Interstate Highway 540 at U.S. Highway 1 and Triangle Towne Boulevard
Development of a busy new mall changed transportation needs in Raleigh, North Carolina. The mall's access roadway interchanged with an interstate highway very near the converging of two major highways.
North Carolina Department of Transportation sought greater capacity while providing motorists safe access to both interchanges. The HDR | ICA team proposed and executed designs with minimal footprint and the fewest possible traffic-control issues. Our designs also took great care not to impact the natural environment.
Interstate Highway 540 and the mall's access road cross about a mile from the busy junction of I-540 and U.S. Route 1. An urban loop, I-540 links outlying areas to the urban center. Oft-traveled U.S. 1 passes north and south through Raleigh and runs the full length of the East Coast. Consequently, it sees its share of local and non-local traffic.
We designed two adjacent interchanges. The easternmost junction marked the first Single Point Urban Interchange in North Carolina. This type of interchange can be more efficient than a standard diamond interchange and takes up less space. It allowed traffic to interchange between I-540 and the mall access road, using a single traffic signal.
Just a mile west, we designed braided ramps to move traffic in all directions, between I-540 and U.S. 1. We also took U.S. 1 from a four-lane to a six-lane, divided highway. We graded for two additional lanes to allow for growth.
Environmental issues were a concern throughout the project. The U.S. 1 interchange required two Letters of Map Revision to work around nearby Perry Creek. Stream restoration was implemented throughout the construction of the interchange and braided ramps.
We also overcame sensitive traffic-control challenges caused by a nearby street-widening project.