North Carolina Department of Transportation—I-540 On-Ramp Signals

Raleigh is one of the fastest growing metropolitan areas in North Carolina and among the fastest growing areas in the US. But along with this population growth comes increases in traffic congestion on the area freeways. In response to growing traffic congestion, the North Carolina DOT installed the state’s first ramp meters at four locations in the westbound direction of I-540 in Raleigh. Ramp metering is considered as a way of obtaining additional peak period freeway capacity that is less costly than building additional lanes Ramp meters also provide benefits of increased safety and reductions in emissions.

The ramp meters began operation on September 27, 2017. The system was monitored and adjustments were made throughout the end of 2017 to ensure optimal operation, including upgrading the controller algorithms. The corridor now operates as a dynamic system, with each ramp meter controllers adjusting metering rates according to the mainline traffic and ramp traffic queue conditions. Drivers now enjoy an easier ride to their destinations and a safer and greener commute.