The now-$133.5 million improvement project at the infamous Interstate 75-Interstate 24 "Split" near the Tennessee-Georgia state line was officially completed Thursday at midnight, but it hasn't answered all of the interchange's problems yet.
Traffic flow through the interchange is improved in most directions. But the ramp from northbound I-75 to westbound I-24 near East Ridge's Exit 1 still narrows from two lanes into one, which has been the situation throughout the six-decade life of the interchange. That will remain a bottleneck until additional lanes contained in phase 2 of the Split project are done in the years to come, according to the Tennessee Department of Transportation.
The reason is pretty obvious to drivers heading west on I-24 under the new Spring Creek Road bridges: There's nowhere for additional lanes to go.
So the backup on I-75 north will linger for a while, as phase 2 won't start until spring 2023, according to TDOT. Likewise, rush-hour backups on the southbound I-75 ramp to westbound I-24 also won't be fully addressed until a third lane is added in the next phase.
That's pretty disappointing for daily commuters like Chattanooga resident John Daly, who drives to work in Dalton, Georgia, every day. Heading north doubles his trouble, he said.
"I drive it every day. It's twice as long coming back home from Dalton as it is getting there in the morning," Daly said. "Very frustrating after all of the new construction to end up with a tight bottleneck."
Longtime through-driver Ben Partin, of Tullahoma, Tennessee, goes to Georgia via Chattanooga several times a year and is always wary of construction.
He said Wednesday he had plans to travel to Dalton this weekend.
"I have been through there several times over several years as I go to coin shows in Dalton as well as Camp Jordan there in East Ridge. Each one has two a year," Partin said.
"Coming back I've been caught many times when the traffic would just jam up on that [interchange] there getting back off onto I-24, and you'd come up there and tires just squall and you'd see all the white smoke and you hope the guy behind you doesn't hit you," he said. "It was a nightmare."
In the past, Partin said, he sometimes dodged the work by taking a route though East Ridge.
"It takes a little longer but it seems to be a lot easier, stress-wise, going on through the Bachman Tunnels because the traffic's not as bad as one would think on a Saturday afternoon," he said.
Partin was glad to know most of the problems were improved but said he's leaving his detour route in place as an alternative to sitting in traffic.
The first phase didn't address all the problems because the size and cost of the overall project led to the need to break it into two parts. That was due to funding constraints and the fact the state agency does not go into debt to fund its projects, TDOT officials said.
"We are a pay-as-you-go state. This project was too expensive to complete under a single contract, which is why it had to be broken up into two separate projects," TDOT spokesperson Rae-Anne Bradley said this week via email.
"The total project's [phases 1 and 2] aim was to improve safety and alleviate the bottlenecking issue at the I-75 north to I-24 west ramp," Bradley said, noting phase 1 did improve some elements of the bottleneck.
"Phase 1 accomplished this in part by eliminating the I-75 north merge movements at Ringgold Road and the welcome center," Bradley said. The Ringgold Road loop ramp now starts the fourth lane of I-75 north, and a ramp has been tied to the welcome center that allows traffic to head either north or west, she said.
"Additionally, capacity has been added to I-75 north with a fifth lane beginning just north of the Ringgold Road overpass," she said.
Until phase 2 is complete, here's a tip for victims of the bottleneck on I-75 north.
After entering the right lanes on I-75 north marked exit only for I-24 west, work to stay in the left exit only lane going toward the overpass to allow room for traffic from East Ridge and the Welcome Center to merge in from the right. The right lane ends soon, so all vehicles must make it to the left exit only lane eventually before entering I-24 west.
But because phase 1 also had to meet and tie back into the existing three lanes on I-24 west, that meant the on-ramp from northbound I-75 to westbound I-24 had to be reduced back to one lane before reaching the Spring Creek Road underpass to link with the two on-ramp lanes from I-75 south to I-24, Bradley said.
The end of phase 1 and the beginning of phase 2 on the westbound side of I-24 are indicated by four red, diamond-shaped signs and a sudden end of the pavement.
Drivers will notice a new permanent posted speed limit throughout the interchange of 50 mph.
Phase 1 also included replacement of the Spring Creek Road bridges over I-24, and that portion of the project also wrapped up last week with new sidewalks and bike lanes. The contractor didn't install crosswalks because there are no sidewalks beyond the intersections with North Terrace and South Terrace, and traffic signals at those intersections are on city property, Bradley said.
The cost of phase 1 rose from the original contract amount of $132.6 million to $133.5 million because of about $850,000 in change orders, Bradley said. She said the state has paid Marietta, Georgia-based C.W. Matthews Contracting Co. $131.7 million so far, and officials are proud the project was "completed on time, on budget."
TDOT says phase 2 work will have more impact on the bottleneck.
"In the future, the I-75 north to I-24 west ramp will have three through-lanes to I-24 west — meaning no merging will be required to remain on I-24 west — and the middle lane of I-75 morth will be an option lane," Bradley said.
There will be a total of six lanes where the two I-24 ramps meet at the Spring Creek Road bridges, she said.
In phase 2 on I-24 west between Spring Creek and Germantown roads, the sixth lane will end just past Spring Creek Road, the fifth lane will end just past the Moore Road exit and the fourth lane will end between Belvoir Avenue and Germantown Road to match the existing three lanes that cross Missionary Ridge, according to TDOT.
"This should alleviate remaining traffic congestion now being experienced on the ramps from I-75 to I-24 west," Bradley said. "Phase 2 will also complete the widening of I-75 to the East Brainerd Road interchange."
In phase 2 on I-24 East, a fourth lane will start past the Belvoir Avenue overpass, the Moore Road on-ramp will become the fifth lane and five lanes will pass under the south end of the Spring Creek Road bridges as they approach the on-ramps for I-75 north and south, officials said.
Phase 2 has been funded for fiscal year 2022-2023 and is expected to be under contract by the end of 2022, meaning drivers should see construction underway in spring of 2023, Bradley said.
"Also of note, phase 2 will also be constructed using the design-build alternative delivery method," she said.
The current project at the Split is an example of that method, which "combines all or some portions of the design and construction phases of a project — including design, regulatory permit approvals, utility relocation, and construction — into a single contract," Bradley said. "This means the project will move forward quickly once awarded."
Phase 2 of the Split project is in Tennessee's updated transportation funding plan for fiscal years 2022-2024, TDOT officials said in May. That plan was released April 28.
Ongoing improvements to the I-24 corridor in the phase 2 area are also contained in a separate $32.9 million project by Bell and Associates Construction that includes the new overpass completed in March on Belvoir Avenue over I-24 that provides room underneath for additional phase 2 lanes, and new bridges on I-24 over Germantown Road that also provides room to add lanes in the future.
The now-finished interchange improvement project at the Split started in spring 2019 in answer to decades of daily backups and crashes that often left traffic at a standstill. The improvement project widened existing roads and ramps, increased the radiuses of ramps, reconfigured entrance and exit ramps on I-75, shifted the interchange to the west and modified the Tennessee Welcome Center area traffic circulation.
During a 2017 project kickoff event, then-TDOT Commissioner John Schroer called the Split "about the worst interchange in the state of Tennessee."
Contact Ben Benton at email@example.com or 423-757-6569. Follow him on Twitter @BenBenton.
Top 10 bottlenecks in U.S. for 2021
— Fort Lee, N.J.: Interstate 95 at State Route 4.
— Cincinnati: Interstate 71 and Interstate 75.
— Atlanta: Interstate 285 at Interstate 85 North.
— Atlanta: Interstate 20 at I-85 West.
— Houston: Interstate 45 at Interstate 69/U.S. 59.
— Chicago: Interstate 290 at interstates 90 and 94.
— Chattanooga: Interstate 75 at Interstate 24.
— St. Louis: Interstates 64 and 55 at Interstate 44.
— Rye, N.Y.: Interstate 95 at Interstate 287.
— San Bernardino, Calif.: Interstate 10 at Interstate 15.
Source: American Transportation Research Institute