Background
The Great Belt Bridge (called the “Storebæltsbroen”) is part of the road and rail-crossing over the Great Belt in eastern Denmark. The eastern part of the belt is crossed by the eastern bridge for cars and a tunnel for trains. At the small Sprogø island in the middle of the stream (which was extended to 4x its size from 38 to 154 hectares during construction of the crossing) the railway line emerges from the tunnel and joins the road for the western bridge, running to the north of the cars.
Using the crossing is the Copenhagen-Fredericia railway, a 221km/137mi double-tracked electrified main line opened in 1883 (then with a ferry across the Great Belt). When the Great Belt Crossing opened in 1997 the capacity vastly increased while travel-time was cut down as trains can now cross the 12km/7.5mi wide waterway at over 100kph/62mph. The western bridge is fitted with two sensor stations to measure wind speeds, above certain thresholds speed limits or even cancellations of service are meant to ensure safe operation. These limits are programmed into the safety-system and will automatically close the bridge to certain kinds of traffic when limits are surpassed.
The vehicles involved
Travelling eastbound from Aarhus to Copenhagen Airport was IntercityLyn 210. The Lyntog-trains are a special kind of national express train by the DSB (Danish national railway) which only stops very few times between its starting point and destination to cut down travel time on popular connections. On the day of the accident the connection was served by a double-traction of 2 DSB MG trains (also referred to as the IC4) holding 131 passengers and 3 crew members including the driver. Introduced in 2005 the IC4 is a 4-part diesel multiple unit intended for long distance passenger service, weighting 160 metric tons at 86m/282ft long. The trains offer 187 seats in a two-class configuration, with another 21 folding seats available for peak hours. Powered by 4 engines mounted below the floor the trains reach up to 200kph. To increase capacity up to four of the trains can be coupled together and controlled from one driver’s cab. After their introduction the trains proved to be severely flawed, being placed in storage several times with 6 units having already been scrapped when their defects proved too costly to fix.
Coming the other way from the freight yard at Høje Taastrup and headed towards Fredericia was G9233, a freight service nicknamed the “beer train”. The train consisted of eight special type Sdggmrs TWIN-I six-axle articulated flatbed cars for semi trailers, so called pocket cars. Each car consists of two halves resting on a shared center bogie, each holding a semi trailer without the truck attached. This form of combined transport (KLV) is the evolution of the rolling road (which carries the entire truck), saving the space and weight from the trucks and the passenger car for the drivers. As a downside, the trailers can’t roll on or off the train but require a crane to be loaded and unloaded. The “beer train” is a chartered service running between the harbor and Fredericia transporting beer from the Carlsberg-brewery (eastbound) or returning crates of empty bottles for reuse (westbound). Each of the pairs weights 35.5 metric tons empty (not counting the semi trailers) and measures 34.2m/112ft in length.
Loaded onto the forward-most pair were two Krone SDP-02 curtain trailers owned by TIP Trailer services and long-term rented to the Carlsberg brewery, thus wearing the brewery’s livery and logos. The trailers weighed 6.6 metric tons empty at 13.86m/45.5ft long and had been introduced into service in late 2015. Each trailer of this type consists of a basic frame holding the fifth wheel coupler (“kingpin”) in front and the wheels and brakes in the rear, along with protections against wedging/de-roofing in case of a car striking the trailer. The forward wall of the trailer is a profiled steel plate while the rear consists of 2 vertical profiles holding a pair of doors, connected to the forward wall with long struts resting on six (three per side) smaller vertical supports. The top of the trailer is a fixed tarp while the sides can be opened along rails integrated into the horizontal profiles and the frame, giving the trailer its name. According to Krone these trailers can be twisted 5–8 degrees lengthwise when empty. It’s unknown if or how much cargo was inside the second trailer, but the first one was empty at the time of the accident.
Pulling the train on the day of the accident was DB (German national railway) series 185 401, owned by DB Cargo Scandinavia, a Danish subsidiary of the DB’s cargo division. Delivered in 2009 the 185 401 is a member of Bombardier’s second generation “Traxx”-family of both diesel and electric multipurpose locomotives, in this case an electric locomotive set up to run in Sweden, Denmark and Germany. Measuring 85 metric tons at 18.9m/62ft long the locomotive can pull freight trains at up to 140kph/87mi.
The accident
After the low pressure area nicknamed Alfrida had brought severe storms to Denmark during the first of January 2019 the Great Belt Bridge had been closed for all road traffic in the evening for that day. However, as rail traffic didn’t use the higher, more wind-sensitive eastern bridge it had been allowed to proceed. At around 7:20am on the second of January the sensors on either end of the western bridge reported gusts of wind reaching up to 20.9 meters per second (75.5kph/47mph) from the north, coming in at 90° to the bridge. Had they exceeded 21 meters per second freight trains would have been limited to 80kph/50mph. Above 25 meters per second (90kph/56mph) freight trains would’ve been banned from the bridge. As it was, G9233 left the tunnel at 7:24am and entered the western bridge at approximately 120kph/75mph. Around the same time the IC4 running as ICL 210 is entering the western end of the bridge. The driver later reports feeling the the wind push on his train, seeing the overhead wires move in the storm. Normally the intercity would cross the bridge at 180kph/112mph, but due to the conditions the driver chose to reduce the speed to approximately 115kph/71.5mph as he entered the bridge. He trusted the safety-system of the bridge, his train might get rocked a bit but there was no doubt that it would cross the western bridge and reach the tunnel without issue.
Unbeknownst to either driver the freight train should’ve never been allowed to enter the bridge, much less dispatch in the first place. The forward part of the first car carried an empty semi trailer which hadn’t been secured correctly due to both lacking maintenance and an error during the loading-process. When loaded onto the train the kingpin of the trailers sits on a special cross-brace at the right level to both secure the front of the trailer and keep the trailer level without the back of the truck holding it up. A lack of maintenance, most importantly lubrication, had caused the cross brace to not attach properly to the trailer. At first glance it was sitting on the brace looking like it had been properly secured, when in fact it was not secured. Shortly after entering the bridge the wind-gusts managed to dislodge the trailer, pushing it partially off the freight train. Dragging along on the track it created a large shower of sparks, something captured by a security camera.
The driver of the IC4 also sees the sparks in the distance, coming towards him. Seeing the overhead wires create sparks as they move left to right or maybe a little up and down, especially during high winds, is nothing special, in fact it’s why different cargo dictates which pantograph a locomotive is supposed to use. But those sparks were created much lower, close to the track. As the freight train started to separate from the darkness the driver suddenly saw a large undefined object hang off the side of the freight train, too late to not collide with it. At 7:29:28am the driver of the passenger train triggers an emergency stop, desperate to shave off as much speed as he can. A moment later the passenger train strikes the trailer at essentially full speed. the leading axle of the trailer is torn off as the frame hooks into the nose of the train on the left hand side, crushing part of the driver’s side and ripping the forward car open. The collision pushes the back of the trailer up, tearing the overhead wire and cutting power to the trains. The toilet behind the driver’s cab is destroyed, windows are pushed in and their frames are torn and bent as, finally, both trains start to slow down from emergency stops. The trailer’s frame becomes lodged in the leading car as the second trailer, moved by the impact of the first one, scrapes along the rest of the train, denting the sidewall and breaking several more windows. The freight train comes to a stop on dry land, a few meters past the end of the bridge, while the IC4 rolls to a stop on the bridge. Both trains are damaged, but somehow neither derailed.
7 passengers were killed when the train car caved in during the collision with the trailer, an eighth died after being struck by flying debris inside the second car. 16 people survive with injuries, including the driver who dove out of the way at the last moment. A massive “collision block”, a square structure in the nose of the train meant to deflect impacting cars and trains, probably saved his life.
Aftermath
Responders are stationed near the end of the bridge, they only take a few minutes to reach the severely damaged passenger train.
On their way they come past a massive field of debris, various pieces of both IC4, freight train and semi trailer are strewn along the tracks. A piece of the IC4’s nose-section marks the approximate point of impact, but responders also find a door from the train, a piece from the trailer holding the license plate, various shreds of the tarp and half the torn-off cross-brace meant to hold the truck in place, among a near-literal sea of empty beer crates.
The responders are met by most of the passengers standing, sitting on or wandering the tracks. Luckily, as it would turn out, none fell off the bridge due to the wind or when trying to climb over the small gap between the road- and the railway-bridge. Approaching the wreckage from the west responders don’t see the extent of the damage until they passed the stopped train, half the leading car has been all but destroyed. The sleek nose has been obliterated, a gaping hole replaces the left wall of the driver’s cabin, countless windows have been broken and many of the window frames are gone or bent inwards. Instead a massive sheet of steel replaces the windows, having pushed the rear doors of the leading car inside and leaving most of the trailer’s wheels where the driver’s cabin used to be.
The gash caused by the trailer runs almost 15m/49feet down the side of the train, the driver’s cab is destroyed to an extent that the report acknowledge it barely beyond something that used to exist.
The further investigators move down the train the lighter the damage gets, while the rear car of the leading IC4 has missing windows and torn metal around the leading bogie the rear IC4 is completely unharmed aside from minor scratches on the nose-section. Making their way inside the near-empty train responders find the bodies of 6 passengers, most died when they were struck by the trailer at over 200kph/124mph. One passenger’s body is found further back in the second car, the investigation later concludes that a smaller piece of debris came flying through the window and fatally struck him in the head.
While most of the trailer either became lodged in car 1 or dropped back into the space between the trains some debris struck car 2 severe enough to break welds and cave in the doors as well as a number of window frames. The fire department helped injured and uninjured passengers over the gap between the bridges as safely as possible, later also recovering six victims as well as the train’s data-logger. By 10:52am the road next to the tracks is reopened, only to be shut down by 4pm after a long traffic jam was caused by people stopping to take photos or videos of the wreckage. 40 drivers are pulled over on site by the police and get fined for illegally recording the site, a behavior condemned by the police and government as incredibly respectless and tone-deaf. The police had divers search the water below the bridge as well as other units on the nearby shoreline look for 2 missing victims.
Later in the day the train was towed off the bridge to a maintenance yard inaccessible to the public for further investigation as well as storage.It was here that, while cutting the leading car apart, the last two bodies are found. Many of the dead are so severely injured that the coroner’s office has to aid the identification via DNA and dental records. Cellphones, IDs and other luggage were of little help, as those had been strewn all over the wreckage during the accident. It’s hard to imagine what the moments of the collision must’ve been like when the massive frame of the trailer tore through the interior of the train at an insane speed.
Turning their attention to the freight train investigators don’t take long to find the cause of the accident. The lever controlling the locking mechanism for the kingpin is moved by a spring and requires regular lubrication, if it doesn’t properly lock in place a visual indicator is visible next to the plate carrying the pin. While the first car’s cross brace is found in the wreckage incomplete and severely damaged investigators find two other trailers on the freight train not properly locked in place.
Presumably lacking maintenance caused insufficient lubcrication, which is why the spring couldn’t fully retract and lock the kingpin. That the outer retaining notch was still showing should have alerted the workers during the load-process to this, but it was overlooked either consciously or unconsciously. The investigation noted that the visual difference is very small, so it is very much a possibility that a worker operating the mechanism assumes it’s properly locked.
But even if it wasn’t locked properly the loose trailer should have remained on the train, after all the train was going in a straight line. Had the trailer being unsecured alone been enough it would have flown off the train the moment the freight train left the tunnel. Investigators headed to a local university’s wind tunnel, building a scale model of the bridge and using an H0-scale model train to examine how the wind moved across the bridge.
The tests in the wind tunnel showed that wind speed limits had been calculated wrongly, if a train was passing over one of the bridge’s pillars force of the wind was much stronger than between the supports. The investigation explains in the report that the constant change in wind pressure from passing over support pillars created a pulsating motion, worsened by the soft suspension of the trailer (compared to, say, a flatbed container car), the elasticity of the trailer’s body and a parachute-effect of the tarps. Taking those factors into calculation, as well as the possibility that the wind reached slightly higher speeds than officially registered, the forces were too strong for the empty trailer to remain on the train simply by gravity. The other two trailers found to be improperly loaded stayed in place because they were loaded, making them heavy enough to remain in place. On the 8th of January 2019 the traffic-ministry banned the use of pocket cars for containers, semi-trailers or swap-trailers until the operators can present a system to ensure every single locking mechanism has properly secured the load. The generalized pre-departure inspection is deemed insufficient. On the 11th of January Hector-Rail, a Swedish freight service provider, received permission to restart using pocket cars, with CFL Cargo and TXL, two more providers, following on the fifteenth. DB cargo chose to cease operation of the beer train and use trucks to transport the cargo for the time being. During the investigation a union representative at DB cargo caused a small scandal when he deleted the name of the employee performing the pre-departure inspection of the involved freight train from documents before those were handed over to the investigators. According to him it wasn’t that person who actually performed the check, but he wouldn’t say who did it or why the wrong person would sign the protocol. The employee was suspended on the 11th of January and fired by May, having been sentenced to 20 days of suspended jail time for evidence tampering, a judgement upheld on appeal. In the end no-one could be held accountable for the death and injury caused, and the investigation closed with recommended changes to the operation of trains on the bridge. The windspeed-limits for freight trains were drastically lowered, now 20 meters per second (72kph/45mph) sees freight traffic cancelled. Exempt from this rule are locomotive-trains, a kind of train used to ferry locomotives for various purposes, as they’re much heavier.
Contradicting the old guidelines passenger trains now also have a wind speed limit which causes cancellation of connections across the bridge, if the average over 10 minutes rises past 25 meters per second (90kph/56mph) passenger services no longer use the bridge. Accidents with trucks blowing off freight trains aren’t new, in 2009 a truck driver died when his truck, loaded with styrofoam, was blown off a flatbed car carrying it from the German mainland across the Hindenburg dam to the island Sylt. There had been accidents with pocket cars suffering dislodged cargo, but those had only caused material damage. It had simply been unknown how easy it is for the locking mechanism to malfunction. The accident had been Denmark’s worst railway-tragedy since a derailment in 1988 claimed 8 lives and injured 72 survivors, and had been the second lethal accident involving the bridge after a freighter had rammed the bridge in 2005, killing a seaman as he fell into the cargo-hold.
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