On the evening of July 18, 2013, a CSX freight train carrying municipal solid waste on tracks of the Hudson Line along the Harlem River Ship Canal in the New York City borough of The Bronx partially derailed between the Marble Hill and Spuyten Duyvil stations. While no one was injured, the derailment caused over US$800,000 in damage and took several days to clean up. Commuter rail service by Metro-North Railroad, which owns the line, was suspended for two weekends in order to fully restore normal operations.
After investigating the accident, the National Transportation Safety Board (NTSB) found it had been caused by the track stretching to an excessive gauge at the point of derailment. It did not fault the crew, instead criticizing Metro-North for failing to maintain the track and surrounding ballast to the point that the track went out of gauge. Later in the year, in a comprehensive safety review after another derailment of a passenger train nearby resulted in the first passenger fatalities in Metro-North's history, the NTSB cited the maintenance shortfall as part of an inadequate "safety culture" at the railroad.
Background
The CSX train left Oak Point Yard near Hunts Point in the South Bronx at 6:30 p.m. that evening. The weather was clear and hot—temperatures were above , as they had been for the previous three days, enough for the National Weather Service to have issued a heat advisory for the city. A crew of four, an engineer and conductor plus a trainee for those positions, led a consist of two SD40-2 locomotives and 24 flatcars specially modified to carry four large containers of solid waste collected by New York's sanitation department to a landfill in Virginia.
From Oak Point the train went first south along the Northeast Corridor line also used by Amtrak, until it left to follow a spur west along the north side of the Bronx Kill and, after that, the Harlem River, where the track turned northwest to follow the river. At Highbridge Yard, the train followed the track as it merged onto those used by Metro-North Railroad's Hudson Line commuter rail service from Grand Central Station to points along the east bank of the Hudson River as far north as Poughkeepsie. It was one of four such waste trains that regularly use the Hudson Line's tracks each night; two northbound with full containers and two southbound returning the emptied ones.
There are generally two tracks along this stretch, both electrified with third rails for Metro-North's electric multiple unit trains serving the stations along the Hudson Line south of Croton-Harmon in Westchester County. With a few exceptions, they are immediately adjacent to the river and almost completely level. They consist of ribbon rail laid in standard gauge on prestressed concrete ties supported by a bed of crushed trap rock ballast.
In Metro-North territory, the train passed the Morris Heights and University Heights stations, serving those areas of the Bronx. Just north of the latter, a third track diverged to allow trains to bypass the Marble Hill station, in a mainland section of Manhattan, where passenger trains stop more frequently, allowing a transfer to the nearby subway station. Metro-North rates the tracks in this area as Class 2 under Federal Railroad Administration (FRA) guidelines, allowing a passenger speed limit of and a freight speed limit of 10 mph below that allowed by the FRA.
Accident
Almost two hours after leaving Oak Point, the CSX train reached the Marble Hill station, where the train was on the outside track closest to the river and away from the elevated platform. Metro-North train #781, an EMU consist making all local stops up to Croton-Harmon, was stopped at the station while the freight had priority. Ahead, at the control point marking exactly 10 miles (16 km) from Grand Central, was a red signal. The engineer later told NTSB investigators he used the dynamic brakes to slow the train down. It was almost stopped when it changed back to green, allowing the train to proceed.
The CSX engineer began accelerating his train again, preparing to merge on to one of the two main tracks. He was mindful also of a slight curve into a rock cut just past the control point. He followed his usual practice of taking the curve by notching the throttle up until the train had reached Metro-North's 15 mph speed limit, then taking it back down to idle so as to drift through the curve, then notching it up again slowly as it lost speed in the curve.