Why is there a need for an ATDM Chapter in the HCM?

The HCM provides a comprehensive 

set of methodologies for predicting the 

capacity and the performance of a given 

highway facility design. However, except 

for signal timing, these methodologies 

are not sensitive to advanced traffi c 

operations and demand management 

techniques. Moreover, real world daily 

variations in weather and incident 

conditions and travel demand typically 

do not enter into HCM computations. As 

a result, transportation engineers cannot 

use resource effi cient HCM methods 

to assess the benefi ts of advanced 

management techniques that reduce 

the adverse impacts of these factors on 

highway capacity and performance. 

The 2010 edition of the HCM contains 

Chapter 35 dedicated to Active Traffi c 

Management (ATM) strategies. 

However, this chapter is mostly 

introductory in nature, defi ning ATM, 

describing typical ATM strategies, and 

citing some research on ATM strategies. 

This FHWA project is intended to 

develop procedures for predicting how 

ATDM strategies can affect facility 

demand, and improve travel time 

reliability and facility performance. The 

research will provide content to support 

a new permanent chapter on ATDM 

integrated into subsequent editions of 

the HCM. 

Project Purpose

The Federal Highway Administration 

(FHWA) Offi ce of Operations is sponsoring 

a research project to develop new and/or 

updated methodologies, data sets, and 

content for the Highway Capacity Manual 

(HCM) that will better refl ect the demand 

and traffi c fl ow behavior that results from 

the application of active transportation 

and demand management strategies. 

Although the developed methodology 

is currently limited in its ability to model 

dynamic operations, the method allows for 

the analysis of operational strategies under 

varying demand and capacity conditions, 

which serves as an important foundation 

for analyzing Active Transportation 

and Demand Management. FHWA will 

continue to support research to further 

refi ne these base methodologies. 

Active Transportation 

and Demand Management

U.S. Department of Transportation

Federal Highway Administration

ATDM Analysis Brief: Highway Capacity Manual (HCM)-ATDM Project Overview

Active Demand Management Active Traffi c Management Active Parking Management

Dynamic Ridesharing Dynamic Lane Use Control Dynamically Priced Parking

On-Demand Transit Dynamic Speed Limits Dynamic Parking Reservation

Dynamic Pricing Queue Warning Dynamic Way-Finding

Predictive Traveler Information Adaptive Ramp Metering Dynamic Parking Capacity

What is ATDM? 

ATDM is the dynamic management, control, 

and infl uence of travel demand, traffi c 

demand, and traffi c fl ow of transportation 

facilities. Through the use of available 

tools and assets, traffi c fl ow is managed 

and traveler behavior is infl uenced 

in real-time to achieve operational 

objectives, such as preventing or delaying 

breakdown conditions, improving safety, 

reducing emissions, or maximizing 

system effi ciency. 

Under an ATDM approach the transportation system is continuously monitored. 

Using archived data and/or predictive methods, actions are performed in real-time to 

achieve or maintain system performance. 

Active management of transportation and demand can include multiple approaches 

spanning demand management, traffi c management, parking management, 

and effi cient utilization of other transportation modes and assets. Some example

approaches include:

Source: Minnesota Department of 

Transportation

Source: FHWA, Ramp Management and 

Control, A Primer

Source: Minnesota Department 

of Transportation

Source: Cambridge Systematics, Inc.
The methodologies developed in this research should be 

viewed as an initial, foundational set of methodologies 

primarily focused on traffic management applications. The 

methodologies provide practitioners with an approach to 

represent the varied demand and capacity conditions that 

facilities may be expected to operate under and suggest 

a realistic set of transportation management actions to 

respond to those conditions, thereby representing in 

a macroscopic sense, the dynamic aspects of ATDM. 

Although the methods are intended to support ATDM 

analysis and provide content for Chapter 35 (Active 

Traffic Management) of the HCM, several aspects of the 

methodology can be applied to analyzing non-operations 

or non-ATDM type alternatives. 

Overview of the HCM-ATDM Analysis Framework 

The HCM-ATDM analysis framework uses traditional 

Highway Capacity Manual input data, the operational analysis 

methodologies contained in the HCM, and data on incident 

and weather frequencies to predict the impacts of various 

levels of ATDM strategies on whole-year facility performance, 

specifi cally: mean travel time, travel time reliability, and 

facility demand.

The methodological framework is designed to assist the 

analyst in answering the following questions:

1. How much can I improve facility performance by 

implementing aggressive operations strategies? 

2. How much additional vehicle and person throughput can 

I achieve for a given facility through the application of 

aggressive operations strategies?

3. Which combination of ATDM strategies and at what levels 

produce a target quality of performance for a facility?

The work fl ow of the analysis framework proceeds as follows. 

First, the analyst inputs the demand and facility data typically 

required for a conventional HCM analysis. The conventional 

HCM data is supplemented with local historic data on incidents 

and weather. Work zones may be input as well. Then the 

following analysis steps are performed.

1. The weather, work zone and incident data are used to 

generate a set of scenarios representative of the range 

of conditions that may be present on the facility over the 

course of a year.

2. The effects of weather, work zones and incidents on 

capacity and speed are computed for each scenario. 

3. The adjustments are applied using standard HCM 

operational analysis methodologies to compute 

performance for each scenario.

ATDM Analysis Brief: Highway Capacity Manual (HCM)-ATDM Project Overview

HCM-ATDM Analysis Framework

Source: Cambridge Systematics, Inc.

4. The ATDM response generator is used by the analyst to 

identify the VSL, managed lanes, tolls, travel information, 

and other measures that would be activated in response to 

each scenario.

5. The effect of ATDM on demand is computed and fed back 

to the capacity and speed adjustment module

6. New capacity and speed adjustments are computed 

based on the selected ATDM response (repeat of Step 2)

7. Standard HCM methods are then applied to compute the 

performance with ATDM in effect (repeat of Step 3).

The core of the method is the development of “scenarios”: 

which are combinations of demand, weather, and incident 

characteristics that refl ect the actual conditions that travelers 

experience over time. Each scenario is input to the HCM 

analysis module to produce performance statistics for that 

scenario. All of the scenario results are then combined to 

produce a composite performance picture, including reliability.
ATDM Response for Work Zone Management

Source: Cambridge Systematics, Inc.

ATDM Analysis Brief: Highway Capacity Manual (HCM)-ATDM Project Overview

Example Demand/Capacity Scenarios Used in the Method

Scenario Capacity 

Reduction

5th

Percentile

Demand

20th

Percentile

Demand

50th

Percentile 

Demand

80th

Percentile 

Demand

95th

Percentile 

Demand

No incidents, 

Good Weather 0.00% XXXXX

Single Lane Closure,

Good Weather 35.00% XXXXX

Dual+ Lane Closure,

Good Weather 60.00% XXXXX

No Incidents,

Bad Weather 4.90% XXXXX

Single Lane Closure,

Bad Weather 38.19% XXXXX

Dual+ Lane Closure,

Bad Weather 61.96% XXXXX

The output of this process is: “Before 

ATDM performance”, “After ATDM 

performance”, and if demand response 

is to be taken into account, “Long Term/

After ATDM performance”. 

The impact of ATDM strategies is 

analyzed by changing the procedure’s 

inputs and internal relationships. For 

this reason, a set of linkages between 

ATDM strategies and their effect on 

the how the procedure operates is 

being prepared. For example, work 

zone management strategies will 

affect such things as duration of lane 

closures and reducing demand due to 

traveler information.

It is expected that the research and 

methodologies developed for this 

project will provide a foundation for 

not only estimating and analyzing the 

performance of ATDM strategies, but 

for improving the application of Highway 

Capacity Manual methods in general. 

Among enhancements to the state of 

the practice that could follow from the 

groundbreaking work in this HCM / 

ATDM project include:

• Considering non-ideal (i.e., 

incident) conditions and variable 

traffi c demand when evaluating 

system performance,

• Developing procedures and guidelines for scenario (incident/ demand 

combination) generation and 

analysis,

• Calibrating HCM predicted performance against fi eld conditions,

• Estimating reliability impacts; such 

as the 80th percentile travel times,

• Estimating induced travel due to 

facility improvements.

Even with these enhanced analysis 

capabilities, it should be noted, that some 

limitations inherent in HCM analyses will 

still exist. The analysis remains facility 

based and thus system level impacts are 

not refl ected. Highly dynamic responses 

below the 15 minute threshold of the 

HCM must be modeled approximately. 

In addition, demand effects due to off 

facility strategies (such as through regional 

ridesharing programs) would need to be 

computed externally and real time dynamic 

parameters would not be emulated; i.e., 

the analyst needs to provide the control 

for a given analysis time slice. Finally, 

due to project resource constraints, HCM 

calibration and validation will be performed 

on a limited set of ATDM strategies.
The U.S. Department of 

Transportation (U.S. DOT) is 

advancing the development of 

guidance, planning, case studies, 

and research in the application and 

design of active transportation and 

demand management approaches. 

In addition, the ATDM program will 

provide lessons learned, standards, 

and best practices on key underlying 

ATDM planning, evaluation, 

analysis techniques and design 

elements that serve as a foundation 

for ATDM implementation. 

For more information on this project 

or the FHWA ATDM program 

efforts, please contact:

Jim Hunt

Jim.Hunt@dot.gov

Bob Sheehan

Robert.Sheehan@dot.gov

James Colyar

James.Colyar@dot.gov

Greg Jones

GregM.Jones@dot.gov

FHWA-HOP-12-047

August 2012

FHWA ATDM Program

ATDM Analysis Brief: Highway Capacity Manual (HCM)-ATDM Project Overview

Project Status 

An initial draft guidebook laying out 

the framework has been developed. A 

preliminary research analysis tool was 

developed and an initial set of workshops 

were held to demonstrate methodology/

operational strategies and to solicit 

suggestions and feedback from experts 

in the fi eld for further improvements. 

Analysis methodologies for work zone 

and incident management are being 

added and additional workshops that 

will showcase an improved research 

analysis tool are available from FHWA. 

In addition, SHRP 2 Research 

Project L08, Incorporation of Travel Time 

Reliability into the Highway Capacity 

Manual, is extending the concepts 

developed by this project to provide a 

more comprehensive model for reliability 

prediction and evaluating reliability 

improvement strategies.

German junction control schematic

Source: F. Bolte. “Transport Policy Objectives: 

Traffi c Management as a Suitable Tool, “Federal 

Highway Research Institute (BASt), BergischGladbach, Germany, Presentation to Planning 

for Congestion Management Scan Team, 

June 2006.

ATDM Project 

Informational Briefs

This informational brief is one of 

the ATDM briefs in the Analysis 

category of the FHWA ATDM Brief 

Series. ATDM briefs are or will be 

available in the categories of: 

• ATDM Program: Yellow

• ATDM Planning: Purple

• ATDM Analysis: Orange

• ATDM Design: Green

• ATDM Operations: Red

In addition to this overview brief of the 

ATDM/HCM Analysis method, FHWA 

is releasing additional project briefs to 

provide high-level descriptions of the 

various components of the ATDM/HCM 

methodology and its application.

Source: Cambridge Systematics, Inc.

An example application of the procedure demonstrated the positive effect on average speeds produced 

by implementing ramp metering. The results highlight one of the hallmarks of the method — instead 

of using a single demand level, several levels are modeled. The levels of demand are indicated by the 

percentiles taken from the demand distribution, shown on the vertical axis. This realistically represents 

conditions encountered by travelers — some days have higher traffi c volumes than others.

Effects of Ramp Metering on Whole Year Facility Speed 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 

49 51 53 55 57

After

Before

Demand Level (Percentile)

Average Whole Year Speed (MPH)