I-26 overpass No. 4 on 'substandard' list

The Interstate 26 overpass at Dorchester Road is marked by a foot-long gash in its deck and its underbelly looks like it's patched in two places by sheets of plywood.

The span, which carries an average of 86,100 vehicles per day, is rated "structurally deficient" and holds down the No. 4 spot on a list of the state's Top 20 Substandard Bridges released this week by AAA Carolinas.

Still, officials said there is no reason for worry.

"That doesn't mean it is unsafe," said James Law, media relations specialist for the South Carolina Department of Transportation.

The gash in the overpass deck is on the inner edge of the westbound lanes next to the median wall. Though barely visible from the bridge deck, it's clearly visible from underneath while standing on Dorchester Road.

Near the slender gap in the bridge deck is what appears to be a 3-by-4 piece of plywood pressed against the bridge's underbelly by timbers wedged against a bridge-support beam. A much larger sheet of plywood is supported in the same way beneath the outer edge of the westbound lanes.

The gash will be fixed soon but the exact repair date is unknown, Law said. "We know there are some repairs that need to be done to the deck."

The plywood and support timbers are relics of earlier concrete deck-repair jobs on the overpass, which was built in 1961. "They just left it there when the concrete was poured," Law said. The outer edge of the bridge deck in the westbound lanes has a big concrete patch in a lighter shade of gray that appears to match the location of the left-behind wooden support structure underneath.

No serious problems with the overpass were found when it was inspected in October 2008. The next inspection will be in October, Law said.

Three other tri-county bridges, all of them in Charleston County, made the AAA Carolinas list of the Top 20 Substandard Bridges: the I-26 overpass at Cosgrove Avenue; the Wappoo Bridge; and the North Bridge over the Ashley River.

Those three bridges made the list because they are considered "functionally obsolete."

Bridges deemed structurally deficient have deteriorating decks, piers and other components. Not all are unsafe, but some might need immediate repairs or have speed and weight restrictions. Inspectors rate structurally deficient bridges using a formula that takes into account traffic, age and many other factors.

"It doesn't really mean that it's dangerous," said Tom Crosby, vice president of communications for AAA Carolinas.

"Functionally obsolete" means having inadequate design for current traffic volume, according to AAA Carolinas.

"None of South Carolina's substandard bridges are in danger of collapsing or pose an immediate threat to motorists at this time," AAA Carolinas said in a statement it released accompanying the substandard bridge rankings.

AAA Carolinas receives substandard bridge data from the SCDOT and then uses an additional formula involving average daily traffic to select the top 20 substandard bridges that affect the largest number of motorists.

The Legislature needs to increase transportation funding before the problem gets in the way of attracting businesses, David E. Parsons, president and chief executive officer of AAA Carolinas, said in a prepared statement.

The state gas tax is among the lowest in the nation and has not changed since 1987. The cost of construction, diesel fuel, concrete and other materials has gone up significantly over the past 23 years, according to AAA Carolinas.

Reach Prentiss Findlay at 937-5711 or pfindlay@postandcourier.com.