Highway capacity expansion projects, involving the building of new roadways or addition of lanes to existing facilities, are often justified at least in part on their ability to reduce traffic congestion. But studies examining that approach consistently show that adding roadway capacity in congested areas increases network-wide vehicle miles traveled (VMT) by a nearly equivalent proportion within a few years, reducing or negating the initial congestion relief. That increase in VMT is called “induced travel.” To assist public agencies in estimating the amount of induced travel that may result from a capacity expansion project, UC Davis researchers in a previous project developed the Induced Travel Calculator. This project will explore possible improvements to the calculator and develop recommendations for any further improvements that would require additional resources. The research team will explore three types of improvements to the calculator: 1) Improvements to the explanation and documentation of the calculator on the website and in related resources; 2) Improvements to the calculator itself, such as refinements to the calculations and/or the data used by the calculator; and 3) Validation of the calculator in different contexts.
