Background
Rheinweiler is a town of 1003 people (as of 2021) in the far southwest of Germany, located 14km/8.5mi east-southeast of Mulhouse (France) and 40km/24.5mi southwest of Freiburg (Germany) in the federal state of Baden-Württemberg (both measurements in linear distance). The town sits right on the eastern shore of the Rhine River, which forms the border to France.
Rheinweiler lies on the Mannheim-Basel rail line, also called the Rheintalbahn (“Rhine River Valley Railway”), a 271km/168mi double-tracked electrified main line. Opening in sections until 1855 the line is one of Europe’s main railway corridors, connecting Germany with Switzerland and Italy. The line sees everything from freight trains and regional passenger services to international express trains, allowing speeds of up to 250kph/160mph.
The train involved
D370, named the “Schweiz-Express” (Switzerland Express) was an international passenger servce from Basel all the way to Kopenhagen (Denmark). On the day of the accident it consisted of eight four-axle passenger cars pulled by DB (German national railway) 103 106. Introduced in 1970 the Series 103 is a heavy six-axle electric locomotive designed to pull heavy express trains at speeds of up to 200kph/124mph. They were a big step forward for the DB and held a flagship role in the fleet. Each Series 103 measures 19.5m/64ft in length at a weight of 114 metric tons. Each axle has its own motor, with the combined power output of up to 7780kW/10433hp making them the strongest single-section locomotives in the world at the time of their introduction. At the time of the accident the train carried around 300 passengers, putting it at 75% capacity, running under the command of Mister Mitsch.
On the 21st of July 1971 express train D 370 is approaching Rheinweiler at approximately 1:05pm, travelling at 140kph/87mph. Its driver, 52 years old Mister Mitsch, is on his third solo trip on the new series 103. He has a clean track record, being known as a reliable train driver with good knowledge of the area. Since departing Basel he already managed several speed limits dictated by the curvy route the tracks take along the upper Rhine valley. By 1:08pm the train is approaching another tight right hand turn at the entrance to Rheinweiler station, which has a 75kph/46.5mph speed limit. Instead, Mister Mitsch’s train enters the turn without decelerating at all, at almost twice the speed limit. The train derails just a few feet into the turn, being thrown from the tracks to the left as the locomotive separates from the passenger cars. The locomotive inverts and crashes into a construction pit upside down, crushing the driver’s cab. The leading car, weighing around 40 metric tons alone, crashes through a house next to the tracks, a six years old child dies as the home is reduced to little more than its foundation. Six of the train cars make their way down a five meter (16.5ft) embankment, with only the rear two remaining mostly on the tracks. Twenty-two people die on the train, bringing the death toll to 23 in total, with 121 more being injured.
Aftermath
Mister Hugenschmidt is working on the new Autobahn going past Rheinweiler downhill from the rail line, braving the summer heat when he suddenly hears a deafening crash and sees a big dust cloud rise from the hillside. A moment later a local resident pulls up at the construction site and breaks the news that a train has derailed just up the hill. Hugenschmidt, in his free time commander of the local volunteer fire department, runs over to the fire station, sets off the siren, grabs his gear and sprints up the road to the wreckage. Locals are already climbing all over the wreckage, rescuing and regrouping survivors and rendering first aid. In the chaos of debris, train cars and survivors it takes a while before anyone even notices that a house is missing.
The small town’s responders are overwhelmed in an instant, raising the level of alarm almost by the minute. Civilian responders from the surrounding cities come to their aid, soon extended to involve Swiss and French responders along with the German and French Military as a catastrophic event is declared. Within a short time well over a hundred professional responders are at the site, with helicopters shuttling back and forth between the hillside wreckage and various hospitals. It takes time to even make sense of the wreckage, with some parts of it being barely recognizable for what they used to be. The rail line is completely locked down, any train meant to use it either has to take a long detour through France or be substituted with buses.
With the survivors and victims taken care of the site is handed over to the responders, who have to figure out how the DB’s new flagship locomotive ended up halfway down a hillside, upside down. Everyone wants answers, and they have to try and beat rumors to the public conscience. The series 103 is a big step forward for the DB, in power, speed, technology and operations. Among the changes is a reduction in staff, a driver’s assistant is only needed at speeds above 140kph/87mph. To appease criticism from the public and train drivers alike the locomotives carry state of the art control systems to improve operational safety. Among them is a new automatic drive control (ABF), which has drivers pre-select the desired speed before the locomotive will reach and maintain the selected speed by itself rather than requiring careful operation of the throttle to achieve the desired speed. The system also interacts with the automatic train control, meaning it will not breach the speed limit even if the selected speed would be past the limit.
As investigators recovered the data-logger from the remains of the locomotive they immediately stumbled over an issue. The train had been travelling at 140kph/87mph up until the moment it derailed, in a section of the line limited to 120kph/75mph. The speed limit wouldn’t be raised to 140kph/87mph until several kilometers past Rheinweiler.
It was unusual for Mister Mitsch to speed, in fact earlier in the train’s journey he had apparently elected to only speed up to another section’s speed limit well after it began, certainly not the behavior to expect from a negligent driver. Then why did the train go too fast even before it reached the turn? The investigators couldn’t examine the driver’s cab, after the impact with the far end of the construction pit there was nothing left of it. They were able to tell that Mitsch had pressed the dead-man’s switch (SiFa) seven seconds after the train accelerated past the speed limit, 50 seconds ahead of the crash. But, being unable to prove a technical defect, the investigation had to also consider negligence, human error or some form of medical emergency as the cause of the devastating derailment.
The original investigation concludes in April 1973, with Freiburg’s public prosecutor ending the investigation against the DB as their responsibility couldn’t be proven. With that decision on paper the DB also didn’t have to pay damages to the survivors.
Two lawyers, each representing a number of survivors and victims’ relatives, urged investigators to keep working on finding the cause. Their main argument is a 150-page paper by two Swiss experts, deemed irrelevant by the past investigation, who looked into the Series 103’s technical history. As it turns out, the nice shiny flagship of the DB wasn’t all that nice at all, with complains starting to come in as soon as the first drivers climbed aboard. Not only do drivers complain about having to work up to 14 hours in up to 50°C in summer while lacking footwell-heating freezes their feet in winter, but the ABF also has a history of dramatic malfunctions. One of the first drivers to be instructed for the new type, Mister Mehl, reports selecting 105kph/65mph only for the locomotive to rapidly speed up to 160kph/99mph. In another case a driver noticed the train overshooting the intended speed by 20kph/12.5mph, just like 103 106 did ahead of the accident. The paper argues that this violates one of the basic principles of rail safety, to have any technical defect fail in a way that doesn’t compromise safety. Meaning that a failed speed control should only result in lower speeds, not higher. And the DB seems to secretly agree that the system is flawed, ordering ABF to be deactivated on all series 103’s shortly after the accident.
Even will all the evidence they do have the two lawyers fail to get a new investigation started, because of one simple fact. None of their information proves that the AFB failed on 103 106. And the DB isn’t responsible if their employee acted negligently, became incapacitated or confused about his location. The last attempt to restart the investigation is shot down by 1978, with the decision not to hold the DB responsible changing the responsibilities about rail traffic accidents going forward. Previously, the DB would have been responsible unless an outside factor was proven to be the cause.
Critics point out how the speed limits in the driver’s printout are organized by signage along the tracks which can be hard to see in the dark, fog, rain or, crucially, at high speed. Still, not enough to place blame on the DB, despite their admittance to know about this problem and promising to improve the signs going forward.
Throughout the investigations stands one piece of evidence pushing the fault on the driver. The sharp turn that derailed the train became visible 400m/1300ft before the train reached it, enough, as experts agree, for an attentive driver to trigger an emergency stop and slow the train enough to make it through the turn without derailing. Instead of doing any such thing Mitsch, as the data-logger shows, had his hand on the SiFa-button until the very end. In the end neither party can prove that the other was to blame, nobody knows if the driver sped on purpose, by negligence/error or because he became incapacitated in some way that kept his hand on the SiFa-button. To this day, 51 years on, the exact cause of the accident is undetermined.
There are two more weaknesses that played a role in the accident which the DB addresses after the accident. Firstly, the SiFa-system installed on the series 103 is deemed to be too patient. It requires a button to be pressed by the driver, otherwise the locomotive will automatically trigger a stop after 50 seconds. On the day of the accident, the train wouldn’t have come to a stop until after it was already going through the turn. As a consequence the DB has the system modified, shortening the period before a stop is triggered to 30 seconds.
Another lies in the automatic train control systems. Passing a magnet in the tracks allows the system to register a train’s speed and stop a speeding train regardless of driver input. But the pre-signal outside Rheinweiler, where the speed limit for the turn began, wasn’t equipped with the system, it would’ve only kicked in had the train somehow made it through the turn and raced past the following main signal. After the accident the DB installs 1100 further train control magnets on main lines and 900 on branch lines, expanding the system to include speed limits at pre-signals. The problem had been noted already after another derailment earlier the same year, but the DB only addressed it after the derailment at Rheinweiler.
Today a simplistic memorial stands at the site, a large stone cross standing in a small clearing between the rail line and the main road, right at the entrance to the fateful right hand turn. A new house stands where the leading passenger car mowed through the former one, claiming a life and injuring two people. The construction site that the locomotive crashed into is now a house with a garage roughly where the locomotive came to a halt.
DB 103 106 was the first locomotive of the type to be written off, two more would follow her after severe accidents. By 1997 the DB started retiring the series 103 in favor of the ICE high speed trains and the new series 101, decades of service in front of heavy express trains had worn the locomotives down. Late in their lives some locomotives were used for regional trains, the constant stopping and starting rapidly wore out the systems designed for long distance services. By 2003 the last of the 145 locomotives was retired. A handful was temporarily un-retired over the following years when need arose, but by December 2016 scheduled trains being pulled by the 103 were a thing of the past. 17 units still exist today, six of which in operational condition. 103 222 is the last locomotive still in commercial service, being used by RailAdventure to ferry new locomotives and train cars between the factories and new owners.
The AFB-system, although likely a factor or even the cause of the accident, outlives the series 103. Today the system is used in various locomotives and high speed trains, apart from the ease of operation the automatic acquisition and maintenance of a set speed also allows energy efficient operation.
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