Tennessee Widening Project to Improve Safety, Increase Capacity

State Route 35 in Tennessee, an 81-mi.-long route, serves as a major corridor from Greenville to Maryville through counties including Jefferson and Sevier. Despite it being a significant roadway, drivers may not be aware of the road. That’s because the section of SR 35 in northeast Tennessee (about 35 mi. east of Knoxville) runs concurrently with U.S. 411. The Tennessee Department of Transportation (TDOT), along with Jones Bros., are in the middle of a widening project along U.S. 411/SR 35.

New Alignment, Increasing Capacity

The purpose of the project is to improve traffic operations along SR 35 to accommodate future traffic projections and provide an acceptable Level of Service (LOS) along the facility through 2037. The project also is needed to assist in system linkage to other sections of SR 35 that are already constructed or planned for improvement.

The route is utilized by local and regional motorists and provides connections to Knoxville, Sevierville and I-40.

“The purpose and need for the project is a combination of needed geometrical improvements that increase safety paired with functional improvements that reduce crashes and improve capacity of routes,” said Jacob Gasnow of TDOT, who is serving as the construction team lead

Photo courtesy of TDOT

Currently, the 3.778-mi.-long segment of U.S. 411/SR 35 is two lanes, and it has reached its peak traffic capacity. The ADT in 2016 was approximately 7,500, and it’s projected to reach more than 11,300 in 2040.

To alleviate the congestion and improve safety of the route, the team is widening the road from two to five lanes. The lane configuration will consist of five 12-ft. travel lanes, including a 12-ft. center turn lane and 12-ft. shoulders (10 ft. paved). The existing roadway has minimal shoulders throughout.

Congestion has increased during construction. This is due to several small sideroads being closed, which results in longer travel times for residents.

Most of the project is new alignment, which allows the contractor to work in an environment without traffic disruption. It also reduces potential safety issues for the construction workforce.

The new alignment will be constructed to reflect modern standards that allow for improved sight distance, access for businesses and residents along the corridor, and improved accessibility for motorists that use the route between Sevierville and Newport.

The project also includes the construction of seven box culverts which will carry the streams and the placement of fill material throughout the new corridor. The largest box culvert on the project is a triple barrel 14 ft. by 12 ft. reinforced concrete box culvert at a length of 429 ft. It will carry Flat Creek.

“During construction of the box culvert, the stream will be maintained through a temporary diversion channel that was designed and included in the contract documents,” Gasnow said.

As part of the grade work, the team is excavating and hauling 1.5 million cu. yds. of material. Crews are blasting a large presplit wall.

“When encountering areas of solid rock, the department will include areas to which rock is presplit by a means of technical, controlled blasts,” said Gasnow. “The rock that remains will be a near vertical plane adjacent to the roadway that mimics a retaining wall.”

Team Has Experience

The significant amount of earthwork (in addition to low bid) on this project made Jones Bros. a good choice for the project.

“Jones Bros. has extensive experience in mass earthwork moving along with specialized earthmoving equipment,” Gasnow said. “Their equipment and experience allow them to max out their mass hauling phases to move all the material that is required efficiently.”

They also have worked with TDOT regularly over the years and have been good partners.

Jones Bros. is using large Caterpillar 777 haul trucks, which they maintain on-site to transfer the material. The team is doing controlled blasting for the rock excavation and construction of the presplit.

Other members of the team include:

• Charles Blalock & Sons who participated in constructing several box culverts on the project
• Stratified — the drilling and blasting sub that is performing the production and presplit blasts
• Kimberly (DBE) is performing the erosion and sediment control for the project.

Helpful Heads-Up

There are bound to be some surprises when new road construction is being done. In this case, TDOT’s preconstruction staff conducted a good site investigation.

Photo courtesy of TDOT

“The preconstruction staff was able to give the construction crews a lot of really good information on what to expect,” Gasnow said.

However, the construction team has run into some site conditions that they were not anticipating. East Tennessee is known for its geotechnical variations in subsurface conditions.

“While there was extensive drilling during preconstruction geotechnical investigations, due to the nature of the existing rock, the construction team has had to make minor field adjustments to accommodate field identified rock lines prior to presplit operations,” Gasnow said.

“During construction, we handle the unexpected site conditions by maintaining open communication between field staff and geotechnical staff,” Gasnow said. Because of the variability of geography in east Tennessee, TDOT maintains a geotechnical presence in the Region 1 headquarters. As potential issues arise, geotechnical engineers quickly assist with questions, which allows projects to maintain scope and schedule.

Sticking to Details

Begun in May 2023, the project is set to be completed by October 2026. The project is slightly behind when looking at time expended compared to payments administered; however, according to the project schedule, the contractor is relatively on track for timely completion.

Photo courtesy of TDOT

During the project, the department has adjusted the alignment of utility poles and tie-ins between the new alignment and the existing road. The contractor has been diligent in progressing work efficiently despite the modifications required.

The construction budget for the project was a tick below $65 million. The federal government is contributing 80 percent of the funding, and the state is paying the remaining 20 percent. So far, the project is tracking to be on budget.

The driving public will benefit greatly when the U.S. 411 (State Route 35) project is over, as the road widening will make the route safer and enable more reliable drive times. Despite the improvements, commuters might still be uncertain about the route number they’re driving on. CEG