The video explores the new diverging diamond interchanges (DDI) that are being built at 14 Mile and Big Beaver roads. MDOT said the interchange improves driver safety by eliminating conflict points.
The video also looks at a 4-mile-long drainage tunnel that is being built 100 feet below the northbound service drive from just north of Meyers Avenue to just north of 12 Mile Road. The drainage tunnel will collect rainwater from the freeway and surface street through drainage shafts. It’s meant to prevent freeway and other area flooding issues during heavy rainfall.
The modernization project has been ongoing for more than two years. MDOT said the project is meant to make I-75 safer.
According to MDOT, a DDI is a design that is meant to improve safety and mobility. A conventional diamond interchange is the most common in the United States -- that’s an interchange where the exit and entrance ramps make a diamond shape between the freeway and surface street. Right-hand turns are handled the same at both a DDI and a diamond interchange.
A DDI interchange is different in how it handles left turns:
The intersections with the freeway ramps smoothly move traffic on the surface street from the right side of the roadway to the left side of the roadway as the road crosses the freeway. Traffic is on the left-hand side of the roadway between the signals at ramp intersections, all left turns occur at the entrance/exit ramps without having to cross opposing traffic.MDOT