Wednesday, July 24, 2024

NCDOT proposes plans new interchange for Isabel Holmes Bridge intersection

The NCDOT has three distinct construction plans for the increasingly congested intersection on the western side of the Isabel Holmes Bridge.

Changes are being proposed by NCDOT for the intersection at the west end of the Isabel Holmes Bridge (Port City Daily/Courtesy Google)
Changes are being proposed by NCDOT for the intersection at the west end of the Isabel Holmes Bridge (Port City Daily/Courtesy Google)

WILMINGTON — Traffic conditions in and out of Wilmington continue to degrade as surrounding communities like Leland and Hampstead grow in population.

For example, existing traffic on U.S. 74 near its intersection with U.S. 17/421 sees about 31,000 vehicles per day and traffic on U.S. 17/421 sees 44,000 vehicles per day.

Increasing traffic on the western, Leland side of the Isabel Holmes bridge, is expected by the North Carolina Department of Transportation to reach 55,000 vehicles per day, which is why NCDOT is proposing improvements for the intersection.

According to NCDOT, “The intersection currently experiences congestion due to heavy left-turn movements from U.S. 74 to U.S. 17/U.S. 421 south; this will continue to worsen in the near future.”

There are three different alternatives NCDOT is proposing for the intersection: a diverging diamond interchange, a flyover, and a trumpet interchange.

Diverging Diamond Interchange

A diverging diamond interchange (Port City Daily/Courtesy NCDOT)
A diverging diamond interchange (Port City Daily/Courtesy NCDOT)

A diverging diamond interchange, like the one in downtown Leland, is one option.

“U.S. 17/U.S. 421 traffic is shifted to flow on the opposite side of the road within the interchange. By crossing traffic to the opposite side of the road between signalized crossover intersections, vehicles making a left turn onto or off of ramps do not conflict with vehicles approaching from the other direction. This allows for traffic signals to be reduced to two phases,” according to NCDOT documents.

Flyover

A flyover interchange (Port City Daily photo/Courtesy NCDOT)
A flyover interchange (Port City Daily photo/Courtesy NCDOT)

Construction of a flyover will allow the left turns from U.S. 74 to U.S. 17/U.S. 421 to become free-flowing.  All other movements at the intersection would remain under signal control. This allows for the traffic signal to be reduced to two phases.

Trumpet Interchange

A trumpet interchange (Port City Daily photo/Courtesy NCDOT)
A trumpet interchange (Port City Daily photo/Courtesy NCDOT)

Converting the existing intersection to a trumpet interchange would make all movements free-flowing, removing the need for a traffic signal.

Construction is not expected to commence until 2022, according to NCDOT plans.


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