Building Risks: The 1992 Hoofddorp (Netherlands) Train Derailment
Background
Hoofddorp is a town of 77885 people in the western Netherlands, located in the North Holland Province 11.5km/7mi south of Haarlem and 17.5km/11mi southwest of Amsterdam (both measurements in linear distance).
The town lies on the Schiphollijn, an electrified, mostly double-tracked main line running from Weesp in the southwest to Leiden in the northeast on 53km/33mi of track. The line’s first section opened in 1978, with the last section not opening until spring 1993. The line is used by various regional and long-distance passenger services at speeds of up to 160kph/99mph. The line does run through Amsterdam, the Dutch capital, and serves both the city’s airport and stations in Amsterdam, but does not include the city’s main station.
The Train Involved
Intercity 2127 was an express passenger service from Amsterdam to Vlissingen. The train consisted of two type ICM electric multiple units coupled together, bringing the total train to 7 cars. The ICM (Intercitymaterieel, literally meaning “Material for Intercity trains”) was a three- (first batch) or four-car (second batch) electric multiple unit introduced in 1983. The trains measure 80.6m/264ft in length (second batch: 107.1m/351ft) at a weight of 144 metric tons (192t) empty and can carry 187 passengers (253) in a two-class configuration at speeds of up to 160kph/99mph. The train involved in the accident consisted of one unit from each batch, with the unit from the second batch leading.
Forming trains out of several units was a big part of the train’s development, and the end cars were thus fitted with an elevated driver’s cab allowing passengers to move between coupled-together end cars beneath the driver. This gave the trains a unique, somewhat intimidating front end design. It also earned them the nickname “Koploper”, which translates to “head-runner” as you could walk through the train’s head.
The Incident before the Accident
Work was underway in late 1992 remodel the southern side of Hoofddorp station due to extension of the local rail yard. The old and new sections of track were not quite aligned, requiring a temporary S-curve to be constructed so trains could still move through the site. A specialized tamping-machine meant to construct the curve was sourced, intending to build the S-curve wide enough for trains to maintain the local 90kph/56mph speed limit. The machine broke down before the work was finished, but the curve was still constructed and opened in mid-November 1992. Something did appear off with the curve quite soon though, as the first six trains to pass through the side all reported strong vibrations which led to the traffic managers suggesting a 30kph/19mph speed limit. Close inspection of the curve led to a speed limit of 60kph/37mph being issued.
On the 28th of November the express service from Paris-North to Amsterdam Centraal (the main station) was diverted via Hoofddorp. The train consisted of several four-axle express passenger cars pulled by a Belgian class HLE 25.5 locomotive. The driver of the train failed to decelerate ahead of the curve and entered it at approximately 120kph/75mph. The heavy locomotive made it through the curve but destroyed the track, dragging the first two passenger cars along with the third derailing. Somehow, nobody was hurt in the derailment.
The Accident
The curve was rebuilt the day after the accident, being opened with a 30kph/19mph speed limit which was raised to 60kph/37mph for the 30th of November. The first train over the site that day was IC 2127, consisting of two ICN-units. The train reached the curve at 7:12am and immediately derailed. The leading car tilted out of the curve, dug into the ground, tore off its train and overturned, landing next to the tracks pointed in the opposite direction. The remaining six carriages also derailed but remained aligned with the track. Five people died, all in the leading car, with 33 more being injured.
Aftermath
It was soon determined that the rails had been intact before the derailment, with evidence suggesting that, just like the derailed train 2 days prior, the train had been speeding as it attempted to pass through the site. Calculations by the investigation showed that the curve’s critical speed had been between 85 and 105 kph/53 and 65mph, meaning that a derailment was risked if a train exceeded 84kph/52mph. This was below the official speed limit of 90kph/56mph, which itself is meant to be slightly below the critical speed.
The ICN has no equipment to log the driven speed, but the investigation’s examination of the wreckage resulted in the estimation of the speed at 123 to 130kph/76 to 81mph, the site’s usual speed limit when there was no construction work, with the train driver only braking right before the accident (barely reducing the speed). The driver, who survived the accident, insisted that he hadn’t been informed about any lowered speed limit, but the initial investigation insisted that the NS (dutch national railway) has an established system for such information and thus concluded with the theory that the driver had received the written instruction regarding the limit and hadn’t read both it and the trackside signage announcing the limit.
The NS had originally issued form TSB 49 (“temporary speed limits week 49”) to its drivers, which included a 90kph/56mph speed limit for passenger trains at the site with freight trains being given a lower speed limit. After the first derailment an amendment was issued (ATSB 49-I), dropping the speed limit in the area to 60kph/37mph and to 30kph/19mph at the curve in particular. The amendment was issued to drivers not along the same way as the TSB-list was issued (per mail) but instead handed to the train drivers in the form of a written notice by the platform supervisors at surrounding stations.
The train driver insisted that he had known about TSB 49 but had no knowledge of ATSB 49-I existing, claiming that he believed the speed limit was 90kph/56mph and thus entered the curve at 80kph/50mph. This was above the 60kph/37mph speed limit, but below the critical speed calculated by the investigation. The train driver stated that he had seen a 30kph/19mph speed limit sign right before the derailment and triggered an emergency stop, while he said he had seen the 60kph/37mph speed limit signage as 90kph/56mph signs due to the positioning of the ICN’s driver’s cab which was higher and further back than most locomotives. His claims could be neither proven nor disproven, and while he was removed from his position on the reasoning of having caused the derailment by speeding no criminal charges were filed against the driver.
The railway accident board found several issues with both the NS’ organizational structures and the investigation, admitting that this created uncertainty in the investigation’s objectivity. First and foremost, the TSB-forms were distributed to train drivers via regular mail, meaning they had to show up in around 400 mailboxes with perfect timing or a train driver would only know about speed limits if they spotted and correctly read the trackside signage, assuming those were set up properly by the construction crews. The distribution of the amendments was also called into question, since relying on the platform supervisors to hand the drivers the piece of paper (and for the train driver to immediately read it) was deemed insufficient for such a critical matter. The board thus suggested that the driver be rehabilitated and be given his job back, something the NS ended up doing.
The aftermath of the derailment also brought three main changes to how the NS operated:
- The preparation and performance of construction work was overhauled. Mainly, technical drawings were now required if a curve was to be constructed and the allowed maximum speed would need to be calculated. Before this rule-change the speed limit would be estimated.
- The production and distribution was improved with dependability in mind, ending the reliance on the regular mail and the platform supervisors.
- The rules for the installation of temporary speed limit signs were tightened.
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