Traffic 

Monitoring 

in 

Recreational 

Areas

FHWA-WFL/TD-10-003 August 2010

Federal Highway Administration

U.S. Department of Transportation U NITED STATES O F A M ERIC A

DEPARTMENT OF TRANSPORTATION
Technical Report Documentation Page

1. Report No.

FHWA-WFL/TD-10-003

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

4. Title and Subtitle

Traffic Monitoring In Recreational Areas

5. Report Date

August 2010

6. Performing Organization Code

7. Author(s)

Shawn Turner, P.E., Texas Transportation Institute; Jodi Carson, Ph.D., 

P.E., Texas Transportation Institute; Carol A. Zimmerman, Battelle; L.J. 

Wilkinson, Chaparral Systems, Inc.; Kathy Travis, Chaparral Systems, Inc.

8. Performing Organization Report No.

9. Performing Organization Name and Address

Battelle Memorial Institute

505 King Avenue

Columbus, OH 43201

Texas Transportation Institute 

3135 TAMU 

College Station, TX 77843

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

 Federal Highway Administration

 Western Federal Lands Highway Division

 610 East 5th St.

 Vancouver, WA 98661

13. Type of Report and Period Covered

Final Report 2009

14. Sponsoring Agency Code

HFL-17

15. Supplementary Notes

COTR: Amit Armstrong, Ph.D., P.E.

This technology deployment was funded under the FHWA Federal Lands Highway Coordinated Technology 

Implementation Program (CTIP).

16. Abstract

Traffic monitoring in recreational areas is often challenged by distinct traffic and roadway characteristics and the 

multitude of agencies responsible for the management of Federal lands and/or the collection of supporting traffic 

data. These challenges are exacerbated by a lack of consistent procedural guidance; existing national traffic monitoring 

guidelines lack sufficient direction and detail for recreational travel.

In an effort to improve/lend consistency to traffic monitoring in recreational areas, the Coordinated Technology 

Implementation Program tasked the Office of Federal Lands Highway-Federal Highway Administration (FHWA) with 

conducting an assessment of the nationwide practices for recreational traffic data collection. A review of pertinent 

literature related to recreational traffic data collection was conducted. A targeted survey of various State and local 

agencies responsible for traffic monitoring was administered. A workshop focused on traffic monitoring in recreational 

areas was also conducted. Key findings from these activities are briefly described herein.

17. Key Words

Traffic Monitoring, Recreation, Traffic Counting

18. Distribution Statement

No restriction. This document is available to the 

public from the sponsoring agency at the website 

http://www.wfl.fhwa.dot.gov/programs/td/publications

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

44

22. Price

$0.00

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

In Recreational 

Areas

Technology Deployment Program

Western Federal Lands Highway Division

Federal Highway Administration

610 East 5th St.

Vancouver, WA 98661

Technology Deployment Report Report Number: FHWA-WFL/TD-10-003
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 inch 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 ton”) 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

*SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. 

(Revised March 2003)
Table of Contents

List of Acronyms ................................................................................... viii

Executive Summary .................................................................................. 1

National Guidance for Traffic Monitoring in Recreational Areas ..................................1

Vehicle Classification ..........................................................................................................2

Recreational Traffic Monitoring as Described in the Literature ....................................3

Recreational Traffic Monitoring as Observed in Practice...............................................3

Targeted Survey of State and Local Agencies.......................................................................................................3

Recreational Traffic Monitoring Workshop ..........................................................................................................3

Broader Traffic Monitoring Challenges.................................................................................................................5

Next Steps ............................................................................................................................5

Introduction........................................................................................... 6

Investigation Purpose and Methodology ........................................................................6

Literature Review ......................................................................................................................................................6

Targeted Survey of Traffic Monitoring in Recreational Areas............................................................................6

Recreational Traffic Monitoring Workshop ..........................................................................................................7

Background ............................................................................................ 7

Recreational Traffic and Roadway Characteristics ..........................................................8

Agencies Responsible for Recreational Traffic Monitoring............................................8

Bureau of Land Management.................................................................................................................................8

Fish and Wildlife Service ..........................................................................................................................................9

Forest Service.............................................................................................................................................................9

National Park Service...............................................................................................................................................9

State Departments of Transportation...................................................................................................................9

Federal Lands Highway Program........................................................................................................................ 10

National Guidance for Traffic Monitoring in Recreational Areas ................................10

Traffic Monitoring Guide ...................................................................................................................................... 11

Guidelines for Traffic Data Programs................................................................................................................. 12

HPMS Field Manual for the Continuing Analytical and Statistical Database ............................................. 12

Vehicle Classification ........................................................................................................13

Recreational Traffic Monitoring as Described in the Literature ..................................17

Recreational and/or Seasonal Factor Groups................................................................................................... 17
Methods to Support Determination of Recreational and/or Seasonal Factor Groups.............................. 17

Errors Associated with Factoring Short-term Traffic Counts.......................................................................... 19

Other Related Literature ....................................................................................................................................... 20

Interpretation of Data Requirements for Federal Lands Management Agencies

21

Summary of Federal Data Requirements .......................................................................21

23 CFR 500: Management and Monitoring Systems........................................................................................ 21

23 CFR 970: National Park Service Management Systems.............................................................................. 21

23 CFR 924: Highway Safety Improvement Program....................................................................................... 22

23 USC 204: Federal Lands Highways Program ................................................................................................ 22

Interpretation of Requirements ......................................................................................23

23 CFR 500: Management and Monitoring Systems........................................................................................ 24

23 CFR 970: National Park Service Management Systems.............................................................................. 24

23 CFR 660: Special Programs (Direct Federal), Subpart A—Forest Highways........................................... 25

SAFETEA-LU Public Law 109-59, August 10, 2005 ............................................................................................ 25

Recreational Traffic Monitoring as Observed in Practice ..........................25

Targeted Survey of State and Local Agencies ...............................................................25

State Departments of Transportation................................................................................................................ 26

Metropolitan Planning Organizations............................................................................................................... 26

Recreational Traffic Monitoring Workshop....................................................................27

Traffic Data Collection Technologies.................................................................................................................. 27

Vehicle Classification ............................................................................................................................................ 28

Short-Duration Counts......................................................................................................................................... 29

Recreational or Seasonal Factor Groups ........................................................................................................... 29

Traffic Data Use, Quality, Reporting, and Sharing........................................................................................... 30

Broader Traffic Monitoring Challenges.............................................................................................................. 32

Next Steps ............................................................................................33

APPENDIX A: 23 CFR 500: Management and Monitoring Systems, Subpart

B—Traffic Monitoring System ...........................................................35
List of Figures

Figure 1. Example of Existing NPS Vehicle Classification Scheme .............. 15

List of Tables

Table 1. Standard Sample Volume Groups and Precision Levels for Rural

Areas (FHWA, 2005 p. C-1) .............................................................. 13

Table 2. Length-Based Vehicle Classification in British Columbia .............. 16

Table 3. Seasonal Factor Group Analysis in Delaware ............................. 18

Table 4. Recreational Factor Groups in Selected State Traffic Monitoring

Programs ......................................................................................... 26
List of Acronyms

AASHTO American Association of State Highway and Transportation Officials

AADT Annual Average Daily Traffic

ADT Average Daily Traffic

ATR Automatic Traffic Recorder

AVC Automatic Vehicle Classifier

AWDT Average Weekday Traffic

BLM Bureau of Land Management

BMS Bridge Management System

CMS Congestion Management System

CV Coefficient of Variation

DOT Department of Transportation

FARS Fatal Accident Reporting System

FDOT Florida Department of Transportation

FHWA Federal Highway Administration

FLH Office of Federal Lands Highway

FLHP Federal Lands Highway Program 

FLMA Federal Land Management Agency

GIS Geographic Information System

HPMS Highway Performance Monitoring System

LTPP Long-Term Pavement Performance

MPO Metropolitan Planning Organization 

MTC Metropolitan Transportation Commission

NATMEC North American Travel Monitoring Exhibition and Conference

NPS National Park Service 

PMS Pavement Management System

PRPTIP Park Road Program, Transportation Improvement Program

RIP Road Inventory Program

RV Recreational Vehicle

SMCOG Southwest Missouri Council of Governments

SMS Safety Management System

TMG Traffic Monitoring Guide

TMS Traffic Management System

TRIS Transportation Research Information System 

TTI Texas Transportation Institute

U.S. DOT U.S. Department of Transportation

USDA-FS U.S. Department of Agriculture, Forest Service

USFWS Fish and Wildlife Service 

VMT Vehicle-Miles Traveled 

WIM Weigh-in-Motion 
Traffic Monitoring Guide,

1 Guidelines for 

Traffic Data Programs,

2

 and the Highway 

Performance Monitoring System Field Manual 

for the Continuing Analytical and Statistical 

Database3—recommend a traffic monitoring 

framework that comprises: (1) a modest 

number of permanent continuous monitoring 

locations that adequately characterize the 

variation of traffic by day of the week and 

month/season of the year, and (2) a large 

number of portable short-term (typically 

24 to 72 hours) monitoring locations that 

can support determination of “annualized” 

estimates using monthly/seasonal and dayof-week adjustment factors derived from the 

permanent continuous monitoring locations.

Recreational traffic can vary greatly by 

day of the week and month of the year, 

challenging the calculation of seasonal and 

day-of-week adjustment factors. National 

guidance documents recognize recreational 

traffic monitoring challenges but provide 

little substantial guidance to address them. 

Existing national guidance documents focus 

attention on major commuting and throughtraffic routes because: (1) recreational traffic 

has greater variability and specific procedures 

for monitoring it are less formulaic on a 

national basis, and (2) recreational traffic 

comprises a small percentage of the total 

vehicle-miles traveled that must be monitored 

by resource-constrained State agencies. 

Consequently, most State Departments of 

Transportation (DOTs) focus traffic monitoring 

efforts on high-volume, high-mileage roadway 

classes that more significantly impact Federalaid apportionment.

1 Traffic Monitoring Guide. FHWA-PL-01-021. Office of Highway Policy 

Information, Federal Highway Administration, U.S. Department of 

Transportation. Washington D.C. May 2001.

2 Guidelines for Traffic Data Programs. American Association of State highway 

and Transportation Officials. Washington D.C. 1992.

3 Highway Performance Monitoring System Field Manual for the Continuing 

Analytical and Statistical Database. Office of Highway Policy Information, 

Federal Highway Administration, U.S. Department of Transportation. 

Washington D.C. May 2005.

Executive Summary

Traffic monitoring in recreational areas 

is often challenged by distinct traffic and 

roadway characteristics and the multitude 

of agencies responsible for the management 

of Federal lands and/or the collection of 

supporting traffic data. These challenges are 

exacerbated by a lack of consistent procedural 

guidance; existing national traffic monitoring 

guidelines lack sufficient direction and detail 

for recreational travel.

In an effort to improve/lend consistency 

to traffic monitoring in recreational areas, 

the Coordinated Technology Implementation 

Program tasked the Office of Federal Lands 

Highway-Federal Highway Administration 

(FHWA) with conducting an assessment of the 

nationwide practices for recreational traffic 

data collection. This work was performed 

by the Texas Transportation Institute and 

Chaparral Systems, Inc., under contract to 

Battelle. 

There were three primary tasks: 

(1) a review of pertinent literature related 

to recreational traffic data collection

(2) a targeted survey of various State 

and local agencies responsible for traffic 

monitoring

 (3) the conduct of a workshop focused on 

traffic monitoring in recreational areas. 

Key findings from these activities are 

briefly described below and are related to: 

national guidance for traffic monitoring in 

recreational areas, vehicle classification, 

recreational traffic monitoring as described 

in the literature, and recreational traffic 

monitoring as observed in practice.

National Guidance for Traffic 

Monitoring in Recreational Areas

Current national traffic monitoring 

guidance documents—including the 

1
For these documents to have utility for 

traffic monitoring in recreational areas, 

additional detail and direction is required. 

This amendment process is not uncommon for 

Federal lands; distinct roadway design criteria 

and aesthetic guidelines have been previously 

developed in place of or as a supplement to 

more generalized national guidance.

Vehicle Classification

Recreational traffic is distinct with respect 

to the types of vehicles in the traffic stream; 

recreational traffic generally comprises a 

higher proportion of recreational vehicles 

(RVs), buses, and vehicles pulling trailers. 

The proliferation of various vehicle classes 

(the variety of which depends on the season 

and Federal Land unit) suggests that the 

commonly used FHWA vehicle classification 

scheme is insufficient in adequately 

characterizing recreational traffic. Under the 

FHWA vehicle classification scheme, the types 

of vehicles and vehicle combinations that 

frequent recreational areas are aggregated 

with other passenger cars, buses, and 

trucks across 6 of the 13 possible vehicle 

classifications.

Alternative vehicle classification schemes 

better distinguish the types of vehicles 

and vehicle combinations that frequent 

recreational areas from the general traffic. 

For example, the American Association of 

State Highway and Transportation Officials 

(AASHTO) defines 19 different vehicle classes 

for calculating design dimensions for the 

geometric design of roadways, intersections, 

and interchanges.4 Similarly, the Highway 

Capacity Manual distinguishes passenger cars, 

trucks, buses, and recreational vehicles when 

calculating the effect of various vehicle types 

on the capacity of roadways, intersections, 

4 AASHTO Green Book - A Policy on Geometric Design of Highways and Streets, 

5th Edition. American Association of State and Highway Transportation 

Officials. November 2004.

and interchanges.5 National safety databases, 

such as the Fatal Accident Reporting System, 

include van-based or pickup-based motor 

home, medium/heavy truck based motor 

home, and camper or motor home-unknown 

truck type among other vehicle types.6 

Looking outside the United States, the 

Province of Alberta in Canada uses a vehicle 

classification system consisting of five classes 

including recreational vehicles.7 Most directly 

reflecting the types of vehicles and vehicle 

combinations that frequent recreational areas, 

the National Park Service (NPS) developed 

a unique vehicle classification scheme that 

consists of eight vehicle types: motorcycles, 

passenger cars, RVs, vehicles pulling trailers 

(including RVs), transit/shuttle buses, tour 

buses, light-duty trucks, and heavy-duty 

trucks.8

Automated methods for data capture 

have been developed largely around the 

FHWA vehicle classification scheme. A noted 

challenge is the accurate classification of 

individual vehicles across the 13 categories 

when similarities exist in the number of axles 

(i.e., a passenger car pulling a camper trailer 

may be misclassified as a four-axle single-unit 

or single trailer truck). Alternatives to axlebased data capture mechanisms are currently 

focused on vehicle length and vehicle profile. 

The Minnesota DOT has initiated a pooledfund study that will investigate issues related 

to length-based vehicle classification.9 The 

Province of British Columbia in Canada uses 

a length-based vehicle classification system 

similar to the one proposed here. Perhaps 

more appropriate for distinguishing the types 

5 Highway Capacity Manual. Transportation Research Board, National 

Research Council. Washington D.C. 2000.

6 http://www-fars.nhtsa.dot.gov/Vehicles/VehiclesAllVehicles.aspx, accessed 

December 17, 2008.

7 Clayton, Alan, Jeannette Montufar, Dan Middleton, and Bill McCauley. 

Feasibility of a New Vehicle Classification System for Canada. North American 

Travel Monitoring Exhibition and Conference (NATMEC). August 2000.

8 National Park Service. Traffic Data Report. 2004.

9 http://www.pooledfund.org/projectdetails.asp?id=416&status=4, 

accessed December 18, 2008.

2
Recreational Traffic Monitoring as 

Observed in Practice

Additional information regarding traffic 

monitoring in recreation lands at Federal, 

State, and local levels was gathered through 

a targeted survey of State and local agencies 

and the conduct of a recreational traffic 

monitoring workshop.

Targeted Survey of State and Local 

Agencies

A targeted survey of ten State DOTs 

(Colorado, Florida, Idaho, Indiana, Missouri, 

Nevada, New Jersey, Utah, Wisconsin, and 

Wyoming) and three metropolitan planning 

organizations (Metropolitan Transportation 

Commission—San Francisco Bay Area, 

Metroplan Orlando, and Southwest Missouri 

Council of Governments) was conducted 

as part of this investigation. Survey 

participants were asked to respond to a 

series of questions related to: their agency’s 

conduct of continuous traffic counts; the 

number of automatic traffic recorders (ATRs) 

and automatic vehicle classifiers used for 

recreational and non-recreational traffic 

data collection; the nature and extent of any 

recreational, seasonal, or daily factor groups 

in use; and the nature and extent of roadway 

mileage under the agency’s jurisdiction.

Nearly all of the participating State DOTs 

maintain one or more seasonal factor groups 

for recreational traffic monitoring. Several 

States that have distinct winter and summer 

recreational traffic maintain two factor groups. 

The Florida DOT reported using more than 

two recreational traffic factor groups while the 

Indiana DOT reported using no factor group 

for recreational traffic.

None of the planning agencies that were 

contacted indicated that they routinely 

monitor recreational traffic; instead, planning 

agencies rely upon their respective State DOTs 

to collect this data. Planning agencies may 

occasionally collect data in recreational areas 

of vehicles and vehicle combinations that 

frequent recreational areas are automated 

systems that capture the full vehicle profile. 

A variety of profiler systems are available 

commercially. Technology costs increase 

with sophistication and performance; 

traffic monitoring agencies must reconcile 

these added costs with the perceived value 

of accurate vehicle classification data for 

recreational areas.

Recreational Traffic Monitoring as 

Described in the Literature

Not surprisingly, researchers observed a 

disproportionate focus on traffic monitoring 

in urban rather than recreational areas in 

the published literature. Publications that 

did address recreational traffic monitoring 

generally considered: (1) the use of 

recreational and/or seasonal factor groups, 

(2) methods to support determination of 

recreational and/or seasonal factor groups, 

and (3) the likely errors associated with 

factoring or annualizing short-term counts on 

roads with high-variability traffic.

In general, a review of the literature 

confirmed that a number of traffic monitoring 

agencies in the United States and Canada are 

currently using one or more recreational factor 

groups. Recommended methods to improve 

upon factor group determination considered 

the use of the coefficient of variation, cluster 

analysis, plots of monthly traffic factors, and 

geographic mapping of continuous count 

sites. In one study, traffic monitoring agencies 

were encouraged to focus on accurately 

assigning short-term counts to factor groups, 

rather than on conducting longer duration 

counts (e.g., 72-hour counts). Based upon 

observed estimation errors, proposed 

alternatives to the traditional factor approach 

included regression analysis and artificial 

neural networks; however, mixed results 

in improving average annual daily traffic 

estimates were reported.

3
2 or 3 years. They are often scheduled: 

in the same month each year at a given 

site; during different months per site 

annually by design to account for 

seasonal variability and/or to verify and 

refine factor groups; or as scheduling 

or weather permits. Exceptions include 

the Nevada DOT, which conducts 7-day 

counts on an annual basis to account for 

unique recreational traffic patterns, and 

the Washington State DOT and Manitoba 

Infrastructure and Transportation, which 

conduct 48-hour counts twice per year 

in recreational areas. 

•	 Factor groups in use by participating 

agencies—differing in both number and 

characteristics—are often assigned on 

the basis of: roadway functional class, 

traffic composition, travel patterns, 

proximate/destination land use, climatic 

region, relative importance for capturing 

recreational trips, and/or resources/

costs. Resources/costs are supported 

by (in order of preference): data from 

proximate ATRs, cluster analysis, and/

or knowledge of the area/professional 

judgment.

•	 The motivation for collecting traffic data 

was to: meet ongoing Federal reporting 

requirements; support decisionmaking related to safety concerns; 

obtain estimates of demand (i.e., 

visitation) for comparison with supply 

inventories, economic assessment 

and/or determination of resource 

impact; support decision-making 

related to system design, maintenance, 

and management; and/or support 

determination of cost allocations under 

cost sharing arrangements.

•	 Neither existing data quality nor the 

data quality requirements were able to 

be effectively described for participating 

agencies.

•	 Over time, the reporting of traffic data 

has migrated from published annual 

to support planning uses, but this is done as 

part of a “special studies” process.

Recreational Traffic Monitoring 

Workshop

The purpose of the workshop was to bring 

together State and Federal land agencies 

to discuss current and preferred practices 

for monitoring traffic in recreational areas 

and to identify opportunities for improving 

traffic monitoring to and within Federal lands. 

Representatives from each of the participating 

Federal, State, and Provincial agencies 

described specific traffic monitoring practices 

related to: the use of supporting traffic data 

collection technologies; the conduct of shortduration counts; the use and characteristics 

of recreational or seasonal factor groups; 

vehicle classification; and traffic data use, 

quality, reporting, and sharing. In addition, 

participants collectively identified broader 

challenges related to traffic monitoring 

in recreational areas. Key findings are 

summarized below:

•	 Use of combined permanent and 

portable counters for data collection 

was generally reported, but differences 

in the number of sites used, the 

subsequent geographic coverage, 

and the types of technologies were 

observed.

•	 Vehicle classification data is not 

routinely collected; participants cited 

challenges related to technological 

limitations, inadequate recreational 

road geometry/structure, difficulties in 

annualizing vehicle classification counts 

based on short-duration counts, and 

a lack of consensus among State and 

Federal agencies regarding the value 

of vehicle classification data compared 

to the additional costs of equipment, 

installation, and data processing.

•	 Short-duration counts are commonly 

conducted: in 48-hour durations, on 

Tuesday through Thursday, once every 

4
characteristics of participating agencies and 

the respective lands under their jurisdiction 

became evident. Despite the motivation 

towards more consistent recreational traffic 

monitoring, any proposed changes to existing 

practices cannot be a “one size fits all” 

approach. It must remain flexible to address 

the respective differences in underlying 

mission and priorities and the nature and 

extent of their jurisdictional land areas and 

associated roadway network among agencies 

tasked with managing recreational areas.

reports to the Internet, providing 

timely on-line access to data; however, 

associated modest concerns over the 

potential for liability have been raised.

•	 Data sharing is variable but generally 

limited among participating agencies. 

Data sharing opportunities between 

the FHWA Office of Highway Policy 

Information and the Office of Federal 

Lands Highway were identified and 

appear promising.

Broader Traffic Monitoring Challenges

In addition to these practice-specific 

observations, a number of overarching 

challenges to traffic monitoring in recreational 

areas were identified. These challenges 

generally relate to: differing organizational 

structures and priorities among agencies 

related to the importance placed on 

recreational areas and the traffic monitoring 

function; funding and resource constraints 

and associated difficulties in replacing staff 

and technology assets; and the unique 

aesthetic, cultural, and environmental 

considerations in recreational areas.

Next Steps

Two fundamental opportunities emerged 

as a result of this investigation related to: 

(1) resource and data sharing 

(2) the pivotal role of FHWA’s Office 

of Federal Lands Highway in improving/

lending consistency to traffic 

monitoring in recreational lands.

In the short-term, opportunities exist 

to share both resources and data among 

agencies responsible for recreational traffic 

monitoring. For longer-term efforts, FHWA’s 

Office of Federal Lands Highway should 

play a key role in facilitating and supporting 

improvements to recreational traffic 

monitoring among diverse partners.

Through this investigation, the unique 

5
Literature Review

A comprehensive literature review was 

conducted at the onset of this investigation 

with a focus on traffic data collection in 

recreational areas. Primary sources of 

literature included the online Transportation 

Research Information System (TRIS); other 

related Internet sites; various conference 

compendiums (e.g., Transportation Research 

Board’s Annual Meeting); and the TTI and 

Texas A&M University library collections.

Not surprisingly, researchers observed a 

disproportionate focus on traffic monitoring 

in urban rather than recreational areas 

in the published literature. Much of the 

literature found to address recreational 

traffic monitoring considered: (1) the use of 

recreational and/or seasonal factor groups, 

(2) methods to support determination of 

recreational and/or seasonal factor groups, 

and (3) the likely errors associated with 

factoring or annualizing short-term counts on 

roadways with high-variability traffic.

Targeted Survey of Traffic Monitoring in 

Recreational Areas

As a second task in this investigation, a 

targeted survey of 10 State Departments of 

Transportation (DOTs) (Colorado, Florida, 

Idaho, Indiana, Missouri, Nevada, New 

Jersey, Utah, Wisconsin, and Wyoming) and 

three metropolitan planning organizations 

(Metropolitan Transportation Commission—

San Francisco Bay Area, Metroplan Orlando, 

and Southwest Missouri Council of 

Governments) was conducted to identify 

current practices in collecting traffic data 

at and near recreational areas. Survey 

participants were selected based on: (1) the 

ability to provide geographic diversity, (2) the 

likely presence of recreational travel, and (3) 

the research team’s familiarity with State and 

local agency staff.

Survey participants were asked to respond 

to the following series of questions:

Introduction

Approximately 70,000 miles of federallyowned public roads serving recreational traffic 

fall under the purview of the Federal Highway 

Administration (FHWA) Federal Lands Highway 

Program (i.e., Park Roads and Parkways, Forest 

Highways, Public Lands Highways, and Refuge 

Roads). To adequately support planning and 

management efforts for the preservation and 

use of Federal lands, land managers must have 

a clear understanding of the transportation 

and visitor circulation patterns within their 

jurisdiction. Traffic data is often collected to 

support decision-making; however, distinct 

recreational traffic and roadway characteristics 

and the multitude of responsible agencies 

often challenge these efforts. The challenge 

of collecting recreational traffic data is 

exacerbated by a lack of consistent guidance. 

Existing national guidelines for traffic 

monitoring practices lack sufficient direction 

and detail for recreational travel.

Investigation Purpose and 

Methodology

In an effort to improve/lend consistency 

to traffic monitoring in recreational areas, 

the Coordinated Technology Implementation 

Program tasked the Office of Federal Lands 

Highway-Federal Highway Administration 

(FHWA), with conducting an assessment of the 

nationwide practices for recreational traffic 

data collection. This work was performed by 

the Texas Transportation Institute (TTI) and 

Chaparral Systems, Inc., under contract to 

Battelle, through three primary tasks:

1. A review of pertinent literature related 

to recreational traffic data collection; 

2. A targeted survey of various State and 

local agencies responsible for traffic 

monitoring; and

3. The conduct of a workshop focused on 

traffic monitoring in recreational areas.

6
traffic in recreational areas and to identify 

opportunities for improving traffic monitoring 

to and within Federal lands. The same 

information was originally intended to be 

collected as part of a domestic scan tour 

to various States, but a gathering under 

a workshop proved to be a more efficient 

opportunity for information exchange.

The workshop was held on June 3, 2009, 

in Lakewood, Colorado with 27 on-site and 

3 remote participants. The workshop’s 

agenda was comprised of presentations 

regarding traffic monitoring in recreational 

areas as performed by five distinct Federal 

land agencies (Office of Federal Lands, 

Bureau of Land Management, Forest Service, 

Fish and Wildlife Service, and National 

Park Service), six State agencies (Colorado, 

Florida, Nevada, Utah, Washington, and 

Wyoming DOTs), and one Provincial agency 

(Manitoba Infrastructure and Transportation). 

Opportunities for general questions and 

discussion were provided following the 

presentations made by representatives from 

the various agencies. A smaller group of 

approximately 15 workshop attendees was 

convened for an additional half day on June 

4, 2009, to discuss workshop outcomes and 

brainstorm future directives. 

Background

To provide a better understanding of 

the current state of traffic monitoring in 

recreational areas, background information is 

provided related to:

•	 Recreational traffic and roadway 

characteristics;

•	 Agencies responsible for recreational 

traffic monitoring;

•	 National guidance for traffic monitoring 

in recreational areas;

•	 Vehicle classification; and

•	 Recreational traffic monitoring as 

described in the literature.

(1) Does your agency have seasonal or 

daily factor groups for your recreational 

areas? If Yes:

(a) How many seasonal or daily factor 

groups does your agency have?

(b) For each seasonal or daily factor 

group:

•	 Can you provide a brief

description of the factor group 

(i.e., summer recreational, regional 

recreational, summer and winter 

recreational—town highways)

•	 How many automatic traffic

recorders (ATRs) are used to 

support the factor group?

•	 How many automatic vehicle

classifiers (AVCs) are used to 

support the factor group?

•	 Approximately how many roadmiles are included in each factor 

group?

(c) How many total ATRs does your 

agency operate?

(d) How many total AVCs does your 

agency operate?

(e) Approximately how many total 

road-miles are included in the 

network?

(f ) On a scale of 1 to 5 (with 1=very 

low, 2=low, 3=moderate, 4=high, 

and 5=very high), what priority does 

your agency give to data collection in 

recreational areas?

(2) If your agency does not conduct 

continuous traffic counts, can you describe 

your traffic data collection efforts to 

capture recreational traffic trends?

Recreational Traffic Monitoring 

Workshop

To supplement information gathered 

through the literature review and targeted 

survey, a recreational traffic monitoring 

workshop was conducted. The purpose of 

the workshop was to bring together State 

and Federal agencies to discuss current 

and preferred practices for monitoring 

7
•	 U.S. Department of the Interior, Bureau 

of Land Management (BLM);

•	 U.S. Department of the Interior, Fish and 

Wildlife Service (USFWS);

•	 U.S. Department of Agriculture, Forest 

Service (USDA-FS); and

•	 U.S. Department of the Interior, National 

Park Service (NPS).

These agencies differ in their underlying 

mission and priorities and the nature and 

extent of their jurisdictional land areas and 

associated roadway network.

Bureau of Land Management

The BLM administers a variety of programs 

for the management and conservation of 

resources on 256 million surface acres as 

well as 700 million subsurface mineral acres 

of land in the United States. These public 

lands comprise approximately 13% of the 

total land surface of the United States and 

more than 40% of all land managed by the 

Federal Government. Most of the public 

lands are located in the Western United States 

(including Alaska) and are characterized by 

grassland, forest, mountain, arctic tundra, 

and desert landscapes. The BLM manages 

the land’s resources and uses including 

energy, minerals, timber, recreation, wild 

horse and burro herds, fish and wildlife 

habitat, wilderness areas, and archaeological, 

paleontological, and historical sites.10

An estimated 600,000 miles of roadways 

service these public lands. Of these roads 

90,000 miles are identified as “system routes” 

and are eligible for planning, maintenance, 

and funding. No formal process for managing 

or maintaining the remaining 510,000 

miles of roadway presently exists. Visits to 

recreation sites on BLM lands and waters have 

significantly increased over the years from 51 

10 http://www.blm.gov/wo/st/en/info/About_BLM.html, accessed July 15, 

2009.

Recreational Traffic and Roadway 

Characteristics

Recreational traffic is distinct with respect 

to the types of vehicles in the traffic stream 

and the corresponding average vehicle 

occupancy. In general, recreational traffic 

comprises a higher proportion of recreational 

vehicles (RVs), buses, and vehicles pulling 

trailers. Alternative transportation initiatives, 

such as the Paul S. Sarbanes Transit in the 

Parks Program, may increase the volume 

of buses in certain recreational areas. The 

average vehicle occupancy tends to be higher 

than that of commuter or local traffic.

Recreational trips can be either 

destination-focused or for leisure, where 

much of the drive time is considered to be 

recreation. Trip routing is directly influenced 

by its purpose. Recreational trips also have 

a high temporal variability (e.g., by time of 

day, day of week, season) depending upon 

the nature of recreational activities available. 

Unlike commuter or local traffic where the 

mean time between trips is both minimal 

and somewhat predictable, the mean time 

between recreational trips can range from 

several days to one week to one year or more. 

Recreational trips are discretionary, and as 

such, are readily influenced by factors such as 

weather, gas prices, etc.

The roadways that support recreational 

travel differ significantly from roads that are 

primarily commuter or industrial. Roadways 

that predominantly support recreational travel 

are generally of lower functional class, have 

constrained geometric design features, and 

may be paved, gravel, or native surfacing. 

Many are low or extremely low volume roads.

Agencies Responsible for 

Recreational Traffic Monitoring

At the Federal level, primary agencies 

that are directly responsible planning and 

managing the preservation and use of 

recreational areas include:

8
network established to support timber harvest 

and log removal. Approximately 66,000 miles 

of USDA-FS roadway is maintained to support 

passenger car traffic; the remaining roadway 

network supports only high-clearance 

vehicles. An estimated 1.7 million vehicles use 

these roads each day to visit national forests.13

National Park Service

About 29,000 miles of State and local 

roads are designated as Forest Highways. 

As indicated in 23 U.S.C. 202, 203, and 204, 

the Forest Highways program, developed in 

cooperation with State and local agencies, 

provides safe and adequate transportation 

access to and through National Forest System 

(NFS) lands for visitors, recreationists, resource 

users, and others which is not met by other 

transportation programs. Forest highways 

assist rural and community economic 

development and promote tourism and travel.

The NPS manages a network of nearly 

400 natural, cultural, and recreational sites 

across the Nation with the intent of preserving 

the sites for the enjoyment, education, and 

inspiration of current and future generations. 

The NPS also cooperates with partners to 

extend the benefits of resource conservation 

and outdoor recreation throughout the United 

States and the world.14

Approximately 8,500 miles of roadway 

service NPS lands; 5,456 miles of which are 

paved. An estimated 90 percent of the road 

miles exist in just 10 percent of the parks.15 

The NPS roadway network also includes 

1,736 bridges and 67 tunnels. Alternative 

transportation systems operate in 96 of 

the nearly 400 parks. The NPS routinely 

monitors the number of vehicles entering 

297 parks along highways, parkways, and 

tour and access roads (paved and unpaved). 

13 http://www.fs.fed.us, accessed July 15, 2009.

14 http://www.nps.gov/aboutus, accessed July 15. 2009.

15 Kathryn Gunderson. National Park Service Practices and Perspectives. 

Recreational Traffic Monitoring Workshop. June 2009.

million in 2001, to 57 million in 2008.11

Fish and Wildlife Service

The USFWS is dedicated to the 

conservation, protection, and enhancement 

of the habitats of fish, wildlife, and plants. The 

agency is also responsible for implementing 

and enforcing some of the Nation’s 

environmental laws, including the Endangered 

Species Act, Migratory Bird Treaty Act, Marine 

Mammal Protection Act, North American 

Wetlands Conservation Act, and Lacey Act.

The USFWS manages the 96 million acre, 

548-unit, National Wildlife Refuge System. 

More than 4,900 miles of roadway currently 

service USFWS lands. Visits to recreation sites 

on USFWS lands and waters are expected 

to significantly increase from 41 million in 

2008 to 51 million in 2015. The USFWS also 

operates 70 National Fish Hatcheries, which, in 

conjunction with Fish Health Centers and Fish 

Technology Centers, restore native aquatic 

populations, mitigate for fisheries lost as a 

result of Federal water projects, and support 

recreational fisheries throughout the United 

States.12

Forest Service

The USDA-FS manages public lands 

in 155 national forests and 20 grasslands, 

encompassing 193 million acres. The USDA-FS 

is the largest forestry research organization 

in the world, and provides technical and 

financial assistance to State and private 

forestry agencies.

Access to USDA-FS lands is provided 

through a combination of public highways, 

local public roads, and classified USDA-FS 

roads within the National Forest System. An 

estimated 380,000 miles of classified USDA-FS 

roadways exist, with much of this roadway 

11 Placchi, Jack. Bureau of Land Management Perspective. Recreational Traffic 

Monitoring Workshop. June 2009.

12 Fish and Wildlife Service Agency Overview: Conserving the Nature of America. 

November 2008.

9
Federal Lands Highway Program

The Office of Federal Lands Highway 

(FLH) FHWA, under the U.S. Department of 

Transportation, provides funding for public 

roads and highways within federally owned 

lands and tribal lands that are not a State or 

local government responsibility. The FLH 

has close partnerships with State and local 

governments and works with numerous 

Federal land management agencies including 

the Bureau of Land Management, Fish and 

Wildlife Service, Forest Service, National 

Park Service, Bureau of Indian Affairs, Bureau 

of Reclamation, Surface Deployment and 

Distribution Command, and the U.S. Army 

Corps of Engineers.

National Guidance for Traffic 

Monitoring in Recreational Areas

The challenge of collecting recreational 

traffic data is also complicated by a lack 

of consistent guidance; existing national 

guidelines for traffic monitoring practices lack 

sufficient direction and detail for recreational 

travel.

Current national guidance documents 

related to traffic monitoring include the 

following:

•	 Traffic Monitoring Guide (TMG),

17

published by FHWA;

•	 Guidelines for Traffic Data Programs,

18

published by the American Association 

of State Highway Transportation 

Officials (AASHTO); and

•	 Highway Performance Monitoring System 

(HPMS) Field Manual for the Continuing 

17 Traffic Monitoring Guide. FHWA-PL-01-021. Office of Highway Policy 

Information, Federal Highway Administration, U.S. Department of 

Transportation. Washington D.C. May 2001.

18 Guidelines for Traffic Data Programs. American Association of State highway 

and Transportation Officials. Washington D.C. 1992.

Approximately 110 million vehicles or 

218 million visitors enter the NPS lands 

for recreational purposes each year. An 

additional 218 million vehicles are estimated 

to access NPS lands for non-recreational 

purposes (e.g., NPS employees or contracted 

services, through traffic, etc.).16

State Departments of Transportation

At the State level, DOTs collect traffic data 

to meet Federal reporting requirements and 

to support decision-making needs within 

the State. Each State DOT must comply with 

the reporting requirements of the Highway 

Performance Monitoring System (HPMS). 

These data—focused on traffic volumes 

for a subset of roadways in a State—are 

used to produce statewide estimates of 

total vehicle-miles traveled (VMT) and the 

subsequent apportionment of Federalaid funds. Additional data collected to 

support State-level decision-making varies 

widely depending on each State DOT’s 

traffic counting needs, priorities, budgets, 

geography, and organizational constraints.

Differences in the nature and extent 

of recreational activity in each State and 

its relationship to the roadway network 

exacerbate differences in recreational traffic 

monitoring. For example, recreational 

areas and activities are highly concentrated 

in Florida; as a result, a high proportion 

of the system and secondary roadways 

carry recreational trips. The State’s traffic 

monitoring activities are designed to account 

for this. Comparatively, Colorado’s system 

roadways also carry recreational trips but this 

segment of travelers is likely considered to 

be secondary when planning and designing 

traffic monitoring activities. In Wyoming, 

many of the major system routes currently 

monitored directly feed recreational areas in 

the State.

16 Butch Street. National Park Service Practices and Perspectives. Recreational 

Traffic Monitoring Workshop. June 2009.

10
the variability of recreational traffic and 

development of seasonal factor groups 

through the following statements:

•	 “Statistics and the desire to have factors 

that yield [annual average daily traffic] 

AADT estimates with ±10 percent 

accuracy with 95 percent confidence 

tend to require a factor group size of 

between 5 to 8 counters. ... Recreational 

or special groups often have only a 

single continuous counter” (pp. 2-45–2-

46). 

•	 “Urban roads tend to have a much lower 

level of daily traffic variability than rural 

roads. Recreational areas have much 

higher levels of variability than nonrecreational areas” (p. 3-12).

•	 “...recreational roads usually experience 

major traffic peaking at specific times 

necessitating frequent information” 

(p. 3-18).

•	 “Typical monthly variation patterns 

for urban areas have a coefficient of 

variation under 10 percent, while those 

of rural areas range between 10 and 25 

percent. Values higher than 25 percent 

are indicative of highly variable travel 

patterns, which reflect ‘recreational’ 

patterns but which may be due to 

reasons other than recreational travel” 

(p. 3-34).

•	 “The reliability levels recommended are 

10 percent precision with 95 percent 

confidence, 95-10, for each individual 

seasonal group, excluding recreational 

groups where no precision requirement 

is specified” (p. 3-35).

•	 “Recreational factor groups usually 

are monitored with a smaller number 

of ATRs, simply because recreational 

patterns tend to cover a small number 

of roads, and it is not economically 

justifiable to maintain five to eight ATRs 

to track a small number of roads. The 

number of stations assigned to the 

Analytical and Statistical Database,

19

published by FHWA.

In general, these documents recommend 

a traffic monitoring framework with two basic 

elements:

1. A modest number of permanent 

continuous monitoring locations that 

adequately characterize the variation 

of traffic by day of the week and 

month/season of the year; and

2. A large number of portable shortterm (typically 24 to 72 hours) 

monitoring locations that can support 

determination of “annualized” 

estimates using monthly/seasonal 

and day-of-week adjustment 

factors derived from the permanent 

continuous monitoring locations.

The calculation of seasonal and dayof-week adjustment factors is typically 

straightforward, particularly on major 

highways in urban and rural areas carrying 

significant commuter or through-traffic that 

does not vary much by season or during the 

work week. However, recreational traffic can 

vary greatly by day of the week and month/

season of the year. Because recreational traffic 

has greater variability than urban commuter 

traffic, special consideration should be 

given in designating permanent monitoring 

locations for one or more recreational traffic 

seasonal factor groups.

Traffic Monitoring Guide

The TMG, last updated in 2001 (previous 

editions were published in 1995, 1992, and 

1985), is intended for use by State and local 

highway agencies with an emphasis on 

knowing what data to collect. The TMG also 

addresses the national data requirements 

for the HPMS. The 2001 TMG recognizes 

19 Highway Performance Monitoring System Field Manual for the Continuing 

Analytical and Statistical Database. Office of Highway Policy Information, 

Federal Highway Administration, U.S. Department of Transportation. 

Washington D.C. May 2005.

11
HPMS Field Manual for the Continuing 

Analytical and Statistical Database

The HPMS Field Manual provides guidance 

to State and local agencies for the reporting 

of traffic and roadway inventory data for 

compilation in the national HPMS—a 

nationwide inventory for all of the Nation’s 

public road mileage. The HPMS is used 

to identify the condition, performance, 

and investment needs for legislation and 

apportionment for Federal-aid. The HPMS 

includes both universe data elements (data 

that are reported for all public roads [e.g., 

length]) and sample data elements (data 

that are measured on a statistical sample of 

public roads and “expanded” to other nonsampled roads [e.g., traffic counts and road 

characteristics]).

Each State DOT is responsible for 

submission of State-level HPMS data on Stateand federally-owned roads to FHWA. The 

HPMS database should reflect the mileage of 

all public roads in Federal lands. However, 

few samples may be collected on Federal 

lands depending upon the location of the 

random statistical samples; traffic volumes on 

certain Federal lands roadways may instead be 

estimated from similarly classified rural roads 

within the State.

In Appendix C of the HPMS Field Manual, 

precision levels for various functional classes 

in both rural and urban areas are specified. 

Table 1 below summarizes the volume groups 

and precision levels for rural areas. Note 

that the previously described TMG does not 

prescribe precision levels for recreational 

factor groups. Lower traffic volumes that 

are variable in nature lead to higher error 

tolerances for factoring low volume traffic 

counts. On such routes, it may be sufficient to 

determine that the road has low volume (250 

to 400 vehicles per day as defined by AASHTO) 

or very low traffic (less than 250 vehicles per 

day as defined by AASHTO).

Sample size estimation procedures 

recreational groups depends on the 

importance assigned by the planning 

agency to the monitoring of recreational 

travel, the importance of recreational 

travel in the State, and the different 

recreational patterns identified” 

(p. 3-35).

•	 “Roughly six ATRs are needed for each 

“factor group” in order to develop stable, 

representative factors. ... The major 

exception to this rule of thumb is for 

recreational routes and other “unusual” 

roads which experience unique travel 

patterns. In these cases, a single ATR 

may be all that is necessary to monitor 

each unique pattern” (p. 3-39).

The TMG was written to accommodate the 

diverse traffic monitoring needs of 50 States, 

acknowledging that “[a]ctual implementation 

will vary from agency to agency” (p. E-1). 

In addition, the TMG focuses attention 

on major commuting and through-traffic 

routes because: (1) recreational traffic has 

greater variability and specific procedures for 

monitoring it are less formulaic on a national 

basis, and (2) recreational traffic comprises a 

small percentage of the total VMT that must 

be monitored by resource-constrained State 

agencies.

Guidelines for Traffic Data Programs

The Guidelines for Traffic Data Programs

is similarly lacking in addressing the unique 

challenges of recreational traffic monitoring. 

Unlike the TMG which focuses on what data 

to collect, AASHTO’s Guidelines for Traffic 

Data Programs primarily focus on how to 

collect, process, and store traffic data. Little 

detail is provided on sampling designs 

and establishing factor groups for traffic 

monitoring in recreational areas. The planned 

2009 update provides additional detail 

compared to the content in the 1992 edition, 

but still falls short in providing definitive 

guidance for low-volume roads with heavy 

recreational traffic patterns.

12
vehicles (RVs), buses, and vehicles pulling 

trailers. The adequacy of existing vehicle 

classification schemes to accurately describe 

recreational traffic is considered below.

The predominant vehicle classification 

scheme used for traffic monitoring in the 

United States was developed by FHWA nearly 

two decades ago and consists of 13 vehicle 

classes:

1. Motorcycles;

2. Passenger cars;

3. Other two-axle, four-tire single unit 

vehicles;

4. Buses;

5. Two-axle, six-tire, single-unit trucks;

6. Three-axle single-unit trucks;

7. Four or more axle single-unit trucks;

8. Four or fewer axle single-trailer trucks;

are provided in Appendix D of the HPMS 

Field Manual. However, these sample size 

procedures require an estimate of the 

variability in the AADT data. The variability 

observed by each State DOT may be different 

and may not account for the true variability 

among State- and Federal-owned roadways.

The HPMS is currently being reassessed, 

which is likely to provide some enhancement 

and improvements to the database. However, 

the main purpose of HPMS will continue 

to be the apportionment of Federal-aid 

funds, which is based on length, lane-mile, 

and VMT information. Most State DOTs 

will likely continue to focus their efforts on 

high-volume, high-mileage road classes that 

provide the most impact on their Federal-aid 

apportionment.

Vehicle Classification

As noted previously, recreational traffic is 

distinct with respect to the types of vehicles in 

the traffic stream; recreational traffic generally 

comprises a higher proportion of recreational 

13

Table 1. Standard Sample Volume Groups and Precision Levels for Rural Areas 

(FHWA, 2005 p. C-1)

AADT 

Volume 

Group

Interstate Other Principal Arterial Minor Arterial Major Collector

90% confidence, 

5% error

90% confidence, 

5% error

90% confidence, 

10% error

80% confidence, 

10% error

01 0- 9,999 0- 4,999 0- 2,499 0- 2,499

02 10,000- 19,999 5,000- 9,999 2,500- 4,999 2,500- 4,999

03 20,000- 29,999 10,000- 14,999 5,000- 9,999 5,000- 9,999

04 30,000- 39,999 15,000- 19,999 10,000- 19,999 10,000- 19,999

05 40,000- 49,999 20,000- 29,999 20,000- 29,999 20,000- 29,999

06 50,000- 59,999 30,000- 39,999 30,000- 39,999 30,000- 39,999

07 60,000- 69,999 40,000- 49,999 40,000- 49,999 40,000- 49,999

08 70,000- 79,999 50,000- 59,999 50,000- 59,999 50,000- 59,999

09 80,000- 89,999 60,000- 69,999 60,000- 69,999 60,000- 69,999

10 90,000-104,999 70,000- 84,999 70,000- 79,999 70,000- 79,999

11 105,000-119,999 85,000- 99,999 80,000- 89,999 80,000- 89,999

12 120,000-134,999 100,000-114,999 90,000- 99,999 90,000- 99,999

13 > or = 135,000 > or = 115,000 > or = 100,000 > or = 100,000
Vehicles: All two-axle, four-tire vehicles 

other than passenger cars. Included in 

this classification are pickups, panels, 

vans, and other vehicles such as campers, 

motor homes, ambulances, hearses, 

carryalls, and minibuses. Other twoaxle, four-tire single-unit vehicles pulling 

recreational or other light trailers are 

included in this classification.

•	 Buses: All vehicles manufactured as 

traditional passenger-carrying buses

with two axles and six tires or three 

or more axles. This category includes 

only traditional buses (including school 

buses) functioning as passengercarrying vehicles. Modified buses should 

be considered to be a truck and should 

be appropriately classified. 

•	 Two-Axle, Six-Tire, Single-Unit Trucks: 

All vehicles on a single frame including 

trucks, camping and recreational vehicles, 

motor homes, etc., with two axles and 

dual rear wheels.

•	 Three-Axle Single-Unit Trucks: All 

vehicles on a single frame including 

trucks, camping and recreational vehicles, 

motor homes, etc., with three axles” 

(emphasis added).22

Alternative vehicle classification schemes 

included in other national guidance 

documents or reporting systems better 

distinguish the types of vehicles and vehicle 

combinations that frequent recreational 

areas from the general traffic. For example, 

AASHTO defines 19 different vehicle classes 

for calculating dimensions for the geometric 

design of roadways, intersections, and 

interchanges. Vehicle classes include motor 

home, passenger car with camper trailer, 

passenger car with boat trailer, and motor 

home and boat trailer. Six different classes of 

buses are also delineated, including intercity 

bus (40 ft. length) and intercity bus (45 ft. 

22 http://www.fhwa.dot.gov/policy/ohpi/vehclass.htm, accessed December 

17, 2008.

9. Five-axle single-trailer trucks;

10. Six or more axle single-trailer trucks;

11. Five or fewer axle multi-trailer trucks;

12. Six-axle multi-trailer trucks; and

13. Seven or more axle multi-trailer 

trucks.20

The process that led to the development 

of the FHWA vehicle classification scheme 

was based on a review of classifications then 

in use, anticipated data types that would be 

needed to address then-emerging issues, 

current data needs expressed by major data 

users, and recommendations of the States. 

The use of the FHWA vehicle classification 

scheme in the original TMG led to its adoption 

in various national efforts such as the HPMS 

and the Long-Term Pavement Performance 

(LTPP) Program as well as being adopted for 

use by various States.21

A shortcoming of the FHWA vehicle 

classification scheme as applied to the 

monitoring of recreational traffic is that it 

does not support the capture of disaggregate 

recreational vehicle types such as motor 

homes, RVs, tourism motor coaches, and 

vehicles towing camper or boat trailers. 

Under the FHWA vehicle classification 

scheme, the types of vehicles and vehicle 

combinations that frequent recreational areas 

are aggregated with other passenger cars, 

buses, and trucks across 5 of the 13 possible 

vehicle classifications: 

•	 “Passenger Cars: All sedans, coupes, 

and station wagons manufactured 

primarily for the purpose of carrying 

passengers and including those 

passenger cars pulling recreational or 

other light trailers. 

•	 Other Two-Axle, Four-Tire Single Unit 

20 http://www.fhwa.dot.gov/policy/ohpi/vehclass.htm, accessed December 

17, 2008.

21 Kashuba, Ed. Vehicle Classification System: FHWA Perspective. North 

American Travel Monitoring Exposition and Conference (NATMEC). August 

2000.

14
and vehicle combinations that frequent 

recreational areas, the NPS developed a 

unique vehicle classification scheme to 

support their traffic database. The NPS vehicle 

classification scheme consists of eight vehicle 

types:

•	 Motorcycles;

•	 Passenger cars;

•	 RVs;

•	 Vehicles pulling trailers (including RVs);

•	 Transit/shuttle buses;

•	 Tour buses;

•	 Light-duty trucks; and

•	 Heavy-duty trucks. 

The NPS Traffic Database was designed 

to provide a means for linking with other 

NPS and FHWA databases, such as the Road 

Inventory Program (RIP) and Geographic 

Information System (GIS) databases. In 

Traffic Data Reports produced periodically 

for NPS units, the relationship between 

the NPS vehicle classification scheme and 

the FHWA vehicle classification scheme is 

indicated. An example is provided (figure 1) 

from the “Yellowstone National Park Traffic 

Package” within the NPS 2004 Traffic Data 

Report. It should be noted, however, that 

the current NPS traffic data program only 

length).23 Similarly, the Highway Capacity 

Manual distinguishes passenger cars, trucks, 

buses, and recreational vehicles when 

calculating the effect of various vehicle types 

on the capacity of roadways, intersections, 

and interchanges. Recreational vehicles 

include motor homes, cars with camper 

trailers, cars with boat trailers, motor homes 

with boat trailers, and motor homes pulling 

cars. Buses include intercity (motor coaches), 

city transit, school, and articulated buses.24 

National safety databases, such as the Fatal 

Accident Reporting System (FARS), include 

van-based or pickup-based motor home, 

medium/heavy truck based motor home, and 

camper or motor home with unknown truck 

type.25 The Province of Alberta in Canada 

uses a vehicle classification system consisting 

of five classes: passenger cars, recreational 

vehicles, buses (including school buses and 

intercity buses), single unit trucks, and tractor 

trailer combination trucks.26

To better reflect the types of vehicles 

23 AASHTO Green Book - A Policy on Geometric Design of Highways and Streets, 

5th Edition. American Association of State and Highway Transportation 

Officials. November 2004.

24 Highway Capacity Manual. Transportation Research Board, National 

Research Council. Washington D.C. 2000.

25 http://www-fars.nhtsa.dot.gov/Vehicles/VehiclesAllVehicles.aspx, accessed 

December 17, 2008.

26 Clayton, Alan, Jeannette Montufar, Dan Middleton, and Bill McCauley. 

Feasibility of a New Vehicle Classification System for Canada. North American 

Travel Monitoring Exhibition and Conference (NATMEC). August 2000.

15

M

PC

RV

V+T

BUS

TOUR

LT

HT

Motorcycles

Passenger Cars

Recreational Vehicles

Vehicles/RV pulling Trailer

Transit/Shuttle Buses

Tour Buses

Light-duty Trucks

Heavy-duty Trucks

Class 1

Class 2

N/A

N/A

Class 4

Class 4

Classes 3, 5

Classes 6 - 13

No. Vehicle Type FHWA Class

CLASSIFICATION LEGEND:

Vehicle Classification

Location: STATION 27022

RV

2.97%

V+T

3.01%

BUS

0.05%

TOUR

0.38%

PC

86.67%

M

4.24%

HT

0.33%

LT

2.36%

Figure 1. Example of Existing NPS Vehicle Classification Scheme
classification and support development 

of a wider range of vehicle classification 

schemes. Alternatives to axle-based data 

capture mechanisms are currently focused 

on vehicle length and vehicle profile. In-road 

or off-road non-intrusive sensors are used to 

detect vehicle length; vehicle lengths are then 

correlated with various vehicle classes such as 

car, single-unit truck, and combination truck.

The Minnesota DOT has initiated a pooledfund study that will investigate issues related 

to length-based vehicle classification. The 

study objectives are to develop field test 

installation methods for loops to determine 

the most cost effective and best performing 

procedures and materials; determine the 

number of bins and the length spacing for 

each of those bins for uniform collection of 

length based classification data; and establish 

calibration standards for vehicle length based 

measurements.28

The Province of British Columbia in Canada 

uses a length-based vehicle classification 

system. The relationship of British Columbia’s 

vehicle classification scheme to FHWA’s 

28 http://www.pooledfund.org/projectdetails.asp?id=416&status=4, 

accessed December 18, 2008.

calls for an 8-hour sample in one or two 

locations per monitored park. This may not be 

sufficiently representative in certain parks and 

conditions.27

The FHWA vehicle classification scheme 

relies upon the identification of both the 

number of axles and the number of trailers 

in each vehicle. Automated methods for 

data capture (such as in-road sensors and 

supporting software) have been developed 

with these information needs in mind. A 

noted challenge for existing automated 

vehicle classification systems is the accurate 

classification of individual vehicles across the 

13 categories when similarities exist in the 

number of axles. For example, a passenger car 

pulling a camper trailer may be misclassified 

as a four-axle single-unit or a single trailer 

truck.

Driven largely by the proliferation of 

electronic tolling systems in the United 

States (where vehicle type determines toll 

rates, which differ for commercial and noncommercial traffic), alternative technologies 

are in use and under development that can 

improve the accuracy of individual vehicle 

27 National Park Service. 2004 Traffic Data Report. 2005.

16

Table 2. Length-Based Vehicle Classification in British Columbia

Bin Vehicle Type FHWA Equivalent

0 - 6 m 

Motorcycles (1); passenger cars (2); light 

single unit trucks (3)

6 - 12.5 m

 

Buses (4); two axle, 6 tire single unit trucks 

(5); three axle single unit trucks (6); four axle 

single unit trucks (7)

12.5 - 22.5 m

4 axles or fewer, single trailer truck (8); five 

axle single trailer truck (9); six or more axle 

single trailer truck (10)

22.5 - 35 m

B-trains (8, 9, 10); five axle, multi-trailer 

truck (11); six axle, multi-trailer truck (12); 

seven axle, multi-trailer truck (13)

> 35 m Multi-trailer (13)
in Vermont, three of which are devoted to 

recreational traffic:

•	 Summer recreational—8 permanent 

counters;

•	 Summer and winter recreational, US and 

Vermont routes—7 permanent counters; 

and

•	 Summer and winter recreational, town 

highways—7 permanent counters.30

In a report published in 2007, the New York 

State DOT described the use of three basic 

seasonal factor groups:

•	 Urban traffic patterns—seasonal 

coefficient of variation less than 10 

percent;

•	 Suburban traffic patterns—seasonal 

coefficient of variation between 10 and 

25 percent; and

•	 Recreational traffic patterns—seasonal 

coefficient of variation greater than 25 

percent.

Within each of these main factor groups, 

two additional “minor” factor groups are 

provided to slightly increase or decrease the 

seasonal peaking characteristics.31

In a related study published in 2000, 

Lingras et al. enumerates the seasonal factor 

groups that are used in the province of 

Alberta, Canada:

•	 Group 1: Highly recreational; 

•	 Group 2: Regional recreational;

•	 Group 3: Long distance;

•	 Group 4: Urban commuter; and

30 Bernard F. Byrne. Revised Method for Estimating Design Hourly Volumes 

in Vermont. Transportation Research Record 1993, Transportation Research 

Board of the National Academies, Washington, D.C., 2007, pp. 23–29.

31 2007 Traffic Data Report for New York State, New York State Department 

of Transportation, available at https://www.nysdot.gov/divisions/

engineering/technical-services/highway-data-services/traffic-data.

vehicle classification scheme is depicted in 

table 2.29

Perhaps more appropriate for 

distinguishing the types of vehicles 

and vehicle combinations that frequent 

recreational areas are automated systems that 

capture the full vehicle profile. A variety of 

profiler systems are available commercially. 

The most advanced utilize Doppler radar, laser 

scanner, infrared light curtain and/or machine 

vision technologies to provide a two- or threedimensional image of a vehicle that can then 

be appropriately categorized in a pre-defined 

classification scheme.

Recreational Traffic Monitoring as 

Described in the Literature

When conducting a review of literature 

related to traffic monitoring in recreational 

areas, researchers originally sought 

information on applied research and statistical 

methods that address traffic monitoring 

system coverage, data content, and data 

quality issues related to the composition 

and variability of recreational traffic. Not 

surprisingly, researchers observed a 

disproportionate focus on traffic monitoring 

in urban rather than recreational areas. 

Much of the literature found to address 

recreational traffic monitoring considered: 

the use of recreational and/or seasonal factor 

groups, methods to support determination 

of recreational and/or seasonal factor groups, 

and the likely errors associated with factoring 

or annualizing short-term counts on roads 

with high-variability traffic.

Recreational and/or Seasonal Factor 

Groups

The observed published literature served 

to define and characterize select recreational 

and/or seasonal factor groups currently in use 

at the State level. Most recently (2007), Byrne 

described the use of six seasonal factor groups 

29 http://www.th.gov.bc.ca/trafficData/vcc, accessed December 18, 2008.

17
developed seasonal adjustment factors for 

vehicle classification counts for the State of 

Kentucky. Their research indicated that many 

States do not use seasonal adjustment factors 

for short-term vehicle classification counts. 

In this study, the authors used two years of 

vehicle classification data from Kentucky to 

develop class count factor groups. In their 

conclusions, the authors emphasized the 

importance of seasonal adjustment factors for 

accurate annual estimates.34

In 2000, Aunet described the Wisconsin 

Department of Transportation’s efforts to 

address traffic variability when developing 

seasonal factor groups. He emphasized that 

traffic data inherently has variability, both 

spatially and temporally, and recommended 

focusing traffic data analysis efforts on 

measuring or quantifying this variation and 

developing methods to account for it. He 

suggested a combination of approaches 

to develop seasonal factor groups and 

adjustment factors:

•	 Statistical measures such as coefficient 

of variation;

•	 Cluster analysis;

•	 Plots of monthly traffic factors; and

•	 Geographic mapping of continuous 

count sites.35

34 Nikiforos Stamatiadis and David L. Allen. Seasonal Factors Using Vehicle 

Classification Data. Transportation Research Record 1593, Transportation 

Research Board, National Academies, Washington, D.C., 1997, pp. 23–28.

35 Bruce Aunet. Wisconsin’s Approach to Variation in Traffic Data. Paper 

presented at NATMEC 2000 Conference, 14 pages.

•	 Group 5: Regional commuter.32

Methods to Support Determination of 

Recreational and/or Seasonal Factor 

Groups

Shifting focus to the methods to support 

determination of recreational and/or 

seasonal factor groups, Faghri et al. reported 

recommendations for an integrated traffic 

monitoring system for Delaware in 1996. 

The authors recommended the use of four 

seasonal factor groups based on the monthly 

coefficient of variation (CV). Statistical 

analysis of the within-group variability was 

used to determine the required number of 

permanent count stations for an 80 percent 

confidence level and 10 percent error. The 

statistical analysis indicated that very few 

permanent count stations were required for 

urban and rural factor groups; the variability 

for the remaining two recreational factor 

groups indicated large required sample sizes, 

more than were possible given available 

resources. Taking these resource limitations 

into account, the authors provided final 

recommendations for the seasonal factor 

groups and number of permanent count 

stations (table 3).33

One year later, Stamatiadis and Allen 

32 Pawan Lingras, Satish C. Sharma, Phil Osborne, and Iftekhar Kalyar. Traffic 

Volume Time-Series Analysis According to the Type of Road Use. ComputerAided Civil and Infrastructure Engineering, Volume 15, 2000, pp. 365–373.

33 Ardeshir Faghri, Martin Glaubitz, and Janaki Parameswaran. Development 

of Integrated Traffic Monitoring System for Delaware. Transportation 

Research Record 1536, Transportation Research Board, National Academies, 

Washington, D.C., 1996, pp. 40–44.

18

Table 3. Seasonal Factor Group Analysis in Delaware

Factor Group Monthly CV Existing Permanent 

Count Stations

Permanent Count Stations 

Based on Variability

Recommended 

Permanent Count 

Stations

Urban 7% 24 4 27

Rural 16% 16 13 19

Recreational 29% 6 35 12

Predominantly Recreational 20% 7 75 11
In 2003, Robichaud and Gordon 

reviewed traffic monitoring procedures 

for several Canadian provinces to provide 

recommendations to the British Columbia 

Ministry of Transportation. The authors 

reported on the results of studies in New 

Brunswick and Prince Edward Island that 

showed the use of regression was consistently 

more accurate for expanding short-term 

counts to annual estimates than the factoring 

method. However, the analysis of British 

Columbia data showed that factoring could 

be more accurate than regression if longerduration short-term counts are used (on the 

order of 7 days once per year).36

More recently (2004), Li et al. conducted 

a regression analysis to identify factors 

that most strongly affected seasonal traffic 

fluctuations in Florida. Currently the Florida 

DOT assigns short-term counts to a seasonal 

factor group based largely on spatial proximity 

to the permanent monitoring locations. The 

results of the analysis indicated that roadway 

functional class was not a significant factor, 

but the following were significant factors for 

seasonal traffic fluctuation:

•	 Density of hotels and motels for tourism;

•	 Number of retired people between the 

ages of 65 and 75 with high income; and

•	 Extent of retail employment.37

These land use variables could be obtained 

from the planning departments and/or 

agencies.

36 Karen Robichaud and Martin Gordon. Assessment of Data-Collection 

Techniques for Highway Agencies. Transportation Research Record 1855, 

Transportation Research Board of the National Academies, Washington, 

D.C., 2003, pp. 129–135.

37 Min-Tang Li, Fang Zhao, and Yifei Wu. Application of Regression Analysis 

for Identifying Factors That Affect Seasonal Traffic Fluctuations in Southeast 

Florida. Transportation Research Record 1870, Transportation Research 

Board of the National Academies, Washington, D.C., 2004, pp. 153–161.

Errors Associated with Factoring Shortterm Traffic Counts

A significant body of work related to the 

potential for errors when factoring shortterm traffic counts, spanning nearly a decade, 

was authored by Satish C. Sharma. In 1993, 

Sharma and Allipuram used data from 61 

permanent traffic monitoring locations in 

Alberta, Canada to analyze the frequency and 

duration of seasonal traffic counts. According 

to the authors, there is wide variation in how 

long and often seasonal counts are taken 

in the Canadian provinces. The researchers 

developed an algorithm that could be used to 

optimize the seasonal traffic count schedule 

based on three road types (i.e., commuter, 

average rural, recreational).38

In 1996, Sharma et al. analyzed the 

tradeoffs in precision of annual traffic counts 

when using seasonal traffic counts. In this 

study, researchers examined the collection 

of counts for two, three, and four noncontiguous months. Seasonal traffic counts, or 

several short-term counts spread throughout 

the year, are sometimes used as an alternative 

to a single short-term count when there are 

significant or unknown seasonal fluctuations. 

The study found the following errors at a 95% 

confidence level:

•	 8% error for two noncontiguous months;

•	 6% error for three noncontiguous 

months; and

•	 4% error for four noncontiguous 

months.39

During the same year, Sharma et al. 

analyzed data from several permanent count 

stations in Minnesota to determine the effects 

of various factors on the statistical precision 

38 Satish C. Sharma and Reddy. R. Allipuram. Duration and Frequency of 

Seasonal Traffic Counts. Journal of Transportation Engineering. Volume 119, 

No. 3, May/June 1993, pp. 344–359.

39 Satish C. Sharma, Peter Kilburn, and Yongquiang Wu. The precision of 

average annual daily traffic volume estimates from seasonal counts: Alberta 

example. Canadian Journal of Civil Engineering, Volume 23, 1996, pp. 302-

304.

19
(i.e., short-term counts taken during several 

seasons of the year) to provide solid prior 

information for assigning short-term counts to 

a seasonal factor group.43

Most recently (2007), Lewis and Albright 

described the errors associated with the 

application of default traffic count adjustment 

factors. In this case, city engineers were 

using default national factors in the Highway 

Capacity Manual to adjust average weekday 

traffic counts (AWDT) to AADT counts. The 

authors indicated that the default national 

factors were different than those provided by 

the State’s traffic monitoring agency. Further, 

the authors suggested improvements to 

the States’ seasonal factor groups which are 

currently based on area type and roadway 

functional class.44

Other Related Literature

Two additional publications are worthy 

of note. In 1980, Erickson et al. considered 

automatic time-interval counts for use in the 

planning and management of recreational 

areas. The authors collected hourly directional 

counts in the Daniel Boone National Forest 

using punch cards over a 4-month period. An 

interesting finding from this effort was that, 

at several locations, the entering traffic had 

much different traffic peaking patterns than 

exiting traffic. The authors also highlighted 

the variability throughout the data collection 

period that was presumably due to adverse 

weather conditions.45

43 Gary A. Davis. Accuracy of Estimates of Mean Daily Traffic: A Review. 

Transportation Research Record 1593, Transportation Research Board of the 

National Academies, Washington, D.C., 1997, pp. 12–16.

44 Martin Lewis and David Albright. Evaluating the Highway Capacity Manual’s 

Adjustment Factor for Annual Weekday to Annual Average Daily Traffic: 

Applying a Consistent Traffic Data Methodology. Transportation Research 

Record 1993, Transportation Research Board of the National Academies, 

Washington, D.C., 2007, pp. 117–123.

45 D.L. Erickson, C.J. Liu, and H.K. Cordell. Automatic, Time-Interval Traffic 

Counts for Recreation Area Management Planning. Paper presented at the 

National Outdoor Recreation Trends Symposium, Durham, NH, April 20-23, 

1980, 10 pages.

of AADT estimates. Consistent with other 

studies, researchers found that the AADT 

estimation errors are very sensitive to the 

assignment effectiveness (i.e., the correctness 

with which a sample site has been assigned 

to a factor group). Additionally, the authors 

indicated that traffic monitoring agencies 

should place more emphasis on accurately 

assigning short-term counts to factor groups, 

rather than on conducting longer duration 

counts (e.g., 72-hour counts). The study 

findings from Minnesota were confirmed 

with permanent count data from Alberta and 

Saskatchewan analyzed in the same year.40

In two related reports published in 2000 

and 2001, Sharma et al. reported results 

of various analysis techniques to estimate 

annual average traffic counts on low-volume 

roads. Researchers found that artificial 

neural networks were more favorable for 

AADT estimation than the traditional factor 

approach. In particular, one advantage of the 

neural network approach is that the definition 

and designation of seasonal factor groups is 

not necessary. Results also indicated a clear 

preference for two 48-hour short-term counts 

as compared to other frequencies (one or 

three) or durations (24- or 72-hour).41 42

In 1997, Davis reviewed the procedures 

used to estimate the accuracy of “annualized” 

short-term counts and found that many 

attempts failed to include the error from using 

incorrect seasonal or day-of-week adjustment 

factors. Based on his research, Davis 

recommended the use of seasonal counts 

40 Satish C. Sharma, Brij M. Gulati, and Samantha N. Rizak. Statewide Traffic 

Volume Studies and Precision of AADT Estimates. Journal of Transportation 

Engineering, Volume 122, No.6, November/December 1996, pp. 430-439.

41 Satish Sharma, Pawan Lingras, Fei Xu, and Peter Kilburn. Application 

of Neural Networks to Estimate AADT on Low-Volume Roads. Journal of 

Transportation Engineering, Volume 127, No. 5, September/October 2001, 

pp. 426-432.

42 Satish C. Sharma, Pawan Lingras, Guo X. Liu, and Fei Xu. Estimation of 

Annual Average Daily Traffic on Low-Volume Roads: Factor Approach Versus 

Neural Networks. Transportation Research Record 1719, Transportation 

Research Board of the National Academies, Washington, D.C., 2000, pp. 

103–111.

20
•	 23 CFR 970: National Park Service 

Management Systems;

•	 23 CFR 971: Forest Service Management 

Systems (Forest Highway Program 

Management Systems);

•	 23 CFR 972: Fish and Wildlife Service 

Management Systems;

•	 23 CFR 924: Highway Safety 

Improvement Program;

•	 16 USC 1a-7: National Park System 

Development Program;

•	 NPS Director’s Order #82: Public Use 

Reporting;

•	 Safe, Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy For 

Users (SAFETEA-LU), Public Law 109-59, 

August 10, 2005; and

•	 Transportation Equity Act for the 21st 

Century (TEA-21), Public Law 105-178, 

June 9, 1998.

Relevant sections of these Federal 

regulations are outlined and discussed in the 

following sections.

23 CFR 500: Management and Monitoring 

Systems

Subpart A of this section requires the 

development and implementation of 

pavement, bridge, safety, congestion, public 

transportation, and intermodal management 

systems in each State. Subpart A also requires 

the development of a traffic monitoring 

system for highways and public transportation 

facilities and equipment. A traffic monitoring 

system is defined as “... a systematic process 

for the collection, analysis, summary, and 

retention of highway and transit related 

person and vehicular traffic data” (§ 500.202, 

p. 142). Later sections indicate that these 

traffic monitoring systems should conform 

to standard industry practices as indicated in 

several national traffic monitoring guidelines.

Oddly, § 500.104 indicates that a State may 

elect not to implement any of these systems 

In 2005, Dunning documented the impacts 

of transit service on traffic conditions in 

national parks and gateway communities. 

Dunning described the difficulties of 

monitoring changes in visitation due to 

management actions, such as the introduction 

of transit services. She indicated that 

changing methods for monitoring visitation 

traffic can confound an accurate before-after 

comparison. Additionally, she noted that 

in parks where traffic counts and a vehicle 

occupancy multiplier are used to estimate 

visitation, the assumed vehicle occupancy 

may also change in the “after” evaluation 

period. She concluded that visitation counts 

could give general insights but could not fully 

describe the impacts of transit service.46

Interpretation of Data

Requirements for Federal Lands

Management Agencies

This section summarizes key Federal data 

requirements and presents an interpretation 

of these requirements with respect to traffic 

monitoring.

Summary of Federal Data 

Requirements

There are numerous Federal regulations 

that prescribe or imply data system 

requirements for Federal lands:

•	 23 USC 204: Federal Lands Highways 

Program;

•	 23 USC 303: Management Systems;

•	 23 USC 402: Highway Safety Programs;

•	 23 CFR 660: Special Programs (Direct 

Federal), Subpart A–Forest Highways;

•	 23 CFR 500: Management and 

Monitoring Systems;

46 Anne E. Dunning. Impacts of Transit in National Parks and Gateway 

Communities. Transportation Research Record 1931, Transportation 

Research Board of the National Academies, Washington, D.C., 2005, pp. 

129–136.

21
except for the congestion management 

system and the traffic monitoring system.

Subpart B of this section details the 

requirements for the development and 

implementation of a traffic monitoring system. 

In § 500.203, the requirements indicate that 

the “coverage of federally owned public roads 

shall be determined cooperatively by the 

State, FHWA, and the agencies that own the 

roads” (p. 143). The full text of this section 

is included as appendix A because of its 

importance.

23 CFR 970: National Park Service 

Management Systems

This section requires the development and 

implementation of safety, bridge, pavement, 

and congestion management systems for 

roads funded under the Federal Lands 

Highway Program (FLHP). The management 

systems are intended for use in developing 

transportation plans and making resource 

allocation decisions in the Park Road Program 

transportation improvement program 

(PRPTIP). The relevant sections of this 

regulation are included below:

•	 “The NPS may tailor all management 

systems to meet the NPS goals, 

policies, and needs using professional 

engineering and planning judgment 

to determine the required nature and 

extent of systems coverage consistent 

with the intent and requirements of this 

rule” (§ 970.204, p. 470).

•	 “Existing data sources may be used by 

the NPS to the maximum extent possible 

to meet the management system 

requirements” (§ 970.204, p. 470).

•	 “The minimum PMS [pavement 

management system] database shall 

include: ...Traffic information including 

volumes and vehicle classification (as 

appropriate)” (§ 970.208, p. 471).

•	 “The minimum BMS [bridge 

management system] database 

shall include: ... Traffic information 

including volumes and other pertinent 

information” (§ 970.210, p. 471).

•	 “The SMS [safety management system] 

shall be designed to fit the NPS goals, 

policies, criteria, and needs and shall 

contain the following components: (1) 

An ongoing program for the collection, 

maintenance and reporting of a data 

base that includes: ... Traffic information 

including volume, speed, and vehicle 

classification, as appropriate” (§ 970.212, 

p. 472).

•	 “A CMS [congestion management 

system] will: (i) Identify and document 

measures for congestion (e.g., level 

of service); (ii) Identify the causes of 

congestion” (§ 970.214, p. 473).

23 CFR 971: Forest Service Management 

Systems

This section establishes the policy for 

various management systems on Forest 

Highways, and indicates that the Forest 

Service, the Federal Highway Administration, 

and the respective state DOTs are responsible 

for implementing these management 

systems. The management systems include 

pavement, bridge, safety, and congestion. 

Traffic information is noted throughout the 

requirements as an essential element of these 

management systems.

23 CFR 972: Fish and Wildlife Service 

Management Systems

This section establishes the policy 

for various management systems on 

Refuge Roads, and indicates that the 

Fish and Wildlife Service and the Federal 

Highway Administration are responsible 

for implementing these management 

systems. The management systems include 

pavement, bridge, safety, and congestion. 

Traffic information is noted throughout the 

requirements as an essential element of these 

management systems.

22
23 CFR 924: Highway Safety Improvement 

Program

This section establishes the policy for 

the development and implementation of a 

comprehensive highway safety improvement 

program in each State. This section does not 

specifically mention whether federally-owned 

roads are to be considered in the highway 

safety improvement program.

“The HSIP [highway safety improvement 

program] planning process shall incorporate: 

(1) A process for collecting and maintaining 

a record of crash, roadway, traffic and 

vehicle data on all public roads including for 

railway-highway grade crossings inventory 

data that includes, but is not limited to, the 

characteristics of both highway and train 

traffic” (§ 924.9, p. 461).

23 CFR 660: Special Programs (Direct 

Federal), Subpart A–Forest Highways

This section establishes the Forest 

Highway Program within the Federal Lands 

Highway Program. It also establishes the same 

requirements for a pavement, bridge, and 

safety management system.

23 USC 204: Federal Lands Highways 

Program

Included here is an excerpt of 23 USC 204 

which outlines the responsibilities of the 

Federal Lands Highways Program:

“(a) ESTABLISHMENT.—

(1) IN GENERAL.—Recognizing the 

need for all Federal roads that are 

public roads to be treated under 

uniform policies similar to the policies 

that apply to Federal-aid highways, 

there is established a coordinated 

Federal lands highways program that 

shall apply to public lands highways, 

park roads and parkways, refuge roads, 

and Indian reservation roads and 

bridges.

(2) TRANSPORTATION PLANNING 

PROCEDURES.— In consultation with 

the Secretary of each appropriate 

Federal land management agency, 

the Secretary shall develop, by rule, 

transportation planning procedures 

that are consistent with the 

metropolitan and statewide planning 

processes required under sections 134 

and 135.

(3) APPROVAL OF TRANSPORTATION 

IMPROVEMENT PROGRAM.—The 

transportation improvement 

program developed as a part of the 

transportation planning process under 

this section shall be approved by the 

Secretary.

(4) INCLUSION IN OTHER PLANS.—All 

regionally significant Federal lands 

highways program projects—

(A) shall be developed in 

cooperation with States 

and metropolitan planning 

organizations; and

(B) shall be included in appropriate 

Federal lands highways program, 

State, and metropolitan plans 

and transportation improvement 

programs.

(5) INCLUSION IN STATE PROGRAMS.—

The approved Federal lands highways 

program transportation improvement 

program shall be included in 

appropriate State and metropolitan 

planning organization plans and 

programs without further action on 

the transportation improvement 

program.

(6) DEVELOPMENT OF SYSTEMS.—The 

Secretary and the Secretary of each 

appropriate Federal land management 

agency shall, to the extent 

appropriate, develop by rule safety, 

bridge, pavement, and congestion 

management systems for roads funded 

under the Federal lands highways 
program” (pp. 148-149).

Interpretation of Requirements

This section contains the contractor’s 

interpretation of these requirements as well as 

a discussion of how these requirements could 

be implemented. The Federal regulations 

listed in this section are written so general 

and vague that they are open to widely 

varying degrees of interpretation. Different 

stakeholders (e.g., different groups within 

FHWA, the federal lands management 

agencies [FLMAs], State DOTs, and regional 

transportation planning agencies) may 

interpret these regulations to mean different 

things, based mostly on their own role in 

the transportation development process. 

Therefore, as a general strategy to improve 

traffic monitoring on Federal lands, the 

contractor recommends against trying to 

discern extensive implementation details from 

these Federal regulations among the many 

stakeholders.

Instead, the contractor recommends that 

FHWA FLHD proceed with the recognition 

that:

•	 Federal regulations clearly call for 

management and monitoring systems;

•	 Implementation details for these 

management and monitoring systems 

cannot be clearly discerned from the 

Federal regulations; and

•	 Implementation details on these 

management and monitoring systems 

will have to be a negotiated consensus 

among stakeholders based on:

ɱ A common-sense approach to 

making informed decisions using 

data;

ɱ A recognition of severe resource 

constraints among the FLMAs;

ɱ A long-term goal of matching the 

current state of the practice (as 

evidenced in State DOTs) in traffic 

monitoring; and

ɱ Recognition that small, 

evolutionary improvements 

represent the most likely 

implementation path to this longterm goal.

23 CFR 500: Management and Monitoring 

Systems

23 CFR 500 outlines the requirements 

for management and monitoring systems 

within each State. It is implicit within this 

section that this requirement is for each 

State DOT, since the State DOT is responsible 

for the maintenance and management of 

major highways within the State. In Section 

500.203, the regulations indicate that “[c]

overage of federally owned public roads shall 

be determined cooperatively by the State, the 

FHWA, and the agencies that own the roads” 

(p. 143). Therefore, this is interpreted to mean 

that the coverage of federally owned public 

roads in a State traffic monitoring system is 

to be determined on a State-by-State basis 

and must be agreed upon by the State, FHWA, 

and the applicable FLMAs. In certain States, 

State DOTs may strongly desire the coverage 

of federally-owned public roads because these 

roads could have a significant impact on their 

statewide transportation system. In other 

States, State DOTs may not have the interest 

or resources to include federally-owned public 

roads because they do not feel this impacts 

their decisions or planning process. 

This section does not specify who must 

initiate the cooperation, only that the 

decision must be made cooperatively. My 

interpretation is that the State and the FLMA 

are the two primary stakeholders, with 

FHWA (the Federal Lands Division) playing 

an intermediary/overseer role. Further, it is 

my opinion that this intermediary/overseer 

role should be invoked when FHWA has 

supporting evidence that highway decisionmaking could be significantly improved if the 

State DOT included federally-owned public 

roads in their management and monitoring 

systems. For example, if a State DOT is making 

24
this example, one could benchmark the 

National Park Service management systems 

against State DOT and metropolitan planning 

organization (MPO) management system 

practices.

It is interesting to note that 23 CFR 970 

does not explicitly require a traffic monitoring 

system that supports these management 

systems. However, in the author’s 

interpretation, the requirement for a NPS 

traffic monitoring system is implicit since all 

of these management systems require traffic 

data as an input.

23 CFR 660: Special Programs (Direct 

Federal), Subpart A—Forest Highways

23 CFR 660 establishes the Forest 

Highway Program within the Federal Lands 

Highway Program. It also establishes the 

same requirements for a pavement, bridge, 

and safety management system. Similar to 

23 CFR 970, 971, and 972, this section, this 

section does not explicitly require a traffic 

monitoring system that supports these 

management systems. However, in the 

author’s interpretation, the requirement for 

a Forest Highways traffic monitoring system 

is implicit since all of these management 

systems require traffic data as an input.

SAFETEA-LU Public Law 109-59, August 

10, 2005

Section 204 of SAFETEA-LU, “Federal 

Lands Highways Program,” indicates that 

“the Secretary [of Transportation] and the 

Secretary of each appropriate Federal land 

management agency shall, to the extent 

appropriate, develop by rule safety, bridge, 

pavement, and congestion management 

systems for roads funded under the Federal 

lands highways program.” My interpretation 

of this language is that there is more 

discretion in the rigor of management systems 

implemented within the FLMAs that do not 

already have specific Federal regulations 

(like NPS). The key phrase is “to the extent 

funding decisions that would be dramatically 

different if federally-owned public roads were 

included in the DOT’s management system, 

then FHWA has an obligation to encourage 

cooperation between the State DOT and 

FLMAs. However, if the State DOT and Federal 

land management agencies do not believe 

that coverage of federally-owned public roads 

in the State management system will affect 

decision-making, and FHWA does not have 

supporting evidence to the contrary, then 

all agencies should agree that there is little 

benefit to forcing data sharing where it does 

not affect decisions.

23 CFR 970: National Park Service 

Management Systems

23 CFR 970 requires the development 

of several management systems for roads 

funded under the Federal Lands Highway 

Program (FLHP). It is clear from the 

regulations that traffic data (e.g., traffic 

volumes, vehicle classification, vehicle 

speeds) play a foundational role in several of 

the management systems. The regulations 

indicate that existing data sources may be 

used. Each of the management systems is 

defined differently, but the common element 

is that these management systems are “a 

systematic process” for making transportation 

decisions. 

Section 970.204 outlines general 

requirements for the management systems. 

As with many Federal regulations, these 

requirements can be interpreted to mean 

different things to different people. 

When regulations like these are open to 

interpretation, my recommendation is to 

look at common industry practices as a 

benchmark for what should be implemented. 

For example, how are other agencies 

implementing requirements for management 

systems? How integrated and accessible 

are these agencies’ databases? What level 

of resources has been provided for data 

collection, management, and analysis? In 

25
appropriate.” For example, a full-blown 

congestion management system with rigorous 

data collection may not be appropriate for 

Federal lands that do not routinely experience 

congestion. Ultimately, however, the details 

are left up to the FLMAs and FHWA.

Recreational Traffic Monitoring

as Observed in Practice

Building upon the information gathered 

during the review of published literature, 

additional information regarding traffic 

monitoring in recreation lands at Federal, 

State, and local levels was gathered through 

a targeted survey of State and local agencies 

and the conduct of a recreational traffic 

monitoring workshop.

Targeted Survey of State and Local 

Agencies

A targeted survey of ten State DOTs 

(Colorado, Florida, Idaho, Indiana, Missouri, 

Nevada, New Jersey, Utah, Wisconsin, and 

Wyoming) and three metropolitan planning 

organizations (Metropolitan Transportation 

Commission—San Francisco Bay Area, 

Metroplan Orlando, and Southwest Missouri 

Council of Governments) was conducted to 

identify current practices in collecting traffic 

data at and near recreational areas. Survey 

participants were selected based on the 

ability to provide geographic diversity, the 

likely presence of recreational travel, and the 

research team’s familiarity with State and local 

agency staff.

Survey participants were asked to 

respond to a series of questions related to: 

their agency’s conduct of continuous traffic 

counts; the number of ATRs and AVCs used for 

recreational and non-recreational traffic 

data collection; the nature and extent of any 

recreational, seasonal, or daily factor groups 

in use; and the nature and extent of roadway 

mileage under the agency’s jurisdiction.

State Departments of Transportation

Key responses from the ten participating 

State DOTs are summarized in table 4. Nearly 

all of the participating State DOTs maintain 

one or more seasonal factor group for 

26

Table 4. Recreational Factor Groups in Selected State Traffic Monitoring Programs

State DOT ATRs 

Statewide Recreational Factor Groups ATRs per Recreational Factor Group

Colorado 100

Recreational: Ski Traffic 14

Special Case: Non-Ski Traffic, Casino Traffic 25

Florida 274 Many Different Recreational Factor Groups NA

Idaho 209 Recreational Traffic

Indiana 103 No Recreational Factor Groups NA

Missouri 95 SFG004: All Recreational Traffic 14

Nevada 93 Recreational: Northern State Recreational–Tahoe 3

New Jersey 65 Recreational Traffic 10

Utah 97

Northern Recreational 11

Southern Recreational 11

Wisconsin 150

Urban Tourist Recreational 5

Rural Tourist Recreational 35

Wyoming 162 Recreational Traffic 6
No information was uncovered related to 

the distinct consideration of recreational 

traffic.

Metroplan Orlando is the MPO for Orange, 

Osceola, and Seminole Counties. The 

metropolitan area of Orlando has one of the 

fastest growing populations in the country, 

and, as a result, the number of new motor 

vehicles coming into the area is growing 

rapidly. Due to this growth, and the fact that 

the private automobile is the predominant 

mode of transportation, the area’s highway 

system is becoming increasingly congested.

One of the main methods for measuring 

the level of activity on an area’s highway 

system is the collection of traffic counts on 

major roadways. More than 300 traffic counts 

for various locations in Orange, Seminole, and 

Osceola Counties are obtained each year by 

the Metroplan Orlando staff from the Florida 

Department of Transportation (FDOT), the 

three counties, and from the City of Orlando. 

This information is published in a traffic count 

report that provides FDOT’s daily (24-hour) bidirectional traffic counts averaged annually on 

major roadways.

No information was uncovered related 

to the distinct consideration of recreational 

traffic.

The Southwest Missouri Council of 

Governments (SMCOG) is a voluntary 

association of local governments in the 

ten-county area of southwest Missouri in 

the Springfield area. These include Barry, 

Christian, Dade, Dallas, Greene, Lawrence, 

Polk, Stone, Taney, and Webster counties. 

Branson is located in Taney County. SMCOG 

is administered and operated through 

the Center for Resource Planning and 

Management at Missouri State University. 

SMCOG is the only regional council in Missouri 

affiliated with a university. Through this 

unique partnership, SMCOG has access to 

a wide variety of resources and technical 

assistance at the university.

recreational traffic monitoring. Several 

States that have distinct winter and summer 

recreational traffic maintain two factor groups. 

The Florida DOT reported using more than 

two recreational traffic factor groups while the 

Indiana DOT reported using no factor group 

for recreational traffic.

Metropolitan Planning Organizations

None of the planning agencies that were 

contacted indicated that they routinely 

monitor recreational traffic; instead, planning 

agencies rely upon their respective State 

DOTs to collect this data. Planning agencies 

may occasionally collect data in recreational 

areas to support planning uses, but this is 

done as part of a “special studies” process. 

Responses from the three metropolitan 

planning organizations are summarized 

below.

The Metropolitan Transportation 

Commission (MTC) is the transportation 

planning, coordinating, and financing agency 

for the nine-county San Francisco Bay Area. 

MTC staff analyze and report on State highway 

system traffic count data collected by the 

California State Department of Transportation. 

Technical summaries, available for years 1989 

through 2007, include information on:

•	 Route number, post mile, direction, and 

location description;

•	 Minimum, maximum, mean, and 

standard deviation of traffic volumes;

•	 Number of traffic counts at location;

•	 Volumes for a.m. peak period hours 

(0600-0700, 0700-0800, 0800-0900);

•	 Volumes for p.m. peak period hours 

(1500-1600, 1600-1700, 1700-1800); and

•	 24-hour daily directional volumes.

Persons interested in AADT counts or 

congestion and vehicle hours of delay 

estimates are directed to the California 

Department of Transportation databases.

27
No information was uncovered related to 

traffic counts conducted by SMCOG or the 

distinct consideration of recreational traffic.

Recreational Traffic Monitoring 

Workshop

To supplement information gathered 

through the literature review and targeted 

survey, a recreational traffic monitoring 

workshop was conducted. The purpose of 

the workshop was to bring together State 

and Federal Land agencies to discuss current 

and preferred practices for monitoring 

traffic in recreational areas and to identify 

opportunities for improving traffic monitoring 

to and within Federal lands. A desired 

outcome of the workshop was sufficient 

information exchange leading to the 

development of guiding principles of traffic 

monitoring for recreational areas.

The workshop’s agenda comprised 

presentations regarding traffic monitoring in 

recreational areas as performed by Federal, 

State, and Provincial agencies. Specific traffic 

monitoring practices that were described 

related to:

•	 The use of supporting traffic data 

collection technologies;

•	 The conduct of short-duration counts;

•	 The use and characteristics of 

recreational or seasonal factor groups;

•	 Vehicle classification; and

•	 Traffic data use, quality, reporting, and 

sharing.

In addition, participants collectively 

identified broader challenges related to traffic 

monitoring in recreational areas.

Traffic Data Collection Technologies

Use of combined permanent and portable 

counters for data collection was generally 

reported; but differences in the quantity of 

count sites used (i.e., the number of units 

available), the subsequent geographic 

coverage, and the types of technologies (i.e., 

simplistic to advanced) were observed.

Regarding the use of technology in 

recreational areas, a number of field-related 

challenges were identified:

•	 The geographic expanse and 

remoteness on recreational areas limit 

the accessibility for site visits and 

preventative or routine maintenance of 

technology or equipment;

•	 Availability of power and telephone line 

utilities;

•	 Wireless communications may be 

limited (e.g., cellular coverage);

•	 Traffic is operating in a low speed 

environment, challenging the accuracy 

of automated technologies; and

•	 Traffic on recreational roadways does 

not consistently lane track (travel 

ways may be narrow, no lanes may be 

defined, or drivers may be more casual 

at lower speeds), again challenging the 

accuracy of automated technologies.

Representatives from the Wyoming 

DOT reported using satellite as alternative 

to cellular to overcome challenges related 

to communications coverage. Despite its 

perceived high cost, the use of satellite 

communications in Wyoming suggests 

that this technology is or is becoming a 

viable option where cellular coverage is 

unavailable or unreliable and where line-ofsight technologies are too costly or visually 

intrusive in sensitive areas.

Participants from NPS noted success in 

using:

•	 A long-term product vendor;

•	 Simplistic technologies that require less 

maintenance; and

•	 “Ranger-proof” data collection systems 

that had fewer features but a very 

simple interface.

28
through Wyoming on the way to the Annual 

Sturgis Motorcycle Rally in South Dakota. 

Motorcycles traveling in tandem are often 

erroneously classified as passenger cars using 

automated methods. This innovative practice 

was developed to more accurately explain and 

characterize traffic patterns during this time of 

year.

Short-Duration Counts

Short-duration counts are commonly 

conducted:

•	 In 48-hour durations;

•	 On Tuesday through Thursday; and

•	 Once every 2 or 3 years.

However, there were a few special 

practices for handling recreational traffic 

that were noted that did not conform to this 

pattern. The Nevada DOT conducts 7-day 

counts on an annual basis to account for 

their unique recreational traffic patterns 

related to casinos, and for consideration 

of weekend trips. No other participants 

reported conducting short duration counts 

on Friday, Saturday, Sunday, or Monday when 

recreational traffic may be more predominant. 

Instead, traditional traffic monitoring 

scheduling practices, better suited to reflect 

commuter traffic, are more often followed. 

The Washington State DOT conducts 48-hour 

counts twice per year in recreational areas 

to better capture seasonal variability. In 

Manitoba, Canada, 48-hour counts are also 

conducted twice per year, but this is not 

limited to only recreational areas.

When short-duration counts are 

scheduled, a portion of participants reported 

scheduling site counts:

•	 In the same month each year (i.e., traffic 

counts are typically conducted during 

the same month each year at a given 

site);

•	 During different months per site 

annually by design to account for 

Vehicle Classification

Vehicle classification data is not routinely 

collected despite its noted value for decisionmaking. Cited limitations that currently 

prevent its collection include the following: 

•	 Existing/new technologies intended 

to automatically classify vehicles are 

challenged to accurately characterize 

recreational vehicle types;

•	 Length-based classification technologies 

are not routinely calibrated, which 

affects the underlying accuracy of the 

data and perceived performance of the 

technology;

•	 Recreational road geometry/structure 

may not adequately support vehicle 

classification equipment; 

•	 The additional equipment, installation, 

and data processing resources required 

may not be available; 

•	 A lack of consensus and differing 

priorities among State and Federal land 

agencies regarding the value of vehicle 

classification data, particularly when 

compared to the additional costs for 

data capture; and

•	 Short-duration classification counts are 

particularly difficult to translate to an 

annualized estimate of vehicle class.

Weigh-in-motion (WIM) systems have 

been used to reduce misclassification errors 

associated with recreational vehicle types. 

However, the previously reported challenges 

related to the potentially high cost of 

permanently installed WIM systems and/or the 

low reported accuracies of less costly portable 

WIM systems limit this application.

On a related note, the representative from 

the Wyoming DOT presented a novel “virtual 

lane” equipment installation for distinguishing 

tandem motorcycle traffic from passenger car 

traffic. Each year in late July and early August, 

Wyoming DOT observes a significant spike 

in motorcycle traffic as motorcyclists travel 

29
seasonal variability and/or to verify and 

refine factor groups (i.e., if counts taken 

in different months of the year do not 

produce similar AADTs, the assigned 

factor group is likely not appropriate); or 

•	 As scheduling or weather permits.

Estimates of AADT may be seasonally 

adjusted using high volume average daily 

traffic (ADT) months. In Washington State, 

significant variation between different weeks 

in the same month necessitated the creation 

and use of week-specific instead of monthly 

factors.

Recreational or Seasonal Factor Groups

Factor groups in use by participating 

agencies differed in both number and 

characteristics. Several of the participating 

agencies do not have defined “recreational” 

factor group(s). Factor groups are often 

assigned on the basis of:

•	 Roadway functional class;

•	 Traffic composition;

•	 Travel patterns (e.g., high weekend, 

seasonal volumes);

•	 Proximate/destination land use; 

•	 Climatic region (i.e., climate conditions 

that affect travel patterns);

•	 Relative importance for capturing 

recreational trips; and/or

•	 Resources/cost.

Factor group assignment is generally 

supported by, in order of preference:

•	 Data from proximate ATRs;

•	 Cluster analysis; and/or

•	 Knowledge of the area/professional 

judgment.

In Manitoba, Canada, traffic analysts 

use a factor group assignment algorithm 

that utilizes a series of questions that lend 

consistency to the decision-making process. 

While consistent questions are posed, this 

process does allow for some subjectivity in 

response.

For mixed-traffic facilities, consideration of 

traffic volumes on adverse weather days may 

distinguish recreational and “other” traffic. 

When the necessity of this information was 

questioned, participants indicated that there 

was value in determining the proportion 

of recreational traffic to support economic 

development considerations.

Traffic Data Use, Quality, Reporting, and 

Sharing

While traffic volumes are consistently 

captured, other traffic characteristics are less 

frequently captured despite their perceived 

value to enhance data quality and decisionmaking, such as:

•	 Classification;

•	 Weight;

•	 Speeds; 

•	 Occupancies; and

•	 Origin/destination.

As mentioned earlier, the capture of 

vehicle weight, in particular, is challenged 

by the potentially high cost of permanently 

installed WIM technology and/or the low 

reported accuracies of less costly portable 

WIM systems.

Among participating agencies, the 

motivation for collecting traffic data varied 

but generally included the following:

•	 To meet ongoing Federal reporting 

requirements;

•	 To support decision-making related to 

safety concerns;

•	 To obtain estimates of demand (i.e., 

visitation) for comparison with supply 

inventories, economic assessment, and/

or resource impact;

•	 To support decision-making related 

to system design, maintenance, and 

30
management; and/or

•	 To support determination of cost 

allocations under cost sharing 

arrangements.

In general, Federal agencies tasked with 

managing recreational areas are primarily 

concerned with visitation and resource 

protection while State DOTs are more 

interested in roadway use and infrastructure 

preservation.

Ongoing development of and reliance 

upon management systems—particularly 

pavement/bridge, safety, and congestion 

management systems—will increase the 

importance for traffic data. The level of data 

detail required to support planning-level 

decisions and operations/maintenance-level 

decision differs. In addition, the sensitivity 

of decision-making outcomes to the nature 

and characteristics of input data varies by 

application and the level of sophistication 

of supporting computer models (e.g., some 

models provide less precise, qualitative 

outcomes and hence, require less precision 

from the input data).

Private industry also relies upon traffic 

data to support development/business 

decisions. Two examples provided by the 

NPS related to the production of ColemanTM 

camp stoves based on observed increasing 

or decreasing recreational travel trends and 

the site selection for new IMAXTM theatres that 

requires a minimum passing traffic volume 

(market) for development.

Data quality was reported to be dependent 

upon available costs and resources. 

Participating agencies reported the use of 

automated data validity checks prior to its 

use and distribution. The participant from 

the Utah DOT also noted that GIS programs 

provide convenient graphical displays for 

visually detecting problems with the data.

Missing data was generally reported 

directly as such by participating Federal land 

management agencies. State DOTs reportedly 

utilize formal procedures (AASHTO methods) 

for extrapolating data across missing time 

periods.

Data quality was thought to be often taken 

for granted. In a special study conducted to 

determine the adequacy of planned coverage 

counts and factoring processes for NPS 

lands, estimated AADT errors of nearly 50 

percent were observed. For Forest lands, a 

pilot traffic data project, which attempted to 

factor sample counts using various surrogate 

information, concluded that reliability of 

traffic estimates cannot be determined 

without continuous traffic count (reference) 

data. This outcome not only suggests a high 

variability in recreational traffic but also raises 

questions as to the adequacy of “percent 

error” as a metric on highly variable and/or 

low volume roads. For lower volume roads, 

instead of characterizing data quality solely in 

terms of percent error, perhaps a combination 

of percent and absolute error could be 

reported. One participant reported that the 

Ohio DOT reports absolute error when traffic 

volumes are below a specified threshold and 

percent error when traffic volumes exceed 

the same threshold. For recreational roads 

with considerable and varying levels of traffic 

and/or peak surge periods, it may be most 

appropriate to set a realistic data value target 

that meets specific requirements of the users 

instead of attempting to comply with an 

unrealistic standard precision requirement 

common to other roads.

None of the workshop participants 

provided a clear indication of data quality 

requirements, either in general or for specific 

data applications. As such, few workshop 

participants reported having a clear and 

comprehensive understanding of their 

existing data quality (i.e., without defined data 

quality requirements, scarce resources will be 

directed to activities other than determining 

data quality). A systems engineering 

approach was recommended to define data 

31
existing FHWA Traffic Management System 

(TMS) traffic data repository were discussed 

and appear promising. The FHWA Office of 

Highway Policy Information also offered to 

make the HPMS traffic data currently reported 

by States available to participating agencies 

through the FHWA Federal Lands Highway 

Division to support related decision-making.

At the State level, participants from the 

Colorado DOT described their successes in 

developing a comprehensive integrated 

database using multiple traffic count data 

sources, noting a 35 percent increase in 

traffic count data available to the Colorado 

DOT valued at $87,000. The Colorado DOT 

also noted that the development of such 

a database requires the use of common 

terminology and a common attribute of 

interest (e.g., traffic volumes) among all 

contributors. A common traffic monitoring 

database such as this must also recognize 

and account for different quality levels when 

various data sources are being integrated/

combined.

Broader Traffic Monitoring Challenges

A number of broader, overarching 

challenges to traffic monitoring in recreational 

areas were identified. These include the 

following:

•	 Recreational travel may be perceived to 

be less important.

•	 The lack of perceived importance is 

exacerbated when the responsibilities 

for traffic monitoring/roadway 

management and commerce/tourism 

are maintained in distinct agencies.

•	 The traffic monitoring function was 

observed to vary in priority among 

participating agencies.

•	 Contrary to needs for roadway 

infrastructure/management, 

recreational traffic is sometimes more 

difficult and costly to monitor than 

less variable traffic, is often limited in 

needs, verify that the requirements are 

met, and validate that the requirements are 

appropriate.

An underlying challenge to this effort is 

that quality improvements may not be viewed 

as necessary by all participating agencies. 

While general consensus indicated that data 

shortcomings currently exist, improving traffic 

data extent or quality may not be a priority 

and/or may not be supported by existing 

resources.

Over time, the reporting of traffic data 

has migrated from published annual (or more 

frequent) reports to CDs, DVDs, and most 

recently, the Internet, providing timely online access to data. The level of reporting 

detail and frequency was observed to vary 

among participating agencies. A number of 

participating agencies reported including 

caveats regarding data quality to limit the 

potential for liability.

Data sharing is variable but generally 

limited among participating agencies. 

Some examples of successful data sharing 

partnerships include the following:

•	 NPS Public Use Statistics Office (focused 

on visitation) utilizes data from NPS 

Field Operation Technical Support 

Center (focused on roadways) to support 

decision-making. Unfortunately, 

traffic data collected by NPS Public Use 

Statistics Office is not routinely shared 

with the NPS Field Operation Technical 

Support Center.

•	 The Forest Service, Montana DOT, and a 

local county cooperatively participate in 

a pavement management system.

•	 Wyoming DOT utilizes data from NPS 

Public Use Statistics Office. 

•	 NPS and various State DOTs partner to 

install permanent traffic counters in 

park jurisdiction and share data across 

both agencies.

Opportunities to include FLMAs in the 

32
geographically, and represents a small 

proportion of vehicle-miles traveled.

•	 Monitoring of recreational traffic is more 

effective/reliable if the recreational 

route coincides with roadways that 

require monitoring under FHWA 

requirements or other dual-purpose 

applications.

•	 Participating agencies differ in their 

organizational approaches; the NPS and 

USDA-FS are generally centralized with 

agency-wide guidance while the USFWS 

and BLM are generally decentralized, 

allowing for more discretion at the 

regional and local level.

•	 Each participating agency noted 

challenges resulting from limited 

funding and resources that often 

resulted in a reduction in traffic 

monitoring program size.

•	 Staffing reductions and turnovers 

challenge the performance of 

collecting, processing, and maintaining 

functions, resulting in a loss of 

expertise, institutional knowledge, and 

momentum.

•	 Road instrumentation in recreational 

areas is often not directly identified as 

a road asset and as such, may not be 

replaced if damaged.

•	 The unique aesthetic, cultural, and 

environmental considerations in Federal 

and other protected lands serving 

recreational travel introduce additional 

implementation constraints.

•	 Existing national guidance for traffic 

monitoring practices lacks sufficient 

direction and detail for recreational 

travel—additional guidance may be 

available through the Forest Service’s 

National Visitor Use Monitor Program 

which standardizes sampling approach, 

data collected, and data definitions and 

the Fish and Wildlife Service’s Visitor 

Estimation Handbook that includes 

methods for traffic monitoring.

Next Steps

Two fundamental opportunities emerged 

as a result of this investigation related to 

resource/data sharing and the pivotal role 

of FHWA’s Office of Federal Lands Highway 

in improving/lending consistency to traffic 

monitoring in recreational lands.

In the near term, opportunities exist 

to share both resources and data among 

agencies responsible for recreational traffic 

monitoring. Interagency agreements 

may help to facilitate the joint installation 

and maintenance of traffic monitoring 

equipment (e.g., if a counter fails, the agency 

responsible for maintenance must respond 

in a timely manner to minimize the impact 

to all agencies reliant upon the data). Dual 

derivation methods were proposed to 

increase data quantity for both traffic and 

visitation applications. For example traffic 

monitoring data could be more widely used 

to estimate visitation based on assumed 

vehicle occupancies, and visitation data that is 

derived from sources other than traffic counts 

(e.g., surveys, turn-styles, etc.) can be used 

to estimate traffic volumes, again assuming 

average vehicle occupancy. Attaching a 

quality report to data would allow data users 

to determine whether the data is sufficient for 

their intended application; the challenge lies 

in accurately determining the data quality.

For longer-term efforts, FHWA’s Office of 

Federal Lands Highway should play a key role 

in facilitating and supporting improvements 

to recreational traffic monitoring among 

diverse partners. Agencies tasked with 

managing recreational areas differ in their 

underlying mission, priorities, and the nature 

and extent of their jurisdictional land areas 

and associated roadway network. A lack of 

understanding of and possible inconsistencies 

within each agency’s mission results in 

uncertainties regarding what data needs to 

be collected and reported. FHWA’s Office 

33
exists—Federal agencies must find ways 

to cooperate with other Federal agencies. 

FHWA’s Office of Federal Lands Highway can 

act as a catalyst for identifying and securing 

funds to support multi-agency efforts focused 

on improving/lending consistency to traffic 

monitoring in recreational areas.

Through this investigation, the unique 

characteristics of participating agencies and 

the lands under their jurisdiction became 

evident. Despite the motivation towards more 

consistent recreational traffic monitoring, 

any proposed changes to existing practices 

cannot be a “one size fits all” approach. It 

must remain flexible to address the respective 

differences in underlying mission, priorities, 

and jurisdictional nature and extent of the 

land areas among the agencies tasked with 

managing recreational areas.

of Federal Lands Highway can facilitate 

and encourage improved understanding 

and awareness within and among partner 

agencies, leading to improvements and 

greater consistency in recreational traffic 

monitoring. A four-stage approach was 

recommended to initiate improvements to 

existing traffic monitoring in recreational 

lands:

•	 Stage 1-Continuous Counts. Develop 

guidelines that support the selection 

of continuous count locations based on 

the number of access points, distance to 

nearest ATR, etc. and determine when 

the installation of a new continuous 

count station may be warranted (i.e., 

instead of “massaging” data from distant 

ATR).

•	 Stage 2-Coverage Counts. Develop 

guidelines that describe the location, 

scheduling, and duration of shortduration coverage counts.

•	 Stage 3-Data Analysis. Consider the 

development/use of predictive models 

that distribute traffic over the network 

to minimize required traffic data 

collection, as well as opportunities for 

data sharing/integration.

•	 Stage 4-Special Spot Studies. Develop 

guidelines that describe when isolated 

special studies are appropriate.

•	 Stage 5-Store Traffic Data. Store traffic 

data in an easily-accessible database 

that can easily be integrated with other 

management systems.

In addition to facilitating longer-term 

development efforts, FHWA’s Office of Federal 

Lands Highway should support these efforts 

financially. Under traditional scenarios, the 

Federal Government is able to allocate Federal 

funds to the States for performance of certain 

duties under specified guidelines, with access 

to Federal funds being the “carrot” through 

which States participate. For the management 

of recreational lands, no such hierarchy 

34
APPENDIX A: 23 CFR 500: 

Management and Monitoring

Systems, Subpart B—Traffic

Monitoring System

Subpart B—Traffic Monitoring System

§ 500.201 Purpose.

The purpose of this subpart is to set forth 

requirements for development, establishment, 

implementation, and continued operation of 

a traffic monitoring system for highways and 

public transportation facilities and equipment 

(TMS) in each State in accordance with the 

provisions of 23 U.S.C. 303 and subpart A of 

this part.

§ 500.202 TMS definitions.

Unless otherwise specified in this part, the 

definitions in 23 U.S.C. 101(a) and § 500.103 

are applicable to this subpart. As used in this 

part:

Highway traffic data means data used 

to develop estimates of the amount of 

person or vehicular travel, vehicle usage, 

or vehicle characteristics associated with 

a system of highways or with a particular 

location on a highway. These types of data 

support the estimation of the number of 

vehicles traversing a section of highway or 

system of highways during a prescribed time 

period (traffic volume), the portion of such 

vehicles that may be of a particular type 

(vehicle classification), the weights of such 

vehicles including the weight of each axle 

and associated distances between axles on 

a vehicle (vehicle weight), or the average 

number of persons being transported in a 

vehicle (vehicle occupancy).

Traffic monitoring system means a 

systematic process for the collection, analysis, 

summary, and retention of highway and 

transit related person and vehicular traffic 

data.

Transit traffic data means person and 

vehicular data for public transportation on 

public highways and streets and the number 

of vehicles and ridership for dedicated transit 

rights-of-way (e.g., rail and busways), at the 

maximum load points for the peak period 

in the peak direction and for the daily time 

period.

§ 500.203 TMS general requirements.

(a) Each State shall develop, establish, and 

implement, on a continuing basis, a TMS to be 

used for obtaining highway traffic data when:

(1) The data are supplied to the U.S. 

Department of Transportation (U.S. DOT);

(2) The data are used in support of 

transportation management systems;

(3) The data are used in support of 

studies or systems which are the responsibility 

of the U.S. DOT;

(4) The collection of the data is 

supported by the use of Federal funds 

provided from programs of the U.S. DOT;

(5) The data are used in the 

apportionment or allocation of Federal funds 

by the U.S. DOT;

(6) The data are used in the design or 

construction of an FHWA funded project; or

(7) The data are required as part of a 

federally mandated program of the U.S. DOT.

(b) The TMS for highway traffic data should 

be based on the concepts described in the 

American Association of State Highway and 

Transportation Officials (AASHTO) ‘‘AASHTO 

Guidelines for Traffic Data Programs’’4 and the 

FHWA “Traffic Monitoring Guide (TMG),”5 and 

shall be consistent with the FHWA ‘‘Highway 

4 AASHTO Guidelines for Traffic Data Programs, 1992, ISBN 1–56051–054–4, 

can be purchased from the American Association of State Highway and 

Transportation Officials, 444 N. Capitol Street, NW., Suite 249, Washington, 

D.C. 20001. Available for inspection as prescribed in 49 CFR part 7, appendix 

D.

5 Traffic Monitoring Guide, DOT/FHWA, Publication No. FHWA–PL–95–031, 

February 1995. Available for inspection and copying as prescribed in 49 CFR 

part 7, appendix D.

35
through (h) of this section.

(b) Precision of reported data. Traffic 

data supplied for the purposes identified in 

§ 500.203(a) of this subpart shall be to the 

statistical precision applicable at the time 

of the data’s collection as specified by the 

data users at various levels of government. A 

State’s TMS shall meet the statistical precisions 

established by FHWA for the HPMS.

(c) Continuous counter operations. 

Within each State, there shall be sufficient 

continuous counters of traffic volumes, vehicle 

classification, and vehicle weight to provide 

estimates of changes in highway travel 

patterns and to provide for the development 

of day-of-week, seasonal, axle correction, 

growth factors, or other comparable factors 

approved by the FHWA that support the 

development of traffic estimates to meet the 

statistical precision requirements of the data 

uses identified in § 500.203(a) of this subpart. 

As appropriate, sufficient continuous counts 

of vehicle classification and vehicle weight 

should be available to address traffic data 

program needs.

(d) Short term traffic monitoring. 

(1) Count data for traffic volumes 

collected in the field shall be adjusted to 

reflect annual average conditions. The 

estimation of annual average daily traffic 

will be through the appropriate application 

of only the following: Seasonal factors, 

day-of-week factors, and, when necessary, 

axle correction and growth factors or other 

comparable factors approved by the FHWA. 

Count data that have not been adjusted to 

represent annual average conditions will be 

noted as being unadjusted when they are 

reported. The duration and frequency of such 

monitoring shall comply to the data needs 

identified in § 500.203(a) of this subpart.

(2) Vehicle classification activities on 

the National Highway System (NHS), shall 

be sufficient to assure that, on a cycle of no 

greater than three years, every major system 

segment (i.e., segments between interchanges 

Performance Monitoring System Field 

Manual.’’6

(c) The TMS shall cover all public roads 

except those functionally classified as local or 

rural minor collector or those that are federally 

owned. Coverage of federally owned public 

roads shall be determined cooperatively by 

the State, the FHWA, and the agencies that 

own the roads.

(d) The State’s TMS shall apply to the 

activities of local governments and other 

public or private non-State government 

entities collecting highway traffic data within 

the State if the collected data are to be used 

for any of the purposes enumerated in § 

500.203(a) of this subpart.

(e) Procedures other than those referenced 

in this subpart may be used if the alternative 

procedures are documented by the State to 

furnish the precision levels as defined for the 

various purposes enumerated in § 500.203(a) 

of this subpart and are found acceptable by 

the FHWA.

(f ) Nothing in this subpart shall prohibit 

the collection of additional highway 

traffic data if such data are needed in the 

administration or management of a highway 

activity or are needed in the design of a 

highway project.

(g) Transit traffic data shall be collected in 

cooperation with MPOs and transit operators.

(h) The TMS for highways and public 

transportation facilities and equipment shall 

be fully operational and in use by October 1, 

1997.

§ 500.204 TMS components for highway 

traffic data.

(a) General. Each State’s TMS, including 

those using alternative procedures, shall 

address the components in paragraphs (b) 

6 Highway Performance Monitoring System (HPMS) Field Manual for the 

Continuing Analytical and Statistical Data Base, DOT/FHWA, August 30, 1993 

(FHWA Order M5600.1B). Available for inspection and copying as prescribed 

in 49 CFR part 7, appendix D.

36
or intersections of principal arterials of the 

NHS with other principal arterials of the NHS) 

will be monitored to provide information on 

the numbers of single-trailer combination 

trucks, multiple-trailer combination trucks, 

two-axle four-tire vehicles, buses and the 

total number of vehicles operating on an 

average day. If it is determined that two or 

more continuous major system segments have 

both similar traffic volumes and distributions 

of the vehicle types identified above, a single 

monitoring session will be sufficient to 

monitor these segments.

(e) Vehicle occupancy monitoring. As 

deemed appropriate to support the data 

uses identified in § 500.203(a) of this subpart, 

data will be collected on the average number 

of persons per automobile, light two-axle 

truck, and bus. The duration, geographic 

extent, and level of detail shall be consistent 

with the intended use of the data, as 

cooperatively agreed to by the organizations 

that will use the data and the organizations 

that will collect the data. Such vehicle 

occupancy data shall be reviewed at least 

every three years and updated as necessary. 

Acceptable data collection methods include 

roadside monitoring, traveler surveys, the 

use of administrative records (e.g., accident 

reports or reports developed in support 

of public transportation programs), or any 

other method mutually acceptable to the 

responsible organizations and the FHWA.

(f ) Field operations. 

(1) Each State’s TMS for highway traffic 

data shall include the testing of equipment 

used in the collection of the data. This testing 

shall be based on documented procedures 

developed by the State. This documentation 

will describe the test procedure as well as 

the frequency of testing. Standards of the 

American Society for Testing and Materials 

or guidance from the AASHTO may be used. 

Only equipment passing the test procedures 

will be used for the collection of data for the 

purposes identified in § 500.203(a) of this 

subpart. 

(2) Documentation of field operations 

shall include the number of counts, the period 

of monitoring, the cycle of monitoring, and 

the spatial and temporal distribution of count 

sites. Copies of the State’s documentation 

shall be provided to the FHWA Division 

Administrator when it is initially developed 

and after each revision.

(g) Source data retention. For estimates of 

traffic or travel, the value or values collected 

during a monitoring session, as well as 

information on the date(s) and hour(s) of 

monitoring, will remain available until the 

traffic or travel estimates based on the count 

session are updated. Data shall be available 

in formats that conform to those in the 

version of the TMG current at the time of data 

collection or as then amended by the FHWA.

(h) Office factoring procedures. 

(1) Factors to adjust data from short 

term monitoring sessions to estimates of 

average daily conditions shall be used to 

adjust for month, day of week, axle correction, 

and growth or other comparable factors 

approved by the FHWA. These factors will be 

reviewed annually and updated at least every 

three years. 

(2) The procedures used by a State to 

edit and adjust highway traffic data collected 

from short term counts at field locations 

to estimates of average traffic volume shall 

be documented. The documentation shall 

include the factors discussed in paragraph (d)

(1) of this section. The documentation shall 

remain available as long as the traffic or travel 

estimates discussed in paragraph (g) of this 

section remain current. Copies of the State’s 

documentation shall be provided to the FHWA 

Division Administrator when it is initially 

developed and after each revision.

37
Notes

38

Technical Report published by

Technology Deployment Program

Western Federal Lands Highway Division

Federal Highway Administration

610 East 5th St.

Vancouver, WA 98661

For more information or additional copies 

contact:

Amit Armstrong, Ph.D., P.E. 

Phone: 360.619.7668

Fax: 360.619.7846

Amit.Armstrong@dot.gov