The longer article in the Pioneer Press: Bridge collapse didn’t stall commutes, U study finds –
Bridge collapse didn’t stall commutes, U study finds
University of Minnesota report shows times up only slightly
By Jake Grovum
Article Last Updated: 08/28/2008 11:51:43 PM CDT
A year after the Interstate 35W bridge collapse, the average Twin Cities car trip has increased by less than a minute, according to a University of Minnesota study.
The average trip before the bridge collapse was 18.6 minutes, according to the study by University of Minnesota associate civil engineering professor David Levinson. After the collapse, drive time grew by two-tenths of a minute, to 18.8 minutes.
Other studies indicate the commute time to work and back also grew only less than a minute, Levinson said.
In fact, for the majority of the estimated 150,000 motorists who crossed the eight-lane bridge daily — even those now driving in heavily-trafficked areas — the time hasn’t changed much at all. Some have even seen shorter commutes, the study found.
Despite almost 100,000 more cars using Minnesota 280 and 35,000 more cars on Interstate 94 between 280 and I-35W each day, the infrastructure in the metro area is designed to withstand those increases.
Commuters did get help from emergency road improvements after the collapse. An extra I-94 traffic lane was added in each direction between downtown Minneapolis and 280, while two intersections with stoplights were closed on 280 and most ramps were widened or modified for better traffic flow.
Levinson surveyed those affected by the collapse, monitored vehicle counts and used models to analyze post-collapse traffic.
It’s not an issue of people driving less, Levinson said, because traffic levels have been steady for the past year. Despite the collapse and an increase in gas prices, the number of commutes is about the same.
Still, comparable before and after commute times might not be comforting to commuters. Prior to the collapse, the I-35W and I-94 interchange was one of the most heavily congested areas in Minneapolis.
Immediately after the collapse, two main Minnesota Department of Transportation detour sites, 280 to I-94 and Interstate 694 to Interstate 394, endured “severe congestion” and every remaining bridge crossing the Mississippi River became more crowded, according to Levinson’s research, but the improvements helped accommodate motorists.
“Those made those facilities operate pretty well,” Levinson said. “Had those improvements not been made, things would be a lot worse.”
Not everyone is getting around so easily.
Lisa Sweet commutes from Roseville to Plymouth. She plans to sell her house and move closer to her job after seeing an extra 30 minutes tacked onto her drive.
“The commute right away was pretty tough,” she said. “(Now) they’re choosing to drive different ways so the traffic is spread out.”
Sweet has a number of routes she uses, but some take longer than others. Those in her office have been sharing tips for navigating the post-collapse roadways, Sweet said, adding that I-694 “isn’t great on Fridays.”
Brian Kary, MnDOT freeway operations engineer, said commute times went “up significantly” immediately after the bridge collapse but said that after the improvements, most commute times were “comparable,” particularly on I-94.
Still, Levinson’s research seems at odds with a 2008 MnDOT report examining congestion in the metro area. That study found a 40-mile increase in total congested miles (a mile of traffic moving slower than 45 miles per hour) for the first time in four years in 2007, citing the bridge collapse as a reason for the “dramatic” increase.
But MnDOT expects to see “significant congestion relief” when the new 10-lane I-35W bridge is complete, according to its report, although it’s unclear whether the supplemental road improvements will be permanent, Kary said.