CSX Transportation has finished the removal of derailed cars from the Howard Street Tunnel and is expected to resume rail traffic through it by this evening, according to a railroad spokesman.

Thirteen cars of a 79-car freight train left the tracks Thursday in the tunnel and outside its northern portal at Mount Royal Avenue for reasons yet to be determined, said CSX spokesman Bob Sullivan. With the cars removed, he said, railroad officials were repairing and inspecting the tracks to prepare for a resumption of traffic.

Sullivan acknowledged that the incident had disrupted north-south traffic on the CSX line, for which the single-tracked Baltimore Tunnel is a significant bottleneck. But the spokesman said CSX was working with customers to reroute some trains, though they would have to swing far to the west to get through.

In 2001, East Coast freight traffic was disrupted more than a week after cars carrying hazardous chemicals derailed and caught on fire.