Measuring site-generated vehicle travel

State, local, and private-sector climate policies increasingly require estimates of site-generated vehicle miles traveled (VMT) for individual properties. No standard,agreed-upon method exists for this purpose. If alternative methods produce reasonably consistent results,then an analyst may select a method based on convenience. The purpose of this study was to determine whether the selection of an estimation method has an important effect on the magnitude of the estimate. We identified twelve plausible methods for estimating site-generated VMT. We applied these methods to estimate site-generated VMT for eight existing office sites in the San Francisco Bay Area (CA) and the Wasatch Front Region of Utah. We found a wide variation in estimates produced for any single site, with the minimum esti-mate at a single site ranging from 84% to 96% lower than the corresponding maximum. We argue as a result that, in the short term, planning policies requiring site developers or occupants to produce site-level estimates of VMT should specify consistent methods to allow for comparison across sites and over time, as needed. In the long term, if VMT is to be used as a performance metric, industry-wide standards for estimating it for both existing and prospective projects are needed. Alternatively, policymakers should con-sider whether the goals of VMT reduction might be better met with a different performance metric.

Related publications

Voulgaris, C. T., Macfarlane, G. S., & Kaylor, J. C. (2024). Whose Miles Are These Anyway? Estimating Site-Generated Vehicle Miles Traveled. Journal of the American Planning Association, 1–17. https://doi.org/10.1080/01944363.2023.2298962

Related conference presentations

Voulgaris, C.T., G.S. Macfarlane & J. Kaylor. 2022. Whose emissions are these anyway? Estimating vehicle miles traveled at the site level. 101st Annual Meeting of the Transportation Research Board. Washington, DC.