EXPERTS QUESTION VALIDITY OF LEGACY HIGHWAY ANALYSIS:
Say Travel Model is Biased in Favor of Building Highways

Friends of Great Salt Lake, Future Moves, Great Salt Lake Audubon Society, HawkWatch International, League of Women Voters of Salt Lake and Utah Chapter of the Sierra Club release new report, "Preliminary Comments on The Wasatch Front Regional Council Travel Demand Model Improvements" by Caroline J. Rodier and Robert A. Johnston, Department of Environmental Science And Policy, University of California, Davis, March 2000.

The purpose of the report is to assess whether minor improvements made to the travel demand model for the forthcoming Legacy Parkway Final Environmental Impact Statement (FEIS) were sufficient to show more accurate results than the old model used for the Draft Environmental Impact Statement (DEIS). The report concludes that inadequate improvements were made to the model used for the FEIS, the validity of its results cannot be assessed properly, and the model remains biased in favor of highway construction.

Will building the Legacy Highway and further expanding I-15 North make traffic better or worse? How good are the traffic projection models that are being used to answer that question? "The model is insufficiently accurate for plan or project analysis", according to transportation experts Caroline Rodier and Robert Johnston of University of California, Davis in a new report on the adequacy of the slightly modified model used for the forthcoming Legacy Highway Final Environmental Impact Statement (FEIS). "We can only conclude that the model is inadequate to evaluate the travel effects of the proposed I-15 North Corridor and the Legacy Parkway."

The groups releasing the report emphasize that UDOT is prepared to spend hundreds of millions of dollars of public funds to build the first segment of Legacy Highway and further expand I-15 North, but neither UDOT nor the Wasatch Front Regional Council can find the relatively modest amount of money needed to bring the transportation analysis models up to par with recommendations made by an impartial expert committee convened by the U. S. Department of Transportation in 1999.

"How can the public be expected to swallow these massive highway expenditures when they cannot even have confidence that the state is getting the numbers right?" asked Bob Adler of the Sierra Club Legal Committee and a Professor of Law at the University of Utah who specializes in environmental law. "This type of biased study does not meet minimum legal requirements for highway project analysis under a number of federal environmental laws," said Adler.

Rodier and Johnston point out that less than half of the recommendations for near term improvement were made for use in the FEIS. They say, "We can only conclude that the model does not meet the recommended standard for model accuracy established by that committee."

Rodier and Johnston emphasize that a major failing in the slightly improved model as used in the FEIS is that it doesn't represent "induced travel", which is the increase in traffic (vehicle-miles-traveled or VMT) that can be attributed to new highway lanes. They state, "Recent research has provided persuasive evidence for the existence of induced travel. EPA recently conducted a review of the induced travel literature for their Science Advisory Board and concluded that this research has 'not only built a strong case for the existence of induced travel effects, but in some cases suggests that a large fraction of growth in VMT is directly attributed to increases in road capacity'.

The significance of not representing induced travel in the model is that auto trips, VMT, and auto emissions are underestimated and reduction of congestion is overestimated when planning highway expansion. Rodier and Johnston point out that the current model does not capture the land use and transportation interaction. They say, "Our evaluation of the WFRC travel model indicates that this model does not adequately represent the induced effects of changes in land use, changes in trip making, or changes in trip lengths resulting from expansion of highway capacity in the roadway network."

Because these factors are not assessed by the model, decisionmakers are falsely encouraged to build more highways rather than to select other methods of reducing traffic congestion, such as transit and changes in land use patterns designed to shorten trips and to encourage other forms of transportation (such as transit, walking and bicycling). "Their assumptions that the future will be like the past come from models that assume we need to accommodate increased automobile dependence, rather that designing a future that includes more transportation choices and community development patterns that provide options other than the automobile," adds Roger Borgenicht of Future Moves.

Complete text of Report