Switched Cables: The 2004 Süßen Train Collision

Süßen (pronounced like “Suissen”) is a city of 10159 people (December 2019) in the southern-German federal state Baden-Württemberg, 44km/27mi east of Stuttgart and 145km/90mi west-northwest of Munich (all distances measured in linear distance). The city has no airport and no connection to the Autobahn-Network, but is connected to the Fils Valley Railway running from Stuttgart in the West to Ulm, southeast of the city.

The location of Süßen in Europe.

Opened in 1850 the double-tracked electrified railway line is used by regional trains, long-distance high speed trains including the ICE and French TGV and freight trains (some of which need to be pushed on parts of the route due to relatively steep gradients). It’s somewhat mountainous character also makes the Fils Valley Railway popular for testing with new or refurbished rolling stock. Süßen itself only has regional connections, long distance trains pass through the city without stopping.

The approximate site of the collision, right on the south-eastern end of Süßen station.

On the day of the accident the DB (German national Railway) running regular tests on the rail-network in the area. Pulling the short (4 cars) train eastbound through Süßen was DB Series 752 Number 001. Built in April 1979, then named 120 001 the locomotive had been the first prototype of the new series 120 multipurpose electric locomotive. At the time these locomotives were a milestone in development, being the first ones to use three-phase motors. Meant to pull heavy passenger express trains during the day at up to 200kph/124mph and heavy freight trains at night, replacing most electric locomotives in the fleet, the Series 120 weighted 84 tons at 19.2m/63ft in length and had a combined output of 5600kw/7509hp. The prototypes were painted in a beige-red livery reminisced of the famous TEE (“Trans Europ Express”), a European luxury train network of days gone by, while the actual production locomotives received the DB’s standard all-red livery. 120 001 ended up being transferred to the testing and infrastructure-division, being renumbered 752 001 (the DB’s testing, maintenance and special purpose trains have the “7” as their first number). The high top speed and good towing-capacity meant it could test nearly everything the DB considered using. Despite it’s weathered look the locomotive was popular with enthusiasts, both for the increasingly rare livery and for it’s pioneering role.

120 001 being unveiled in 1979.
The train involved in the accident, filmed by enthusiasts the day before the accident.

Travelling the opposite way from nearby Geislingen towards Süßen was DB Series 426 number 011 in double-traction with 426 number 013. The DB Introduced in 1999 the Series 426 is a two-piece electric multiple unit derived from the four-piece Series 425 for routes with less demand and/or smaller stations. Coming in at 36.5m/120ft overall length a Series 426 can carry 100 seated and another 110 standing passengers in a two-class configuration at up to 160kph/99mph. A 426 can not be lengthened with 425’s middle cars, but they can be combined into double- (two units) or even tripple-traction (three units) should the need arise.

426 011 photographed in Geislingen in 2003.

On the 21st of April 2004 at approximately 8:45am DB 752 011 is pulling it’s testing train through Süßen station, heading eastbound towards Geislingen for the steep “Geislinger Steige”, the steepest part of the Fils Valley Railway. Two men are in the driver’s cab of the locomotive, another 2 are in the first and last car of the testing train respectively watching the computers logging data, separated by two ballast cars. It’s unknown how fast exactly the train was going, approximately 110kph/68mph are a realistic estimate. Coming the opposite way is a double-traction of Series 426 multiple units being ferried from Geisling to take passengers and head back east. As such there are no passengers on board, only the 40 years old driver is on the train. Passing under an overpass as it pulls out of a right hand turn on the eastern end of Süßen station the drivers in the locomotive are suddenly faced with the bright red multiple unit heading towards them on their track. It’s unknown if either train’s driver triggered an emergency stop, if they did it didn’t help. At 8:50am the trains collide head-on at speed approximately 350m/ft outside Süßen station, the massive locomotive drilling itself into the lightweight multiple unit. The driver of 426 011 is killed on impact as the locomotive makes it’s way halfway into the forward section of her train, the drivers on 752 001 survive with injuries after either abandoning their train and jumping out or retreating to the engine bay at the last moment (different reports). The testing-train rear ends it’s locomotive, crushing the rear driver’s cabin and causing the locomotive to push itself upwards into the multiple unit’s roof, almost telescoping out the top. Had the multiple units been occupied, the death toll would have undoubtedly been much higher. As it was the driver of the multiple unit is the only victim, the crew of the testing train survives with injuries.

A photo taken by a passerby after responders arrive, showing the mangled and jammed trains.
The other side of the wreckage, the entire first class (half the forward car) has been obliterated.

The first people on site are employees of an adjacent steel factory, at 8:55 the first professional responders make their way to the scene. Both the professional and the volunteer fire department are soon on site, along with police officers, EMTs, members of the THW (federal technical relief agency, mostly providing equipment) and the DB’s own emergency crew. All in all 268 people are involved in the rescue and recovery operation. The fire departments collect about 600l/160US Gallons of spilled hydraulic- and transformer-oil while the THW starts trying to separate the forward train car from the locomotive. The DB sends a 75 metric ton crane to the scene to help with the recovery and possibly re-tracking of the locomotive which, at the time, has it’s forward end over 1m/3 feet off the ground, being jammed between it’s own train and the multiple unit it tore through. Piece by piece responders cut up the multiple unit, trying to make their way to what’s left of the driver’s cabin. At 2pm one of the doctors on site makes his way to the front of the destroyed train, but can only confirm the death of the driver.

At 5pm a crane manages to pull the locomotive’s wreckage out of the multiple unit, had they remained at the controls the two people on board would not have survived. Later reports talk about the locomotive, a much stiffer and heavier construction, “excavated” the multiple unit’s forward section during the collision. Late at night the trains are pulled apart and re-tracked before being towed into Süßen station for storage and further investigation.

THW-workers inside the remains of 426 011, preparing to install temporary wheel sets.
752 001 at Süßen station before being covered up with tarps.

Even before that investigators form the DB examine the local signal box, talk to the employees. 426 011 was supposed to run on the left hand (usually wrong) track, that way it wouldn’t have to proceed past Süßen in order to get to the right platform for the eastbound trip. It was the testing train that was meant to switch over, make way for the scheduled train to pass. The signalmen on duty claim innocence, pointing to indicators showing the route set correctly with 752’s path diverting around the incoming multiple unit. Looking at the set of points in question they are found to be working just fine, but pointing the opposite way of what is indicated up in the signal box. The investigators follow the wires from either end and find the error. A pair of wires had been switched during maintenance, meaning everything worked but the indication in the signal box was wrong. The indicators showed the points leading straight when they diverted and vice versa. Records are found incomplete, and by the time the police arrives at the signal box the wires have been switched back. Two technicians are blamed for the accident, being suspected to have acted in gross negligence. They consistently blame each other, with their claims also opposing statements of the signalmen about having tested the points and the wiring with no defect found. Along with the records being missing/incomplete the public prosecutor’s office ends up having to end the investigation in 2007 without a definitive person at fault, no-one is ever put on trial since no-one can be proven to be at fault beyond reasonable doubt.
The railway line is repaired by the next day and reopens, 752 001 and 426 011 are removed from fleet lists on the 29th, sold to a local recycling company and broken up at Süßen station. 426 013, the rear unit of the double-traction, is repaired and returned to service some time after the accident. The damage to trains and infrastructure ends up at 5.3 million Euros/6.4 million USD. The historic value of the lost locomotive can’t be valued in Euros.

752 001 nearing the end of it’s disposal in May 2004.

Today nothing at the site or in Süßen points to the accident, there is no memorial or informative plaque. 3 of the five series 120 prototypes still exist, none in operating condition. The Series 120 itself is on it’s last legs, with the last long distance service pulled by one being IC 2161 from Stuttgart to Munich on the 5th of July 2020. A handful of them is still used in regional traffic. 752 001 was the first to be scrapped, of 65 made 14 more have followed since, 24 more are stored in non-operational condition. Most of them are serving as parts-donors for other locomotives and the ICE 1 (which is based on the locomotive) before they will be scrapped. The series 426 is still in service, including the repaired 426 013, but with increasing privatization of regional traffic they won’t be around for much longer.

426 013 in service in 2019.

In 2006 the German model railway manufacturer Brawa started selling an H0-scale (1/87) model of the Series 426 under the article-number 0750. The unit they chose to replicate? 426 011, the one destroyed in the collision at Süßen.

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