The Washington State Department of Transportation (WSDOT) is responsible for planning, operating, and maintaining a highway network consisting of over 18,500 lane-miles of highway. Planning and building highways is, by nature, a long-range enterprise. It requires making many assumptions about future travel demand as well as estimating future fuel tax revenue. In recent years the growing uncertainty about oil prices and availability has made long-range transportation planning even more challenging. Rather than relying on trend extrapolation, this study uses market mechanisms to shed light on key long-range transportation planning assumptions. Although WSDOT is pursuing a variety of alternative fuels and energy sources including Electric Vehicles (EV), biofuels, propane, natural gas, etc. and their respective infrastructures, this study focuses primarily on natural gas. In particular, this study will help WSDOT assess the likelihood natural gas will substitute for petroleum fuels and estimate the impacts changes in fuel prices will have on travel demand, fuel consumption, Greenhouse Gas emissions, and fuel tax revenues.
The results of the modeling show that the potential impacts of Natural Gas Vehicles (NGV) have the potential to have effects on vehicle miles traveled (VMT), emissions, and fuel tax revenue. The effects of these vehicles are muted by the current lack of natural gas vehicles in the fleet. The usage of natural gas vehicles is limited to fleet vehicles and vehicles with high mileage usage. Challenges with widespread integration currently include the increased upfront capital costs associated with vehicles with natural gas, decreased power for heavy vehicles, and range anxiety in locations without developed natural gas fueling infrastructure. Currently the NGV market in the state of Washington is hampered by these factors. The modeling and analysis provided in the document can be used to analyze changing conditions in the NGV market and the effects on key transportation metrics.