Indianapolis' south side is getting a new intersection: Get to know the 'displaced left'

Coming to an intersection near you is a new kind of lane configuration to learn.

No, it's not a Michigan Left.

Under construction now, the intersection of U.S. 31 and Thompson Road on Indianapolis' south side will be the city's first "displaced left."

It'll also be a first for the state, Indiana Department of Transportation spokesperson Mallory Duncan said.

The intersection, now a meeting of a 6-lane highway and 5-lane major road with just one sidewalk, will also get new sidewalks and improved pedestrian crossings when the estimated $5 million INDOT project is complete in early October.

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In a displaced left, also called "continuous flow," drivers cross over the opposite traffic stream hundreds of feet before the intersection, to prepare for their eventual left turn. Then those cars make the left turn at the same time as the rest of the through traffic. All of these movements, including the upstream cross-over, are controlled by traffic signals.

This removes cars from navigating left turns inside the intersection, with the aims of reducing backups and improving safety.

A study of a displaced left turn intersection in Baton Rouge showed a 24% reduction in total crashes and a 19% reduction in fatal and injurious crashes during the two years after it was built, according to the Federal Highway Administration.

The displaced left will apply to north- and southbound traffic on U.S. 31. Crews will reconstruct the medians, repaint lines, build additional right turn lanes for traffic turning onto U.S. 31 and add a traffic signal to the I-465 eastbound exit ramp onto U.S. 31.

The project will include new sidewalks along U.S. 31 on both sides to connect the intersection to bus stops to the south, as well as new crosswalks on the north and south sides.

From 2015 to 2020, there have been 11 serious crashes between the intersection and the I-465 exit ramp onto U.S. 31, one of which was fatal, according to a crash database from the Indianapolis Metropolitan Planning Organization.

Construction in the area began last spring with lane configuration work on the I-465 exit ramp in preparation for the eventual displaced left.

Part of the impetus for getting the project done now is to have a more efficient and safe detour route when the I-69 Finish Line project comes to fruition in Marion County, Duncan said. Work on widening the stretch of I-465 where it meets with I-69 is expected to begin in 2023.

More: What's happening with the I-69 project in 2022, construction maps

While this is the first displaced left to be constructed in Indiana, several more are in the works across the state, from Indianapolis to Evansville, Duncan said.

INDOT is also considering displaced left configurations for a project on Rockville Road between Raceway Road and I-465. An environmental study is underway, and INDOT expects to recommend a design this summer.

From 2021: 'Displaced left turns' could come to Rockville Road. Here's how they work.

Contact IndyStar transportation reporter Kayla Dwyer at kdwyer@indystar.com or follow her on Twitter @kayla_dwyer17.

This article originally appeared on Indianapolis Star: What is a 'displaced left' intersection? Indianapolis will find out