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Insights into traffic congestion

Fiscal constraints to highway expansion: A 2007 study from the Met Council and Mn/DOT concluded that solving congestion by 2030 through expanded highway capacity in the seven-county metro area would require more than $40 billion in government spending, an amount five times greater than total anticipated highway revenues from 2011 through 2030 for the metro highway district. A $2-per-gallon increase in the state’s gas tax would be needed to fund construction at this $40 billion level if the revenues were to come solely from that tax.

Smart public policy on congestion: It turns out that just building roads won’t eliminate congestion, as demonstrated by the failed attempts of metro areas nationwide to build their way out of congestion. Within an established urban transportation network, a more-of-the-same approach must give way to creative strategies for better managing the system.

The issue is access: Too often in the past, the stand-out issue has been mobility, or the speed of the trip. But for travelers, the goal is easy access to where they want to go. Access can be easier even as roadways clog up if the target destination is nearby or is reachable via quick commutes on transit, bike or foot. Researchers for the University of Minnesota’s Access to Destinations study for the Twin Cities area have found that “while until this last decade congestion had been steadily worsening, the actual ease of reaching destinations has been getting better – all over the region.” This is true for access via car, walking, biking and transit.

Twin Cities travel time is not so bad: Long-time residents of the Twin Cities area know well that congestion has grown on the region’s major thoroughfares.  But for all the healthy growth in population and annoying growth in congestion, the 13-county Twin Cities area ranks second in the nation for shortest average travel time to work among the 25 most populous metropolitan areas, according to Census Bureau data. That favorable ranking is a much better showing than might be expected given our population size (10th smallest among the top 25).

Slowing congestion’s growth: While travel times are not as bad as elsewhere, congestion in the Twin Cities area remains an important transportation challenge. Time stuck in traffic during peak commuting periods means wasted fuel consumption, increased engine emissions, and less time at work or at home, and it adversely affects businesses that have freight and workers on the road. Traffic congestion also reduces the public’s return on investment from highways. But high-priority strategies for slowing congestion and increasing access in the Twin Cities now include more than just large-scale road-building.

The iron law of congestion: Experiences here and nationwide demonstrate that added lane miles won’t end congestion. Why? Because of what the transportation planners call the “iron law of congestion”: New lanes, when constructed, are quickly plagued by the very congestion they were expected to cure. An expanded highway attracts new travelers and becomes congested to the point where those same travelers, just as before, find other routes, avoid the congested route during peak traffic times, or use transit or other transportation alternatives. Consequently the expanded route can handle more travelers but usually with the same level of congestion and the same slow speeds.

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