The nightmare for Interstate 670 commuters is coming to an end.

The Ohio Department of Transportation will open all the ramps at the interchange of eastbound I-670 and I-270 by Monday morning, and the SmartLane on eastbound I-670 will open for the first time Wednesday.

Those developments will relieve what has become a major traffic headache for northeast Franklin County commuters as crews built new ramps to realign traffic churning mostly from Downtown.

The SmartLane will run on the left shoulder of eastbound I-670 and act as a relief valve when congestion bogs down the afternoon commute. When average speeds on the eastbound highway dip below 45 mph, an operator in ODOT's traffic management center will have the option to reduce the speed limit and open the shoulder as a traffic lane.

Billboard-size digital signs that have been installed at nine locations between Downtown and the I-670/270 interchange will alert drivers when the SmartLane is open and post the current speed limit. A green arrow will appear above open lanes, and a red X will signify that a lane is closed.

ODOT also has installed 39 new traffic cameras so the traffic management center can keep an eye on the SmartLane, including whether any trash or debris is blocking it. The right shoulder will remain available for traffic stops and disabled vehicles.

Speeds will step down when the SmartLane opens, said Breanna Badanes, an ODOT spokeswoman. Drivers first will have to slow from 65 mph to 55 mph for about a minute, and then from 55 mph to 45 mph for the rest of the time that the lane is open. ODOT generally will open the entire SmartLane rather than use it in sections, she said.

When average speeds on I-670 rise above 45 mph, the SmartLane will be closed.

But first, ODOT will reopen closed lanes and ramps at the interchange, which has been under construction to help eliminate dangerous braking and weaving that happens when drivers shift lanes. That will happen by Monday morning, Badanes said.

The new ramps will force drivers to decide earlier where they want to exit, and dedicated ramps will funnel them into those lanes. Eastbound I-670 drivers will choose between exiting onto northbound I-270 or onto the ramp for Easton Town Center and Route 161. Northbound I-270 drivers will decide whether to remain on the highway or exit for Easton and Route 161.

At 9 p.m. Friday, ODOT will close northbound I-270 at I-670 and the ramp from northbound I-270 to Morse Road. Traffic will be detoured overnight onto westbound I-670, sending drivers near Downtown to northbound I-71, then back to I-270. The new ramp from northbound I-270 to Route 161 and the Easton exit reopens for good at 9 a.m. Saturday.

Ramps from Leonard, 5th and Cassady avenues to eastbound I-670 will close at 7 p.m. Saturday. Starting at 9 p.m., eastbound I-670 will have only one lane open between John Glenn Columbus International Airport and I-270, and ramps will close from International Gateway and Steltzer Road and from eastbound I-670 to northbound I-270. Crews will reopen one lane on the ramp from eastbound I-670 to northbound I-270 at 7 a.m. Sunday.

By 5 a.m. Monday, all lanes and ramps will be open. That includes the ramp from Route 62 to northbound I-270, which has been closed as construction wraps up on the interchange.

The project has cost about $61 million, most of which was spent on rebuilding the interchange.

rrouan@dispatch.com

@RickRouan