Lax oversight by New York City transit authorities and faulty redesign of an automatic stop arm system caused a Brooklyn subway to crash February 9, 1995 into the rear of a standing train, according to the National Transportation Safety Board. The accident resulted in 15 minor injuries and damage estimated at more than $1.5 million.
The design flaw allowed a northbound M train to slow down enough -- a practice called "keying-by" -- to slip by an automatic stopping arm that trips the train's emergency brake to ensure compliance with a red signal. The Board also said the M train went on to accelerate around a blind curve and failed to stop in time to avoid colliding with a stopped 10-car B train. The accident occurred on an elevated track about 1,000 feet south of the Ninth Avenue Station.
The Safety Board formally urged the New York City Transit (NYCT) to make changes in signal system design and management oversight practices. Another collision at the same location occurred five years earlier under similar circumstances. Since July, 1990, there have seven accidents injuring 115 people in the New York subway system because of trains keying-by red signals, according to the NTSB.
"The National Transportation Safety Board determines that the probable cause of the rear-end collision of two ... subway trains ... was the inadequate oversight and compliance program of the Metropolitan Transportation Authority/New York City Transit to ensure that train operators comply with published transit operating rules," said the NTSB in its report.
"Contributing to the collision was the design modification to the automatic 'key-by' feature of the automatic stop arm that enabled the operator of the M train to pass a stop signal contrary to the published operating rules that require stopping at a red signal unless permission to pass is granted by NYCT," the report added.
The M train was on a shuttle run through the Fort Hamilton Parkway Station; thirty-four feet beyond was a signal (D2-532) on the right side of the track; the automatic stop arm device was on the other side. The Safety Board noted that had the operator halted at that red signal, he would have violated NYCT rules against stopping an empty train at a station.
The Safety Board estimated that the M train operator was able to "key-by" at a speed under 5 MPH , and if he hadn't been able to do so "the collision probably would not have occurred." The Board concluded that had the train operator seen the stop arm go down as he stated, he would have been unable to readily see the signal even had he looked because of his train's position.
"The New York City Transit lacks an adequate oversight testing program to ensure operator compliance with critical speed and signal operating rules," declared the Board.
The Safety Board conducted tests to simulate the accident. Based on these, it concluded the M train reached a speed of at least 25 MPH before the operator placed it in emergency braking. "Had the train been traveling at 15 MPH -- the posted speed limit --the collision might not have occurred," said the Board.
In its recomendations, the Safety Board asked NYCT to upgrade specific signals; deactivate the automatic "key-by" feature at certain signals; improve management practices involving employee evaluation and compliance with operating rules and instructions. The NTSB also suggested that NYCT include overspeed protection and positive train separation in the modernization of its signal system.
The Safety Board's complete printed report, PB96-916301, will be available from the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161. The NTIS telephone number is (703) 487-4650.