A project to reduce congestion on Interstate 270 is nearly halfway complete, as it continues to work its way north from Montgomery County, according to the State Highway Administration.
The Innovative Congestion Management project, announced by Gov. Larry Hogan in 2017, is 46 percent complete, with work being done at a number of ramps in Montgomery County, State Highway Administration spokeswoman Shantee Felix said in an email Friday.
The project calls for using technology including more than 25 signs to relay real-time traffic information, more than 30 smart traffic signals, cameras, ramp meters to control the flow of traffic onto the highway, and other technology that planners think will combine to help manage traffic along the highly congested interstate.
The project is separate from a proposal by the state to add toll lanes to I-270 to widen the road and ease congestion.
Crews are finishing infrastructure for the installation of sensors, which should all be active on the southbound side by next spring, SHA Administrator Greg Slater said last week. The overall project is expected to finish by spring 2021.
While most of the work will be done in Montgomery County, some of the technological improvements will also be made at the interchange of I-270 and Md. 80, which is also scheduled to get expanded acceleration and deceleration lanes between interchanges.
Originally expected to cost $100 million, the cost has risen to about $130 million after the state identified additional chances to install additional ramp metering.
The original project proposed metering only along the southbound side, but SHA decided during the procurement process to add metering to the northbound side to more effectively reduce congestion along the entire corridor, Felix said.
Ramp metering limits the flow of traffic onto a highway by monitoring traffic and controlling traffic lights at the top of entrance ramps to prevent a surge of vehicles onto the ramp and the highway all at once.
That can be effective in making traffic flow better on the highway with fewer vehicles, said Paul Lewis, vice president of policy at the Eno Center for Transportation in Washington, D.C.
But the meters require enforcement in order to be effective, by preventing drivers from blowing past the red light at the top of the ramp and moving onto the highway, he said.
And officials have to be careful of unintended consequences.
If you’re solving a problem at one intersection, you need to make sure it’s not causing problems on other roads that are part of the overall traffic system, Lewis said.
Meanwhile, work continues on widening several ramps in Montgomery County to accommodate the new technology.
Ramp widening is being done at the ramps to southbound I-270 from Montrose Road, Md. 28, Md. 117, Md. 124 and Middlebrook Road.