CORNELIUS Nightly lane closures are scheduled to begin Monday on Catawba and West Catawba avenues, as the state begins converting a prime Lake Norman exit at Interstate 77 Exit 28 into a diverging diamond interchange with a lake-themed design.
At least 30,000 vehicles a day travel Catawba and West Catawba avenues, town officials said.
The exit leads onto Catawba Avenue and downtown Cornelius in one direction, and West Catawba Avenue and Lake Norman in the other direction. Numerous lakefront subdivisions are on roads that lead off West Catawba. Many of the town’s retail centers are on West Catawba, including Magnolia Plaza, where a Publix grocery store is planned, and Jetton Village, which includes a Harris Teeter and small retailers.
Blythe Construction Inc. of Charlotte planned to start work last Monday night, but rain has delayed the project by a week, Assistant Town Manager Andrew Grant said.
A diverging diamond intersection allows two directions of traffic to temporarily cross to the left side of the road while on the bridge. Once on the left side of the road, vehicles can turn left onto the I-77 ramps without stopping and without conflicting with through traffic.
That makes such interchanges far safer than traditional interchanges and less traffic-clogged, transportation officials have said.
Diverging diamonds first appeared in France in the 1970s. The first such U.S. interchange opened in Springfield, Mo., in 2009, and diverging diamonds have since spread to North Carolina and other states.
The $6.2 million Exit 28 project will take about 1 1/2 years to complete; it’s one of several diverging diamonds planned or under construction in the Charlotte area.
Blythe will do much of the Exit 28 work at night, which the town requested to lessen the impact on businesses and motorists.
The first phase will involve demolishing the concrete median islands, Blythe project manager Bobby Eaves said Monday.
The overall construction zone for the Exit 28 work will be along I-77, on the bridge, in the ramp areas, and immediately beside the bridge along West Catawba and Catawba avenues, from Torrence Chapel Road to U.S. 21.
The N.C. Department of Transportation has said no Exit 28-related lane closures will occur during major traffic holidays and NASCAR racing events at Charlotte Motor Speedway. Most construction will occur 9 p.m. to 6 a.m. Sunday nights to Friday mornings; and 9 p.m. to 9 a.m. Friday nights to Sunday mornings.
For about a month next summer, one I-77 lane in each direction will be closed during those hours. In the Catawba Avenue corridor, a full traffic stop for up to 15 minutes might occasionally happen at night.
The project, however, will also require significant periods of work during the day.
Over four months next summer, traffic will be limited to only one lane in each direction across the bridge at all times day and night. That will allow for construction of substantial concrete medians, walls, permanent traffic signals and sidewalks.
Also, in August 2014, the bridge will be closed to through traffic crossing the bridge for 32 hours, to allow for a shift in the traffic pattern to the diverging diamond pattern. That’s expected over a single weekend, between midnight on a Friday and 8 a.m. Sunday. Detour signs will be posted.
The I-77 bridge deck won’t have to be rebuilt, which explains why the project is costing far less than the $30 million to $35 million it would take to build an interchange such as Exit 31 (Langtree Road) in southern Iredell County.
Cornelius will pay for all aesthetic features of the diverging diamond, including four planned masonry walls on I-77 and the spots where pedestrians will stand before crossing Catawba and West Catawba avenues into the median, Grant said. Those costs weren’t available last week.
The places where pedestrians will stand before crossing will include seasonally diverse native plantings, colored concrete edging, and brick and granite pavers.
The bridge will have two tensile cable structures that will include a steel mast and coated steel cable. Each will resemble the mast and sails of a sailing boat. The I-77 masonry abutments will include modular brick, precast concrete, a steel-and-glass lantern and “Cornelius” signage.
The town has a diagram on its website, www.cornelius.org, that shows how traffic flows on diverging-diamond interchanges and what the exit will look like when complete.
Marusak: 704-358-5067; Twitter: @jmarusak
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