Congestion Relief: Work underway on interchange project at 146th Street and Allisonville Road


Work is underway on an interchange project at 146th Street and Allisonville Road that is expected to improve traffic flow through the corridor when it is finished in the summer of 2025.

The $44 million project on the border of Noblesville and Fishers will convert the intersection into a grade-separated interchange with 146th Street going over a roundabout on Allisonville Road. The project is intended to not only improve safety but to relieve congestion in the area, Hamilton County Highway Director Brad Davis said.

Davis said the county conducted traffic studies at various locations, including 146th Street and Allisonville Road, in 2017.

“This was one we reviewed, and based on traffic volume and projected traffic volume and what was happening over there at that location, it was recommended that an interchange of some type was the best solution,” Davis said.

Davis said a traditional roundabout most motorists are used to seeing in most places would not be able to handle future traffic growth through the corridor. He said a decision was made to create an interchange “and by doing that, you can greatly improve the level of service at that location over the next several decades” in an effort to alleviate traffic.”

“What we needed to do was, looking at congestion, particularly, it was going to get considerably worse,” Davis said. “And it was time to do something.”

That view was shared by Hamilton County Commissioner Mark Heirbrandt.

“146th Street is the main east-west artery in our county, running 17 miles from the Boone County line to I-69,” Heirbrandt said. “The Allisonville Road intersection in particular is one of the most traveled. Approximately 44,000 vehicles travel through it every day, so it’s critical we make these upgrades to keep up with the growing needs of our community.”

Hamilton County applied for funding through the Indianapolis Metropolitan Planning Organization and received $9.5 million toward construction of the project. A portion of the funding was for congestion relief, according to Davis.

Davis said under the first phase, which is underway, motorists should be aware of restrictions traveling through the area and said that contractors are working in the median on 146th Street and Allisonville Road to remove concrete medians. The first phase is anticipated to be completed around July 1, with contractors working on the outside portion where ramps will be, Davis said.

After the first phase, Davis said there will still be restrictions in place in which there will be no left turns permitted off 146th Street. After July, there will be two lanes east and west, in addition to right turn lanes on 146th Street.

On Allisonville Road, there will still be right and left turn lanes, in addition to thru-lanes, in both directions, Davis said. The only restriction is that there will be no left turn off 146th Street, he added.

However, Davis said the county is actively monitoring the area as the project continues.

“We know there’s backups and some delays that are occurring, but what we try to do and what we’re doing is frequently going out and trying to monitor the traffic, and our technician is constantly tweaking the traffic signal to kind of optimize the best we can the compromise that you get between allowing traffic on 146th and Allisonville Road,” Davis said. “Predominantly, because of the volume during peak volumes of the day, 146th Street, you get more green time on that signal, and again, it’s a constant monitoring and tweaking of signals to make the best use out of it until we get through this phase.”

Davis said the signals will be adjusted based on traffic reconfigurations moving forward. However, he said motorists can anticipate the closure of Allisonville Road in early 2024 for about 90 days in the spring that will reopen in June.

“That will be the most impactful for people that will be occurring at that point in time,” Davis said.

Still, Davis asked drivers to be patient as they travel through the area and to seek alternative routes whenever they can. Motorists are restricted to 35 mph in the area, which is monitored by law enforcement.

“It’s inevitable and unavoidable that people have to use the corridor, but you know, it’s a question of being patient and understanding the short-term situation and that it’ll get better eventually,” Davis said. “We’re doing our best to keep traffic flowing the best we can through the project and trying to communicate to everybody on what’s going on.”

For more on the project, visit

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Construction is underway on a project that will bring a grade-separated interchange with 146th Street going over a roundabout on Allisonville Road.
Work isn’t expected to be completed until the summer of 2025. (Photo by Adam Seif)

By the Numbers

  • 44,000: Approximate number of vehicles traveling through 146th Street daily
  • 44: Total price tag in millions of dollars
  • 35: Miles per hour restriction through the construction site

Source: Hamilton County