Eventually it was found that one of the derailed tank cars, carrying tripropylene, had ruptured and the escaping flammable liquid had caught fire.
Thousands of Baltimore workers were forced to leave their jobs and unable to come back for several days until the city could assure that there was no further danger from either the fire or the water main flooding.
The only other direct rail link is the Amtrak Northeast Corridor, a passenger line with only limited freight operations performed by Norfolk Southern Railway.
According to the U.S. Department of Transportation (DOT) report on the incident, officials had long known that the possibility existed for a fire or other disaster to cause a significant problem in the Howard Street Tunnel.
An article published in the Baltimore Sun on July 19, 2001, contains a 1985 quote from an unidentified federal transportation safety official who observed, "... the problem would be getting in there to fight the fire...
To avoid the Howard Street Tunnel, CSXT had to send freight trains west to Cleveland, north to Albany, New York, and then south to Baltimore, incurring a three- to four-day delay.
[2]According to the DOT report on the incident, firefighting efforts could not begin until the exact location of the fire within the tunnel could be found, which finally occurred at 5:00 a.m. (Eastern Daylight Time, 10:00 UTC) on July 19, 2001.
According to a November 2005 Report to Congress[2] The severed optical fiber cable in the tunnel was a major east coast internet communication link belonging to WorldCom.
According to the DoT report, WorldCom was able to install a fully redundant network bypass around the incident within 36 hours, allowing resumption of east coast and transatlantic internet communications.