selected.

• Estimated total cost must have a non-negative numeric value. 

• Maintenance Coordinate Latitude must have a floating point value.
108

• Maintenance Coordinate Longitude must have a floating point value.

• Running total of the cost percentages should be equal to 100. 

Creating a New Maintenance Form That is Not Associated with an Existing Site

One of two methods can be used to create a new maintenance form for a site that has not been 

previously rated. The first method is to simply click on the “Maintenance Form” tab from the 

navigation bar. This will open a blank Maintenance Form that can be filled out with location 

data and submitted. An alternate method is to navigate to the Map page and create a 

maintenance event using geographic information. First, the map must be set to display only 

maintenance information. To do this, select “Maintenance Information Search” from the upper 

left dropdown menu on the Map page. The next step is to right click on the desired location in 

the map to create a location pin. Left clicking on this pin will open a pop-up that contains a 

hyperlink with the text “Add New Maintenance Form,” as illustrated in Figure 6. Click on this 

hyperlink to create a new Maintenance Event associated with that location. Add the information 

to the form as described above and save the information to the database by clicking the submit

button. When submitted, the maintenance pin for sites that are not associated with a rated site 

are white. This color distinction (blue and white pins) was included to alert unstable slope 

managers within agencies to the unstable slopes that may be new and require a slope rating.

Figure 6. Illustration of access to New Maintenance Form through setting of geographic 

pin.

View/Editing an Existing Maintenance Form

To view/edit any existing maintenance form, navigate to the Map page and select the 

“Maintenance Information Search” option from the upper left search drop down. Click on the 

icon for the desired maintenance site on the map, which will open a pop-up window that lists all 

the maintenance form edits by date and time stamp for that particular site as shown in Figure 7. 

Select the hyperlink for the specific maintenance form edit to open an existing Maintenance 

Form. After making the necessary changes, click on the submit button to save the new form and 

its changes to the database.
109

Figure 7. Pop-up associated with maintenance pin.

QRA

The quantitative risk analysis (QRA) web page is designed to help users analyze risk associated 

with unstable slopes. Calculations are automatically made using information entering into the 

cells. Individual entries into each of these cells are stored in the URL for this website so that a 

record of the information can be saved by copying the web address and saving it in a bookmark 

folder on your Internet browser. Consult Appendix G for further help on individual entries into 

the QRA online form. The required fields and formats for the input values on the QRA form are 

listed below.

• Length of hazard zone (positive number)

• Average travel speed (positive number)

• Recurrence interval (positive number)

• Probability of an unstable slope event not triggered by an earthquake (number between 0 

and 1)

• Probability of an unstable slope event triggered by an earthquake (number between 0 and 

1)

• Boulder size (positive number)

• Vulnerability of death or injury (number between 0 and 1)

• Number of People visiting the hazard zone per year (positive number)
110

Account

The account page allows users to change their password by entering it twice and clicking Change 

Password. An administrator may additionally add new users by setting their ID and password. 

The administrator can also change the permission level for new and existing users. The 

administrator can click on Show Users link to see a list of all users and their permissions. Next 

to each user is a dropdown with their permission level. Click Change to confirm. Finally, the 

administrator may remove a user by clicking the Delete user link next to a user in the list.

Logout

The Logout link in the top taskbar logs out the current user from the site.

DATABASE SEARCHING AND REPORTING FUNCTIONALITY

Conducting a Search of the Database

To perform a database search, first navigate to the Map page on the USMP website. Select the 

type of information you want to search from the drop down in the upper left of the page. Three 

new dropdown lists will open: Slope Rating Information Search, New Slope Event Information 

Search, and Maintenance Information Search. First, select the information area to narrow your 

search criteria. Under each of these three information areas, three additional drop downs will be 

available to further refine your search from the available fields within the database.

When the “Search on Map” button is clicked, the data was incorrectly formatted when entered in 

the search so an error message will be displayed, as shown in Figure 8. If the input criteria are 

formatted correctly and the database contains one or more sites that satisfy the entered search 

criteria, those sites will be graphically displayed on the Map page.

Figure8. Example error message for incorrect search criteria.

Further information on a particular site can be viewed by clicking on any of the icons displayed 

on the map and opening a pop-up window. New searches are possible by returning the search 

boxes back to the default settings by clicking on the reset link under the navigation bar.

When searching and reporting tool, note that it is good practice to check the “Latest edit only” 

box so only the latest unstable slope rating form edits for each site are searched and reported. 

Leaving the checkbox unchecked could result in multiple slope rating forms for a single site 

being reported during the search. This is a helpful search method when looking at maintenance 

and new slope event forms, but not for the slope rating form searches.
111

Exporting search results

To export search results into a comma-delimited file, click on the “Export as CSV” button once a 

search is complete. Search results will be saved as a .CSV file containing all the information 

from the database for the sites meeting the search criteria.

FINDING AND USING THE USMP IOS/ANDROID MOBILE APPLICATIONS

The Slope Rating, New Slope Event, and Maintenance Forms were packaged in an application 

for hand-held devices that would allow for quick entry of field information and upload of photos 

to a stable iOS or Android device. When out of the range of Internet service, the applications 

will also save information in an offline condition. Temporarily stored information can be 

uploaded (one at a time) from the application(s) to the website once Internet service is available.

In order to download these applications to your preferred hand-held field devices, search for 

“USMP” on the Google Play store, or the Apple App store, depending on the type of your mobile 

device. Install the mobile application by clicking Install.

Starting the Mobile Application

Click on the “USMP” icon to start the app.

Beginning a New Form

To access the three rating forms, press on the toolbar on the top left hand corner to open the main 

menu (see Figure 9). Select the desired form from the menu. Once open, the form can be filled 

out similarly to the USMP website. If using the “Get Coordinate Button” in the App for the 

forms, be sure to stay in the beginning and ending location long enough that when you press the 

“Get Coordinate” button it shows the same results at least two times in a row. The satellite 

geometry will take some time to coordinate your location and patience during this data field 

collection can save a lot of time later. Even though the applications have a geographic 

coordinate button, it is recommended that a secondary device to double-check the coordinates be 

used. Location data needs to be accurate to be useful. In addition, make sure to click out of the 

last entry field for the calculations to update the forms properly. The form automatically saves 

the information as the user fills in information. The same required fields are used in the 

application. Please refer to the earlier sections of this appendix for the required fields for these 

three forms.
112

Figure 9. Main menu for mobile application.

Viewing and Editing Saved Sites

To view or edit a saved site, select “Offline Saved Sites” on the main menu in the upper lefthand corner of the screen. A list of saved sites will appear, as shown in Figure 10. Tap on the 

‘Edit’ button of the desired site to open the site’s slope rating form. Make the necessary edits to 

the form and go back to the home screen and the form will automatically save the changes. A 

rated site with information can be deleted if you select the “Delete” button. This feature should 

be used carefully and with proper intent.

Figure10. Example of offline saved sites.

Transmitting Saved Information from Mobile Apps to the USMP Database:

Once connected to the Internet, select the Offline Saved Sites option in the main menu. Tap on 

one site at a time and click on the “Submit Site” button for submission to the database. A 

message will automatically be generated indicating the success of the transfer, and the saved 

information will automatically be removed from the offline database associated with the mobile 
113

app (see Figure 11). Note that the successful transmission message may take up to 10 seconds or 

more to generate following the upload. If impatient, and the uploader attempted to upload the 

site several times before the successful transmission message appears, multiple duplicative 

uploads will occur and the USMP website will not let you edit the site until you delete the 

submitted duplicates for that site. Please note that while the research and development team 

recognize that the application is not perfect and has some limitations, the goal for the investment 

was primarily directed to functionality and improving the efficiency of field-going and 

maintenance personnel in limiting redundant work efforts to collect much needed data for the 

unstable slope assets to be managed.

Figure11. Example message indicating successful data transfer from mobile app to USMP online database.
114

APPENDIX D. BENEFIT/COST APPROACH FOR ROCK AND SOIL SLOPES

This document presents a series of alternative approaches for benefit/cost prioritization of slope 

preservation, mitigation, and reconstruction for roads and trails. All the approaches are based on 

roadway examples utilizing widely-accepted principles of risk management and asset 

management, with varying levels of data requirements. The approaches are meant to provide an 

objective and consistent means of summarizing the degree to which each project may contribute 

to agency objectives while minimizing long-term cost and risk.

INTRODUCTION

Transportation Asset Management (TAM) is a strategic and systematic process of maintaining

and managing infrastructure assets throughout their life cycle, focusing on business and 

engineering practices for resource allocation and utilization. It uses data and analysis to improve 

decision making, with the objective of providing the required level of service in the most costeffective manner (Gordon et al 2011).

For certain major asset classes such as pavements and bridges, the techniques of TAM are 

codified in law (23 USC 119, FHWA 2015) and in various standards documents (Thompson and 

Hyman 1992, GASB 1999, Cambridge et al 2002, NAMS 2006, BSI 2008, Gordon et al 2011). 

Mature data collection processes are in place for these asset classes, with relatively advanced 

models and information systems (Cambridge 2003, Hawk 2003, Sobanjo and Thompson 2011

and 2013).

Federal laws and regulations encourage agencies to apply asset management principles to all 

physical assets within the right-of-way corridor. State and Federal agencies have begun to 

specifically recognize the importance of geotechnical assets to corridor performance. (Anderson 

and Rivers 2013, Anderson, et al. 2014). State DOTs such as Alaska, Washington, Oregon, and 

Colorado are starting to do this for rock and soil slopes, and other geotechnical assets (WSDOT 

2010, ODOT 2011, Thompson et al 2014.) 

For agencies and asset classes that lack a history of data collection and lack sophisticated tools, 

the appropriate methods for geotechnical assets are much simpler than those that are commonly 

used for pavements and bridges. Nonetheless, the adoption of certain basic well-structured 

practices, relying on a systematic inventory and condition survey, can substantially enhance the 

consistency and objectivity of priority setting and resource allocation. This can reduce long-term 

costs and establish the groundwork for continuous improvement over time.

Purpose 

TAM is generally understood as a medium-range process for planning investments to preserve 

and enhance the ability of existing physical assets to contribute to agency objectives. Typically 

the planning of preservation and risk mitigation projects looks ahead for up to four or five years, 

and the strategic planning of investment funding requirements may look ahead for 10 years or 

more. 
115

For the 10-year timeframe of investment analysis, it is common to forecast the development of 

new needs, resulting from normal deterioration or extreme events, using probabilistic models. 

This can be analyzed quantitatively for each asset, but is summarized at the network level, 

without identifying specific assets, for reporting of results.

Benefit/cost analysis is the fundamental framework for setting priorities and allocating resources 

in asset management. In TAM practice, the benefit of a project may include the delay or 

avoidance of costs, the reduction of risk (either the likelihood of an adverse event or service 

disruption, or the consequence, or both), or other contributions to transportation objectives such 

as safety, mobility, or environmental and cultural resource sustainability. 

The need for prioritization and resource allocation arises because of limitations on funding. The 

list of attractive projects that need to be completed is always more costly than can be 

accomplished with available funds. If two projects are expected to have the same benefit, then in 

principle the one with lower cost is given more priority. If two projects have the same cost, the 

one with higher benefit is given more priority. A list of projects sorted by benefit/cost ratio 

provides a consistent way to determine the maximum benefit that is achievable for any given 

amount of funding, and selects the list of projects that can achieve this high level of benefits.

If these concepts of benefit and cost can be quantified in a useful way, then the agency is 

provided with a tool that is relatively simple to use for:

• Priority setting: deciding which projects should be funded within a specific timeframe 

given limited resources.

• Resource allocation: deciding how much funding should be allocated to different parts of 

the asset inventory at different times.

• Level of service standards: deciding what levels of condition or resilience should be 

considered acceptable or unacceptable for any given asset, thus determining which assets 

need risk reduction corrective action.

• Performance targets: deciding what network-wide conditions can be achieved over a long 

timeframe if a given funding level is provided and consistent asset management practices 

are implemented.

To support these management functions, the challenge then is to define a reasonable and useful 

way of quantifying benefits and costs.

Basic Principles

It is understood that quantitative asset management will be a relatively new capability for Federal 

Land Management Agency (FLMA) unstable slopes. Gathering of inventory and condition data 

has only recently begun on pilot corridors. In this context, a key goal is to find a relatively simple 

way to quantify benefits and costs, which can be developed using the data anticipated to become 

available, and which gives a fair representation of agency objectives and costs over time 

considering the major variables that distinguish one project from another in the asset inventory. 
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This would be used as a decision support tool, providing information to be weighed by decision 

makers along with non-quantitative considerations and other high priority facility demands 

within a given FLMA jurisdiction. The product should be:

• Consistent with agency mission and objectives, as typically defined in the mission 

statement or strategic plan. This can vary from one agency to another. Ideally all agency 

objectives that are affected by unstable slope preservation and mitigation projects should 

be reflected in some way in the measurement of benefits.

• Objective and consistent across the inventory, across inspectors, and over time. To the 

extent possible, the methodology should minimize subjectivity in the determination of 

project benefits. Where the application of judgment is unavoidable in determining 

benefits, it should be applied by professionals experienced in assessing geotechnical 

issues and made consistent using documentation, training, and analysis methods that are 

applied in the same way for every asset.

• Based on reliable data to the extent possible. The methods should require field data that 

would be economical to obtain in a relatively quick visual inspection process. Where 

possible, existing agency systems and processes should be leveraged to obtain needed 

data.

• Based on sound engineering and economic reasoning. The concepts that feed into benefit 

and cost calculations should follow generally-accepted engineering and economic 

principles that are stable over time. This will help to ensure long-term compatibility of 

the methods across asset classes in an agency-wide decision-making process.

• Tolerant of missing or estimated data. It should be possible to substitute estimated data or 

a simpler method in cases where essential data are missing, so all assets in the inventory 

can be addressed. The method can be used as a way of prioritizing the gathering of 

supplementary data where needed.

• Able to be improved over time with research, development, and better data. Substantial 

improvements in the state of the practice are routine in all branches of asset management. 

The FLMAs should be able to take advantage of these with a smooth transition by 

adopting more accurate or useful methods for computing benefits and costs as these are 

developed.

These tools will be used by a range of practitioners that may include planning, maintenance, and 

management personnel who are not necessarily engineering geologists or geotechnical engineers 

and who may be non-technical in their orientation. Although geological and engineering 

reasoning and experience may be required in making certain assessments, the benefit/cost 

analysis should reduce these considerations into a form that is more broadly understandable for 

effective usage and communication.
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Objectives and Tradeoffs

Transportation agencies typically list their major goals and objectives in their enabling 

legislation, mission statements, strategic plans, or other broad policy documents that 

communicate with stakeholders and the public. 

National Goals

For transportation asset management in general, a set of national goals have been defined by the 

Congress in 23 USC 150(b):

(1) SAFETY.—To achieve a significant reduction in traffic fatalities and serious injuries 

on all public roads.

(2) INFRASTRUCTURE CONDITION.—To maintain the highway infrastructure asset 

system in a state of good repair.

(3) CONGESTION REDUCTION.—To achieve a significant reduction in congestion on 

the National Highway System.

(4) SYSTEM RELIABILITY.—To improve the efficiency of the surface transportation 

system.

(5) FREIGHT MOVEMENT AND ECONOMIC VITALITY.—To improve the national 

freight network, strengthen the ability of rural communities to access national and 

international trade markets, and support regional economic development.

(6) ENVIRONMENTAL SUSTAINABILITY.—To enhance the performance of the 

transportation system while protecting and enhancing the natural environment.

(7) REDUCED PROJECT DELIVERY DELAYS.—To reduce project costs, promote jobs 

and the economy, and expedite the movement of people and goods by accelerating project 

completion through eliminating delays in the project development and delivery process, 

including reducing regulatory burdens and improving agencies’ work practices.

Congestion reduction, system reliability, and freight movement are often considered together as 

“mobility.”

USDA Forest Service Goals and Objectives

As an FLMA example, the USDA Forest Service goals and objectives can be found in the 

document, “US Forest Service Accomplishments FY2013 Federal Lands Transportation 

Program.” Additional information on the Forest Service Road Maintenance Management System 

can be located in the Forest Service guidance document: “FSH 7709.59 - Road System 

Operations and Maintenance Handbook – Chapter 60 – Road Maintenance.” These goals and 

objectives can be summarized in the following three categories:
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• Overall goals and objectives from investment strategy – maintain and preserve and if 

possible improve access to high priority areas.

• Specific goals and objectives:

o Ensure safe access

o Reduce bridge deficiencies

o Focus on high priority roads for maintenance and improvement

• FS strategic plan goals and priorities

o Facilitate outdoor recreation opportunities

o Enhance social, health, economic, etc. opportunities and experiences for visitors

o Provide seamless transportation access from public roads to NFS destinations

o Implement forest plans

o Improve rural economic opportunities

o Manage transportation to protect natural resources

These strategic priorities imply transportation objectives of safety, mobility, and protection of 

natural resources.

Asset characteristics as Measurable Evidence of Objectives

As a part of maximizing these system objectives, each asset makes its contribution by satisfying 

various criteria for its level of service:

• Condition (lack of material defects or performance deficiencies that occur with age and 

usage)

• Functionality (ability of an asset to perform the functions for which it was designed)

• Safety (ability of an asset to support itself and the road in a stable configuration)

• Resilience (asset characteristics which minimize the likelihood of service disruption)

Unstable slopes impact these performance measures primarily by means of the risk of service 

disruption caused by unstable slope events, whether rockfall, landslide, or debris flows. It is for 

this reason that the field assessment of condition, currently estimated by USMP score ratings, is 

expanded to include factors that affect each slope’s ability to resist these hazards and minimize 

the likelihood of service disruption.

In exchange for the service provided by each asset, the agency incurs a cost. This includes the 

initial cost of constructing the asset, and the cost of ongoing work to keep the asset in service and 

functioning as designed. Typically, an agency will seek to minimize the life cycle cost of 

keeping assets performing acceptably according to level of service criteria. These criteria can 

vary depending on the asset’s role in the overall transportation system.

FACTORS AFFECTING BENEFITS AND COSTS

The design of a benefit/cost framework is based on a cause-and-effect understanding of the 

factors affecting the priority of typical projects. The major determinants are:
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• Treatments: actions the agency may take to improve condition or resilience.

• Performance framework: accepted interpretations of long-term cost and risk that are 

independent of asset class.

• Causal variables: measurable asset properties affecting performance and costs.

Because of the need for simplicity and convenient usage, not all influential variables can be 

included in the methodology. It is necessary to set priorities and select those which are most 

important for subsequent use.

Treatments for Consideration

It is important that the benefit/cost analysis provide enough detail to distinguish among the 

different treatments to be evaluated. How a given treatment is classified depends on agency 

standard operating procedures, especially the structure of the planning and programming process 

in which the benefit/cost analysis is to be used. In asset management, three general classes of 

treatment are considered:

• Routine maintenance: Treatments that are interval-based or condition-based, which do 

not require planning or programming. Typically, a crew examines a site, sees a need for 

maintenance work, and responds within a short time, generally within the same 

construction season if not the same day. Examples are cleaning of rockfall catchment 

ditches, maintaining drainage ditches and structures to shed surface runoff, and minor 

patching or sealing of cracks and spalls in pavement. 

• Programmed construction: Treatments are planned a year or more in advance, and need to 

be programmed for long-term maintenance or capital funding. These are initiated by the 

routine inspection process. Examples are landslide mitigation, cut and embankment 

reconstruction, and slope scaling and construction of other risk reduction rockfall 

mitigation measures.

• Adverse event recovery: Treatments are executed on a quick-response or emergency 

basis due to unplanned events that interfere with transportation service. These events 

typically have high agency and user costs. Examples are scaling a hillside before removal 

of rock from a road surface, reconstruction of a slide-damaged pavement, and accident 

site recovery.

Routine maintenance and event recovery have no formal planning process associated with 

individual work orders, because they are assumed either to be too small or short-term to justify a 

planning effort, or require immediate work of highest priority. The costs of routine maintenance 

are included in the normal annual cost of ownership of each asset, and their magnitude will 

typically vary by condition state. Recovery costs are analyzed using a risk analysis, where the 

likelihood of unexpected adverse events will vary by condition. Projects which reduce this 

likelihood may recognize a project benefit.
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Programmed construction treatments represent the decision variable to be analyzed in the 

benefit/cost analysis. Their costs appear in the denominator of the benefit/cost ratio. They 

include:

• Installation, construction, or improvement of risk reduction mitigation features such as 

earth retaining walls, shear key rock buttresses, rockfall barriers along the edge of the 

road, and/or on-slope rockfall risk reduction mitigation measures.

• Preservation activities such as full-depth pavement patches (deep patches), subgrade or 

slope reinforcement, rock slope scaling, or rock reinforcement (rock bolts and/or rock 

dowels).

• Reconstruction activities such as embankment reconstruction, slope flattening, ditch 

expansion through a new cut, or road realignment.

In general, the simplest way to conceptualize the benefit of a treatment is to compare it with an

alternative treatment for the same asset. The alternatives to be compared should be mutually 

exclusive. For example, an agency might choose to patch a pavement, or reconstruct the entire 

embankment, but would not choose both at the same location. In most cases the base alternative 

represents taking no action in the program year under consideration, but instead delaying action 

to the following year. This “No Action” alternative is defined as having zero benefit and zero 

cost. All other alternatives for the asset have a cost greater than zero, and a benefit which may be 

more or less than zero. This way of organizing alternatives is especially appropriate in year-byyear programming applications where a slope is likely to require work eventually, so the primary 

decision-making concern is timing.

Performance framework

A benefit/cost analysis requires a basis for quantifying the benefit of each project. This quantity 

does not necessarily have to be expressed in dollars, but it is important to try to be objective and 

consistent, to be able to combine dissimilar benefits in a meaningful way, and to provide a 

migration path so the benefit estimate can be improved over time with better data and research. 

As a result, in common TAM practice, if benefits are not expressed in dollars, they are expressed 

in a form that can be related to a dollar quantity in a predictable (not necessarily linear) way 

(Patidar et al 2010). The methods in common use for quantifying project benefits include:

• Life cycle agency cost: All of the current costs and forecast future costs of maintenance 

and programmed work are estimated over a long-time period of at least as long as the 

typical service life of the asset. Future costs are discounted to consider the agency 

preference to delay large costs for as long as possible. The key tradeoff considered in the 

analysis is the possibility that a small preservation expenditure made today, might yield a 

substantial delay in the need for a much larger expenditure later (Hawk 2003).

• User cost: In pavement and bridge management it is common practice to express project 

benefits from enhancements in safety, mobility, and sometimes sustainability in an 

economic form representing the public’s willingness to pay for better transportation 
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service. While this might seem complex, there is a large body of research on the topic, 

which has been simplified and standardized by AASHTO in its Red Book (AASHTO 

2010). 

• Risk analysis: Geotechnical assets affect transportation performance primarily by the risk 

that they may fail and cause disruptions in transportation service, or may incur 

exceptional maintenance costs to maintain service. The potential for service disruptions is 

always subject to the uncertainty of natural materials. Asset characteristics that reduce the 

likelihood of disruptions are collectively known as resilience (or its opposite, 

vulnerability). If a disruption does occur, its consequence may depend on roadway 

utilization, the availability of alternate routes, and factors affecting recovery costs 

(Sobanjo and Thompson 2013).

All of these are relevant perspectives, which can be combined to give a complete picture of 

project benefits. It is necessary, however, to simplify each perspective to work with the unstable 

slope inventory and assessment data that are expected to be available, and to keep the 

computations reasonably quick. 

For example, it is assumed that FLMAs will not have the necessary tools in the near future to 

perform life cycle cost analysis for each project. However, the cost and benefit tradeoffs between 

preservation or risk mitigation and reconstruction can be estimated using typical data values, 

resulting in a simpler set of metrics that give preservation or risk mitigation actions a reasonable 

weight in priority-setting.

Similarly, the standardized user cost models in the AASHTO Red Book can be used in place of a 

consequence model for risk analysis. This would provide a simple and valid means of 

quantifying risk in terms of the agency objectives of safety, mobility, and sustainability.

The alternative methods described in the next chapter describe different ways of combining these 

methods and simplifications to define priority-setting formulas based on valid engineering and 

economic concepts, which are straight-forward for routine use by agencies which are just getting 

started in geotechnical asset management.

Expected Behavior of Key Variables

Relatively few data items are required for a useful benefit/cost analysis at the level of detail 

discussed here. The formulas that are developed based on the preceding discussion should be 

expected to affect priorities in a predictable way. The major variables and effects are as follows:

• Maintenance Level: This classification system describes the expected usage and 

importance of each route. It provides a framework for establishing level of service 

standards under normal service and for adverse event recovery. The higher maintenance 

levels would be expected to have higher project benefits and higher costs, with higher 

priorities overall.
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• Condition State: The definitions of condition states are based on ranges of USMP score. 

In most TAM applications, condition is purely a classification of degradation, 

disintegration, damage, and deformation of materials. In the current system, however, it 

also includes resilience factors such as drainage, stability, and movement history. Assets 

in Good condition typically are not considered for risk reduction corrective action. Those 

in Fair condition may be considered, and should recognize additional benefits if there is 

significant potential for life cycle cost savings.

• Size of slope: As a first approximation, life cycle cost, initial cost, and recovery cost are 

all proportional to the area of a rock slope, or the length of a soil slope. 

• Traffic volume: Higher volume roads will have proportionately greater safety and 

mobility impacts from service disruption. Therefore, treatments that reduce the likelihood 

of adverse events have higher benefits on these roads. The importance of traffic volume 

tends to reduce the relative importance of slope size in the numerator (but not the 

denominator) of the benefit/cost ratio. In some agencies and in some road corridors, 

traffic volume may need to be estimated.

• Detour distance: Mobility impacts of service disruption are greater on roads with long or 

non-existent detour routes. As a result, long detour routes increase the benefit of risk 

reduction projects.

Given these considerations, a general form of the benefit/cost priority formula can be expressed 

as:

BBBBBBBBBBBBBB

CCCCCC = [LL cccccccc aaaa bb ] + [RR RR rr rrrr bb ]

[PP PP cc ]

Inserting the major causal variables, this formula becomes:

BB

CC = LL (CC , SS SS ) + SS ( LL, CC , AAAAAA) + ( , CC , AAAAAA, , ) + RR (SS SS ) + EE

II (CC , SS SS )

Where:

LCB(CS,Size) = Life cycle benefit is a function of condition state and slope size,

SB(ML,CS,ADT) = Safety benefit is a function of maintenance level, condition state, 

and traffic volume,

MB(ML,CS,ADT,DL,DT) = Mobility benefit is a function of maintenance level, condition, 

traffic, detour length, and detour time,

RB(Size) = Recovery benefit is a savings in recovery cost as a function of size,

EB = Environmental benefit is estimated on a site-specific basis to include damage to 

streams caused by rockfall or soil slope movement, and, if applicable, cultural or 

community impacts, and

IC(CS,Size) = Best estimate of initial cost is a function of condition and size.
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In each of the risk reduction factors, condition state and maintenance level affect the likelihood 

of transportation service disruption, while the remaining variables affect the consequence of 

service disruption. The next chapter develops alternative approaches for computing these metrics 

for unstable rock and soil slopes.

ALTERNATIVE APPROACHES

Appendices 1 and 2 of this document derive formulas for detailed calculation of benefits and 

costs that incorporate life cycle cost analysis and risk analysis. Depending on data availability 

and desired level of detail, these calculations may be simplified in various ways. The following 

sections summarize the alternatives.

Alternative #1: Computed benefits and costs

If sufficient data are available for a given slope, the most precise estimate of benefit/cost ratio 

would fully utilize the formulas in Appendices 1 and 2 of this document. Combining the life 

cycle cost and risk components, the ratio would be:

BB

CC = LL + LL h ×CCCC CC CC

II

LL = SS SS ×AA $

LL h AA2 − 1

CCCC CC CC = AAAAAA×�7.25 + ×(0.207 + 39.65 )� + SS SS ×RR $ + EE

II = SS ×CCCCCC $

Where:

Size = For rock slopes: Slope size = 0.65 × length along the road × height

= For soil slopes: Slope size = length along the road

ABen$ = Unit agency benefit of risk reduction corrective action (Table A1-3)

ADT = Average annual or seasonal daily traffic

DD = Number of days that traffic is detoured (Table A2-1)

DL = Detour length in miles

DT = Detour time in hours (detour length divided by detour speed)

Rec$ = Estimated unit cost to recover if a disruption occurs

$1/sq.ft for rock slopes, $50/ln.ft for soil slopes

(based on expert judgment from Alaska research)

EB = Environmental benefit is estimated on a site-specific basis

Cost$ = Typical unit cost of risk reduction corrective action (Table A2-3)

If a formal cost estimate is available, such as from a design study, the IC term can be replaced 

with the actual cost estimate. The maintenance and recovery costs used in this analysis are initial 

order-of-magnitude estimates that can be improved over time through research, interviews, or 
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data mining of existing maintenance records. Similarly, any of the other terms of the equation 

can be replaced with better estimates if available from analysis or judgment. The consequence 

factors $7.25/daily vehicle, $0.207/detour mile, and $39.65/delay hour are derived from the 

AASHTO Red Book as discussed in Appendix 2 of Appendix D of this document.

For roads that have very low traffic volume but nevertheless have a strong need to remain open, 

a minimum ADT value may be assigned. Similarly, for seasonal traffic it is appropriate to use 

average seasonal ADT computed for the busiest months.

Data requirements for Alternative #1:

• Length of slope along the road.

• Height of slope (for rock slopes).

• Average annual or seasonal daily traffic.

• Detour length in miles.

• Detour time in hours, or detour speed in miles per hour.

• Estimate of environmental cost of slope failure, if applicable, on a site-specific basis to 

include damage to streams caused by rockfall or slope movement, cultural, or community 

impacts. Since there is no established methodology to compute this, it would generally be 

omitted unless a study has been done to quantify it. However, it is very important to the 

mission of many of the FLMAs.

• Maintenance level.

• Condition state.

Advantages of Alternative #1:

• Offers the most precise estimate of benefits and costs.

• Recognizes the life cycle benefit of preservation, which may save money in the long 

term.

• Uses all available data.

• Most reliable for defending programming decisions.

Disadvantage of Alternative #1:

• Requires the most data of the three alternatives

Alternative #2: Priority index

If detour information is not available, but the manager can make a rough estimate from 

knowledge of the site, the term (0.207 DL + 39.65 DT) in Alternative #1 can be approximated 

using Table A2-2 to yield an estimate of the user cost of detours in dollars per vehicle. For routes 

where no detour route exists, a common method is to rely on marine or air fares for users who 
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must make the trip by an alternate mode. For leisure trips, or trips where no alternative mode is 

available, road users might decide not to make the trip at all if the road is closed. In this case, the 

social cost might be the lost revenue from businesses that lose access.

However, a further simplification can be achieved if the detour computation is omitted entirely. 

This would be valid if detour distances are relatively consistent from one site to another, or if 

drivers are relatively insensitive to detour distances. In this case, it can be recognized that 

mobility benefits tend to be correlated with safety benefits since both are strongly dependent on 

the likelihood of service disruption and traffic volume. Using median values of input data from 

the test data sets used in the Appendices of this document, the mobility benefit is about 1.5 times 

the safety benefit. In this case the formula in Alternative #1 can be simplified to:

BB

CC = SS SS ×AA $ + LL h ×(18 AAAAAA + SS SS ×RR $ + EE )

SS SS ×CCCCCC $

Or if environmental benefit is also omitted, the expression can be simplified still further to:

BB

CC = AA $ + LL h ×(18 AAAAAA/SS SS + RR $)

CCCCCC $

Where:

Size = For rock slopes: Slope size = 0.65 × length × height

= For soil slopes: Slope size = length

ABen$ = Unit agency benefit of risk reduction corrective action (Table A1-3)

Likelihood = Based on maintenance level and condition state (Table A2-1)

ADT = Average annual or seasonal daily traffic

Rec$ = Estimated unit cost to recover if a disruption occurs

$1/sq.ft for rock slopes, $50/ln.ft for soil slopes

EB = Environmental benefit is estimated on a site-specific basis

Cost$ = Typical unit cost of risk reduction corrective action (Table A2-3)

This latter formula might be more properly called a priority index, since it is moving away from 

expressing benefits and costs explicitly, and dollar values cannot be added to the numerator or 

denominator to reflect additional project impacts. In addition, this simpler formula is not valid if 

the unit cost of risk reduction corrective action is zero, or if no traffic exists on the road (for 

example, USFS Maintenance Level 1, where this type of analysis would not normally be used).

Data requirements for Alternative #2:

• Length of slope along the road.

• Height of slope (for rock slopes).

• Average annual or seasonal daily traffic.
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• Estimate of environmental cost of slope failure, if applicable, on a site-specific basis to 

include damage to streams caused by rockfall or slope movement, cultural, or community 

impacts.

• Maintenance level.

• Condition state.

Advantages of Alternative #2:

• Simpler than computing costs and benefits.

• Moderate data requirements.

• Recognizes the life cycle benefit of preservation.

Disadvantages of Alternative #2:

• Does not account for sites with long detour routes, which may be problematic if these 

routes also have heavy traffic.

• Not able to consider additional information that may be known about specific sites, such 

as an actual cost estimate.

Alternative #3: USMP Score Priority Index

Since the USMP score is already being calculated, a third alternative is to use it without any 

economic data. For example, the following formula captures three of the most significant 

variables:

PP ii = UU UU SS ×

AAAAAA

SS SS

Where:

Size = For rock slopes: Slope size = 0.65 × length × height

= For soil slopes: Slope size = length

ADT = Average annual or seasonal daily traffic, or estimated number of trail users

Here the USMP score is a proxy for condition and the likelihood of service disruption, ADT is a 

proxy for consequence and user benefit, and Size is a proxy for the cost of risk reduction 

corrective action. This is known as a “worst-first” indicator because it does not consider life 

cycle costs. Therefore, this alternative is not able to assign a benefit to preservation actions. 

Note that this alternative is likely the most applicable for trails due to the fewer data inputs 

required.

For roads or trails that have very low traffic volume but nevertheless have a strong need to 

remain open, a minimum ADT value may be assigned. Similarly, for seasonal traffic it is 
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appropriate to use seasonal average ADT computed for the busiest months. Data requirements 

for Alternative #3:

• Length of slope along the road or trail.

• Height of slope (for rock slopes).

• Average daily traffic.

• USMP score (29 variables).

Advantage of Alternative #3:

• Smallest additional data requirements (assuming the USMP score is already being 

collected).

• Method most applicable for use on trails.

Disadvantages of Alternative #3:

• Cannot consider preservation actions, so it will produce more expensive programs in the 

long run.

• Does not account for maintenance and recovery costs.

• Does not account for sites with long detour routes, which may be problematic if these 

routes also have heavy traffic.

• Not able to consider additional information that may be known about specific sites, such 

as an actual cost estimate.

• Not compatible between asset classes.

• Unsuitable for resource allocation or computation of fiscally-constrained performance 

targets.

• More difficult to communicate to executives, planners, and the public outside the 

geotechnical area.

Alternative #4: Hybrid of #1 and #2

Alternatives #1 and #2 are mutually compatible in that they both approximate a benefit/cost ratio 

using the same factors for scaling. It is possible to use them together on different projects within 

the same priority list. This is especially useful for agencies that have only partial coverage of 

some of the data items in the inventory. The strategy would be to use #1 whenever possible, but 

fall back on #2 when necessary because of missing data.

Advantages of Alternative #4:

• Offers maximum reliability even with a partially completed database.

• Maximum soundness from an engineering and economic perspective.

• Most amenable to scenario analysis, such as considering fiscal alternatives and 

performance targets, because more of the inventory can be covered than in #1 alone.
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• The approximate analysis using Alternative #2 can be used to prioritize additional data 

gathering for Alternative #1.

Disadvantage of Alternative #4:

• Similar to Alternative #2 for sites having incomplete data.
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APPENDIX 1 TO APPENDIX D: DEVELOPMENT OF LIFE CYCLE AGENCY 

BENEFIT FACTORS

A significant benefit of risk reduction corrective action on unstable slopes is a potential reduction 

in ongoing routine maintenance costs, and a potential delay in major reconstruction costs. Life 

cycle cost analysis (LCCA) is a tool to quantify the balance between the immediate cost of risk 

reduction corrective action and future cost savings (Hawk 2003, Thompson et al 2012).

LCCA relies on models of deterioration, cost, and effectiveness. It follows an asset through its 

life cycle, simulating deterioration and appropriate actions to correct or limit deterioration, using 

a set of decision rules to select these hypothetical future actions. Future costs are discounted to 

reflect the value of delaying expenditures as long as possible. The sum of these discounted costs 

is the total life cycle agency cost (LCAC). 

Two competing treatment alternatives for a slope can be compared by computing the LCAC of 

each alternative. Usually one of these alternatives involves a risk reduction corrective action in 

the year under consideration, and the other alternative, denoted “do nothing,” postpones risk 

reduction corrective action until the following year or later. If the risk reduction corrective action 

has a lower LCAC, then the difference in LCAC results between the two alternatives is part of 

the project benefit.

In the course of carrying out this project, Microsoft Excel was utilized for example life cycle cost 

analyses for rock and soil slopes, using typical values of input parameters. Applying the 

calculation methods previously described proved useful to provide a reasonable benefit estimate 

for preservation and reconstruction activities, without requiring a separate LCCA for every site. 

This helps to make the final product simpler and easier to use. The input data applied to the 

example are as follows:

• Discount rate: The benefit (cost reduction) from delaying a cost by one year, expressed as 

an interest rate. The default value used in this analysis is 2.1%, which is typical in asset 

management applications.

• Deterioration model: Parameters governing how quickly slopes deteriorate from one 

condition state to the next. The default model for rock slopes has 38 years as the median 

time to deteriorate from Good to Fair, and 54 years to deteriorate from Fair to Poor. The 

default model for soil slopes has 55 years as the median time to deteriorate from Good to 

Fair, and 36 years to deteriorate from Fair to Poor. These are based on an analysis 

developed for unstable slopes in Alaska (Thompson et al., 2016).

• Cost models: Rock slopes have costs in $/sq.ft (Table A1-1) for routine maintenance and 

risk reduction corrective actions in each condition state. Soil slopes have costs in $/ln.ft 

(Table A1-2) for routine maintenance and risk reduction corrective actions in each 

condition state. These costs tend to increase as conditions worsen. The costs are based on 

models developed for Alaska DOT (Beckstrand and Mines, 2016). They are regarded as 

rough estimates suitable for network level use.
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• Action effectiveness model: These are based on judgment. In Fair and Poor condition in 

the default model, slopes have a 20% chance of remaining in the same condition after a 

treatment, and an 80% chance of improving. From Poor condition, the typical major 

renovation projects have a 50% chance of resulting in Good condition.

Table A1-1. Default unit cost of maintenance and risk reduction (RR) corrective action –

Rock slopes

Costs in 2015 dollars/sq.ft by condition state

Good Fair Poor

Routine 

maintenance 0.05 0.20 1.00

RR Corrective 

action

0.00 2.00 12.00

Table A1-2. Default unit cost of maintenance and risk reduction (RR) corrective action –

Soil slopes

Costs in 2015 dollars per linear foot by condition state

Good Fair Poor

Routine 

maintenance 100 200 500

RR Corrective 

action 0 1500 3500

This analysis used a Markov deterioration model, which is the simplest form that is applicable to 

condition state data. It is widely used in bridge management systems and many other 

applications (Thompson et al 2012).

NCHRP Report 483 (Hawk 2003) has a thorough discussion of how discount rates are 

determined. In short, they are determined by agency policy, which should be consistent across all 

types of assets and all investments of similar lifespan. A common source of guidance is The 

White House Office of Management and Budget (OMB) Circular A-942

. Typically, inflation is 

omitted from life cycle cost analyses because this practice simplifies the computations. A riskless 

and inflationless cost of capital for long-lived investments may use 30-year US Treasury bonds 

for guidance, with a 2015 real interest rate of 1.4%3. Transportation agencies usually specify 

 2 http://www.whitehouse.gov/omb/circulars_a094/

3 http://www.whitehouse.gov/omb/circulars_a094/a94_appx-c/
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higher discount rates than this, in the 2 to 5 percent range, because of uncertainties in long-term 

funding, future travel demand, and infrastructure requirements.

Using the default parameters as described here, Table A1-3 shows the estimated unit life cycle 

agency benefits computed. For any given project, life cycle benefits are computed from:

LL (CC , SS SS ) = SS SS ×AA $

Where:

CS = Condition state, based on ranges of USMP scores

Size = For rock slopes: Slope size = 0.65 × length × height

= For soil slopes: Slope size = length

ABen$ = Unit agency benefit of risk reduction corrective action (Table A1-3)

The slope area formula for rock slopes was developed in research for Alaska DOT by 

photographic analysis of slope configurations across a large range of size, type, and geologic 

compositions (Beckstrand et al., 2016).

Table A1-3. Unit benefit of risk reduction corrective action (Ben$)

Benefits in 2015 dollars by condition state

Good Fair Poor

Rock slopes ($/sq.ft) 0.00 0.23 0.55

Soil slopes ($/ln.ft) 0.00 101.38 260.47

These models are relatively insensitive to discount rates, deterioration rates, and effectiveness. A 

10% change upward or downward in any of these inputs causes less than a 5% change in the unit 

benefits. The benefits are linearly proportional to the unit costs that are input. This stability 

makes it reasonable to use the parameter values in Table A1-3 in a priority formula, within a 

normal range of uncertainty. For agencies that feel more resolution is needed between condition 

states, it is possible to interpolate using judgment.
132

APPENDIX 2 TO APPENDIX D: DEVELOPMENT OF USER BENEFIT FACTORS

As discussed in the document section entitled, “Expected Behavior of Key Variables,” a generic 

benefit/cost formula for unstable slopes can be expressed as a function of the most influential 

variables using the equation:

BB

CC = LL (CC , SS SS ) + SS ( , CC , AAAAAA) + ( , CC , AAAAAA, , ) + RR (SS SS ) + EE

II (CC , SS SS )

Where:

LCB(CS,Size) = Life cycle benefi is a function of condition state and slope size,

SB(ML,CS,ADT) = Safety benefit is a function of maintenance level, condition state, and 

traffic volume,

MB(ML,CS,ADT,DL,DT) = Mobility benefit is a function of maintenance level, condition, 

traffic, detour length, and detour time,

RB(Size) = Recovery benefit is savings in recovery cost as a function of size,

EB = Environmental benefit is estimated on a site-specific basis to include damage to 

streams caused by rockfall or slope movement, and, if applicable, cultural or community 

impacts, and

IC(CS,Size) = Initial cost is a function of condition and size.

Life cycle benefit is discussed in Appendix 1 to Appendix D above. The remaining terms in the 

equation are discussed below. The manager can modify input parameters to customize the 

priority formula to suit the needs of different agencies.

Safety

The safety benefit of a risk reduction corrective action is the savings in user cost that would be 

achieved if the action is taken this year, rather than waiting until the following year. It is 

therefore one year of the expected user cost caused by a deteriorated condition.

Safety user cost is based on an estimate of the number of avoidable crashes likely to be caused 

by a service disruption event such as rockfall or a landslide. These events can entail vehicles 

being struck by falling debris, vehicles striking debris that is already lying in the road, or 

vehicles that lose control, or are damaged due to debris avoidance or pavement damage. For this 

analysis, these incidents are assumed to be single-vehicle crashes. The AASHTO Red Book 

(AASHTO 2010) has procedures and research-based metrics that consider typical crash injury 

severity rates and property damage. The safety benefit is:

SS = LL h ×

AAAAAA

AAAAAA

×CC CCh rr ×AA $

Where:
133

Likelihood = Probability of a service disruption event (Table A2-1)

ADT = Average annual or seasonal daily traffic

Median ADT = Median traffic volume for the population of slopes in the inventory

Crash rate = Fraction of disruption events that result in crashes, 10%

ACC$ = Average cost per crash ($43,525 in 2015$)

The likelihood of service disruption is derived from the table of road closure event frequency 

performance standards (Table 4) in the document contained in Appendix F, using the assumption 

of one unstable slope per five miles of road. These values are summarized in Table A2-1.

Table A2-1. Annual frequency of service disruption events (Likelihood)

Forest 

Service 

Maintenance

Event probability (events/year) by condition 

state Duration

level Good Fair Poor (days)

1 0.00 1.00 1.00 183

2 0.00 1.00 2.50 14

3 0.15 0.30 1.00 5

4 0.10 0.15 1.00 2

5 0.02 0.04 0.15 1

The crash rate is an estimate of the average number of crashes per disruption event. Based on 

judgment this rate is assumed to be 10%. Since the crash rate is proportional to traffic volume, it 

is normalized so that the 10% corresponds to the median traffic volume in the inventory. These 

metrics should be adjusted to fit an agency’s actual data once a sufficient inventory has been 

gathered. It is appropriate to adjust this factor to account for seasonal variations in crash risk.

Average accident cost per crash is based on the AASHTO Red Book (AASHTO 2010, page 5-

24). This figure is an average over all vehicle classes and accident types, assuming each accident 

involves only one vehicle. It is updated to 2015 dollars using the Consumer Price Index. Using 

all the default parameter values, safety benefit can be estimated as:

SS = LL h ×AAAAAA×7.25

Mobility

Similar to the safety benefit, the mobility benefit is a one-year savings in user costs, which 

includes the travel time and vehicle operating cost associated with avoidable detours caused by 

service disruption events. Vehicle operating cost includes fuel, tires, wear-and-tear, and 

maintenance. Detour distance and time are the additional travel made necessary because of an 

adverse geotechnical event. The mobility benefit is:

= LL h ×AAAAAA× ×( ×VV $ + × $)
134

Where:

Likelihood = Probability of a service disruption event (Table A2-1)

ADT = Average annual or seasonal daily traffic

DD = Number of days that traffic is detoured (Table A2-1)

DL = Detour length in miles

VOC$ = Average vehicle operating cost per mile ($0.207 in 2015$)

DT = Detour time in hours (detour length divided by detour speed)

TT$ = Travel time cost per vehicle-hour ($39.65 in 2015$)

The duration of a service disruption is derived from the table of Average Time to Clear Incident 

and Reopen Road (Table 5) in the performance measures document contained in Appendix F. 

These values are summarized in Table A2-1.

Average vehicle operating cost can be found in the AASHTO Red Book (AASHTO 2010, page 

5-10). This is based on the “large car” column and includes fuel, oil, maintenance, and tires. It is 

updated to 2015 dollars using the Consumer Price Index.

Travel time cost is also in the AASHTO Red Book (AASHTO 2010, page 5-4). This figure uses 

the average over all occupations, computed as an opportunity cost. It is updated to 2015 dollars 

using the Consumer Price Index. It is multiplied by average vehicle occupancy of 1.3, a value 

suggested in the AASHTO Red Book. On state highway networks, a common default value for 

detour speed is 45 miles per hour (mph) in the absence of site-specific data. For FLMAs this 

may be 35 mph or lower.

In general, the travel time component of the mobility benefit equation is larger than the vehicle 

operating cost component. At a speed of 45 mph, the travel time unit cost of $39.65/hour 

converts to $0.881/mile, which is much greater than the vehicle operating cost of $0.207/mile. In 

this example, if detour speed is unknown, and the default value of 45 mph is used and the 

mobility benefit reduces to:

= LL h ×AAAAAA× ×1.088×

If detour distance and time cannot be obtained from an agency’s geographic information system

or other records, it is possible to ask maintenance personnel or inspectors to estimate these 

quantities in the field or from their knowledge of the sites, using approximate ranges. From this 

information, an estimate of detour cost (Detour$) can be derived, and used in the following 

mobility benefit equation:

= LL h ×AA × × $

Reasonable range limits were identified based on an analysis of bridge sites in the Pontis 

database of Florida, a state with what is believed to be a representative sparse road network and 

high quality detour data. The ranges represent the 3rd, 5th, and 7th deciles in the data distribution, 

rounded to convenient values. The 5th decile is the median, a value that can be used if no other 
135

estimate is possible. Table A2-2 shows the ranges of detour length and speed, typical values that 

are representative of each range, and the detour cost per vehicle Detour$.

Table A2-2. Default detour cost estimates (Detour$)

User cost of detours, 2015 dollars per vehicle

Ranges Length < 1 mile < 5 miles >= 5 miles

Speed Typical values 0.6 mi 2 mi 15 mi

< 30 mph 20 mph 1.31 4.38 32.84

< 55 mph 45 mph 0.65 2.18 16.32

>= 55 mph 60 mph 0.52 1.74 13.02

Recovery Costs

The cost of recovery from an extreme event may include removal of debris from the road 

surface, repairs to damaged roadside features and protective systems, restoration of surface 

geometry, and paving. It may also include stabilization of the slope itself such as slope 

reconstruction, and/or installation of rock reinforcement, mesh on the slope, or rockfall barriers. 

The magnitude can be quite site-specific and incident-specific. For the purpose of a general 

benefit/cost analysis, the recovery benefit is estimated as:

RR = LL h ×SS SS ×RR $

Where:

Likelihood = Probability of a service disruption event (Table A2-1)

Size = For rock slopes: slope size = 0.65 × length × height

= For soil slopes: slope size = length

Rec$ = Estimated unit cost to recover if a disruption occurs

$1/sq.ft for rock slopes, $50/ln.ft for soil slopes

The rock slope area formula was developed in research for Alaska DOT by photographic 

analysis of typical slope configurations. Recovery costs are assumed to be proportional to the 

size of the slope, and are based on expert judgment from Alaska research. 

Initial Cost

If a project is under consideration for immediate implementation, the agency may already have a 

site-specific cost estimate. This should be used in the denominator of the benefit/cost formula if 

available. In the absence of this, the following cost formula may be used:

II = SS SS ×CCCCCC $

Where:
136

Size = For rock slopes: slope size = 0.65 × length × height

For soil slopes: slope size = length

Cost$ = Typical unit cost of corrective action (Table A2-3)

Table A2-3. Default unit cost of corrective action (Cost$)

Costs in 2015 dollars by condition state

Good Fair Poor

Rock slopes 

($/sq.ft) 0 2.00 12.00

Soil slopes ($/ln.ft) 0 1500 3500

The rock slope area formula was developed in research for Alaska DOT by photographic 

analysis of typical slope configurations.

Note that these costs and all previous costs in this appendix are expressed in 2015 dollars. They 

should be adjusted upward using the Consumer Price Index for user costs, and the ENR 

Construction Cost Index for agency costs, for accurate usage in the future if agency-specific 

costs have not been developed.
137

REFERENCES FOR APPENDIX D

AASHTO. 2010. User and Non-User Benefit Analysis for Highways. American Association of 

State Highway and Transportation Officials.

Available at https://bookstore.transportation.org/collection_detail.aspx?ID=65. 

Anderson, S. & Rivers, B. 2013. “Corridor Management – A Means to Understanding of 

Geotechnical Impacts on System Performance,” Transportation Research Record: Journal 

of the Transportation Research Board No. 2349, pp. 9-15.

Anderson, S., Stanley, D., and Loehr, E. 2014. “Managing Geotechnical Assets to Improve 

Highway System Performance”, Geo-Strata, March/April 2014 issue, the Geo-Institute of 

the American Society of Civil Engineers, Reston, VA, pp 20-24.

Beckstrand, D., Mines, A., Thompson, P., Benko, B., 2016, Development of Mitigation Cost 

Estimates for Unstable Soil and Rock Slopes Based on Slope Condition, TRB 

Compendium of Papers, No. 16-4286

BSI. 2008. Asset Management Part 1: Specification for the optimized management of physical 

assets. British Standards Institute, Publicly Available Specification 55-1 (PAS 55-1).

Available at http://shop.bsigroup.com/en/ProductDetail/?pid=000000000030171836. 

BSI. 2008. Asset Management Part 2: Guidelines for the application of PAS 55-1. British 

Standards Institute, Publicly Available Specification 55-2 (PAS 55-2).

Available at http://shop.bsigroup.com/en/ProductDetail/?pid=000000000030187096. 

Cambridge Systematics, Inc., Parsons Brinckerhoff Quade and Douglas Inc., Roy Jorgensen 

Associates Inc., and Paul D. Thompson. 2002. Transportation Asset Management Guide. 

American Association of State Highway and Transportation Officials.

Available at http://downloads.transportation.org/amguide.pdf. 

Cambridge Systematics, Inc. 2003. Pontis 4.3 Technical Manual. American Association of State 

Highway and Transportation Officials.

FHWA. 2015a. Notice of Proposed Rule-Making on National Performance Management 

Measures. Federal Register 80:2, Pages 386-393. Federal Highway Administration. 

January 5, 2015.

Available at http://www.gpo.gov/fdsys/pkg/FR-2015-01-05/pdf/FR-2015-01-05.pdf. 

FHWA. 2015b. Notice of Proposed Rule-Making on Transportation Asset Management Plans. 

Federal Register 80:34, Page 9232 and 9236. Federal Highway Administration. February 

20, 2015.

Available at http://www.gpo.gov/fdsys/pkg/FR-2015-02-20/pdf/2015-03167.pdf. 
138

GASB. 1999. Basic Financial Statements — and Management’s Discussion and Analysis — for 

State and Local Governments. Government Accounting Standards Board Statement 34.

Available at http://www.gasb.org. 

Gordon, M., G.J. Smith, P.D. Thompson, H. Park, F.D. Harrison, and B. Elston. 2011. AASHTO 

Transportation Asset Management Guide, Volume 2: A Focus on Implementation. 

Prepared under NCHRP Project 08-69. American Association of State Highway and 

Transportation Officials.

Available at https://bookstore.transportation.org/item_details.aspx?id=1757. 

Hawk, H. 2003. Bridge Life Cycle Cost Analysis. National Cooperative Highway Research 

Program Report 483, Transportation Research Board of the National Academies.

Available at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_483a.pdf. 

NAMS Steering Group. 2006. International Infrastructure Management Manual (IIMM). 

National Asset Management Steering Committee, New Zealand.

Available at http://www.nams.org.nz/digitiseshop/prod-67/2011-InternationalInfrastructure-Management-Manual.htm. 

ODOT. 2011. Asset Management Strategic Plan. Oregon Department of Transportation.

Available at http://www.oregon.gov/ODOT/TD/asset_mgmt/docs/plans/04-amsp-10-

111711_final.pdf. 

Patidar, V., S. Labi, K. Sinha, and P.D. Thompson. 2007. Multi-Objective Optimization for 

Bridge Management Systems. National Cooperative Highway Research Program Report 

590, Transportation Research Board of the National Academies.

Available at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_590.pdf. 

Sobanjo, J.O., and P.D. Thompson. 2011. Enhancement of the FDOT’s Project Level and 

Network Level Bridge Management Analysis Tools: Final Report. Florida Department of 

Transportation Contract BDK83 977-01.

Available at http://www.dot.state.fl.us/researchcenter/Completed_Proj/Summary_MNT/FDOT_BDK83_977-01_rpt..pdf. 

Sobanjo, J.O., and P.D. Thompson. 2013. Development of Risk Models for Florida’s Bridge

Management System: Final Report. Florida Department of Transportation Contract 

BDK83 977-11.

Available at http://www.dot.state.fl.us/researchcenter/Completed_Proj/Summary_MNT/FDOT-BDK83-977-11-rpt.pdf. 

Thompson, P. D., Beckstrand, D., Mines, A., Vessely, M., Stanley, D., Benko, B., 2016, 

Geotechnical Asset Management Plan., Transportation Research Record: Journal of the 

Transportation Research Board, vol. 2596, https://doi.org/10.3141/2596-05.
139

Thompson, P.D. and W.A. Hyman. 1992. AASHTO Guide for Bridge Management Systems. 

American Association of State Highway and Transportation Officials.

Available at https://bookstore.transportation.org/Item_details.aspx?id=343. 

Thompson, P.D., K.M. Ford, M.H.R. Arman, S. Labi, K. Sinha, and A. Shirolé. 2012. Estimating 

Life Expectancies of Highway Assets. National Cooperative Highway Research Program 

Report 713, Transportation Research Board of the National Academies.

Available at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_713v1.pdf. 

Thompson, P.D., L.A. Pierson, D.L. Beckstrand. 2014. “Condition Indices, Performance 

Measures, and Managing Performance Data for Geotechnical Asset Management: Don’t 

Get Buried!” Geo-Strata 15:2. American Society of Civil Engineers. March/April 2014, 

pp. 26-30.

Available at http://cedb.asce.org/cgi/WWWdisplay.cgi?318669. 

WSDOT. 2010. WSDOT’s Unstable Slope Management Program. Brochure.

Available at http://www.wsdot.wa.gov/NR/rdonlyres/7D456546-705F-4591-AC5B7E0D87D15543/78408/UnstableSlopeFinaFolioWEBSMALL.pdf. 
140

APPENDIX E. GIFFORD PINCHOT NATIONAL FOREST COST ESTIMATION

This appendix contains the conceptual design and cost estimation forms for the Gifford Pinchot 

National Forest, which were completed for this project. 
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date: 6/30/15

Road/Trail No.: FS 25 Trail Created by: DLB Road 

Beginning MP: 21.71 Ending MP: 21.86 Side R Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 251 Previous Rating Agency Landslide Tech Previous Rating Date 9/30/14

Current Rating (if re-rated) Photo # Range

Problem Statement

Moderate rockfall hazard with raveling volcanic breccia/tuff. Ditch is wide enough to catch most rockfall and there is 

not too much activity. Rockfall warning sign is present.

Proposed Correction

Concrete barrier to improve ditch effectiveness to nearly 100%

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Concrete barrier - used LF 550 100 $55,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $55,000.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/29/15

Road/Trail No. FS 25 Trail Created by: CIC Road 

Beginning MP 24.45 Ending MP 24.28 Side LT Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 416 Previous Rating Agency Landslide Tech Previous Rating Date 10/1/14

Current Rating (if re-rated) Photo # Range

Problem Statement

170 feet long

Rotational Slump

2:1 embankment, outer shell of rock on ends

Proposed Correction

Top Berm 30” wide width

Clear and Grub down 2 ‘

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Excavation (Access/Toe ) 2’ x 10 x 170 CY 350 $15 $5,250.00

Toe Berm Fill CY 2800 $15 $42,000.00

Drainage Blanket Rock CY 200 $40 $8,000.00

Geotextile SY 800 $2.50 $2,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $57,250.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/30/15

Road/Trail No. FS 25 Trail Created by: DLB Road 

Beginning MP 24.63 Ending MP 24.75 Side R Weather Sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 465 Previous Rating Agency Landslide Tech Previous Rating Date 7/22/14

Current Rating (if re-rated) Photo # Range

Problem Statement

Hard rock cut slope with wide jointing. Boulders up to 6’ in ditch, impact crater on the inside lane. Ditch is fair but 

blocks should be removed to restore functionality. 

Proposed Correction

Clean ditch by busting boulders – scale and bolt rock face to stabilize select boulders/blocks.

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Clean ditch of large blocks LS 1 10,000 $10,000.00

Scale – light scaling 400sq ft/hr HR 125 225 $28,125.00

Rock bolt 140 x 10 LF 1,400 200 $280,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $318,125.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/30/2015

Road/Trail No. FS 25 Trail Created by: CIC Road 

Beginning MP 24.70 Ending MP 24.73 Side LT Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 28.6 Previous Rating Agency Landslide Tech Previous Rating Date 7/22/14

Current Rating (if re-rated) Photo # Range

Problem Statement

150’ Long, Outboard Lane, cracks in middle of outboard lane, boulders in fill.

Proposed Correction

Half width deep patch

Excavate Down 4 feet, 3-4 layer geogrid

Use on site material for fill

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Deep Patch FT 150 300 $45,000.00

Excavation (15’ x 150’ x 4’) CY 350 15 $5,250.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $50,250.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/29/15

Road/Trail No. FS 25 Trail Created by: DLB Road 

Beginning MP 25.11 Ending MP 25.28 Side R Weather Sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 354 Previous Rating Agency Landslide Tech Previous Rating Date 10/2/14

Current Rating (if re-rated) Photo # Range

Problem Statement

Raveling Case 2 type slope with a low visibility curve and ditch as narrow as 2’. An upper layer has cobbles and small 

boulders that are slowly eroding out. Only northern segment of cut is mitigated in this design.

270 slope length w/60’ average height

Proposed Correction

Lay back the upper 1/3 of the slope to reduce the incidence of cobbles, and boulders, and then install draped mesh. 

Alternative lower cost. Higher maintenance option is to install concrete barrier with high tensile strength wire mesh 

fence extension on top.

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Crest excavation 250’ x (42’ x 6’1/2) = 1200 cy CY 1200 20 $24,000.00

Draped high tensile strength mesh (270 x 80’ = 21,600) SF 21,600 6 $129,600.00

Clean up scaling HR 40 225 $9,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $162,600.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/29/15

Road/Trail No. FS 25 Trail Created by: CIC Road 

Beginning MP 25.15 Ending MP 25.20 Side LT Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 492 Previous Rating Agency Landslide Tech Previous Rating Date 10/2/14

Current Rating (if re-rated) Photo # Range

Problem Statement

Over-steepened at roadway

At south end cracks extend into middle of NB lane

Upslope cut in volcanic tuff appears competent

30’ width available at road

Existing lane cut slope upslope

Proposed Correction

MSE WALL Excavating to competent bedrock

 Assume 15 – 30’ Excavating, Average height 25’

 Excavating end width 20’

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

MSE Wall (25 tall x 205’) SF 5125 $60 $307,500.00

Guardrail FT 300 $20 $6,000.00

Excavation (Include Temp Shoring) CY 3,000 $20 $60,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $373,500.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/29/2015

Road/Trail No. FS 25 Trail Created by: CIC Road 

Beginning MP 28.33 Ending MP 28.36 Side Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow Settlement

Shallow slump | Erosional Failure

Previous Total Rating 336 Previous Rating Agency Landslide Tech Previous Rating Date 10/3/14

Current Rating (if re-rated) Photo # Range

Problem Statement

100’ Long

Full Width Fill with 42” CMP culvert

Culvert distress at D/S 1/3 point

Roadway Settlement, 2-3” drop at north crack, 1⁄2”-1” drop at south crack

Proposed Correction

Move bypass material inside of curve, 100’

Deep Patch North Crack Area, 40’ along CL, Full Width

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Unload Excavation CY 70 $15.00 $1,050.00

Deep Patch FT 40 $600.00 $24,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $25,050.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/29/15

Road/Trail No. FS 25 Trail Created by: DLB Road 

Beginning MP 28.36 Ending MP 28.42 Side Left Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 401 Previous Rating Agency Landslide Tech Previous Rating Date 10/3/14

Current Rating (if re-rated) Photo # Range

Problem Statement

Rock cut has case 2 till/overburden slope above and blocky rock material is raveling out of upper cut and getting on the 

road.

Proposed Correction

Lay back the upper portion of the slope to a flatter angle and revegetate. Bring lay back portion to base of slope on 

north and consider pinned high tensile strength mesh as alternative. Some scaling on rocky base.

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Excavation CY 890 20 $17,800.00

Scaling HR 80 225 $18,000.00

Pinned high tensile strength mesh SF 24,000 15 $360,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $395,800.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/25/15

Road/Trail No. FS 25 Trail Created by: CIC Road 

Beginning MP 29.44 Ending MP 29.51 Side RT Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 371 Previous Rating Agency LT Previous Rating Date 7/13/14

Current Rating (if re-rated) Photo # Range

Problem Statement

Gabion wall area: slope 13’ V x 20’ H Pullout Area Failure

Length 270 ft

1:1.25 Slope with RSS

No cracks in roadway

Ditch Debris dumped on out board slide

Proposed Correction

Deep Patch only at select locations where cracks were cracks extend into road.

RSS embankment

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Excavation (Unload: 750 cu yd) (RSS FND: 1200 cu yd) CY 1,950 15.00 $29,250.00

RSS Slope (12’ tall x 260’ long) SF 3,120 45.00 $140,400.00

Deep Patch @ Ends (110’ total) FT 110 600.00 $66,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $235,650.00
FLMA - Unstable Slope Management Program Field Mitigation Cost Estimating Form Rev 1.0 (June 18, 2015)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

CONCEPTUAL DESIGN AND COST ESTIMATE FORM – UNSTABLE SLOPE SITE INFORMATION

Management Area: Gifford Pinchot National Forest Date 6/29/15

Road/Trail No. FS 90 Trail Created by: DLB Road 

Beginning MP 13.26 Ending MP 13.32 Side Left Weather sunny

Hazard 

Type

Rockfall Planar | Wedge | Toppling

Raveling/Undermining | Rock Avalanche 

Indeterminate Rock Failures | Diff. Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow

Shallow slump | Erosional Failure

Previous Total Rating 446 Previous Rating Agency Landslide Tech Previous Rating Date 7/24/14

Current Rating (if re-rated) Photo # Range none taken

Problem Statement:

Rock blocks on west end could use bolting after scaling while raveling on east end is the main problem. Very little ditch 

results in nearly all rockfall reaching the road with many roadway scars and rockfall debris on the opposite side. 

Proposed Correction

Scaling and draped mesh with a modest bolting program on larger blocks on west end of the slope.

ESTIMATING FACTORS

Item Unit Amount 

Required

Unit Cost Total Cost

Draped high tensile strength mesh 80 x 420 long. Average 

height 90’ SF 34,000 6 $204,000.00

Moderate scaling 300 Ft/hr HR 120 225 $27,000.00

Rock bolts on west end - spot bolts 35 x 12’ each LF 420 200 $84,000.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

$ 0.00

ESTIMATED TOTAL COST $315,000.00
151

APPENDIX F. UNSTABLE SLOPE PERFORMANCE MEASURES FOR FLMAS USING 

USMP RATINGS

APPROACH

The Forest Service manages its roadway system by utilizing five distinct Maintenance Levels, 

each with its own usage goals and objectives. Performance Measures (PMs) have been divided 

into two general categories, Condition Performance Measurement (Tables 1 through 4) and 

Management Performance Measures (Tables 5 and 6). The PMs described herein are specific to 

roadway classifications used by the Forest Service and may not apply to other Federal Land 

Management Agencies (FLMAs).

CONDITION PERFORMANCE MEASUREMENT 

Performance measurement based on condition follows and expands upon examples outlined in an 

FHWA Office of Transportation Performance Management factsheet describing a Notice of 

Proposed Rulemaking (NPRM)4 for pavements and bridges. FHWA is proposing measures to 

assess the conditions of pavement and bridge assets with performance targets set by states or 

Metro Planning Organizations (MPOs) receiving Federal funding. This NPRM also proposes a 

minimum condition level as required by MAP-21. For pavements, the minimum condition level 

is no more than 5% of Interstate System lane miles in a Poor condition. For bridges, the 

percentage of Structurally Deficient bridges cannot exceed 10% of overall deck area throughout 

a state. For non-Interstate pavements, no minimum condition level was proposed with this rule. 

This differential status illustrates the challenge of setting performance measures for FLMAs such 

as the Forest Service, and minimum condition levels appropriate to the asset. FLMAs may 

develop policies following the example illustrated in this NRPM and propose minimum 

condition levels for only their road systems with the highest performance expectations.

For unstable slopes on roads and trails, the PM approach is based on condition rating and 

periodic re-rating of unstable slopes. For purposes of this USMP for FLMAs study, USMP total 

score ranges shown in Table 2 may be used as analogs for Good/Fair/Poor. As the FLMA 

system matures, this approach should be further refined as data is collected and geotechnical 

asset management systems become more common. For tracking purposes, a subcategory of 

“Poor” may indicate “Unpassable” when due to an unstable slope failure(s) that remains in 

disrepair for a prolonged period. As an initial start, the Forest Service advocates a PM of 

percentage of slopes rated as Fair or Better, along with a target of minimum accepted percentage 

of routes rated as “Unpassable” due to unstable slope issues. 

The PM system allows for adjustments to goals and minimum conditions based on an existing 

Forest Service Maintenance Level scheme. Note that in the example presented in this appendix, 

only road corridors were selected for the demonstration project in the Gifford Pinchot National 

Forest in southwest Washington State, but this example and guidance is applicable to trail

systems as well. At this early stage of program development, the goals can be applied only to 

 4 http://www.fhwa.dot.gov/tpm/rule/pmfactsheet.pdf
152

those roads and trails that have had inventory and condition assessments performed. As the 

program matures and more inventories are completed, the Condition Performance Measures can 

be evaluated on a Regional Unit basis (such as Forest Service Regions 1, 2, 3, 4, 5, 6, 8, 9, and 

10), and finally a Network basis, though some revisions may have to be made. 

In addition to rerating slopes at regularly scheduled intervals (approximately every five years is 

proposed), it is important that all maintenance activity related to unstable slopes, including minor 

pavement patches and rockfall debris clean-ups, be tracked along with the size, scope, and repair 

cost/time in a format as provided in the USMP’s Maintenance Tracking Form (Appendix B and 

C). Generalized record keeping, such as “one-week of pavement patching on FS-90 MP 25 to 

30, using 5 crew, two trucks and 20 CY of AC patch” is not adequate to perform the follow up 

ratings and evaluations. Recording maintenance activities such as “cleaned 1.5 CY of rock off 

the inboard lane at site ID FS90_MP25.44 at a cost of $250” provides the data resolution needed 

to identify deteriorating conditions and eventually, more informed life-cycle cost analysis. 

Tracking of road closure events by individual site ID is also strongly recommended. Ideally, 

these items may be tracked by modifying some information gathered in an existing maintenance 

management system, but estimates made based on existing data will likely have to be made. 

FHWA GOOD/FAIR/POOR CLASSIFICATION

Recent research5 and proposed regulations in the January 5, 2015 NPRM into categorizing 

condition assessments into Good/Fair/Poor divisions have been carried out on behalf of FHWA. 

This is intended to improve FHWA’s ability to assess the health of the nation’s roadway

infrastructure and serves two primary objectives:

• Define a consistent and reliable method of assessing infrastructure health with a focus on 

bridges and pavements on the Interstate Highway System.

• Develop tools to provide FHWA, and State Departments of Transportation (DOT) 

personnel ready access to key information that will allow for a better and more complete 

view of infrastructure health nationally. 

To meet these objectives, the research focused on the development of an approach for 

categorizing assets, mainly bridges and pavements at this point, as Good, Fair, or Poor, which 

can be used consistently across the country. Asset performance in this context is based on 

condition information. This research has recommended the following parameters for 

Good/Fair/Poor for bridges and pavements:

• Good condition – Bridge and pavement infrastructure that is free of significant defects, 

and has a condition that does not adversely affect its performance. This level of 

condition typically only requires preventive maintenance activities. 

• Fair condition – Bridge and pavement infrastructure that has minor deterioration of 

bridge elements; or isolated surface defects or functional deficiencies on pavements. 

This level of condition typically could be addressed through minor rehabilitation, such as 

 5 Improving FHWA’s Ability to Assess Highway Infrastructure Health - Pilot Study Report, FHWA-HIF-12-049
153

crack sealing, patching of spalls, and corrosion mitigation on bridges; and overlays and 

patching of pavements that do not require full depth structural improvements.

• Poor condition – Bridge and pavement infrastructure that is exhibiting advanced 

deterioration and conditions that impact structural capacity. This level of condition 

typically requires structural repair, rehabilitation, reconstruction or replacement

Table 1. Sample Condition Ranges for Site Total USMP Scores.

Good Fair Poor

Preliminary Rating 

Score Range < 21 pts 21 ≤ Score ≤ 161 > 161

Detailed Rating 

Score Range < 200 200 ≤ Score ≤ 400 > 400

MANAGEMENT PERFORMANCE MEASUREMENT 

Performance measures based on management are intended to track how well an agency is 

proactively managing and improving its unstable slope assets over time using data obtained 

during the slope rating procedures and tracking of maintenance records for road-closing unstable 

slope events, as well as mitigation and risk reduction repair projects. The occurrence of failures, 

patching, and road closures that are directly the result of geotechnical deficiencies should 

decrease over time. However, due to the sporadic nature of slope failures and close relationships 

to climatic events, many years could pass prior to observing a marked decrease in reactional 

responses and system-wide performance improvements.

The performance of unstable slope assets can be assessed using several different scales: a roadmile linear scale (0.25, 1-mile, 5-mile), a route or corridor scale (FS 99, FS90 mileposts 12 to 

30), or an Administrative Unit scale (Gifford Pinchot NF or FS Region 6). For example, 

pavement condition indices are typically reported on a per mile basis, but recent Federal 

guidelines recommend condition being reported on a 0.10-mile basis while minimum condition 

levels are being proposed on the State or MPO Level. For illustrative purposes, the example 

contained in this document is appropriate for a Route-level assessment, and recommendations for 

minimum condition levels for unstable slopes are provided in the following tables. The process 

for developing PMs is contained in Figure 1 below.
154

Figure 1. Flow Chart for Determining Performance Measures.

Identify 

critical 

corridors 

and plan 

ratings 

(Table 2)

Step 

1 Prelim 

slope 

ratings on 

Level 3 - 5 

roads. 

Filter 

results for 

Fair and 

Poor 

Slopes.

Step 

2

Perform 

full ratings 

for Fair & 

Poor 

Slopes on 

Level 4 - 5 

Roads

Step 

3

Assign 

Good-FairPoor 

Conditions 

to Site 

Ratings 

(Table 1)

Step 

4 

Compile 

rating 

results and 

create 

maps of 

unstable 

slope 

inventory

Step 

5 Calculate 

Condition 

Performance 

Measures 

(Tables 3 & 

4)

Step 

6 Repeat at 

regular 

intervals & 

determine 

performance 

trends 

(Tables 5 and 

6)

Step 

7
155

Table 2. Unstable Slope Condition Performance Measurement Approach for Forest 

Service Maintenance Levels

Forest Service Maintenance Levels (ML) Management 

Approach

Assessment 

Approach

Assessment 

Planning

ML-1: These are roads that have been placed in 

“storage”, a planned condition for more than a year 

that may economically be closer to 10 years, between 

intermittent uses. The period of storage must exceed 

1 year. Basic custodial maintenance is performed to 

prevent damage to adjacent resources and to 

perpetuate the road for future resource management 

needs. Emphasis is normally given to maintaining 

drainage facilities and runoff patterns. Planned road 

deterioration may occur at this level. Appropriate 

traffic management strategies are to "prohibit" and 

"eliminate" all traffic. These roads are not shown on 

motor vehicle use maps.

Roads receiving ML-1 may be of any type, class, or 

construction standard, and may be managed at any 

other maintenance level during the time they are 

open for traffic. However, while being maintained at 

level 1, they are not open to vehicular traffic but may 

be available and suitable for nonmotorized use.

ROAD MANAGEMENT: No Motorized Use – Placed 

in storage

Slopes are 

maintained in a 

reactionary manner 

to minimally repair 

failed slopes to 

facilitate 

nonmotorized road 

passage, alleviate 

adverse drainage 

and runoff patterns, 

prevent damage to 

adjacent resources, 

and perpetuate the 

road for future 

resource 

management needs.

Judgment 

based, no 

unbiased 

metric 

available.

No 

Geotechnical 

Asset 

Management 

(GAM) 

inventory has 

been 

performed or 

is planned.

ML-2: Assigned to roads open for use by high 

clearance vehicles. Passenger car traffic, user 

comfort, and user convenience are not 

considerations. Warning signs and traffic control 

devices are not provided with the exception that 

some signing, such as W-18-1 “No Traffic Signs,” 

may be posted at intersections. Motorists should 

have no expectations of being alerted to potential 

hazards while driving these roads. Traffic is 

normally minor, usually consisting of one or a 

combination of administrative, permitted, dispersed 

recreation, or other specialized uses. Log haul may 

occur at this level. Appropriate traffic management 

strategies are either to: a) Discourage or prohibit 

passenger cars, or b) Accept or discourage high 

clearance vehicles. 

ROAD MANAGEMENT: High Clearance Vehicles, 

no comfort, convenience, or speed considerations in 

management considerations.

Slopes are 

maintained in a 

reactionary manner 

to sufficiently 

repair failed slopes 

to facilitate road 

passage by high 

clearance vehicles. 

A significant 

geotechnical failure 

may make the road 

‘unpassable,’ rather 

than ‘closed,’ until 

repair activities are 

completed.

Judgment 

based, no 

unbiased 

metric 

available.

No GAM 

inventory has 

been 

performed or 

is planned. 

Reactive 

maintenance 

actions are 

tracked and 

indexed by 

location and 

cause.

ML-3. Assigned to roads open and maintained for 

travel by a prudent driver in a standard passenger car. 

User comfort and convenience are not considered 

priorities. The Manual on Uniform Traffic Control 

Devices (MUTCD) is applicable. Warning signs and 

traffic control devices are provided to alert motorists 

of situations that may violate expectations.

Slopes are 

maintained in a 

proactive and 

reactionary manner 

to rehabilitate or 

repair using 

standard 

Percentage of 

slopes in 

Good 

Condition 

and in Poor 

Condition. 

Measured 

Preliminary 

GAM 

inventory and 

condition 

assessment 

has been 

performed. 
156

Forest Service Maintenance Levels (ML) Management 

Approach

Assessment 

Approach

Assessment 

Planning

Roads in this maintenance level are typically low 

speed with single lanes and turnouts. Appropriate 

traffic management strategies are either "encourage" 

or "accept." "Discourage" or "prohibit" strategies 

may be employed for certain classes of vehicles or 

users.

ROAD MANAGEMENT: Passable by passenger car. 

Reasonable expectation of predictable road 

conditions and warning signs.

engineering 

investigation and 

evaluation 

techniques and 

approaches. 

every five 

years.

Reactive 

maintenance 

actions are 

tracked and 

indexed by 

location and 

cause.

ML-4. Assigned to roads that provide a moderate 

degree of user comfort and convenience at moderate 

travel speeds. Most roads are double lane and 

aggregate surfaced. However, some roads may be 

single lane. Some roads may be paved and/or dust 

abated. Manual on Uniform Traffic Control Devices 

is applicable. The most appropriate traffic 

management strategy is "encourage." However, the 

"prohibit" strategy may apply to specific classes of 

vehicles or users at certain times.

ROAD MANAGEMENT: Passable by passenger car. 

Reasonable expectation of predictable road 

conditions and warning signs.

Slopes are 

maintained in a 

proactive manner 

to prevent failure 

and in a reactionary 

manner when 

needed. 

Rehabilitation or 

repair designed 

using standard 

engineering 

investigation and 

evaluation 

techniques and 

approaches. 

Percentage 

of slopes in 

Good 

Condition 

and in Poor 

Condition. 

Measured 

every five 

years.

Detailed 

GAM 

inventory and 

condition 

assessment 

has been 

performed. 

Reactive 

maintenance 

actions are 

tracked and 

indexed by 

location and 

cause.

ML-5. Assigned to roads that provide a high degree 

of user comfort and convenience. These roads are 

normally double lane, paved facilities. Some may be 

aggregate surfaced and dust abated. Manual on 

Uniform Traffic Control Devices is applicable. The 

appropriate traffic management strategy is 

"encourage." 

ROAD MANAGEMENT: Passable by passenger car. 

Reasonable expectation of predictable road 

conditions and warning signs.

Slopes are 

maintained in a 

proactive manner 

to prevent failure 

and in a reactionary 

manner when 

needed. 

Rehabilitation or 

repair designed 

using standard 

engineering 

investigation and 

evaluation 

techniques and 

approaches. 

Percentage 

of slopes in 

Good 

Condition 

and in Poor 

Condition. 

Measured 

every five 

years.

Detailed 

GAM 

inventory and 

condition 

assessment 

has been 

performed. 

Reactive and 

proactive 

maintenance 

actions are 

tracked and 

indexed by 

location and 

cause.
157

Table 3. Route Condition Performance Measures & Minimum Condition Levels for 

Unstable Slopes.

Slope Condition Performance Measures for each Maintenance Level (ML). “Fair” is the 

goal for Maintenance Levels 1 and 2 and “Fair” or Better for Levels 3 through 5.

Maint. 

Level Good Fair Poor

1 Numerical evaluation not 

applicable. Judgment 

indicates few to no known 

slope deficiencies.

Numerical evaluation not 

applicable. Judgment 

indicates few or 

occasional (1 to 2 per 

mile) known slope 

deficiencies.

Numerical evaluation 

not applicable. 

Judgment indicates 

many (3 or more per 

mile) known slope 

deficiencies.

2 Numerical evaluation not 

applicable. Judgment 

indicates few to no known 

slope deficiencies and 

unstable slopes do not affect 

log haul when active.

Numerical evaluation not 

applicable. Judgment 

indicates few to no known 

slope deficiencies and 

unstable slopes slightly 

impacting log haul when 

active.

Numerical evaluation 

not applicable. 

Judgment indicates few 

to no known slope 

deficiencies and 

unstable slopes 

regularly impacting log 

haul when occurring.

3 Minimum Condition Level for 

Good: More than 80% of 

inventoried slope assets are in 

good condition and less than 

10% of slope assets are in 

poor condition. 

Minimum Condition Level 

for Fair: More than 70% 

of inventoried slope assets 

are in good condition and 

less than 15% of slope 

assets are in poor 

condition.

Poor Condition Level:

More than 40% of 

inventoried slope assets 

are in Fair or Poor 

condition.

4 Minimum Condition Level for 

Good: More than 85% of 

inventoried slope assets are in 

good condition (Detailed 

USMP score less than 200) 

and less than 5% of slope 

assets are in poor condition 

(Detailed USMP score greater 

than 400). 

Minimum Condition Level 

for Fair: More than 80% 

of inventoried slope assets 

are in good condition and 

less than 10% of slope 

assets are in poor 

condition. Frequency of 

Poor Condition Slopes are 

less than two per mile.

Poor Condition Level:

More than 30% of 

inventoried slope assets 

are in Fair or Poor 

condition. Frequency 

of poor condition 

slopes are greater than 

two per mile.

5 Minimum Condition Level for 

Good: More than 95% of 

inventoried slope assets are in 

good condition and less than 

2% of slope assets are in poor 

condition. Frequency of Poor 

Condition Slopes are less than 

one per five miles.

Minimum Condition Level 

for Fair: More than 90% 

of inventoried slope assets 

are in good condition and 

less than 4% of slope 

assets are in poor 

condition. Frequency of 

Poor Condition Slopes are 

less than one per mile.

Poor Slope Condition:

More than 20% of 

inventoried slope assets 

are in Fair or Poor 

condition. Frequency 

of poor condition 

slopes are greater than 

one per mile.
158
159

Table 4. Route-level Unstable Slope Performance Measures – Road Closing Event 

Frequency

Slope Performance/Road Closure Measures for each Maintenance Level (ML). “Fair” is 

the goal for Maintenance Levels 1 and 2 and “Fair” or better for Levels 3 through 5.

Maint. 

Level Good Fair Poor

1 Minimum Performance 

Level for Good: Road 

not blocked by slope 

deficiencies. Few 

geotechnical problems 

exist on corridor. No 

deficient drainage 

features due to poor 

slope performance or 

condition.

Corridor Unstable Slope 

Performance: Minor 

rehabilitative efforts 

needed on slope assets to 

reopen as Level 2. 

Geotechnical problems are 

common. Few deficient 

drainage features due to 

poor slope performance or 

condition.

Corridor Unstable Slope 

Performance: Major 

reconstruction efforts for 

slope assets required to 

reopen as Level 2. A 

significant percentage of 

problems are geotechnical 

in nature. Many deficient 

drainage features due to 

poor slope performance or 

condition.

2 Minimum Performance 

Level for Good: Road 

not blocked for passage 

by high clearance 

vehicles by geotechnical 

deficiencies if high 

clearance vehicles are 

accepted.

Corridor Unstable Slope 

Performance: Road is 

commonly blocked for 

short periods by 

geotechnical deficiencies at 

rate of one deficiency per 

five miles of road.

Corridor Unstable Slope 

Performance: Road is 

often blocked for short 

periods (Table 5) by 

geotechnical deficiencies at 

rate of one deficiency per 

two miles of road.

3 Minimum Performance 

Level for Good: Road is 

open to passenger 

vehicles with less than 

one geotechnical-related 

closure per three-year

period per ten miles. 

Corridor Unstable Slope 

Performance: Road is 

open to passenger vehicles 

with geotechnical-related 

closures less than once per 

three years per five miles.

Corridor Unstable Slope 

Performance: Road is 

generally open to 

passenger vehicles, but 

with geotechnical-related 

closures occurring more 

than once per year per five 

miles of road.

4 Minimum Performance 

Level for Good: Road is 

open to passenger 

vehicles with less than 

one geotechnical-related 

closure per three-year

period per fifteen miles. 

Corridor Unstable Slope 

Performance: Road is 

open to passenger vehicles 

with geotechnical-related 

closures less than once per 

three years per ten miles.

Corridor Unstable Slope 

Performance: Road is 

open to passenger vehicles, 

but with geotechnicalrelated closures occurring 

once per year per five 

miles of road.
160

Slope Performance/Road Closure Measures for each Maintenance Level (ML). “Fair” is 

the goal for Maintenance Levels 1 and 2 and “Fair” or better for Levels 3 through 5.

5 Minimum Performance 

Level for Good: Road is 

open to passenger 

vehicles with less than 

one geotechnical-related 

closure per five-year 

period per twenty miles. 

Corridor Unstable Slope 

Performance: Road is 

open to passenger vehicles 

with geotechnical-related 

closures less than once per 

five years per ten miles.

Corridor Unstable Slope 

Performance: Road is 

open to passenger vehicles 

with geotechnical-related 

closures less than once per 

three years per ten miles.
161

Table 5. Management Performance Measures –Safety, Mobility, and Economic Reliability

USFS GOAL - Ensure Safety, Mobility, and Economic 

Reliability

Average time to clear 

incident and reopen road

Key Performance Indicator Description - Incident clearance times for 

slope failure related closures of points, segments or corridors for roads in 

an administrative unit (Region, district, forest). Relates to Table 4.

Prev. PeriodCurrent PeriodGoalTrend

ML-1: Road designated as "closed." No maintenance resources 

expended while closed. Use may be impossible due to slope or 

embankment failure. Road or trail may be re-opened after failures(s) are 

corrected, but the work may require significant expenditure of resources. 

Higher priority roads may result in delays of up to six months before 

remediation of failures to allow safe passage.

6 

Mos.

ML-2: Road is "open" to high clearance vehicles, but standard vehicles 

may be discouraged or prohibited. Slope conditions may result in 

restrictions to free travel due to failures, deferred maintenance leading to 

impassible road lanes, or temporary unpassable sections of the entire 

roadway. Full or partial impasses are remediated with a relatively low 

priority, but should be accomplished within two weeks with safe passage 

restored.

2 

wks

ML-3: Roads open to standard passenger vehicles shall remain open with 

application of normal maintenance routine. Occasional, partial, or full 

impasses may result due to slope instability caused by deterioration 

and/or unusual conditions (such as heavy rainfall causing slope failures) 

that may require repair prioritization behind higher priority roads before 

safe passage can be achieved. Generally, roads are made passable within 

one week of significant events.

5 

days 

ML-4: Roads usually double lane and aggregate surfaced. Some roads 

may be paved and some roads may be single lane. Roads provide user 

with a moderate degree of user comfort and convenience. Traffic is 

encouraged but may be prohibited at times in certain conditions or for 

certain vehicle types. Generally passable by passenger car. Road 

segment should be appropriately signed with conditions and warnings. 

This class of roads has moderately high priority for remaining open to 

travelers. Unpassable sections are rare with safe passage restored to 

fully blocked roads or partial blockages within two days for roads 

following incidents involving failing slopes or embankments.

2 

days 

ML-5: This level is assigned highest priority for remaining open and 

providing safe access to destinations, and through forest lands. These 

roads provide a high degree of comfort and convenience to users and are 

normally paved two-lane roads. Some roads may be aggregate surfaced 

and dust-abated. Travel on these high priority roads is encouraged. 

These routes are expected to be passable by passenger car and should be 

expected to be signed appropriately with information and warning signs. 

Any incidents or events that result in partial or full closures shall result 

in prompt response and re-opening, once safe passage is ensured, within 

one day for roads.

1 

day

This performance measure should be reevaluated annually.
162

Table 6. Road Maintenance Prioritization

USFS GOAL – Focus on High Priority Roads for Maintenance to Prevent Impasses and 

Resiliency Improvement

Performance Measure. Maintain slope condition to applicable 

good-fair-poor service levels, as measured by road closing 

events. Where no unstable slopes exist, the slope rating would 

be considered “Good.” Apply Performance Measure using 

"Good/Fair/Poor" ratings or frequencies from Table 4. 

Prev. Period Closure Frequency & DensityCurrent Period Closure Frequency & DensityPerformance TargetTrend

ML-1: Road designated as "closed." Mainly reactionary 

maintenance resources expended while closed to mitigate 

drainage problems. Vehicle use may be impossible due to slope 

or embankment failure, but road or path may be re-opened and 

failures(s) corrected. 

None

ML-2: Road is "open" to high clearance vehicles, but standard 

vehicles may be discouraged or prohibited. Slope conditions 

may result in restrictions to free travel due to failures, deferred 

maintenance making road lanes impassable, or temporary 

closures of entire roadway. 

Fair

ML-3: Roads are open to standard passenger vehicles and shall 

remain open with application of normal maintenance routine. 

Occasional partial or full closures may result due to slope 

instability caused by deterioration and/or unusual conditions 

(such as heavy rainfall causing slope failures) that may require 

repair prioritization behind higher priority roads. Preventative 

maintenance is performed to reduce impacts over time.

<1 per 

3 

years 

per 10 

miles

ML-4: Roads are open to standard passenger vehicles and shall 

remain open with application of normal maintenance routine. 

Occasional partial or full closures may result due to slope 

instability caused by deterioration and/or unusual conditions 

(such as heavy rainfall causing slope failures) that may require 

repair prioritization behind higher priority roads. Preventative 

maintenance is performed to reduce impacts over time.

<1 per 

3 

years 

per 15 

miles

ML-5: Highest priority roadways. Rare partial or full closures 

may result due to unstable slopes. Preventative maintenance is 

prioritized and performed to reduce impacts over time.

<1 per 

5 

years 

per 20 

miles

This performance measure should be reevaluated every three to five years.
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Table 7. Road Improvement Prioritization

USFS GOAL – Focus on High Priority Roads for Improvement

Performance Measure – Average USMP Score per route. 

Maintain slope condition to applicable good-fair-poor service 

levels, as measured by USMP scores. Where no unstable 

slopes exist, the slope rating would be considered “Good.” 

Use USMP ratings from Steps 2 and 3.

Prev. Period Avg. USMP Score / JudgmentCurrent Avg. USMP Score / Judgment (ML 1 and 2)USMP Score / Judgment GoalTrend

ML-1: Road designated as "closed." Mainly reactionary 

maintenance resources expended while closed. No 

improvement planned while in storage.

None

ML-2: Road is "open" to high clearance vehicles, but standard 

vehicles may be discouraged or prohibited. Slope conditions 

may result in restrictions to free travel due to failures, deferred 

maintenance making road lanes impassable, or temporary 

closures (status change to ‘Storage’) of entire segment. 

Improvement planned only to prevent future high cost 

expenditures.

Fair

ML-3: Roads open to standard passenger vehicles shall 

remain open with application of normal maintenance routine. 

Minor, low cost improvements planned to achieve goals over a 

long-term time frame.

Avg. 

Score 

(prelim) 

<21 

Good

ML-4: Roads open to standard passenger car. User comfort 

and convenience are not considered priorities. Improvements 

to offset high maintenance costs or reduce risk at high scoring 

sites are planned to preserve safety and mobility and reduce 

future maintenance needs.

Avg. 

Score 

<200, 

Good 

ML-5: Roads open and maintained for travel in a standard 

passenger car. Assigned to roads that provide a high degree of 

user comfort and convenience. These roads are normally 

double lane, paved facilities. Improvements are planned to 

offset high maintenance costs or reduce risk at high scoring 

sites to preserve safety and mobility and reduce future 

maintenance needs. 

Avg. 

Score 

<175, 

Good 

This performance measure should be reevaluated every five years coincident with USMP reratings
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APPENDIX G. QUALITATIVE RISK ANALYSIS ONLINE FORM AND USAGE

The Quantitative Risk Analysis (QRA) online form can be found by clicking QRA on the menu 

bar of the USMP website (shown in Figure 1). The QRA form consists of a single web page 

where values can be entered to estimate annualized risk from an unstable slope. 

Figure 1. Online menu for USMP website.

The web form is dynamic and automatically recalculates when individual values are entered into 

value fields. The URL of the QRA form reflects the values entered into the various fields 

(example shown in Figure 2). This enables the data entered into a QRA form to be stored offline 

for future use by copying the URL of the form and saving it. Every time a value in the QRA 

form is changed, the URL will change reflecting the new value entered. 

Figure 2. Screen capture of QRA website illustrating URL data capture.

USING THE QRA FORM

The QRA form starts with attributes of the hazard zone being assessed for risk and continues 

with the four factors needed to estimate annual risk to a person or asset exposed to an unstable 

slope hazard. 
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Hazard Zone Attributes

Hazard zone name (for display in PAIR graph): This is the name, or identifying character string of 

the area that is to be assessed. This name is used in the contextual risk estimate graph shown 

near the bottom of the QRA webpage. 

Form units: Radio buttons are provided to set the units of measure on the QRA form. Choices 

include U.S. customary units of feet, miles per hour, etc. or metric units of meters, kilometers per 

hour, etc. 

Length of hazard zone (length affected roadway, trail, or other area): For roadways or trails this 

is the linear length of the road or trail that could be affected by the unstable slope hazard. For 

other assets, such as buildings, this is the length of the asset within the unstable slope zone. 

Do most people travel the hazard zone once or twice (round trip) during a typical visit to the 

area?: Radio buttons are provided to set the travel direction(s). One way implies that the person 

would be exposed to the unstable slope hazard one time per trip, while Two way implies that the

person would be exposed to the hazard two times per trip (round trip). This affects the 

occupancy time (P(pres)) factor within the risk equation.

Average travel speed: This is the average speed traveled along the transportation corridor 

adjacent to an unstable slope. For roads, one could use the posted or advisory speed limit or 

another speed based on a survey of travelers in that area. For trails, one can use the suggested 

average walking speed based on pedestrian road crossing research (2.73 mph, estimated by 

Knoblauch et al., 1996) or another speed based on a survey of travelers in that area.
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QRA Factors

The four factors of general risk equation for annual individual risk are P(occ), P(loc), P(pres) and, 

P(vul). P(occ) is the probability of occurrence, the annual probability of an unstable slope event 

affecting the hazard zone, the probability of occurrence; P(loc) is the probability of a person, if 

present, being in the path of an unstable soil slope event in the full length of the hazard zone, or 

in the case of rockfall, one or more rocks at a given location, where the entire hazard zone is not 

necessarily affected by every event. P(pres) is the occupancy rate or rate of presence, the amount 

of time spent by an individual in the affected area. P(vul) is the vulnerability, or probability of a 

person being killed or injured by the event.

These four factors need to be estimated or researched for two different unstable slope triggering 

scenarios: 1) unstable slopes events triggered by ground motion due to earthquakes and 2) 

unstable slopes triggered by all other processes, as illustrated in Figure 3. The reason the form 

provides this option is to be able to utilize data from the United States Geological Survey 

(USGS) to help estimate earthquake probability. These fields use decimal numbers, not 

percentages. For example a 50% annual probability that an event will occur should be entered as 

0.5, or an event that occurs once in 20 years would be entered as 0.05. The form automatically 

converts entries into scientific notation to best display low probabilities.

Figure 3. USMP QRA form showing Probability of Occurrence (Pocc).

Probability of Occurrence (Pocc). The first factor needed to estimate risk requires data that 

indicate the occurrence probability or frequency of an unstable slope event. Tracking the 

occurrence of unstable slope events with the USMP through periodic ratings or through new 

slope event forms provides baseline data for this factor. In the absence of such data, scientific 

methods for dating unstable slope events can also be used to estimate occurrence probability. In 

the absence of either some basic tracking of events at a slope or scientific data on even 

frequency, the future probability of the unstable slope event would need to be estimated. 

If small numbers of unstable slope events at a given site have been tracked over many years or 

large numbers of events have been tracked over several years, the recurrence probability (P) of 

event x can be estimated using a simple recurrence equation, x events in n observations:

P(x) = x/n

If an event occurs and there is no, or very little, record of unstable slope events at a site, it is 

reasonable to assume that some slope condition changed or reached a threshold to allow for slope 

instability, and that this slope condition is still in effect. In this “prior” case, the period of 
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observation under the current slope event generating conditions is limited, but it is still 

conservative to assume that there is some real chance of slope events in the future. This is an 

assumption based on an uninformative, yet objective prior, infrequent events over a small 

observation period. Rather than assuming a single or small number of events in a single or small 

number of observation periods is informative, the prior condition mentioned above is not very 

informative and equal probability should not automatically be assumed for either an unstable slope 

event occurring or not occurring in a given observation period. So, in this “uninformative prior” 

case the recurrence probability (P) of event x can be estimated using a statistical formulation for 

events that have occurred without a strong historical record, x times in n observations:

P(x) = (x +1)/(n + 2)

When using either the “simple” recurrence or the “uninformative prior” recurrence estimate, the 

estimates should be adjusted as further observations are recorded and the QRA refined.

The QRA form will automatically use the “simple” recurrence equation when a user indicates the 

number of years unstable slope events have been observed. For example, if five rockfall events 

occurred in 10 years on an unstable slope, the user would enter 10 in the “Number of events of 

event probability within XX years” field and then 5 in the “Probability of an unstable slope event 

not triggered by an earthquake” field. The user may choose to use some other formulation of 

annual probability based on other scientific investigations or an estimate such as the 

“uninformative prior” recurrence estimate discussed above. In this case, the user should enter 

one (1) in the “years” field and then the annual probability in decimal notation in the “Probability 

of an unstable slope event not triggered by an earthquake” field. 

The USGS tools or mapping can be used to help determine the annual recurrence probability of 

an earthquake that would likely trigger an unstable slope event. As of 2017, the USGS Unified 

Hazard Tool can assist with this for many locations in the United States. A link to the Unified 

Hazard Tool is provided on the QRA form. Earthquake shaking that is described as strong, very 

strong, or more violent using the Modified Mercalli Intensity (MMI) (VI and greater) has caused 

significant slope failures during past seismic events. Using relationships between MMI and peak 

ground acceleration (PGA) and peak ground velocity (PGV) (Worden et al., 2012), a MMI of VI 

and higher translates into an unstable slope triggering PGA of 0.12-0.22 g and greater or a PGV 

of 9.6-20 cm/s (3.8-7.9 in./s) or greater. For example, Mackey and Quigley (2014) and Massey 

et al. (2014) documented that rock cliffs subjected to PGA and PGV in this range experienced 

rockfall. For the purposes of the QRA within the USMP, it is conservative to assume that rated 

unstable rockfall slopes subject to this level of shaking would likely experience some degree of 

slope failure. Rated unstable landslide slopes may also be susceptible to earthquake shaking 

induced failure but other contributing or mitigating factors such as ground water conditions 

should be assessed before assigning a ground motion threshold. Since precipitation is the 

primary trigger for debris flow susceptible unstable slopes, the QRA for these slopes can be 
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performed without accounting for recurrent strong ground motion unless there is good reason for 

doing so.

The USGS Unified Hazard Tool outputs a PGA hazard curve in terms of annual probability of 

exceedance for locations in the U.S. (example shown in Figure 4). For estimating the probability 

of occurrence (Pocc) of an unstable slope event triggered by an earthquake, users should find the 

point on the PGA hazard curve that most closely corresponds with probable unstable slope event 

triggering PGA by hovering over the plotted points on the hazard curve. The annual frequency of 

exceedance can be entered into the field in decimal notation.

Figure 4: USGS Unified Hazard Tool showing PGA hazard curve in terms of annual 

probability of exceedance for locations in the U.S.

Probability of Location (Ploc)

The first step to estimate the Probability of Location (Ploc) is to indicate whether the risk analysis 

is for rockfall or landslide susceptible unstable slopes. If the most likely unstable slope event 

will put the entire slope into motion then, for the purposes of the QRA, it is considered a 

landslide; however, if the most likely unstable slope event will involve discrete blocks that will 

not affect the entire length of the slope (hazard zone) during an event then, for the purposes of 

the QRA, it is considered a rockfall. If the landslide radio button is selected (refer to Figure 5), 

the QRA automatically assumes that the most likely landslide affects the entire hazard zone, and 

the probability of a person in the hazard zone being affected by the unstable slope event is 100%. 

If the rockfall radio button is selected (refer to Figure 5), the QRA requires a representative 

boulder size to be input into the form (in feet or meters), and the likely number of boulders 

involved during the rockfall event to be input. As with the Probability of Occurrence (Pocc), 

tracking unstable slope events with the USMP through updated USMP slope ratings, new slope 
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events, and maintenance forms provides baseline data for block size and number of individual 

blocks. If this data is not available, historical data about rockfall for the specific unstable slope 

can also be used. Other geologic factors such as discontinuity spacing, and condition could also 

help with this estimate.

Figure 5: The probability of location section of the QRA form.

To estimate boulder size and number of individual boulders from earthquake-triggered unstable 

slope rockfall events, historical events triggering rockfall on similar slopes could be used as 

proxies. The earthquake triggered rockfall boulder size will likely be close to the maximum 

block size present on the slope, dictated by discontinuity spacing. Also, many blocks of rock are 

likely to be dislodged at an individual rockfall susceptible slope. During an earthquake the entire 

slope experiences the same trigger from ground motion as opposed to other potential rockfall 

triggers such as frost weathering or high groundwater conditions, which may only lead to failure 

at certain locations along the slope. An example of the efficiency of seismic shaking to trigger 

rockfall events were the earthquakes in Christchurch, New Zealand in 2011. More than 650 

individual blocks were dislodged from a 300 m (984 ft) long by 60 m (200 ft) tall section of

highly consolidated, moderately jointed basaltic rock cliff (Mackey and Quigley, 2014). 

Rockfall was triggered by strong earthquakes during an aftershock sequence with a maximum 

magnitude of 6.2 (PGV 47.5 cm/s (18.7 in/s), PGA 2.2g). The cliff was not known to be a major 

source of rockfall before the earthquake sequence. Another example is from Kalepa Point in 

Haleakalā National Park on the Island of Maui. The basaltic rock cliffs at the point were known 

to shed rock on to Highway 31 throughout the year, with a history of near misses and one 

rockfall fatality. However, the road was rendered completely impassable due to rockfall 

following the 2006 magnitude 6.7 earthquake with an epicenter 87 km (54 miles) away. Based 

on a seismic monitoring instrument on Maui, the PGV associated with this earthquake was 

probably greater than 6 cm/s (2.4 in./s) and PGA was greater than 0.10g. The road was closed 

for two years because the route was unsafe until rockfall repair and mitigation work could be 

completed. In the absence of any other information, the number of rock blocks generated by 

strong seismic shaking can be roughly approximated as 10 times the number of blocks involved 

in an unstable slope event not triggered by an earthquake.

Rockfall Probability of Location (Ploc) uses the following equation to estimate the probability 

that a person, if present in the hazard zone, will be in the path of one rock at a given location:

P1(loc) = (2D+d)/L
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where D is the estimated diameter of the rock, d is the diameter of the threatened object, such as 

a person, and L is the length of the hazard zone threatened. The Americans with Disabilities Act 

minimum doorway width of 81.5 cm (32 inches) is used for the diameter (d) when people are 

threatened. 

During a rockfall, the probability of hitting the same location multiple times increases with the 

number of rocks generated by the rockfall event, such that if N rocks are randomly distributed 

across the slope:

P(loc) = 1-(1- P1(loc))

N

Probability of Occupancy (Ppres)

The occupancy rate is the amount of time (measured as percent of time per year) an individual 

spends in the hazard zone. For transportation corridors, this is dependent on the length of the 

hazard zone and the speed a person travels through the hazard zone. The exposure of 

maintenance personnel in a transportation corridor hazard zone should also be considered. For 

points of interest along transportation corridors or for other areas susceptible to unstable slopes 

where people spend time, the number of minutes per year that an individual typically spends in 

the hazard zone can be estimated or determined from use surveys and entered into the form. 

When calculated travel time is selected, the QRA form uses the “length of hazard zone”, “one 

way or two way”, and “average travel speed” fields to calculate the occupancy time. If average 

travel speed is greater than 15 km/h (9.3 mph) then the stopping sight distance is added to the 

length of the hazard zone, because the ability to react to avoid a hazard is more difficult at higher 

speeds. Stopping sight distance is calculated based on NCHRP Report 400, Determination of 

Stopping Sight Distances (Fambro et al., 1997). Ppres is assumed to be the same for either 

earthquake triggered or non-earthquake triggered unstable slope events.

Probability of Vulnerability, P(vul)

Vulnerability is a consequence and must be estimated or based on previous unstable slope 

events. On the QRA form it is assumed that the unstable slope event has occurred and that it has 

impacted whatever is being assessed (structure, person, etc.). The estimated consequence could 

range in severity from damage to destruction of infrastructure, or injury to death for people 

impacted by unstable slope events. The two following empirical examples show how 

consequence may be estimated based on previous events.

• For landslides, the widely reported and researched landslide in Oso, Washington on 

March 22, 2014 killed about 74% of the people that were in its path.

• For rockfall, Grant et al. (2017) found a strong power-law correlation between modeled 

kinetic energy (KE) measured in kilojoules from impact on timber framed house walls

and runout distance (m) into and through the structure (0.064KE0.75) and area (m2

) 

directly impacted within a structure (0.023KE0.97). This work also observed that a 

rockfall event energy threshold may exist at approximately 10 kJ (~3.7 ft-tons). Below 
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about 10kJ, very small portions of each structure within the study were affected, but 

above 10 kJ significant consequences are possible. Based on this work, it is likely that 

above approximately 10 kJ (~3.7 ft-tons), rockfall striking people would likely result in a 

fatality.

Even with some empirical examples, judgment is likely to be required to determine a probability 

of fatality from rockfall or landslide scenarios because particulars can be different for different 

scenarios. Particulars could include the size of the probable rock striking the person and the 

likelihood of striking vital portions of the body. If the unstable slope event is a rockfall, and the 

energy of the rockfall is potentially higher during an earthquake triggered event, because of 

larger boulder sizes or some other factor, the probability vulnerability will be higher for the 

earthquake triggered event. Estimating the probability of injury or damage to a facility may 

involve less uncertainty as any unstable slope event that strikes a person or facility very likely 

causes injury or damage.

Once the values of the four factors of the QRA are input into the online form, the QRA form 

calculates an annual individual risk assuming that non-earthquake and earthquake triggered 

unstable slope events are not mutually exclusive. A quantitative risk estimate is only as accurate 

as the factors that go into the estimate. If most of the factors are best estimates, the QRA will be, 

at best, an “order of magnitude” estimate. As noted above, good event tracking or scientific 

studies can improve the QRA. When performing a QRA, methods of estimating the probability 

factors need to be transparent and clearly documented. It is also possible (and recommended) to 

perform two QRAs using high and low factor estimates, thus providing an estimated range of the 

annual individual risk. Even an “order of magnitude” risk estimate can provide good 

management decision information, as common annual societal risks typically span at least four 

orders of magnitude. 

Comparison with Probabilities of Other Events

The output of the QRA is presented in graphical format compared to customizable risk 

probabilities from other known hazards (see example in Figure 6). Up to five other risk 

probabilities can be manually entered to be displayed on the graph alongside the QRA result. 

Risk data compiled by agencies such as the National Oceanic and Atmospheric Administration 

(NOAA), the Centers of Disease Control and Prevention (CDC), insurance agencies, and various 

FLMAs can be used in the comparative analysis. In the analysis featured in Figure 6, selected 

risk data sources as of 2017 were as follows: 

• NOAA: http://www.nws.noaa.gov/om/hazstats.shtml

• CDC: https://www.cdc.gov/nchs/nvss/deaths.htm

• Worldwide landside: http://blogs.agu.org/landslideblog/2017/01/30/human-cost-oflandslides-2016/

• United States Census Bureau: https://www.census.gov/popclock/
172

Figure 6: Example graphical output of the QRA analysis.

Risk Reduction Cost/Benefit Analysis

Once the life/safety risk has been estimated, the benefit of mitigating the risk can be assigned a 

monetary value using the concept of a Value of a Statistical Life (VSL) for people at risk and/or 

the value of infrastructure at risk. VSL is the estimated cost of mitigating the risk of a fatality. 

The US Department of Transportation Value of a Statistical Life is about $9.6 million in 2017 

dollars(US Department of Transportation, 2013). This figure, multiplied by the estimated risk 

and the number of people at risk, provides an estimate for the value of mitigating the risk. Since 

it is not always possible to completely mitigate risk, this cost benefit analysis assumes a target 

natural hazard annual individual fatality risk probability of one in a million (1E-6, 1×10-6

). This 

risk level would be the goal for full mitigation or significant risk reduction and would bring the 

unstable slope event risk down into the range of other natural hazard risks. An example output 

of the analysis is shown in Figure 7.
173

Figure 7: Example output of risk reduction cost/benefit analysis.

REFERENCES FOR APPENDIX G

Fambro, D. B., Fitzpatrick, K., Koppa, R. J. (1997). Determination of stopping sight distances.

National Cooperative Highway Research Program Report 400, National Academy Press, 

Washington D.C. 

Grant, A., Wartman, J., Massey, C. I., Olsen, M. J., O’Banion, M., & Motley, M. (2017). The 

impact of rockfalls on dwellings during the 2011 Christchurch, New Zealand 

earthquakes. Landslides, https://doi.org/10.1007/s10346-017-0855-2.

Knoblauch, R. L., Pietrucha, M. T., & Nitzburg, M. (1996), Field studies of pedestrian walking 

speed and start-up time. Transportation Research Record: Journal of the Transportation 

Research Board, 1538(1), 27-38.

Mackey, B. H., & Quigley, M. C. (2014). Strong proximal earthquakes revealed by cosmogenic 

3He dating of prehistoric rockfalls, Christchurch, New Zealand. Geology, 42(11), 975-

978.

Massey, C.I., McSaveney, M.J., Taig, T., Richards, L., Litchfield, N.J., Rhoades, D.A., 

McVerry, G.H., Heron, D.W., Ries, W. & Van Dissen, R.J. 2014, Determining rockfall 

risk in Christchurch using rockfalls triggered by the 2010–2011 Canterbury earthquake 

sequence, New Zealand., Earthquake Spectra, 30, pp. 155-181

US Department of Transportation. (2013). Guidance on Treatment of the Economic Value of a 

Statistical Life in U.S. Department of Transportation Analyses. US Department of 

Transportation. Retrieved from 

https://www.transportation.gov/sites/dot.dev/files/docs/VSL%20Guidance%202013.pdf

Worden, C. B., Gerstenberger, M. C., Rhoades, D. A., & Wald, D. J. (2012). Probabilistic 

relationships between ground‐motion parameters and modified Mercalli intensity in 

California. Bulletin of the Seismological Society of America, 102(1), 204-221.