Office of Operations
photos of traffic merging onto congested highway, congestion in snowstorm, variable message sign, cargo, variable speed limit sign in a work zone, and a freeway at night
21st Century Operations Using 21st Century Technologies

Traffic Bottlenecks

Combating Bottlenecks


Reconfiguring interchange ramps (including building roundabouts at the top of the ramps) instead of rebuilding the whole interchange.

Bottleneck Project: Michigan I-75 / M-81 Interchange Reconstruction. This former tight-diamond interchange suffered from heavy truck traffic on the M-81 corridor, plus inefficient signal control at the ramp terminals, plus safety problems as a result of sharp left turns onto and from the ramps that contributed to all-too frequent truck overturns. The interchange was also facing a projected growth of 30% over the next 20 years. The solution was to reconfigure the interchange with a reconstruction of the bridge, construction of roundabouts, which included bypass lanes at the ramp terminals, and removal of the signals. At $5.1M this solution represented a cost savings of $6-7M over typical reconstruction. In essence, the "roundabout solution" has reduced delays, reduced fuel consumption (which has reduced air pollution emissions) and the LOS of C/D has improved to A with on visible traffic back-ups.