Triangle traffic is back, and so are the ramp signals on Interstate 540 in North Raleigh

In another sign that life is getting back to normal after the COVID-19 pandemic, the state is turning on the traffic signals that control the flow of cars getting on westbound Interstate 540 in North Raleigh.

Starting Tuesday morning, the lights will again alternate between green and red to let one or two cars onto the freeway at a time. The goal is to put some space between vehicles coming down the ramps to make it easier for them to merge into traffic on the highway.

The signals, or ramp meters, at Falls of Neuse, Six Forks, Creedmoor and Leesville roads are the first in North Carolina and were turned on in the fall of 2017. They were turned off more than two years ago when the coronavirus pandemic prompted businesses to close or have employees work at home.

Now traffic has rebounded to the point that the N.C. Department of Transportation has decided to turn the system back on, starting with Tuesday morning’s commute.

The system uses sensors in the pavement to determine when traffic on I-540 is heavy enough that the ramps need modulating. That’s generally during the mornings, as workers are heading toward Research Triangle Park, but can also happen when accidents, construction or special events gum up traffic.

Ramp signals have been used in Chicago since the 1960s and are now common in other large cities, including Atlanta, Denver and Houston. NCDOT cites studies from other places that show the signals improve traffic flow on the highway and reduce crashes.

Data compiled by researchers at N.C. State University showed improvements on I-540 early on, but also found that traffic on the four roads leading to the highway did not consistently improve and sometimes got worse, as cars backed up on the ramps.

NCDOT says sensors can adjust the signals when backups occur. When that doesn’t work, the department says cameras allow its traffic operations center to manually adjust the lights.