Project

I-40: widening & DDIs

As one of the fastest-growing places in the U.S., the Raleigh area needed traffic relief! While initially scoped as a four-year, $360 million job, NCDOT added an extra $60 million to the budget along with two additional years of construction.

The core of this design/build project focused on expanding 4-lane sections to 8 lanes, and 6-lane sections to 10 lanes:
- Widening 12.8 miles of highway.
- Constructing 15 new or revamped bridges.
- Building a new flyover bridge from I-440 westbound to I-40 eastbound.
- Creating 2 Diverging Diamond Interchanges.

We utilized around 400 employees, incorporating every division in our company. The project stretched from the 440 Beltline in Raleigh to just north of Cornwallis Road in Johnston County.

Innovation & Efficiency: Asphalt Conveyer

On the eastern end of the project, S.T. Wooten engineered a unique asphalt conveyor to help streamline hauling processes for crews.

The solution helped move asphalt safely from the plant, over the highway, and into a hopper in the median-area work zone. From there, dump trucks were able to transport the asphalt to onsite paving equipment – without having to go through traffic and slow the traveling public.

The conveyor helped save an additional 8,000 loads from being hauled, preventing dump trucks from needing to merge in and out of traffic while working.

The conveyer also reduced the total number of trucks and fuel needed to run the project. A single truck only has to drive around 100 yards to move the asphalt from the plant to the conveyer. Compare this to a 20-mile round trip that might be required without the conveyer.

Scheduling: Two Diverging Diamond Interchanges

While original project plans only called for one DDI, the NCDOT added a second Diverging Diamond Interchange for the I-40 project.

A DDI allows two directions of traffic – guided by traffic signals, pavement markings and concrete barriers – to cross over each other at traffic signals. This design allows drivers to come through an intersection more smoothly and safely.

To accommodate the DDI in the 40/42 area, two new bridges were built and the roads and area around both sides of the bridge were expanded.

NCDOT added a second DDI to address traffic concerns where Jones Sausage Road crosses over the interstate. This DDI was built on the existing bridge, which is not typical and required a retrofit.

Crews had to pave the first lift of surface then adjust and activate new signals for the pattern over a single weekend. Once in this pattern, S.T. Wooten successfully met the 28-day timeline to complete the median barrier and islands and open the full pattern.

Strategy: Safety & Traffic Solutions

Traffic is always a top concern. It impacts not only the traveling public but also our vehicles, work time, and employee safety.

On this project, we planned ways to make it better for everyone:

We installed two asphalt plants close to the project in the towns of Garner and Clayton. This meant shorter trips for trucks, lessening both the traffic and environmental impacts.

We also created a temporary ramp that ran from a closed highway bridge right down into the median for direct site access. This ramp eliminated 34,500 loads of asphalt from being hauled in traffic. After the work in that area was complete, we closed and removed the ramp.