As motorists on Interstate 840 enter Dickson County, they’re heading northwest, and the road is about to end as they approach Interstate 40.
The motorists first encounter Exit 1B to go east toward Nashville. Just ahead at Exit 1A, an overhead sign for Memphis directs all remaining 840 traffic onto a two-lane ramp that rises to the right, curls left and narrows as it descends to I-40 West.
Under a proposal being studied by the Tennessee Department of Transportation, westbound 840 motorists would get a third option as they approach these exits. They could skip them both and continue on a new stretch of 840 to Highway 96 in Burns.
The proposal would be the first extension of 840 since the 77-mile outer Nashville bypass between I-40 near Dickson and I-40 near Lebanon was finished in 2012.
Plans to make 840 an entire loop around Nashville were officially halted by TDOT in 2003, and no plans for that have been restarted, TDOT spokeswoman Kathryn Schulte confirmed.
The Burns extension was inserted into a 2017 state law called the IMPROVE Act, which put nearly 1,000 transportation projects statewide in line for funding.
The Burns extension is in the early planning stages, according to Schulte. TDOT is studying alignments for the extension as well as new ramps at the 40/840 interchange and designs for an 840/96 intersection, she said.
“Right now, the planning document is expected to be complete by the end of the year,” she said in an email. “But the project managers explained that the timeline may change since we will need to coordinate with the Federal Highway Administration regarding the I-40 interchange.”
For highway construction involving multiple components, funding is typically provided in installments over many years. Roadway elements are finished at various times, gradually expanding the number of traffic patterns.
Ultimately, a Burns extension of 840 to Highway 96 would mean four new lanes of a divided highway with new on-ramps and off-ramps at both ends.
In order for the motorists heading from Highway 96 toward I-40 to be able to get on I-40 east and west, two new ramps off the planned roadway would be built. And for traffic on I-40 in both directions to use the 840 extension, two additional ramps would be constructed.
Four new ramps at 40/840 would bring the total to eight, making a complete interchange for the two limited-access highways, as they would cross instead of form a T-junction like they do now.
IMPROVE Act of 2017
The extension of 840 in Burns is listed among 962 transportation projects across Tennessee in the 2017 IMPROVE Act. The state law lowered the food tax and raised the gas tax with the intent to fund the listed projects.
TDOT received a $30 million state budget allocation in fiscal 2020 to study the 840 extension in Burns, Schulte said.
“As part of the investigation of the extension of I-840, the interchange at I-40 is also being studied for additional ramps,” Schulte said in an email. “The ramp geometry is yet to be determined at this time and TDOT is reviewing past studies/plans to determine what the interchange was originally designed to accommodate.”
An 840/96 intersection “is also being investigated using traffic analysis software to determine the intersection type,” she said. “Typically, this analysis will determine if an at-grade intersection will operate at an acceptable level of service prior to investigating more robust grade-separated interchange alternatives.”
According to Schulte: “The study is being funded through state dollars, and the project is likely to shift to a federal-state split once the project moves into additional phases of development.”
Under the National Environmental Policy Act (NEPA), highway projects using federal funds go through environmental review and public participation processes if a project’s impact is expected to be significant. There are different levels of documentation and public participation, depending on a project’s scope.
According to the Federal Highway Administration, the NEPA process seeks to strike a balance between the benefits of improved transportation and the impacts on “parks, wetlands, historic sites, businesses and neighborhoods.”
Schulte said of the Burns extension: “The planning document with the proposed alignment options is the first step in the project’s development. Once that document is completed, environmental studies can begin.”
Back at Exit 1A on 840 West, traffic is climbing and descending the ramp, headed for Dickson and points farther west on I-40.
But even now, 840 West doesn’t exactly end where this ramp begins.
To the left of the ramp are barricades and a road-closed sign, blocking two lanes that continue and then dead-end in the shadow of the curling ramp overhead. As the elevated ramp curves right-to-left, it crosses over the closed lane segments below.
These closed lane segments are striped, like lanes in use. They end just before Iron Hill Road. Parallel to them, across a median, there are two more unused lane stubs that are also striped.
As traffic from I-40 in either direction merges onto 840 and heads southeast out of Dickson County, these other two unused lane segments are in drivers’ rear-view mirrors.