Ending with a Bang: The 1977 Bitterfeld (Germany) Boiler Explosion.

Bitterfeld-Wolfen is a city of 37568 people (as of January 2021), created in 2007 by the fusion of Bitterfeld with the town of Wolfen and three surrounding municipalities. Bitterfeld is located in the federal state of Saxony-Anhalt in eastern Germany, 31km/19mi north of Leipzig and 100km/62mi south-southwest of Potsdam (both measurements in linear distance). Until German reunification in 1990 Bitterfeld was part of the GDR/DDR, better known as East Germany.

The location of Bitterfeld in Europe.

Bitterfeld station lies on the Trebnitz-Leipzig rail line, an 82km/51mi double-tracked electrified main line completed in 1874. Despite being re-electrified (the original system had to be shipped off as reparations after WW2) in 1952 and being one of East-Germany’s most important railway lines with everything from regional traffic and freight trains to long distance express trains running on it the DR (national railway of East Germany, not to be confused with the pre-WW2 German national railway of the same name which ceased operations in 1945) couldn’t go without steam locomotives even for the prestigious express trains.

The site of the accident seen from above today. Note that the area around the station has been remodeled since the accident.

D562 was an express train scheduled to go from Leipzig to Berlin, where it would turn around and return to Leipzig as D567. Starting out D562 is pulled by DR 03 121. The DR series 03 is a large 2C1 (meaning two leading axles, three driven axles and one trailing axle) passenger express train steam locomotive entering service with the DR (pre-WW2, not East Germany’s DR) in 1930. The locomotive weighs 90 metric tons empty at a length of 23.9m/78ft including the pulled tender which can hold 10 metric tons of coal and 34m³/1200cu ft of water. Going forwards the series 03 can reach 130kph/81mph, in reverse it still manages 50kph/31mph. The series 03 is very similar to the series 01, but has a lower axle load allowing it to use lines with an axle load limit of 18 metric tons. In 8 years a total of 298 series 03 were made.

DR 03 121, the locomotive originally pulling the train, photographed in 1967.

After DR 03 121 broke down the DR replaced it with DR 01 1516 for the return trip from Berlin to Leipzig (D567). Introduced in 1925 the DR series 01 is considered the DR’s flagship at the time. It features the same axle-configuration as the series 03 (which is based on the 01) and is the same overall length. Engineered mainly for heavy passenger trains the locomotive weighs 111 metric tons (placing it at an axle-load of 20.2 metric tons) and can reach 130kph/81mph forwards and 50kph/31mph in reverse. Its power-output is listed as 1648kW/2240hp.

DR 01 1516, the second locomotive pulling the train, photographed 2 months prior to the accident.
The driver’s cabin and firebox of an identical DR series 01. The driver stood on the right and the stoker on the left.

On the 27th of November 1977 D562 is heading towards Berlin, pulled by DR 03 121. Up front in the locomotive the crew is driving as fast as the locomotive will let them, with the stoker shoveling a constant supply of coal into the firebox. The fire heats up the water-filled pipes in the boiler, creating steam that is then directed into the cylinders to drive the wheels. Both men are experienced, but on this day they still get their calculations wrong (and seemingly failed to watch the gauges). Just past Wittenberg, 87km/54mi linear distance from their destination, the locomotive runs out of water. As the boiler starts to dry up the heat rapidly increases, as does the pressure.

A sketch of a melting plug connecting the fire box and boiler.

Two “melting plugs”, lead bolts in the roof of the firebox, melt before the steel does, with a rushing sound loud enough to drown out the steam engine the steam floods the firebox and extinguishes the flames. The locomotive comes to a stop independently from the crew braking or not, and it won’t start again anytime soon. This is meant to keep overpressure from blowing up the locomotive, acting like the automatic brakes on modern locomotives when too much electricity is detected.

The driver of 03 121 reports the rather embarassing incident via radio, and the DR sends a series 118 diesel locomotive, a 1472kW/2000hp locomotive intended to help replace aging steam locomotives, to tow the entire train, including the broken down locomotive, the rest of the way to Berlin. While the express train gets taken to Berlin-Lichtenberg station the team at nearby Berlin Ostbahnhof (“Berlin East station”) readies 01 1516 to take the train home to Leipzig. The locomotive had just returned from Meiningen Steam Locomotive Works, a large maintenance and construction facility specializing in steam locomotives. It was scheduled to serve as a backup locomotive, so when the crew from 03 121 got to it they still had to wait for the water and coal reservoirs to be topped up. However, by that point the crew was under significant pressure, already having to explain a large delay to their superiors who expected adherence to the schedule. As such the crew told the workers to only top up the coal but not the water tanks, while telling the dispatch that both had been filled up. This saved several minutes as the locomotive didn’t have to be moved from the coal-station to the water tower but could go straight to the train for the return trip as D567.

As the train was on its way back the drivers asked for a water-stop at Wittenberg, which was denied, and then for one at Bitterfeld, a scheduled stop. At the time of the accident (exact times of the events aren’t known) Bitterfeld station was packed with travelers, estimates claim over 200 people on the platform D567 was to stop at alone. As 01 1516 approached Bitterfeld the heat and pressure within the boiler were climbing past operational limits again as the boiler started to run out of water. As the locomotive changed from a downhill section onto a level section of track and braked the remaining water above the firebox sloshed forwards, exposing the firebox roof, before coming flying back as the locomotive stopped. The water evaporated in an instant, rupturing the roof of the firebox and blowing up the locomotive just as it came to a stop at the platform. The driver’s cab was ripped apart by a sudden release of highly pressurized steam exceeding 200°C/392°F while the boiler shot forwards in its entirety like a giant missile (think of letting go off an inflated balloon without a knot on the opening), as some welds at the front still held on it flipped over lengthwise, throwing burning coal from the remains of the firebox. The coal hit another train on a neighboring track, setting it on fire as the boiler finally tore off the last welds and landed just over 40m/132ft past the leading end of the locomotive’s frame, welding itself to the track as it landed. Five people on the platform were struck and killed by flying debris, another two later succumbed to their injuries at the hospital. The locomotive crew was killed as the driver’s cab was torn apart, their bodies would later be found on the roof of the platform. 45 people survived with injuries, largely from being struck by flying debris and/or exposure to hot steam.

The GDR’s government was very interested in keeping as many people in the dark about the accident as they could, causing information to be a little scarce. There was no report of it outside the country, and next to none inside of it (only one local newspaper article is known). Most people only learned that it had happened after German reunification.

It’s known that after the accident survivors on the platform and the passengers of the train were quickly shooed away, leaving the site to investigators. Retrieving the remains of the firebox it was found that the melting plugs had gotten covered in limescale, a rock hard chalky deposit consisting mainly of calcium carbonate and magnesium carbonate. This had isolated the plugs well enough for them not to melt as they were supposed to be, allowing the temperatures to exceed critical limits. It was never (publicly) clarified how this could’ve been missed during the recent maintenance at Meiningen. Continuing their way through the spread out remains of the locomotive the investigators found that the tanks in the tender were completely empty, an inspection of the firebox roof revealed that it had to have been without water for at least four minutes as it had reached approximately 740°C/1365°F before bursting. At that heat the structural rigidity of the firebox steel declined from 510N/mm² to less than 90N/mm² (Newtons of force per square Millimeter, 1mm=0.04in). In summary, the locomotive crew had lied to the dispatch about how much coal and water they carried and thus had been refused a much needed stop to get more water. They had then failed to see the coming boiler explosion (a situation they were facing for the second time that day), choosing to continue to Bitterfeld instead of stopping on the open track and calling for a tow.

DR 01 1516’s boiler and firebox (on the right) lying upside down on the destroyed tracks after the accident.

With the two people at fault being victims of the explosion there was no one to put on trial, and it was never revealed how the limescale had gone unnoticed. Looking back it is known that the train crew, especially the driver, were under immense pressure to catch up the delay accumulated by breaking down on their way to Berlin, and due to a clear crew hierarchy the stoker couldn’t really voice opposition or rather voice it and expect change. The DR was constantly dealing with shortages, a popular theory is that they had placed 01 1516 on a “rush order” at Meiningen, needing it back as fast as possible (some theories even suggest altered records, that the locomotive was due to head to Meiningen, rather than coming from there). Once they finished up at the site investigators turned their attention to 03 121, and found its stockpile of coal and water similarly drained. Finding several more defects on 03 121 the DR ordered an examination of all Leipzig-based steam locomotives, with the sad record falling to 03 162 with 371 listed faults and defects.

Workers cutting up the remains of 01 1516 for removal.

The western-German DB had already banished most steam engines from their tracks, in 1977 they retired the last few steam engines from freight duties. The last DB steam engine ran on the 26th of October 1977, a month before the accident, when 043 903 pulled a maintenance-train from Oldersum to Emden. In the GDR it would take until 1988 for the last scheduled steam train to run, a chronic oil shortage made an earlier end in favor of diesel locomotives impossible. While the accident was easily avoidable the way it went down was still relatively lucky with the boiler overturning lengthwise, scraping along the station roof. One can’t imagine the outcome had it shot right off the locomotive onto the crowded platform, the death toll would have undoubtedly been higher. Bitterfeld was Germany’s last locomotive boiler explosion, after it new guidelines were introduced in both east and west that call for a regular replacement of the melting plugs which are engraved with the date of their installation. Today the explosion at Bitterfeld is sometimes used to warn new steam locomotive crews of the potential danger, often comparing a steam locomotive to a pipe-bomb on wheels.

03 121 was not returned to service and officially retired in February 1978. Today 5 series 01 locomotives survive in working condition, two of which received an upgrade to run 80kph/50mph in reverse to be less of an obstruction when pulling historic trains backwards (as turntables and track-triangles have gotten rare). The Meiningen Steam Locomotive Works still exist and are an internationally respected address for maintenance, repairs and construction of steam locomotives and other (usually historic) rolling stock.

DR 01 202, owned by a Swiss enthusiast club, pulling a historic train in July 2021.

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