The Five-Mile Viaduct bridge, one of the Lowcountry’s most stylish and decrepit bridges, is being torn down.

New vs. old

The new U.S. Highway 78 bridge will be significantly different than the 1926 original. Here’s a comparison (all figures in feet):

New Old

Length 1,230 688

Width 46 27

Sidewalk width 5.5 3*

Lane width 12 10*

Shoulder width 4-6 1*

* Approximate

The work is moving slowly at first in order to protect a CSX rail line that runs underneath the bridge.

Once this section is sawed apart and gently lifted away, the demolition will kick into a higher gear, said Jeff Rajabi, a bridge construction engineer with the S.C. Department of Transportation.

“In two to three weeks, the bridge will be gone,” he said.

The state signed a $17.1 million contract with Crowder Construction of Charlotte to demolish and rebuild the bridge, a stretch of U.S. Highway 78 that connected King Street Extension to Rivers Avenue.

The bridge was built in 1926, as development was moving up Charleston’s Neck Area toward the then-new Charleston Naval Base and Shipyard.

A plaque installed on its side noted that the bridge was built by the long-gone “Sanitary and Drainage Commission of Charleston County,” as well as the state, the Atlantic Coast Line RR Co. and the Southern Railway System. The plaque was stolen recently but survives as a black and white photo on the Library of Congress’ website.

A 1995 historical survey of North Charleston concluded that the bridge was eligible for the National Register of Historic Places, and its Gothic arches underneath and concrete railing made it more eye-catching than most Lowcountry bridges built later in the 20th century.

The Charleston preservation community never rallied to try to save the bridge, which spanned a largely industrial area.

That may have been because the bridge’s structural problems were as limiting as its design was appealing.

For more than a decade the bridge was closed to trucks weighing more than 3 tons, and its clearance was 2 feet too low for double-stacked trains to pass underneath.

Several sections had suffered from cracks, and chunks of the bridge had fallen into nearby parking areas. Large shrubs sprouted from its supports.

In 2007 the bridge made The Post and Courier’s list of the Lowcountry’s 20 most deficient bridges, a list based on inspection data from the National Bridge Inventory.

Rajabi said its replacement, which should be finished by the fall of 2014, will be taller, wider and straighter. It also will have 5½-foot-wide sidewalks on each side.

Its completion will trigger another $17 million bridge demolition and replacement job — the Cosgrove Avenue bridge over the railroad tracks between Rivers Avenue and Interstate 26.

That project won’t begin until the new viaduct bridge opens, to minimize traffic snarls in southern North Charleston, Rajabi said. The Cosgrove bridge replacement is expected to take about two years, with a 2016 contract finish date, because workers must keep one lane of traffic open in each direction, Rajabi said.

Not all of the Five-Mile Viaduct Bridge is headed to the landfill — the city of North Charleston received several sections of the concrete railing.

City spokesman Ryan Johnson said the sections are being stored at the old tank farm on Carner Avenue. The city plans to install them at a new park there.

“At this point we aren’t sure specifically how they’ll be incorporated,” he said, “but know that they’ll be featured.”

Rajabi noted that these concrete rail sections were attached to the bridge only by gravity — and by notches in the concrete posts.

The demolition work seemed to cause few traffic problems this week. Cars and trucks can use Garner and Meeting streets to traverse the Neck Area.

Motorists are used to avoiding the bridge. It was closed for several months as work to relocate sewer lines continued, with temporary lines installed on the bridge’s surface.

Reach Robert Behre at 937-5771.