One of the most important laws to be enacted this year requires the Virginia Department of Transportation to review the traffic impact of rezoning cases in fast-growth counties. Officially, the law doesn’t go into effect until next year, but it’s already had a test case — in the fastest of fast-growth jurisdictions, Loudoun County.
As chronicled on this blog, VDOT studied the impact of proposed changes to the Loudoun County management plan that would increase the number of dwelling units from 5,000 in the South Dulles region to 28,000. The results, VDOT asserted, would lead to the lowest Levels of Service — gridlock, essentially — for hours a day and miles around. Greenvest, the lead developer, countered that VDOT neglected to include $700+ million in road improvements planned by the private sector and failed to consider that those extra 23,000 households would strain the local transportation system wherever they lived. The Piedmont Environmental Council contended that the study understated the magnitude of congestion by underestimating the length of likely commutes. (See the details in my most recent column, “Loudoun Lightning Rod.“)
This VDOT report won’t settle anything. That’s OK. It’s still early in the game. VDOT, we hope, will continue to refine its methodology. And local planning departments, which supply the underlying data, will continue to collect better information.
At the risk of putting readers to sleep, I will renew a recommendation that failed to elicit any comment whatsoever when I last mentioned it on this blog. To make rational land use and transportation decisions, Virginia needs the best traffic modeling system available. The one that VDOT uses now is state of the art — as in, no one’s got a better one — but it still falls short of what’s needed. Virginia is a national leader in the modeling & simulation of complex systems. We have the capability to build the world’s best traffic/land use model. Why not set the new global standard?
A next-generation traffic modeling system would allow us to delve into the complex interactions between transportation and land use, answering questions that leave Bacon’s Rebellion bloggers and readers chasing their tails in endless circles of argumentation for the lack of conclusive evidence. Thanks to the Division of Motor Vehicles, we know how many miles every car is driven each year, and the address of its owner. With a world-class modeling system, we could cross-tab that data with variables — development density and the presence of sidewalks, grid streets and mass transit, just to mention a few examples — that would yield definitive answers about which types of development are associated with the most driving, and by what margin.
Such a system might be expensive in the sense that it could cost tens/hundreds of millions of dollars to set up and maintain. But that would seem to be a relatively small price if the output would better inform decisions affecting tens/hundreds of billions of transportation improvements and real estate investments. That should be Virginia’s number one transportation priority before spending one more dollar on new roads and rail.