Starting on Monday Hudson Valley drivers may encounter a red light when trying to enter the highway.

The New York State Department of Transportation will begin something called "ramp metering" on October 29. Red and green traffic lights will begin appearing on entrance ramps throughout the Hudson Valley next week.

NYS Department of Transportation

Ramp meters work by controlling the flow of cars and trucks traveling from access ramps onto the interstate. The starting and stopping of traffic help to manage congestion on the roadway, only allowing cars to trickle into congested traffic. The system allows vehicles to keep flowing on the highway instead of coming to a halt as a long line of cars attempts to merge into the right lane.

The ramp meter system will stop cars entering the highway for brief periods of time depending on how contested the highway is. Additionally, the system can monitor how many cars are waiting to get onto the highway to prevent traffic from backing up onto other roadways.

The DOT has released this video that explains how the system works.

You'll start seeing the first Hudson Valley ramp meters on Monday in Westchester County. There will be one on the ramp at Interchange 9 to northbound I-87 and westbound I-287 from Route 119 in Tarrytown. Another will be set up on the ramp at Interchange 1 to westbound I-287 from the southbound Saw Mill River Parkway and Route 119 in Tarrytown and the third will be located on the ramp at Interchange 4 to westbound I-287 from Knollwood Rd, Route 100A/Hartsdale Ave, in Elmsford.

More ramp meters will be installed throughout the Hudson Valley in the future, with all of them expected to be up and running by 2020.