TDOT I-40 SmartWay Cumberland Plateau

Mountainous & Isolated

The I-40 corridor in Putnam and Cumberland counties is a mountainous and isolated four-lane facility known for its high traffic volumes and truck traffic. This 50-mile segment experiences significant elevation changes that present both engineering challenges as well as safety risks—the latter including 2,088 crashes over a three-year period that have led to 24 fatalities.

TDOT called on Gresham Smith to design its Intelligent Transportation System (ITS) I-40 extension along this remote stretch to better manage congestion issues and traffic incidents. Once implemented, the ITS system would provide new ITS coverage along I-40 from Cookeville (eastbound) to State Route 299, enhancing TDOT’s efforts to monitor and maintain this section of corridor that is especially hazardous during the winter.

A Tough Location, Location, Location

One of the most complex challenges addressed by our team was the isolated location that had no direct access for connective communications to TDOT’s Region 2 TMC in Chattanooga, Tennessee.

Adding to the complexity, the 50-mile section of corridor was underscored by rocky, steep grades, sheer drop-offs and a limited area beyond the roadway and shoulder in which fiber-optic cables could be buried, and ITS device poles, cabinets and dynamic sign structures could be placed.

It Took a Village!

To meet these formidable challenges, Gresham Smith harnessed the power of a multidisciplinary team comprising 30 staff from five offices, bringing disciplines to the table such as environmental engineering, GIS mapping, bridge design, utility design, transportation planning, and transportation systems management and operations expertise.

The project also involved collaboration and engagement among a wide range of stakeholders, including TDOT, Tennessee Highway Patrol, the Putman County Office of Emergency Services, and Region 2 TMC staff.

Flying High!

Our design took into account the need to have camera coverage at 2-mile intervals along the corridor, as well as dynamic message signs at key decision points and the ability to provide safe access to cabinets and devices for maintenance personnel. A concern identified early in the design was the extent of coverage the new cameras would provide given the challenging project terrain.

To address this challenge, we flew drones at each proposed camera location and captured video of the view. This allowed us to confirm the proposed camera locations—which would sit atop 80-foot poles and provide TDOT with the coverage needed prior to the installation of expensive equipment that could not be easily relocated. This was the first time TDOT used this technology and process on a project.

Connecting an Island of Technology

Along with being 100 miles from the Region 2 TMC, the nearest TDOT fiber-optic communications cable was located 25 miles away, to the east, on I-75.

To achieve resilient communications, our team’s solution was to use a private VPN tunnel via the TDOT construction office to connect this island of technology back to the Region 2 TMC. The completed project included new fiber-optic backhaul, network hubs, radar detection sensors, dynamic message signs to alert motorists of road conditions, as well as road weather information sensors and CCTV cameras.

Supporting TDOT’s Strategic Highway Safety Plan “Toward Zero Deaths,” Gresham Smith’s technological and operational solutions help TDOT Region 2 TMC keep their eyes on the road, raising the bar on safety along this vital stretch of I-40.