The investigation involved a comprehensive search of transportation databases and Internet sources to ensure comprehensive coverage of reports and papers describing relevant aspects of TDM assessment. In addition, CUTR reached out to nearly 1,000 subscribers in its TRANSP-TDM listserv to identify evaluation and return on investment analyses. The review uncovered a paucity of predictive evaluation approaches to TDM program evaluation and cost effectiveness. Most of the evaluation experience in the U.S. is based on the assessment of individual pilot projects and programs that focus on single TDM measures (such as vanpooling or user subsidies) or on employer sites. Broader evaluations are conducted on a cross-sectional basis over a range of multi-objective
programs. represented by
The most relevant predictive evaluation the Environmental Protection Agency (EPA)
methods and models are COMMUTER model and by
New Zealand and business benefits
Australian experiences[4-6]. The calculators, which are mainly
remaining models are in the form designed to aid employers and
practitioners in setting up specific TDM programs.
In addition, the review of
international experiences dealt with a detailed analysis of manuals and guidelines to TDM program evaluation and effectiveness. These studies provide details and general direction towards a more comprehensive approach to TDM assessment in a fashion similar to that currently employed in the evaluation of transportation infrastructure investments. The bulk of this work has been compiled by the research conducted by the Victoria Transport Policy Institute, based in Canada[7-10].
Section II of the report reviews a set of case studies spanning diverse TDM strategies. The objective is to assess how programs are evaluated, what measures of impacts and assessment are employed, and how these measures vary according to the TDM strategy being assessed. The literature search uncovered a host of case studies. This section focuses on those that are most relevant to this study’s objectives. This section also includes a review of the Commute Trip Reduction Performance Grant Program of Washington State Department of Transportation. Although not related to a specific TDM program or implementation, this case study review was deemed as relevant because it offers an innovative approach to assessing the value of TDM by introducing the market- based concept where buyers and sellers compete to determine the price of a removed single occupancy vehicle (SOV) trip.
Section III provides the rationale for seeking an alternative method to evaluate TDM strategies on a more comprehensive basis. The analysis carried out in Section I and the methods currently in use and described in Section II provide the basis for looking to develop a standard approach to TDM evaluation that overcomes the constraints outlined
in this report. This practitioner experiences
section details a methodology that combines academic to produce a theoretical framework that truly captures what
and is at
the basis of TDM travel behavior: an approach that models consumers’ responsiveness to diverse transportation options by embracing the most relevant offs faced under income, modal price and availability constraints.
The development of the theoretical model leads to the design and implementation of a sketch planning tool, TRIMMS (Trip Reduction Impacts for Mobility Management Strategies) and is detailed in Section IV. The section provides a step by step introduction