A Sampling of Emissions Analysis Techniques for Transportation Control Measures

Introduction

Forecasting Approaches

Selecting a Method

Key Inputs and Outputs for Each Method

References

List of Acronyms

Overview - The "California standardized cost-effectiveness methodology" outlines a series of calculation steps for translating the number of participants in a TDM program into travel changes, emissions benefits, and cost-effectiveness. The California Air Resources Board (CARB) has applied the methodology to assess the impacts of projects funded by motor vehicle registration fees. The Los Angeles Metropolitan Transportation Authority (LAMTA) has applied to the methodology to assess the cost-effectiveness of TDM programs in the Los Angeles region. The methodology is generic and could be applied outside of California.

Strategies Addressed - Improved transit; carpooling and vanpooling promotion; employer-based TDM; telecommuting/work hours; pricing/subsidies.

Methodology - A series of worksheet steps is provided for converting the number of participants in a TDM program into travel changes, emissions benefits, and cost-effectiveness. The methodology is applied at the level at which the strategy is applied (worksite, employment center, etc.). While the methodology was designed for ex-post program evaluations in which user surveys have been conducted, it can also be used in conjunction with pre-implementation surveys or mode shift forecasts to provide forecasts of emissions reductions.

Data Requirements - Number of participants in TDM program by new and prior mode of use; average trip length; emission factors (per trip and per mile) by pollutant.

Outputs - Changes in vehicle-trips, VMT, and emissions.

Level of Effort - The method is easy to apply. Some effort may be required in obtaining valid estimates of program participation.

Advantages - The method provides a standard and easy-to-follow set of calculation steps that accounts for prior mode of travel and trip lengths in calculating overall emissions reductions. Worksheets are provided to account for emissions from changes in transit service as well as changes in personal vehicle travel.

Limitations - The method does not estimate travel behavior changes directly, and so it is not a forecasting method per se. Instead, it relies on surveys or other estimates of program participation as inputs. The user must also supply appropriate emission factors.

Source/Availability - Schreffler, Eric N.; Theresa Costa, and Carl B. Moyer. "Evaluating Travel and Air-Quality Cost-Effectiveness of Transportation Demand Management Projects." Transportation Research Record 1520. For information, contact Eric Schreffler (858-538-9430, enschreff@aol.com).

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