A full freeway? One day. But the reduced-conflict intersection is a change we can make now, at a relatively low cost, to address the worst kind of crash and save lives. It's working.

By Derek Leuer and Douglas Carter

July 31, 2018 at 10:38PM

Hwy. 52 between the Twin Cities and Rochester may look like a freeway in stretches, but it’s not. That vision is many years from becoming a reality. (The Minnesota Star Tribune)

A July 18 commentary ("Hwy. 52 improvements: 'Reduced conflict' or increased confusion?") questioned a new intersection type on Hwy. 52 between Hampton and Coates. As a traffic safety engineer and a state geometrics engineer, respectively, at the Minnesota Department of Transportation (MnDOT), we would like to explain why this intersection type, the reduced-conflict intersection, was selected for this corridor and why it effectively reduces crashes, saves taxpayer money and saves lives.

Reduced-conflict intersections are a newer type of intersection treatment used on high-speed divided highways in the state and across the country. With these intersections, motorists approaching such highways from a side street are not allowed to make left turns or cross traffic; instead, they are required to turn right onto the highway and then make a U-turn at a designated median opening. (For details, see tinyurl.com/mndot-rci.) The intersections are effective because they reroute traffic in a way that eliminates the highest-severity crashes.

Right-angle crashes are the most common type of high-severity crash in Minnesota and nationally. When crashes are reviewed at problem intersections on divided highways, it is often found that most of the fatal and serious-injury crashes are right-angle crashes. These crashes happen after the driver has crossed the two nearest lanes and has attempted to cross the median and merge into oncoming traffic in one movement. The reduced-conflict intersection does not allow drivers to expose themselves, or others, to being hit at a right angle (also called a broadside or T-bone crash).

In the MnDOT study mentioned by the commentary writer, reduced-conflict intersections to date have eliminated fatal and serious-injury right-angle crashes. There has not been a single fatal or serious-injury crash after the installation of a reduced-conflict intersection at any of the 24 sites in Minnesota. No other safety improvement we implement is this effective.

There is a vision of Hwy. 52 being a freeway between the Twin Cities and Rochester. However, based on current statewide needs and budgetary constraints, it is speculated that this could take 50 years or more to achieve. Because of their low cost, reduced-conflict intersections will allow us to provide corridor safety improvements now rather than waiting until interchanges can be fully funded. It is estimated that 10 to 20 reduced-conflict intersections can be built for the cost of one interchange. We are treating as many intersections as possible, being effective with taxpayer dollars and, most important, saving lives with every installation.

Any new intersection treatment may seem confusing at first to those unfamiliar with them. Experience has shown that drivers rapidly acclimate to new conditions and that many drivers come to appreciate the safety benefits associated with reduced-conflict intersections in light of the 350 fatalities each year on our roads.

At MnDOT, we are committed to providing the safest roads in the most cost-effective manner possible for all Minnesotans. Reduced-conflict intersections are one of the best tools to help us meet this goal.

Derek Leuer is assistant state traffic engineer and Douglas Carter is state geometrics engineer at the Minnesota Department of Transportation.