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7. Integration of TDM at the Corridor Planning Level

ATDM Active Transportation and Demand Management
CMP Congestion Management Program
CTR Commute Trip Reduction
CUTR Center for Urban Transportation Research
DOT Department of Transportation
FHWA Federal Highway Administration
GHG Greenhouse Gas
HOT High Occupancy Toll
HOV High Occupancy Vehicle
IDM Integrated Demand Management
ITS Intelligent Transportation Systems
LOS Level of Service
MIS Major Investment Studies
MPO Metropolitan Planning Organization
NCHRP National Cooperative Highway Research Program
SMART Specific, Measurable, Achievable, Realistic, and Time-bound
SOV Single Occupancy Vehicle
TDM Travel Demand Management
TIP Transportation Improvement Program
TMA Transportation Management Area
TMC Transportation Management Center
TRIMMS Trip Reduction Impacts of Mobility Management Systems
TSM Transportation Systems Management
TSM&O Transportation Systems Management and Operations
VMT Ve hicle Miles Travelled
VTR Vehicle Trip Reduction

While TDM has historically been focused on mitigating traffic at localized trip generators (e.g., large employment sites, new developments, etc.), it is increasingly being applied to congested corridors, including interregional corridors that cross county and state boundaries. This is because TDM has focused on the commuter travel market, which, in turn, is associated with peak period congestion on key highway facilities. In fact, one of the nation's first ride-matching services was offered by a radio station attempting to find solutions to traffic congestion on Boston's Southeast Expressway and other key facilities in 1973. Today, TDM is part of an overall scheme to better and more efficiently manage the operations of congested highways. TDM in highway operations is needed because, on a day-to-day basis, the operators of our highway systems cannot add capacity to meet changing conditions, but they work to manage the daily demands placed on our highways. This can be accomplished by offering travelers more and better travel choices.

Managing how many vehicles are on a given facility at any one time, via demand management techniques, can influence the effective capacity of the roadway and maintain traffic flow. This is the premise of the now popular "rice experiment" promoted by Washington State DOT.122 The rice experiment showed that by modulating the rate at which vehicles entered the system (in the experiment, rice through a funnel), travel times can be increased or at least made more reliable.

At a smaller scale, this is the function of ramp metering. However, if travelers can shift their travel time, location, route or mode, fewer total vehicles may be using the facility during peak, congested periods.

From a planning standpoint, TDM needs to be integrated into the planning process to maximize the ability to reduce peak period demand. This is most relevant when considering major improvements to a corridor, so that the benefits of the improvements can be extended by lowering overall demand levels. This might involve strategies to price the facility, provide preferential treatment for HOVs, integrate traditional TDM programs for adjacent employment centers and other major traffic generators, improve facilities/operations of facilities parallel to the new corridor, or manage access to the corridor or land development adjacent to the corridor. But it is also important to explicitly consider TDM strategies, linked to a corridor, when planning for the ongoing operations of a facility with the goal of maximizing efficiency. This might be as simple as including all travel choices in the traveler information provided or linking regional ridesharing providers to the TMC.


Integrating Demand- and Supply-side Strategies in a given corridor can:

  • Influence travel before choices are made and make more efficient use of existing facilities.
  • Improve reliability and system performance. A small change in demand can have great benefits. (Improved traffic flow on a federal or state holiday is an example.)
  • Prolong the need for capacity expansion, lengthen the life of new investments, and/or make managed facilities more efficient and effective.
  • Provide a set of strategies that are relatively low cost and easy to implement.
  • Foster new public/private partnerships to manage system.
  • Mitigate some of the negative impacts of traffic, including environmental and energy-related.

7.1 What Plans Should TDM be Included in?

The integration of TDM into corridor planning efforts is quite broad and can involve organizations at the state, regional, and local level. Some interregional corridor planning activities can even cross state boundaries. Some of the corridor-level plans that might involve TDM integration are enumerated in Table 7.1.

Table 7.1: Corridor Planning
What We Track How to Integrate TDM/Role of TDM
Major Investment Studies
  • States and regions looking at significant improvements that might add capacity in a given corridor can integrate TDM into planning activities through efforts such as MIS.
  • Plans include a TDM or Transit/TDM scenario aimed at assessing the effectiveness of mode choice measures in meeting growing travel demands via trip reduction strategies.
New Smart Capacity Project Plans
  • Integrate demand management in a holistic manner, to create "smarter" capacity improvements, such as managed lanes.
Reconstruction Plans
  • Add enhanced travel options (such as vanpooling and special bus service) and incentives to use them (special discounts or financial rewards).
  • Expand the nature and number of travel options provided through enhanced travel information services.
  • Implement temporary demand management infrastructure, such as HOV lanes, during construction.
Congestion Management Process (CMP)
  • Address system deficiencies that might with relatively short-term, low cost solutions, including TDM.
  • Convene TDM/CMP Task Force to formulate TDM strategies that can address key bottlenecks on congested facilities.
Integrated Corridor Management Plans (ICM)
  • Inform traveler of approaching congestion and the availability of parallel transit service with parking availability to instigate in-route mode shift .
HOV/HOT System Plans
  • Plans, such as HOT corridor studies in Virginia, have integrated TDM and transit supportive measures into the plans in order to maximize the efficiency and person throughput of the enhanced facility.
Interregional Corridor Plans
  • Incorporate discussions on interregional travel which crosses state lines and requires special planning activities through special collaboration.
Corridor TDM Program Plans
  • Develop plan for relieving congestion in corridors to make travel easier for commuters.
  • Identify better travel choices that help to foster responsible economic growth.

There are two significant decisions related to integrating TDM into the corridor planning process - timing of the integration and scope or breadth of the TDM strategies considered.

In terms of timing, TDM strategies, and the general philosophy of balancing demand and supply solutions, should be considered at the start of the corridor planning process. Too often, TDM is considered almost an afterthought – a means to mitigate potential impacts of highway construction or as part of a list of supportive measures that are not truly integrated into the future operation of the facility.

Regarding scope, TDM strategies are often considered in a narrow or piecemeal fashion. The full set of TDM strategies, or travel choices, need to be included in corridor planning efforts. In some cases, the only "alternative" mode considered is transit and in other cases only traditional commuter-based TDM is considered. Time, location, and route choices should be considered in addition to mode choice. The Congestion Management Process is one framework that should help address this deficiency in the link between demand management and corridor solutions. As another example of this disconnect, the synergistic benefits of packaging TDM strategies are sometimes overlooked. For example, efforts to plan HOT lanes assess the impact of pricing on behavior change and facility operations, but often do not include provisions to support HOV services to achieve maximum throughput of the HOT facility.

Finally, involving all key stakeholders in the corridor planning process is important as well. These potential stakeholders are enumerated below, but critical participation is needed from those who will ultimately operate the facility and related services. This includes participation from day-to-day operators and service providers, such as the TMC, other traveler information providers, and service providers, such as transit operators, vanpool providers, and bicycle user groups.

7.2 What Is Your Capability with TDM at the Corridor Planning Level?

This desk reference will be utilizing the guidance based on different levels of existing experience with TDM and transportation planning. Table 7.2 provides examples of how planning agencies might integrate TDM into their corridor planning processes. This should assist users in determining the nature and location of key guidance within this section. Three levels of TDM integration are presented: ad hoc, defined, and optimized. As explained earlier in this document, these levels correspond to the Institutional Capability Maturity Model proposed by FHWA in its Guide for Improving Capability for Systems Operation and Management.123

Agencies with minimal experience in integrating TDM (ad hoc level) into their corridor plans and policies might only be viewing TDM as a mitigation strategy during reconstruction or seeking to use it to improve livability since there might be need to address congestion or air quality. At the next level (defined), an MPO might include TDM in most plans and policies as a means to increase travel choices and meet certain policy objectives, such as clean air or congestion reduction. In this case, TDM is likely one element of the overall plan. Finally, when TDM becomes optimized (Level 3), TDM may become a central focus of the entire plan if the MPO's policy board adopts an overall "philosophy" of managing demand and encouraging sustainable transport.

Table 7.2 provides specific examples of how an MPO might work to integrate demand management into regional transportation planning efforts at different levels of capability. This matrix is intended to assist the reader in determining where his or her organization fits in terms of the capability levels described above. Once the reader has determined his/her capability level and identified the critical step on which he/she is focused, specific actions to move from one level to the next are suggested in the next section.

Table 7.2: Integrating TDM into the Corridor Planning Process: An Overview
Planning Activities Level 1
Level 2
Level 3
Establishing Vision and Goals
  • TDM largely not perceived as a corridor solution
  • TDM goals are not well aligned with corridor goals
  • TDM goals are often seen an afterthought to corridor operational measures
  • TDM is viewed as a means to fulfill corridor level goals
  • Focused primarily on commute applications
  • Not explicitly connected to overall corridor performance
  • Goals embrace a broader definition of TDM and are fully-integrated with corridor operational goals
  • Emphasis on person throughput rather than vehicle throughput
  • Goals go beyond commute trip and include other application markets
  • TDM is seen as the key strategy to enhance corridor operations by reducing overall single occupant vehicle demand
Setting Objectives for TDM
  • TDM objectives focus primarily on marketing and educating the public on the benefits of transportation alternatives available in the corridor
  • Primary use of TDM objectives for short-term or time limited congestion mitigation activities
  • Not developed using a "SMART approach"
  • Objectives for TDM are based on long-term benefits to the corridor in terms of congestion
  • Some objectives are "SMART"
  • TDM objectives are stand-alone and not clearly linked to overall corridor performance
  • Objectives for TDM are based on long-term benefits to the corridor not only in terms of congestion but also for other priorities like mobility, access to destinations, economic development etc
  • All objectives are "SMART" and based on real-world information
  • TDM objectives are integrated into overall regional objectives for corridor performance
Definition of Performance Measures
  • TDM performance measures are primarily oriented around "outputs," including:
    • Awareness of modes
    • TDM services
    • Related benefits
  • TDM performance measures linked to public awareness and satisfaction
  • Performance measures begin to define TDM corridor-level "outcomes," including:
    • Mode split
    • Vehicle throughout
    • Rideshare rates
    • VMT
    • Air quality
  • Performance measures include fully developed TDM corridor-level "outcomes"
    • Reduction in congestion
    • Increase in alternative mode use
    • Increased person throughput
Assessment and Selection of Strategies and Programs to Support Objectives
  • No rigorous analysis/modeling of potential for TDM strategies to meet objectives
  • Typically, at this stage, TDM strategies are not considered and do not drive any alternate scenarios
  • Strategies and programs that do get included (mostly commuter-based):
    • Marketing and education of all modal options and benefits
    • Promotion of active transportation
    • Establishment of short term TDM programs
    • Establishment of TMAs
  • TDM is an integral part of many alternatives
  • Some off-model analysis/modeling of TDM
  • Strategies and programs that do get included may include:
    • Incentives for alternative modes and programs
    • Improvements to alternative modes
    • Partnerships with corridor businesses to provide employer services
  • Developed a rationalized means of assessment of TDM strategies on corridor performance
  • Strategies and programs that may get included:
    • Enhanced linkages with ITS and Traffic Operations
    • Parking management as a core component of demand management
    • Use of technology to support more fluid travel behavior (multi-modal comparative travel times, real-time parking information etc.)
Integration of Strategies into Plans and Funding Programs
  • Level of detail for TDM projects is significantly less than other projects
  • Tend to support traditional projects such as ride-sharing
  • Greater level of detail for TDM projects
  • TDM becomes integral part of corridor short-term solutions especially during reconstruction
  • TDM projects are as fleshed out as other projects
  • TDM continues to be part of long-term corridor management and operations
Monitoring and Evaluation of Progress Toward Objectives
  • Evaluation methods for TDM are different from operational strategies
  • Planners are monitoring awareness levels through surveys, focus groups, and workshops, among relevant stakeholders and the public
  • Formal methodology is in place to evaluate performance metrics
  • TDM and system performance are reported in a similar way (e.g., delay)
  • Performance measurement includes quantitative and qualitative methods
  • Evaluate comparative cost effectiveness of TDM to other capital and operating strategies

7.3 Actions to Move Corridor Planning Process from Level 1 to Level 2

Several specific actions can be suggested to move an agency's corridor planning process from Level 1 (ad hoc integration of demand management) to Level 2 (defined integration). For each action, a rationale is provided, an explanation of how to implement the action, and examples are given where available. Table 7.3 indicates the relative ease or difficulty of implementing each action.

Action 1 – Establish guidance on how to and benefits of integrating TDM into corridor planning at the very beginning
Rationale and ExplanationTDM needs to be integrated early into the corridor planning process in order to realize its full benefits. Too often, TDM is an afterthought or only included as a mitigation strategy during reconstruction projects.

Example – Most guidance related to integrating TDM into corridor planning comes from highway reconstruction efforts. NCHRP Synthesis 273, Project Development Methodologies for Reconstruction of Urban Freeways and Expressways, provides guidance on the role of TDM in mitigating the traffic impacts of reconstruction.124

Action 2 – Determine organizational and inter-organizational responsibilities for TDM in corridor planning
Rationale and ExplanationTDM is often spread across the organizational chart of responsible agencies, including long-range planning, corridor planning, regional ridesharing, congestion management, etc. Corridor planning can be isolated from TDM operations, even when undertaken with in the same organization. It is important that roles be clearly defined in advance of specific corridor planning efforts, such as MIS.

Example – When plans were developed to make operational improvements on the SR 520 corridor in the Puget Sound, TDM strategies were included from the beginning. Improvements include active traffic management, tolling, transit improvements, bicycle facilities, as well as vanpool and telecommute promotion among area employers and TDM agents. This was due, in part, to the fact that Washington State DOT has a very active TDM program and that TDM implementation agents, such as Seattle Metro and area TMAs, were involved from the beginning.

Action 3 – Developing SMART objectives for TDM
Rationale and Explanation – As with many transportation-related policies, objective setting often results in rather vague targets. In TDM, appropriate objectives might be to: offer more travel choices, reduce congestion, improve air quality, or assist commuters. Using a SMART objective setting process, TDM goals and objectives should be as precise as possible. This requires a more involved planning process to reach consensus, especially with regards to measurable targets, but it allows for a more robust planning and evaluation process that allows for better monitoring of objective attainment, strategy correction, and funding decision-making. The objectives from many corridor improvements are based on reducing travel times and increasing the efficiency of the facility to move vehicles in an unimpeded manner. However, by including TDM strategies in corridor plans, partially to mitigate the negative impacts of traffic, other objectives can be more fully addressed, including mobility, accessibility, economic development, and livability.

Table 7.3: List of Actions and Associated Level of Difficulty to Move Corridor Planning Process from Level 1 to Level 2
Integration Actions Policy Support Ease of Implementation Cost Time Requirement Overall
Establishing Vision and Goals
1Establish guidance on how to and benefits of integrating TDM into corridor planning at the very beginning Low Low Low Moderate Low
2Determine organizational and inter-organizational responsibilities for TDM in corridor planning Low Moderate Low Moderate Low
Setting Objectives for TDM
3Developing SMART objectives for TDM Low Low Low Low Low
Definition of Performance Measures
4Identify concrete performance measures for TDM Moderate Moderate Low Low Moderate
5Create means to translate TDM performance metrics into highway operations metrics Moderate Moderate Low Moderate Moderate
Assessment and Selection of Strategies and Programs to Support Objectives
6Draw upon existing tools to improve TDM modeling and analysis Moderate Moderate Moderate Moderate Moderate
7Integrate TDM into all scenarios for corridor improvements Moderate Low Low Low Low
8Seek means to include traditional ridesharing and incentives into corridor plans Moderate Low Low Low Low
Integration of Strategies into Plans and Funding Programs
9Include TDM elements in overall corridor project funding Moderate Moderate Low Low Moderate
Monitoring and Evaluation of Progress Toward Objectives
10Strengthen TDM performance evaluation and monitoring methods and means to report impacts Low Moderate Low Moderate Moderate

Example – The Washington State 2006 CTR Efficiency Act continued a state mandate that goes back to 1991. Cities and counties are able to set their own specific goals and targets for employee commute trip reduction, as long as they met the minimum state targets of a 10% reduction in single occupant commute trips by 2011 to address congestion and a 13% reduction in VMT to address GHG emissions. In the first three years of the program, 154 million VMT have been reduced at over 1,000 worksites representing over a half a million commuters. This is estimated to have reduced highway delay by 8% in the Central Puget Sound region and almost 70,000 metric tons of GHG statewide. While the state legislation behind the CTR Efficiency Act was a major policy effort, the need for and ability to set quantifiable targets was fairly straightforward. Another example involves the 1996 Boulder, Colorado, Transportation Management Plan, which identified 10 multimodal corridors and improvements for all modes of travel along them. As these corridors carried a majority of the trips in the community and linked important activity and commercial centers, maximizing their efficient trip-carrying ability required improving the relationship between the multimodal transportation system, land use, and design along these corridors.

Action 4 – Identify concrete performance measures for TDM
Rationale and ExplanationTDM has largely been used as a means to achieve conformity between transportation and air quality plans. As such, VMT reduction, which can easily be transformed into emission reduction, has been the primary performance measures. As TDM is used to address other policy objectives (congestion, livability, land use, economic development), new performance measures will need to be developed. While many of these will have a link to existing performance measures (mode shift, VMT, etc.), new performance measures will evolve.

Example – The State of Florida has developed and adopted multi-modal LOS standards for comparison among and between modes and projects. FDOT's Quality/Level of Service Handbook of 2009 provides a methodology and analysis tools to develop and use multimodal performance measures for car, transit, bike, and walk travel for a given urban corridor.125

Action 5 – Create means to translate TDM performance metrics into highway operations metrics
Rationale and Explanation – Many of the performance measures used to measure highway operations and congestion are not the same measures used to gauge TDM program performance. This can create a dilemma as each discipline (TDM and highway operations) seeks to understand the impact of TDM on a particular highway. Indicators linked to congestion in a given corridor include:

  • Travel time reliability.
  • Delay (including vehicle hours of travel).
  • LOS.

Performance indicators more appropriate to TDM include:

  • VTR.
  • VMT reduction.
  • Person throughput (HOV use).
  • Mode shift.
  • Transit service reliability.

The measure that likely comes closest to linking the two disciplines is person throughput. Knowing vehicle occupancy, including transit, can help planners understand the efficiency of the facility in moving travelers, not vehicles.

Example – The example shown in the action described below illustrates one means of translating TDM effectiveness, in terms of mode shift, to reductions in delay. In this case, the mode shift impacts documented for the CTR law among employers in downtown Seattle are graphically shown as changes in travel time on I-5.

Action 6 – Draw upon existing tools to improve TDM modeling and analysis
Rationale and ExplanationTDM analysis can often be very piecemeal and based on anecdotal evidence, rules of thumb, and sketch planning techniques, at best. However, several tools are available to assist with the evaluation of TDM strategies as part of the planning, alternatives analysis, and project selection process. Utilizing these tools largely requires the time and commitment to learn about the use of the tools in advance of the planning process.

Example – Chapter 9 includes a description of several tools aimed at allowing for the quantification of TDM impacts for various strategies and packages of strategies. This includes the FHWA TDM Evaluation Model and the TRIMMS available from the CUTR (see more discussion in Section 9 on Tools and Techniques for Evaluating TDM).

However, in terms of tools to evaluate the impact of TDM on corridor operations, CUTR has developed a means to graphically display the temporal and spatial distribution of trip reduction, due to TDM, on a given facility, using CORSIM.

Action 7 – Integrate TDM into all Scenarios for Corridor Improvements
Rationale and Explanation – Corridor analyses, such as those included in MIS, generally involve the assessment of several alternatives. While TDM tends to be included in one alternative (the "TDM" or "TSM/TDM" or "TDM/Transit" alternative), it is important to include TDM in all alternatives, especially if one is to subscribe to the synergistic effects of TDM when integrated into management and operational strategies or as a means to reduce or redistribute demand.

Example – A paper summarizing the use of TDM in MIS conducted by the North Central Texas Council of Governments concluded that TDM and TSM can effectively complement major transportation investments. These strategies promote the use of transit and alternative commute modes, as well as improves transportation system performance. Both TDM and TSM strategies are relatively low-cost, quick-implementation transportation programs and projects, which should not be overshadowed by proposed major transportation improvement(s). Since an MIS is an intensive and comprehensive study of transportation alternatives in a travel corridor, this study process provides an excellent opportunity to explore the implementation of these low-cost, quick-deployment transportation strategies.126

Action 8 – Seek means to include traditional ridesharing and incentives into corridor plans
Rationale and Explanation – One of the most common types of corridor improvements included in plans involves technology enhancements and ITS. As such, many TDM improvements included in these plans are linked to technology, such as dynamic ridesharing and other traveler information enhancements. However, traditional TDM, such as carpool and vanpool promotion, telecommuting, and financial incentives for using alternative modes, can also be an important ingredient in corridor solutions.

Example – During the 2002 reconstruction of U.S. 101 over the Cuesta Grade in San Luis Obispo County, CA, several demand management strategies were implemented to mitigate the impact of the roadwork on commuters. These measures included additional peak period bus service in the corridor, vanpool subsidies, and subsidized fuel cards for carpools. An evaluation of the impact of the demand management program concluded that the combination of measures eliminated 310 cars per day from the facility and about 8,000 miles of vehicle travel by raising overall vehicle occupancy from 1.206 to 1.266. The daily cost to take each car off the road was estimated at $7.50. These reductions contributed to an overall perception by the traveling public that the reconstruction project was less disruptive than originally feared.127

Action 9 – Include TDM elements in overall corridor project funding
Rationale and Explanation – In order to fully integrate TDM into corridor projects, adequate funding is required and should be addressed at the programming phase of planning. TDM is often an afterthought as a mitigation strategy without adequate resources being dedicated.

Example – The Colorado DOT included a comprehensive TDM program in its T-REX project to reconstruct I-25/I-225 and expand light rail. TDM funding was included in the public involvement budget, with specific funds for targeted traveler information, transit and vanpool incentives, and local coordination and outreach.

Action 10 – Strengthen TDM performance evaluation and monitoring methods and means to report impacts
Rationale and Explanation – Agencies that manage highway facilities collect considerable information on operations (volumes, travel times, etc.) but often do not evaluate the impact of TDM or alternative mode initiatives on those operations. New and better methods are required to translate highway operations and TDM effectiveness data into common metrics, such as reductions of VMT and delay.

Example – The evaluation of HOT lane projects often includes data that relate TDM to highway operations, such as vehicle occupancy, person throughput, alternative mode utilization, etc.

7.4 Actions to Move Corridor Planning Process from Level 2 to Level 3

Several specific actions can be suggested to move a corridor's planning process from Level 2 (defined integration of demand management) to Level 3 (optimized integration). Table 7.4 highlights the relative ease or difficulty for each action in moving from Level 2 to Level 3.

Action 1 – Determine range of travel markets that can be influenced by TDM
Rationale and Explanation – While the journey to work is likely the most influential travel purpose for most corridors, other travel markets can heavily influence the timing and location of traffic congestion and general traffic patterns. Large-scale generators, such as universities, airports, and event centers can influence traffic and may require a very different set of TDM strategies to address, given differences in operating hours, type of vehicles, and other characteristics.

Example – An FHWA guidance document entitled "Mitigating Traffic Congestion: The Role of Demand-side Strategies" enumerates many travel markets or applications for TDM, beyond traditional commuters.128 These venues include: schools and universities, recreation and tourism, special events, hospitals, and airports.

Table 7.4: List of Actions and Associated Level of Difficulty to Move Corridor Planning Process from Level 2 to Level 3
Integration Actions Policy Support Ease of Implementation Cost Time Requirement Overall
Establishing Vision and Goals
1Determine range of travel markets that can be influenced by TDMLowLowLowLowLow
2Determine whether TDM is an overall operating philosophy or mitigation strategyDifficultModerateModerateModerateModerate
3Train corridor project managers on TDMLowModerateLowModerateModerate
4Develop new partnerships in key corridorsLowModerateLowModerateModerate
Setting Objectives for TDM
5Set longer term objectives for TDMDifficultModerateModerateModerateDifficult
Definition of Performance Measures
6Develop corridor performance measures tied to person throughputModerateModerateLowModerateModerate
Assessment and Selection of Strategies and Programs to Support Objectives
7Develop procedures for considering demand management strategies prior to other, more capital intensive alternativesDifficultModerateLowModerateModerate
8Use TDM as a means to reduce need to expand road capacityDifficultDifficultLowModerateDifficult
9Develop new tools/approaches to incorporate all travel choices into the analysis processLowLowModerateModerateLow
10Include active demand management to integrate TDM into corridor solutionsModerateModerateModerateModerateModerate
Integration of Strategies into Plans and Funding Programs
11Include TDM as a key element to reducing overall, long-term demandDifficultDifficultLowModerateDifficult
Monitoring and Evaluation of Progress Toward Objectives
12Adopt or develop a standardized approach to reporting TDM performanceLowLowModerateModerateLow

Action 2 – Determine whether TDM is an overall operating philosophy or mitigation strategy
Rationale and Explanation – Agencies that adopt an overriding philosophy of TDM, rather than limit it as a mitigation strategy, are obviously more apt to integrate TDM strategies into all or most aspects of corridor planning and operations. Today, using real-time travel information, much of what TMCs do is manage demand by seeking to reduce or influence traffic at the most congested places and times. Once an agency adopts a philosophy of maximizing travel choices rather than minimizing auto travel times, TDM will become a much larger part of the way facilities are planned and managed.

ExampleFHWA is developing a new program entitled "Active Transportation and Demand Management" (ATDM), which is defined as the dynamic management, control, and influence of travel demand, traffic demand, and traffic flow of transportation facilities. Through the use of available tools and assets, traffic flow is managed and behavior influenced in real time to achieve operational objectives. ATDM is not a set of specific strategies; rather it is an over-arching philosophy for managing a facility through demand management and dynamic traffic management.

Action 3 – Train corridor project managers on TDM
Rationale and Explanation – In keeping with the objective to provide guidance on corridor TDM planning, it would be helpful to offer specific training to project managers that oversee corridor improvements on the fundamentals of TDM. Some planners cite a disconnect between TDM integration into corridor plans and the occasional lack of execution by project managers. In other words, if project managers do not fully understand the how and why of TDM implementation, even the best plans may not be realized.

Example – As noted in the state-level section of this document, Colorado DOT has developed tools to assist its planners and project managers, as well as local government and business, with TDM implementation, including The TDM Toolkit and the TDM Corridor Projects Study (see T-REX example above), which offer a complete list of strategies with TDM successes throughout Colorado and the U.S.129 However, sometimes the skill mix and training of project managers can work to restrict innovations, such as TDM. In fact, the Dutch Ministry of Transport has implemented a program to broaden the types of professionals who are assigned as major infrastructure project managers, retaining not only engineers, but economists, psychologists, social scientists, and anthropologists.

Action 4 – Develop new partnerships in key corridors
Rationale and Explanation – Travel corridors and highway facilities cross jurisdictional boundaries. Therefore, unique partnerships are needed to coordinate planning efforts among public and private interests. These partnerships will include the facility operator (often the state DOT), localities in the corridor, and planning agencies, as well as private interests, such as large employers or developers.

Example – Corridor coalitions have been used extensively for urban segments (U.S. Highway 169 Corridor Coalition) and interregional efforts (I-95 Corridor Coalition). These efforts bring all levels of government as well as the private sector to the table to plan and implement corridor improvements. The U.S. Highway 169 Corridor Coalition's mission is "Working together to enhance safety, reduce congestion and maximize economic development along the U.S. Highway 169 interregional corridor. " This includes freight, intercity, and commuter travel.

Action 5 – Set longer term objectives for TDM
Rationale and ExplanationTDM is often viewed as a short-term, stop gap measure to mitigate traffic during reconstruction, during major events, or until capacity enhancements can be made. However, if TDM is recognized as a means to reduce overall demand on a facility, longer term benefits can be realized. Thus, longer term objectives can be set for TDM, presumably for the entire life of a long-range plan or the life of a highway improvement or expansion.

Example – The UK Department for Transport developed a concept entitled "Integrated Demand Management" (IDM), originally designed to incorporate demand management into comprehensive corridor improvement plans and projects. The IDM concept is being applied to the reconstruction and widening of the M25 motorway around London. The Highways Agency describes IDM as "a holistic approach based upon making best use of the existing road-space and locking in the benefits of widening. " The philosophy behind IDM is to maximize the efficiency of the facility using ATM and to maximize the effective life of the improvement by reducing overall demand for its use.

Action 6 – Develop corridor performance measures tied to person throughput
Rationale and Explanation – Common practice still focuses corridor performance on vehicle movement measures (travel time, level of service) and not person movement. Corridor plans that seek to maximize travel choices should also include related performance measures, such as person throughput, vehicle occupancy (including transit), and overall accessibility. As one observer put it, "Higher person throughput can extend the effectiveness of the managed lane facility, thereby yielding a better return on investment and greater life-cycle performance of the system. This can only be achieved by positively affecting the balance of modes towards high-occupancy vehicles, particularly multi-person carpools, vanpools, and transit."130

Example – The HOT lane demonstration project on I-15 in Salt Lake City, UT, revealed that the Express Lane (open to carpools, vanpools, buses, motorcycles, and paying solo drivers) carried almost twice as many persons as the average general purposes lane during the PM peak period.131

Action 7 – Develop procedures for considering demand management strategies prior to other, more capital intensive alternatives
Rationale and Explanation – While federal planning guidance suggests that alternatives be considered before options that accommodate the SOV, state DOTs may wish to consider structuring this philosophy in the planning process by requiring that specific corridor planning efforts first prove why TDM cannot be a primary solution before considering options that add capacity, or even efficiency improvements. This would require a fundamental change in thinking that involves viewing TDM not as a short-term mitigation strategy, but as a long-term approach to reducing overall vehicle demand.

Example – One example of the full institutionalization of TDM into the planning process comes from Sweden. In 2002, the Swedish National Roads Administration adopted the "four stage principle" that requires planners and engineers to evaluate options in the following order:

  1. Measures that affect the demand for transport and the choice of mode.
  2. Measures that affect the more efficient use of the existing road network.
  3. Measures that make improvements to existing roads.
  4. Measures that make new investments in road capacity or major rebuilding.

Planners are, therefore, required to consider and rule out demand management before they can consider infrastructure improvements.132

Action 8 – Use TDM as a means to reduce need or delay to expand road capacity
Rationale and Explanation – If the broader benefits of TDM are accepted, namely reducing overall demand, the need for capacity expansion may not just be delayed, it might even be eliminated. Agencies that plan corridor improvements are not likely to accept the prospect of eliminating the need for one or more lanes of expansion unless evidence is available to show that TDM can reduce traffic. However, many cities are adopting the concept of "road diets" to reduce space for automobiles and increase that for bicycles and pedestrians.

Example – In a few cities, the TDM philosophy is fully embraced and the result is an overall reduction in car travel. In Lund, Sweden,133 and Arlington, Virginia134, reductions in VMT and vehicle volumes have been observed and documented in line with implementation of aggressive TDM programs. Arlington County, Virginia, has documented a reduction (12-16%) in traffic levels on several key arterials concurrent with considerable growth in public transport ridership (38%) and demand management success with area employers and institutions.

Action 9 – Develop new tools/approaches to incorporate all travel choices into the analysis process
Rationale and Explanation – Moving from the defined approach to a more optimized integration of TDM may require the development of tailored and specialized analytic tools to evaluate the effectiveness of TDM strategies in addressing key policy objectives. While many "off the shelf" tools now exist, in order to analyze the full set of TDM strategies and their impact across a myriad of objectives, specialized tools may be required. This might include new, tailored means of using the traditional four-step travel models or newer activity-based models. It might also involve other new tools, such as the micro-simulation tool, developed by CUTR and discussed earlier in this document, which uses employer TDM data and CORSIM.

Example – The traditional four-step travel demand modeling process can be used to evaluate TDM strategies that can be analyzed in terms of time and cost variables. However, many off-model tools have been developed to analyze congestion pricing strategies, bicycle and walk strategies, and other strategies that cannot be expressed in terms of time and cost indicators. As mentioned above, a good discussion of the means to incorporate TDM into regional travel demand models is provided by CUTR in a report entitled "Incorporating Assumptions for TDM Impacts in a Regional Travel Demand Model." This approach, which was developed for WSDOT, includes a specific TDM Assessment Procedure that uses the CUTR TRIMMS model and processes resulting TDM impacts through standard trip tables.135 In fact, the use of the TRIMMS model itself (discussed in Chapter 9) to perform cost/benefit analysis for TDM strategies could represent a significant movement toward mainstreaming TDM integration.

Action 10 – Include active demand management to integrate TDM into corridor solutions
Rationale and Explanation – As mentioned above, many of the solution strategies used in corridors rely on technology enhancements to move vehicles and data more efficiently. TDM, which is partially dependent on information to influence mode choice, has made many advances in this area over the past 10 years, with the advent of dynamic ridesharing initiatives and instant ridematching. The ability to integrate these TDM technology advancements into corridor plans will create better travel choices for a variety of modes.

Example – The ATDM program, being developed by FHWA, provides examples of four types of "active demand management" strategies to complete active traffic and active parking management. These active demand management strategies include: dynamic ridesharing, on-demand transit, dynamic pricing, and predictive traveler information.136

Action 11 – Include TDM as a key element to reducing overall, long-term demand
Rationale and Explanation – If TDM is accepted, as suggested in Actions 6 and 10, as a means to reduce overall vehicle demand, then the nature and size of corridor projects that flow from the planning process to programming could be rather different. Not only might capital projects be more modest in scope, but TDM programs may take a much larger part of the TIP, in order to fund the necessary efforts to promote, encourage, and maintain the use of sustainable travel options.

Example – As cited in the last section on metropolitan-level planning, the TSM&O plan in the Portland region devotes almost as much funding to TDM as to capital and efficiency improvements.

Action 12 – Adopt or develop a standardized approach to reporting TDM performance
Rationale and Explanation – In order to provide an effective feedback loop to the objective setting and strategy selection process, standardized TDM evaluation methodologies are required. This might involve developing a tailored approach for a given MPO or adopting a widely accepted methodology. Such methodology development or adoption should be vetted with TDM professionals and researchers to assure that it is understandable, rigorous, and usable.

Example – The MAX-SUMO monitoring and evaluation approach developed in Europe is easily adaptable to the U.S. experience for many TDM strategies. The methodology is described in Chapter 9.

7.5 Best Practice Examples: Corridor-Level TDM Integration

Two types of best practice examples are provided here – one focused on TDM and highway reconstruction in Colorado and another focused on planning for TDM and innovative corridor operations (HOT lanes) in Virginia.

TDM and Highway Reconstruction

TDM strategies are increasingly being integrated into highway reconstruction projects and therefore are an integral part of the planning process. One of the most comprehensive examples comes from the T-Rex project in the Denver area (Figure 7-1), the reconstruction of I-25/225 and extension of light rail (completed in 2007).137 During reconstruction, a temporary HOV lane was added to provide a travel time advantage to carpools, vanpools, and buses. TDM was built into the public outreach component of the project at an early stage. Some $3 million was dedicated to TDM to support the following:

  • Support and expansion of a TMA in the corridor.
  • Integration of TDM information into a project traveler information website.
  • Subsidized transit passes, available from TMA.
  • Subsidized vanpools for new vanpool groups in corridor.

Screen shot of web page showing real-time traffic congestion on a map of Denver.

Figure 7.1: Denver T-Rex I-25/225 Reconstruction
Source: Colorado DOT

Colorado DOT noted that the TDM activities reduced the risks associated with the reconstruction project and that follow-up surveys showed that travelers were very supportive of the TDM strategies. CDOT now plans to build TDM into all major reconstruction projects as a matter of procedure.

Many HOT lane projects have provided new or improved transit services as an alternative to paying the toll. However, the conversion of an HOV facility to HOT operations (priced use of excess capacity by drive alone travelers) should consider means to maintain or grow HOV use in order to maximize the operational efficiency and person throughput of the facility. Some plans have been largely based on the assumption that HOV will recognize the benefits of free travel in the HOT lane and continue to share rides. However, in some cases, the vehicle occupancy level is being raised to 3+ occupancy in order to create capacity to sell, creating the need to maintain existing HOV levels so as not to create new drive alone modes.

The Virginia Department of Rail and Public Transportation undertook a planning process to assess the most cost effective use of HOT lane revenue for transit and TDM in order to maintain and enhance HOV utilization as part of planning for the I-95/I-395 HOT lane project in northern Virginia, from Arlington to south of Fredericksburg.138 An I-95/I-395 Transit/TDM Technical Advisory Committee was created to study, analyze, and plan for the best mix of transit and TDM strategies to maintain and grow alternative modes use while introducing HOT lane operations. Two stated objectives for the planning effort were to:

  • Preserve transit and HOV ridership while implementing the HOT lanes by providing improvements that help maintain current market share for transit, carpools, and vanpools.
  • Utilize new HOT lane features to attract new transit and HOV riders by using a corridor management approach to improve existing service and serve new markets.

This is a departure from some plans, which largely assume HOV use to be constant and seek ways to capitalize on unused capacity, by seeking ways to grow HOV and transit use within the context of HOT lane operations. The plan outlines many new and enhanced transit services and many enhanced TDM measures, including: capital assistance for vanpools, enhanced Guaranteed Ride Home programs, financial incentives for vanpools and carpools, rideshare program operational support, TDM program marketing support, and telework program assistance.


CDOT, Colorado 2035 Statewide Transportation Plan, Travel Demand Management Technical Report, March 2008.

FHWA, "ATDM Program Brief: An Introduction to Active Transportation and Demand Management, 2011.

FHWA, Managing Travel Demand – Applying European Perspectives to U. S. Practice, FHWA-PL-06-015, May 2006.

L. Dantas, Incorporating TDM and TSM in Major Investment Studies – The Dallas- Ft. Worth Metropolitan Area Experience, presented at ACT International Conference, 2000.

NCHRP, Project Development Methodologies for Reconstruction of Urban Freeways and Expressways, Synthesis 273, 1999

SHRP II, Guide for Improving Capability for Systems Operation and Management, TRB, prepared by Parsons Brinkerhoff, Report S2-L06-RR-2, 2011.

University of Utah Transportation Lab, "I-15 Express Lanes Evaluation – Final Report" UTL-1106-89, November 26, 2007.

WSDOT, Incorporating Assumptions for TDM Impacts in a Regional Travel Demand Model, prepared by CUTR, report WA-RD-746.1, March 2010.

122 Washington State Department of Transportation Rice Experiment, available at
123 SHRP II, Guide for Improving Capability for Systems Operation and Management, TRB, prepared by Parsons Brinkerhoff, Report S2-L06-RR-2, 2011.
124 NCHRP, Project Development Methodologies for Reconstruction of Urban Freeways and Expressways, Synthesis 273, 1999.
126 L. Dantas, Incorporating TDM and TSM in Major Investment Studies – The Dallas- Ft. Worth Metropolitan Area Experience, presented at ACT International Conference, 2000.
128 FHWA "Mitigating Traffic Congestion: The Role of Demand-Side Strategies," available at
129 CDOT, Colorado 2035 Statewide Transportation Plan, Travel Demand Management Technical Report, March 2008.
131 University of Utah Transportation Lab, "I-15 Express Lanes Evaluation – Final Report" UTL-1106-89, November 26, 2007.
132 FHWA, Managing Travel Demand – Applying European Perspectives to U.S. Practice, FHWA-PL-06-015, May 2006.
133 FHWA, "Managing Travel Demand: Applying European Perspectives to U.S. Practice," Report No. FHWA-PL-06-015, May 2006.
134 Jennings, H., TDM: The Software that Supports the TOD Hardware, Arlington Commuter Services, October 2011.
135 WSDOT, Incorporating Assumptions for TDM Impacts in a Regional Travel Demand Model, prepared by CUTR, report WA-RD-746. 1, March 2010.
136 FHWA, "ATDM Program Brief: An Introduction to Active Transportation and Demand Management", 2011.
137 FHWA, Mitigating Traffic Congestion: The Role of Demand-side Strategies, FHWA-HOP-05-001, 2004
138 VDRPT, 1-95/I-395 Transit/TDM Study: Final Report, 2008, available at

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