Trucks serving the intermodal ports near Charleston, S.C, account for only a small amount of the city's congestion, according to a new study.

The Associated Press reports that the study, prepared for the state Commerce Department, traced trucks coming and going from Charleston-area terminals. The report found that local traffic congestion is caused mainly by non-port traffic.
State port officials said the study confirmed what they've been saying all along.
One area where port traffic is heavy is the Mark Clark Expressway between Long Point Road at the Wando Terminal and Interstate 26. Even without port traffic, two new lanes need to be added to the stretch of highway, according to the report.
Some of the heaviest port-related traffic was found on U.S. Highway 78 heading toward Atlanta.
The study was done in conjunction with efforts to establish an inland port.