The Metropolitan Transportation Planning ... - Saginaw County

The Metropolitan Transportation Planning Process: Key Issues
TRANSPORTATION DEMAND MANAGEMENT (TDM)
What is TDM?
In its broadest sense, TDM is any action or set of actions designed to influence the
intensity, timing, and distribution of transportation demand, in order to reduce
traffic congestion or enhance mobility.
Such actions can include offering commuters alternative transportation modes
and/or services, providing incentives to travel on these modes or at non-congested
hours, providing opportunities to link or "chain" trips together, and/or incorporating
growth management or traffic impact policies into local development decisions.
What is the role of the MPO in encouraging the use of TDM actions?
Transportation demand management strategies are part of the toolbox of actions
available to transportation planners for solving transportation problems. As such,
MPOs should make sure that TDM actions are considered in the planning process.
In areas where congestion management systems are required (populations greater
than 200,000), TDM actions are among the strategies that can reduce congestion
or enhance mobility.
What is the likely impact of TDM actions on transportation system
performance?
Available evidence suggests that well-conceived and aggressively promoted
demand reduction programs can decrease peak period traffic by as much as 10
to 15 percent. In fact, significantly higher demand reduction levels have been
achieved at several employment sites.
Demand reduction efforts, however, unless undertaken on a truly massive scale,
can have only a local impact. They can relieve spot congestion -- for example, at
entrances and exits to large employment centers -- but they cannot appreciably
reduce traffic on freeways and major arterials.
The only exception to this seems to be areawide road pricing practices, such as
tolls and "hot lanes," that (at least as modeled) appear to have significant influence
on travel demand.
Studies have shown that employer support for ride sharing, use of financial
incentives to shift travel to alternative modes, restricting the number and use of
parking spaces, and charging higher prices for parking are important supporting
strategies for changing traveler behavior.
Additional sources of information:
A Toolbox for Alleviating Traffic Congestion and Enhancing Mobility. Institute of
Transportation Engineers: Washington, D.C., 1997.