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.