PDFversion

****

**ATL98FR015****DERAILMENT****MASSACHUSETTS BAY TRANSPORTATION AUTHORITY****BOSTON, MASSACHUSETTS****MAY 4, 1998**
At 3:23 p.m., eastern daylight time, onMay 4, 1998, Massachusetts Bay Transportation Authority (MBTA) passengertrain 642-43-626-27, consisting of four passenger cars and crewed by asingle train operator, derailed its two lead cars as the train proceededwithin a 500-foot-radius curve between Government Center and Bowdoin Stationson the MBTA system's Blue Line. Three of the train's 10 passengers andthe train operator reported minor injuries.
Train 642-43-626-27 was in revenue serviceon the Blue Line, making regularly scheduled stops to pick up and dischargepassengers. The train operator said she had departed Government CenterStation and was proceeding toward Bowdoin Station at 10 mph in a curvewhen she heard a loud "bang" and the power went out. Postaccident testsconducted by the MBTA indicated that train 642-43-626-27 had been movingat 10 mph when the derailment occurred.
Investigation revealed that a wheel onthe number 2 truck of the second car had climbed the rail and caused thecar to derail. The derailment of the second car forced the lead car toderail. The train traveled about 40 feet after derailing and struck theside of the tunnel wall. A wayside telephone on the tunnel wall caughtfire after being struck by the derailed equipment.
The train operator and an MBTA inspectorevacuated the passengers, moving them along the tracks to the Bowdoin Stationplatform. The Boston Fire Department responded to the accident scene andextinguished the fire at the wayside telephone. Emergency medical respondersat the Bowdoin Station treated the injured passengers and the train operator.The train operator and two passengers were transported by ambulance toMassachusetts General Hospital. The passengers were treated for smoke inhalationand released later that day. The train operator was treated for smoke inhalationand dizziness and then released. The carrier's postaccident toxicologicaltest of the train operator for the presence of drugs and alcohol was negative.
To carry out an established renewal plan,the MBTA Right-of-Way Department had been replacing 39-foot sections ofthe rail and track structure each night. The night before the accident,the MBTA Right-of-Way Department had been working on and had replaced aportion of the rail and track structure in the curve where the accidentoccurred. The running rails, restraining rail, and all the ballast, ties,plates, and spikes were removed; and new ballast, ties, running rails,plates, and spikes were installed. The new restraining rail, however, wasnot installed before the track was put back in service for the morningrush on the day of the accident.
A restraining rail is used both to preventderailments and to reduce rail wear. The restraining rail is positionednext to the inside running rail. When a car negotiates a curve, centrifugalforce causes the wheel set to move toward the outside rail. Contact betweenthe inside wheel and the restraining rail prevents the wheel set from pushingagainst the outside rail, which prevents wheel climb and subsequent derailment.
In response to the removal of the restrainingrail, the MBTA Right-of-Way Department established a 10-mph speed limiton this section of track. The speed limitation was communicated to thetrain operator by a flashing yellow lantern located to the right of therail. This particular curved section of track already had a speed limitof 10 mph, even when the restraining rail was in place. The investigationdetermined that the MBTA does not have a policy addressing train operationsover track where restraining rails are required but are not in place.
PROBABLE CAUSE
The National Transportation Safety Boarddetermines that the probable cause of this accident was the failure ofthe Massachusetts Bay Transportation Authority to have adequate proceduresin place to ensure safe operations when restraining rails are not in place.
**Adopted: December 1, 1998**
NTSB Home| Publications