Toll Avoidance and Transportation Funding, Sightline Institute, September 2011

This article, written by Clark Williams-Derry, Research Director at the Sightline Institute, provides an overview of a host of research suggesting that official forecasts of toll road traffic demand are overly optimistic.  

Sightline Institute is an independent, nonprofit research and communications center—a think tank—founded by Alan Durning in 1993.  Sightline equips the Northwest’s citizens and decision-makers with the policy research and practical tools they need to advance long-term solutions to our region’s most significant challenges. Sightline Institute’s mission is to make the Northwest a global model of sustainability—strong communities, a green economy, and a healthy environment. 

This general conclusion of this report, based on a review of dozens of  original research reports, is important as MWAA, Fairfax County, and Loudoun County consider the "official" Dulles Toll Road demand forecast to be provided by Wilbur Smith Associates (WSA) within the next month.  

The Sightline report's key findings are:

• Toll road traffic and revenue tend to fall short of official projections.

In study after study, from the US and beyond, the findings are the same: transportation officials tend to overestimate how much traffic will use tolled facilities, and how much revenue can be generated from tolls. Just as importantly, traffic and revenue projections for tolled road facilities are highly error prone. There appears to be no consistent or reliable method for predicting whether a particular toll road forecast will miss the mark.

• Toll-free alternatives increase traffic diversion. 

The paper concludes that, "Because of the fiscal consequences, members of the public would be wise to take a cautious and skeptical view of official tolling revenue forecasts. Likewise, state transportation officials should carefully consider the long-term fiscal consequences of toll revenue shortfalls, particularly  on facilities where drivers can select alternative,toll-free routes."

The paper includes links to the many papers it quotes as well as contained a lengthy hyper-linked set of endnotes that easily enables readers to become more informed on the issue of toll road traffic demand forecasting.

 Toll Avoidance and Transportation Funding, Sightline Institute, September 2011