NTSB Calls for Tunnel Ventilation During Fire/Smoke Incidents

NTSB is urgently recommending that several transit authorities improve the ventilation procedures for tunnels when a fire or smoke incident occurs.

The agency is recommending that Federal Transit Administration (FTA) conduct a nationwide audit of transit agencies to assess the state of tunnel ventilation systems, written emergency procedures for fire and smoke events, and training to ensure compliance with those procedures. The agency issued similar recommendations to American Public Transportation Association.

NTSB issued three urgent recommendations to the Washington Metropolitan Area Transit Authority (WMATA) to address safety issues that have come to light in the ongoing investigation into the Jan. 12, 2015, electrical arcing and smoke incident near the L'Enfant Plaza station in Washington, DC.

As part of the ongoing investigation, the NTSB found that the WMATA subway system has ventilation fans at strategic locations to remove smoke and heat from tunnels. These fans can be operated in either a supply mode that pulls fresh air into the tunnels or stations, or an exhaust mode that pulls air from the tunnels or stations to the outside. The fans can be operated either remotely from the WMATA Operation Control Center or locally from control panels located at the fans.

According to NTSB, the investigation to date has revealed that WMATA lacks the means to determine the exact location of a source of smoke in its tunnel network; that WMATA maintains no written ventilation procedures for smoke and fire events in the tunnel; and the ventilation strategy that WMATA implemented during the incident was not consistent with best practices.