Viewpoint: Minnesota finds roundabout way to reduce crashes
If you take a road trip in Minnesota this summer, somewhere along the line the chances are you will run into an underappreciated, often disparaged, government-driven breakthrough and not even know it.
While the unconventional intersections often first run head-on into local resistance from drivers, the dramatic results turn public opinion around before long, according to the Minnesota Department of Transportation.
"Minnesota is probably in the top 10 percent of states involved in roundabouts and putting roundabouts out there," said Ken Johnson, a MnDOT traffic expert. "Not just MnDOT, but our cities and counties are active in the installation of them as well. We've got more than 115 roundabouts in the state right now on city, county and state roads, so we've got quite a few out there."
Roundabouts route vehicles into a circular intersection with a center island and exits to connecting roads, slowing traffic while maintaining a steady flow and significantly reducing the risk of head-on crashes prevalent at traditional intersections.
Don't confuse them with traffic circles in place in some cities, which rely on traffic signals and stop signs.
Traffic engineers prefer at least three years of data to evaluate improvements at intersections. But a decade after the first roundabouts went in, they are getting closer to compiling comprehensive results on the innovation's impact in Minnesota.
"Most of studies I've looked at, before and after studies of specific roundabouts that have been installed at least on the state highway system, have indicated a reduction in the number of injury crashes that have occurred at that location," said Johnson.
MnDOT analysis of roundabouts located on Highway 7 in Carver County, Highway 5 inWashington County and Highway 13 in Scott County indicate an overall 41 percent decline in crashes, 70 percent decline in injuries and no fatalities, compared to two deaths before installation.
In fact, the Scott County roundabout has become a national poster child in traffic safety circles, an often cited case study at conferences.
The rural, two stop high-speed intersection of State Highway 13 and County Road 2 used to be an accident waiting to happen. State highway experts experimented with bigger stop signs, vibrant striping and flashing lights to cut down the carnage - without much luck.
In 2005, the Twin Cities suburban county took a chance and built the first of what will be 13 roundabouts. They never looked back, logging a 70 percent reduction in crashes, 79 percent decline in total injuries and no deaths at the once fearsome intersection.
"In the seven years after that's been opened, we've only had seven total, an average of one accident per year, predominately property damage from low-speed, low-impact crashes," said Tony Winiecki, a Scott County traffic engineer.
One cost-benefit analysis recently conducted on Lakeville intersection concluded the safety costs from reduced accidents would be $3.2 million for the roundabout versus $1.9 million for the signal.
While maintenance costs were projected to be comparable, the roundabout's $3.5 million construction cost amounted to less than half the cost of a signal. The roundabout, now under construction, also is expected to save $73 million in operating costs for drivers over 20 years, compared to $49 million for the conventional intersection in this case.
"It's a 10-second less delay per vehicle going through," Johnson said. "It doesn't sound like much, but if you take an intersection that has 30,000 vehicles a day going through there, that adds up."
Thirty-nine additional roundabouts are on the drawing board or under construction in Minnesota from Blue Earth to Nisswa and Worthington to Thief River Falls. While the roundabout does not replace the conventional intersection in many places, drivers can expect to see more circular intersections on their GPS screens. And as motorists become more familiar with the roundabout, some experts say the reduced number of crashes will dip even further.
"Vehicle drivers are becoming more accustomed to how the roundabout operates," said Winiecki. "And I think there is more of a understanding and that accidents will continue to go down at them because of the familiarity with drivers in how they operate."
Steward writes for Watchdog.org's Minnesota bureau