NASHVILLE, Tenn. (WTVF) — It's one of the busiest, most congested and most dangerous interstates in Tennessee and Tuesday, the I-24 corridor from Murfreesboro to Nashville got a little "smarter."
At 5:31 a.m., TDOT flipped the switch on the $64 million tech upgrade to try to make traffic better for the 175,000 drivers who pass through the area every day.
If you're one of those drivers, you've likely experienced several commutes that should have taken 30 minutes but instead took an hour and a half or longer due to a single crash.
"We're trying to figure out how to better maintain the roads we have, because we cannot continue to widen all of our roads, (with) the cost and right-of-way impacts on the properties adjacent to the interstate, it's just not a feasible solution," said TDOT Civil Engineering Manager Michelle Nickerson. "So we're trying to figure out what we can do to help operate these roads better."
TDOT believes the 67 signs, known as gantries, that are live between I-440 in Nashville and S Church St in Murfreesboro are the solution.
Crews have installed fiber, switches in cabinets, routers, Bluetooth, wireless communication and speed sensors to help a team that's sole job is monitoring the 30-mile stretch in order to make the drive more reliable.
"We're not going to be able to reduce the everyday average travel time," said Nickerson. "But if we can reduce those accidents and those incidents that will make your travel time 30 minutes longer than you expect it to be, that’s what we're hoping to address."
This "SMART corridor" technology also allows TDOT to control the traffic lights on Murfreesboro Pike (Hwy 41). So if there's a bad crash and the team monitors an influx of drivers leaving I-24 for the alternate route, they can help the flow of traffic by prolonging the green lights.
Nickerson lives nearby and has been working on the plan to build the new SMART corridor since 2017. She says the team modeled it after I-80 in the Bay Area in California.
"It feels good to finally see it (go live)," she said. "I also drive this corridor every day, so I'm hoping to be able to see some benefits myself!"
The most consistent sign drivers will notice on the electronic boards will indicate the current speed limit. If traffic is flowing without a problem, the signs will show the normal 70 miles an hour.
But if there's heavy traffic, the speed limit will change to reflect the speed traffic is currently flowing, giving drivers a warning to slow down.
"Speed limits will adjust to the speeds (drivers) are going, based on sensors on the roadway," Nickerson said. "Telling our operators 'hey the speed people are going is 55 so people shouldn't be trying to travel into that area at 70.' It’ll step them down into that, instead of having to, all the sudden, having to come to a complete stop."
If you don't follow the posted speed limit, you could get a ticket.
"If you have that kind of crazy driver who's trying to weave in and out doing what he wants to do, then it is enforceable," she said.
Nickerson says if TDOT can reduce secondary crashes in the backup, they can avoid incidents that are often more serious and can have a bigger impact on traffic than the initial issue. That's how they hope to make the commute more reliable.
Beyond the variable speed limit, the signs can change for each lane. If a crash or lane closure happens, the green arrows will show which lanes are open, yellow exes show lanes that are closed ahead and red exes show where lanes are currently closed.
The 67 gantries are spaced a half mile apart, and Nickerson says at least three will show the lane warnings before drivers reach an incident ahead.
On rare occasions, TDOT may even allow drivers to get around an issue with a green arrow pointing to the shoulder.
"Mostly to get you to the next exit," Nickerson explained.
She says there may be some growing pains as drivers get used to the new signs, but that the overall crash count and congestion should eventually decrease.
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