The study details the development of a series of enhancements to the Trip Reduction Impacts of Mobility Management Strategies (TRIMMS(Trade Name)) model.

The study details the development of a series of enhancements to the Trip Reduction Impacts of Mobility Management Strategies (TRIMMS(Trade Name)) model. TRIMMS(Trade Name) allows quantifying the net social benefits of a wide range of transportation demand management (TDM) initiatives in terms of emission reductions, accident reductions, congestion reductions, excess fuel consumption and adverse global climate change impacts. The model includes a sensitivity analysis module that provides program cost-effectiveness assessment. This feature allows conducting TDM evaluation to meet the Federal Highway Administration Congestion and Air Quality (CMAQ) Improvement Program requirements for program effectiveness assessment and benchmarking. The document provides guidance to help TDM professionals to use the model by selecting the appropriate cost parameters, providing referenced sources where to obtain such parameters, and by offering general guidance on how to incorporate data already at their disposal.

Some urban policies are designed to reduce auto and increase transit usage. Evidence is mixed because most empirical research uses ad hoc specifications. We estimate empirical models of the interaction between urban form and transit demand drawn from urban economic theory. Population density has a small impact on transit demand, which decreases when residential location is endogenous. Households living farther from work use less transit, a result of trip-chaining. Reducing the spatial allocation of non-work activities, improving transit accessibility at and around subcenters, and increasing the presence of retail locations in proximity to transit-oriented households would increase transit demand.

We estimate empirical models of the interaction between urban form and motor vehicle travel. We find that population density has a small impact on travel demand, which decreases when residential location is endogenous. Households living farther from work increase tour vehicle miles of travel, a result of trip-chaining. Reducing the spatial allocation of non-work activities and increasing the presence of retail locations in proximity to households would have minimal effects in decreasing motor vehicle travel demand and employment decentralization.