Michigan motorists in Auburn Hills and Grand Rapids will soon be using an innovative interchange that routes drivers temporarily onto the ‘wrong’ side of the road to improve safety.
It’s known as the diverging diamond interchange, and has been used in Europe and other states. It reduces the number of “conflict points,” which create the potential for accidents, by routing traffic temporarily to the left side of the road at a highway interchange. A video from the North Carolina Department of Transportation explains the new traffic flow.
The first such interchange in the state is going in at I-75 and University Drive in Auburn Hills. Construction started in March and it’s projected to be finished in December. The second will go in at I-96 and Cascade Road in Grand Rapids, starting construction in July of this year and finishing in December 2016.
Brad Wieferich, engineer of design for the Michigan Department of Transportation, said a key point of the new-to-Michigan design is that drivers are temporarily routed to drive on the left side of the road.
“Honestly looking at it from a video or an aerial I can see where folks might think that’s a little strange,” Wieferich said.
But he’s driven through these in other states, and says that on the ground it’s easy to navigate. The geometry of the interchange is specifically set up to point drivers in the right direction and it doesn’t feel strange, he said.
There are currently 45 such intersections in the United States. So far just these two are planned for Michigan. The design is being deployed at high-volume interchanges, Wieferich said.
Auburn Hills Mayor Kevin McDaniel is excited to be the site of the first diverging diamond interchange in the state.
“This innovative interchange will benefit our residents and be enormously advantageous to our thriving business community comprised of world-class companies,” said McDaniel. “We are pleased to be partnering with MDOT on this important project that will enhance commerce and vastly improve motorist safety in Auburn Hills. The lasting benefits of the DDI will far outweigh the short term inconvenience during construction.”
G2 Consulting Group is part of the design-build team on the Auburn Hills interchange. Principal Mark Smolinski said the group working on the project had a track record of keeping projects on time and on budget.
Auburn Hills, for its part, is anticipating the intersection will be less expensive to maintain over time than other interchange options.
In other states, the diverging diamond interchange has had an impact on road safety. In Missouri, crash data showed that in the first year of operation crashes were down by 46 percent at the state’s first diverging diamond intersection.
The two Michigan interchanges selected for this are 50-60 years old and needed replacement, said MDOT spokesman Jeff Cranson.
“This is not a great difference in money to replace the traditional way, but it’s going to make them a lot safer,” Cranson said.