TDOT SR-25 – Accelerated Bridge Construction in a Rural Setting

Built in 1954, the existing bridge over Liberty Branch Creek on State Route 25 in rural Sumner County had seen better days after years of service. Additionally, peak-hour traffic volumes and the functional layout of SR 25 would not facilitate a traditional traffic control plan for this location. Recognizing the failing bridge was in need of major and time-consuming repairs, Tennessee Department of Transportation (TDOT) selected Gresham Smith to develop a set of plans for the rural bridge repair project that would provide a reliable structure for years to come while addressing current traffic issues.

lane rural state route

single-weekend road closure to complete ABC

hours ahead of schedule

Finding the Right Solution

The two-lane rural state route proved to be a challenging setting for the bridge rehabilitation project. Concerned that the location didn’t provide an adequate detour route to allow for a more traditional construction project, Gresham Smith and TDOT determined that Accelerated Bridge Construction (ABC)—a process that dramatically reduces construction time as well as long-term inconvenience to motorists—was by far the best solution.

To address concerns associated with the rural location and the use of specialty ABC equipment, we developed an alternate plan set utilizing readily available, traditional construction equipment and precast bridge elements that would allow the bridge to be built during a single-weekend road closure.

Tic-Toc Around the Clock

Starting Friday, July 31, 2015, at 8 p.m., TDOT closed a section of SR 25 just north of Liberty Lane to allow road crews to carry out around-the-clock repair work. This began with the demolition of the existing bridge superstructure and midstream bent. Erection of the new precast bridge elements began at 4 p.m. Saturday and was completed by 6 a.m. Sunday.

Finishing Ahead of the Curve

Once the precast bridge elements were in position, the contractor mixed and placed the concrete closure pours using a high-early-strength concrete mix that would gain strength in less than eight hours. Paving of the approach roadway and sealing of the concrete deck began Sunday afternoon. The remaining work was completed by 11 o’clock Sunday evening, allowing the bridge to open a full six hours ahead of schedule.

Setting the Standard

Completed within a single-weekend road closure, the project has been identified as the prototype ABC project for rural bridge rehabilitation in Tennessee. Along with significantly reducing the project schedule—one weekend as opposed to four to six months that a more traditional phased construction approach would offer—the ABC process also resulted in significant sustainable and environmental benefits, including less disruption to the creek and reduced carbon emissions as protracted traffic delays were greatly reduced. Recipient of ACEC of Tennessee’s 2017 Grand Award in the Small Projects category, the fast-tracked effort represents the first rural ABC weekend-only road closure project undertaken by TDOT.