DOT Officials: Growth Cause of I-40, I-540 Problem
Posted November 1, 2007
Morrisville, N.C. — Unexpectedly high growth was the root cause behind the design flaws at the intersection of Interstates 40 and 540, Department of Transportation officials said on Thursday.
Around 25,000 cars are caught each morning in a bottleneck that was created when the DOT opened a 4.5-mile extension of 540, called N.C. Highway 540, between I-40 and N.C. Highway 55.
The new highway was supposed to ease congestion and give drivers more options for getting into Research Triangle Park, but DOT eliminated one of two collector lanes for drivers exiting westbound I-540 onto westbound I-40, and the new highway did not draw off enough cars to keep that from being a major problem.
"It's an obvious mistake," one driver told WRAL. "If you can't see it's a mistake, then there's something wrong."
DOT engineers said the bottleneck is a symptom of trying to build our way out of congestion while growth in the Triangle continues. Design problems occur when growth exceeds traffic estimates that were made when the project was designed, officials said.
"The original project was done in the early '90s," Wally Bowman, a DOT engineer, said. "We project traffic 20 years in advance, and the traffic forecast at that time, based on land use and on land development at that time, was that traffic in that particular ramp area would not be that heavy."
When local municipalities rezone areas, more growth than expected occurs, skewing engineers' numbers, Bowman said.
The DOT has created a draft plan to add an auxiliary lane to westbound I-40 between I-540 and Page Road to accommodate the merging traffic. Right-of-way purchases would be funded in fiscal 2009, and construction would begin the next year and end in 2011 – if no new obstacles emerge, officials cautioned.
"if it's already a bottleneck now. ... What's it going to be doing by 2010?" driver Phyllis Newman said.
DOT designated $3.8 million for the project in the latest draft of the annual Transportation Improvement Plan, which contains priority highway, ferry and aviation projects statewide over a seven-year period.
Public hearings will be held on the TIP this winter before the plan is presented to the state Board of Transportation for approval next summer.