Emissions Analysis Techniques for TCMs
Overview - The Metropolitan Washington Council of Governments (MWCOG) developed a set of sketch-planning calculations to estimate emissions benefits for TCM strategies that could not be assessed through quantitative modeling. MWCOG used these sketch-planning approaches in conjunction with the TDM Evaluation Model and their regional mode choice model to estimate the impacts of over 50 individual strategies.
Strategies Addressed - Park and ride; carpooling and vanpooling promotion; bicycle and pedestrian facilities; traveler information; telecommuting/work hours; pricing/subsidies; land use; idle control; other strategies.
Methodology - The sketch-planning calculations are applied to strategies proposed for regional-level implementation. Various assumptions about program effectiveness are employed, based on either experience from other areas or judgment. Additional assumptions account for other factors such as prior mode of travel and trip lengths. Impacts are estimated separately for work and non-work trips. Cold start, hot start, and running (VMT-based) emission factors are used.
Data Requirements - Inputs vary by project type, but include factors such as total number of park-and-ride spaces, average trip lengths, utilization of various strategies, employment affected by the strategy, and existing mode shares.
Outputs - Changes in vehicle-trips, VMT, emissions.
Level of Effort - The calculation steps are clearly documented. Some effort may be required to develop assumptions appropriate for local use, and to set up calculations either on paper or in a spreadsheet.
Advantages - Potentially helpful examples of calculations and assumptions are included for a number of strategy types. The calculations account for prior mode of travel as well as both trip and VMT-based emissions.
Limitations - Estimation of travel impacts is frequently based on judgment. (This is due to the lack of reliable data and analytical procedures for estimating the travel impacts of these strategies.) The particular assumptions and calculation approaches may not be appropriate in all situations.
Source/Availability - U.S. DOT. Transportation Control Measure Analysis: Transportation Control Measures Analyzed for the Washington Region's 15 Percent Rate of Progress Plan. Metropolitan Planning Technical Report No. 5, FHWA Publication No. FHWA-PD-95-008, February 1995. Contact Michael Culp, FHWA Office of Metropolitan Planning and Programs (202-366-9229, firstname.lastname@example.org).