Helsinki Syndrome: The 2010 Helsinki (Finland) Central Station Train Crash

Background

Helsinki is a city of 658864 people (as of 2021) and is the capital of the country of Finland. It’s located in the extreme south of the country on the coast of the Baltic Sea, 16km/10mi east of Espoo and 82km/51mi north of Tallinn (Estonia) which sits across the Gulf of Finland (both measurements in linear distance).

The location of Helsinki in Europe.

Helsinki Central Station is the city’s main public transportation hub combining various bus- and metro-lines with the country’s railway system via 19 platforms in a dead-end configuration. Tracks 1–11 use the main, historic station building while the western tracks 12–19 end at a smaller side-building housing a Hotel and a financial advisory company’s offices. These tracks are intended for commuter services while tracks 1–11 are mainly used by intercity services. Every day approximately 400 thousand passengers pass through the station, half of which arrive or depart by train.

The site of the accident on track 13 of Helsinki Central Station.

The train involved

IC71 was an intercity passenger service from Helsinki to Kajaani provided by the VR (Finish national railway) scheduled to depart Helsinki Central Station from track 7 at 8:12am. It consisted of a locomotive and eight passenger cars. The three cars furthest from the locomotive were type Ed bilevel passenger cars made by Transtech (now Škoda Transtech). Each type Ed car measures 26.4m/87ft in length at an empty weight of 51 metric tons and can carry 113 people at up to 200kph/124mph.

A type Ed bilevel passenger car identical to those involved in the accident, photographed in 2002.

The fourth car was a type Rk single-level four-axle restaurant car. The rest of the train consisted of two single-level intercity cars and two more bilevel units, but only the mentioned four train cars on the far end of the train played a role in the accident. On the day of the accident the train only carried the driver in the locomotive, a conductor, a restaurant car worker, a steward and an off-duty conductor.

A type Rk restaurant car similar to the one involved in the accident.

The accident

On the fourth of January the train that would become IC71 departed Ilmala depot for Helsinki main station at 7:37am. The locomotive was pushing the train from the northern end with the conductor in the eighth car (from here on referred to as the “leading” car) oversaw the shunting-operation and communicated with the driver via radio. The train had spent the night at the depot and was being taken to Helsinki main station 4km/2.5mi down the line in preparation of the day’s services, which is why the locomotive did not need to be moved around to the leading end of the train. Unbeknownst to the driver, conductor and restaurant staff an off-duty conductor had boarded the train before its departure at Ilmala, intending to use the Intercity for his commute home and seeing the shunting-operation as the easiest way to get to Helsinki central station.

The southbound route the train was meant to take through Helsinki, from Ilmala depot in the north (top of the image)

The train automatically triggered an emergency stop at 7:46am, coming to a stop just past Pasila station 2.8km/1.7km up the line from Helsinki central station. The locomotive’s onboard system had registered a sudden total failure of the 1500V electrical system, automatically opening the main switch which can be compared to “Pulling the plug” on the locomotive. The driver of an oncoming train radioed in telling IC71’s driver that he had seen a “strong flash of light” in the middle of the train. The driver sent the conductor to investigate, who found that the 1500V-cable was not properly plugged in between the restaurant car and the following single-level intercity-car (car 5). The conductor didn’t manage to plug the cable back into its connector, so him and the driver reached the decision to keep pushing the train into Helsinki central station and have the problem addressed there while waiting for the passengers to board. The disconnected cable also meant the intercom was out of service, so from that point on the conductor and driver communicated by their mobile phones.

The train started moving at 8:02am but only made it 192m/630ft before it came to a stop again as the pneumatic brakes applied from a lack of air pressure in the system. The conductor once again made his way down the train to try and find the reason, hearing a hissing-noise as he approached the restaurant car. He found that air was escaping through the gap between the restaurant car and car 5, right where the 1500V-cable had also been improperly connected. Going outside and inspecting the coupler-area he found that the pneumatic line had started to detach from the valve of car 5.

Due to the buildup of snow and ice around the coupler there wasn’t enough space for the conductor to climb into the gap and fix the faulty connection, so after consulting the dispatch center and getting permission to make the train temporarily maneuverable he retrieved a metal rod (the report does not explain the nature/origin of the piece) from the restuarant car and used it to knock the air-valves closed. This allowed the driver to recharge the braking-system on the locomotive-side while the conductor manually released the brakes on the four leading cars.

The coupler-area of the restaurant car photographed after the accident. It’s assumed that the buildup was more extensive ahead of the accident.

The conductor finished releasing the brakes on the leading cars by 8:24am, at which point he saw the train start moving. He called the driver and asked him to stop so he could climb on, getting the puzzled reply from the driver that he was stationary. The conductor hadn’t noticed that the coupler had become disconnected at some point during the train’s journey so far, so now the leading four cars were slowly rolling away from the rest of the train, heading southbound towards Helsinki central station.

Failing to catch up to the rolling train cars the conductor instructed the driver to notify dispatch of an out of control train heading for the central station, and to also notify the restaurant car staff who might not know that they were travelling without a locomotive. A few minutes earlier the off-duty conductor had wondered about the lengthy unscheduled stop and had left his seat in the second car, intending to find the conductor and ask him about it. He later testified that he noticed the intercom-system showing only four train cars, but since the system had shown wrong numbers before he didn’t get suspicious. Reaching the entrance-area of the restaurant cars he saw the metal rod sitting on the floor and the door open. He asked the steward in the restaurant car about the other conductor’s whereabouts, being told that she and her coworker in the restaurant car didn’t know either. Walking back towards the leading car he noticed the train moving as he reached car 3. Turning back again he noticed that the train stopped again upon reaching the restaurant car. He later said that he assumed that the train had been sectioned to rearrange the order of cars. This was the point when the train had stopped from a lack of air pressure. Once the train cars moved again he made his way to the leading car, meeting the steward who said that she couldn’t find the on-duty conductor either.

In actuality the train cars had almost reached Helsinki main station by this point. The dispatcher had managed to change the path for the train, instead of speeding into the crowded, historic main station area it was being diverted into track 13, part of the commuter-train platforms which featured less people and stronger barriers at the end of the tracks. Derailing there would also not endanger a historic building, and track 13, other than the alternative track 4, didn’t point at main doors for the station-complex. The path for the train cars was set at 8:26am, at which point the signal box crew was ordered to cut power to all tracks in the station, expecting the overhead wires to be torn in the imminent derailment. Loudspeaker-warnings were issued throughout the station to evacuate the area surrounding the western commuter-tracks and leave the station if possible, along with the three guards present at the station being instructed at 8:27am to urge people to leave the site.

Aboard the runaway train the conductor and the steward saw the outer part of Helsinki central station’s platforms speed past the windows, realizing at once that they were about to experience a train crash. Based on their statements the two began to sprint down the length of the train towards the rear of it, trying to use the empty train cars as their crumple zone. By 8:28:00am the guards were still at the base of track 13, urging reluctant people to leave the area. One of the guards spotted the train speeding into the station and took cover just a few feet from the end of the tracks. At 8:28:30 the leading section of IC71 crashed through the barriers at the end of track 13, travelling at 35kph/22mph.

The leading car mounted the platform beyond the end of the track, crossed the station area and penetrated the building beyond the tracks. It destroyed the hotel’s conference room before getting stuck with severe damage to both the building and itself. Cars 2–4 remained largely on track, with the rear two not even derailing. The restaurant car worker had injured his neck and hand when the train’s impact with the building threw him to the ground and the steward and conductor suffered minor injuries not requiring hospitalization, but nobody outside the train was harmed.

The leading bilevel car photographed after the accident, lodged in the building beyond the tracks.

Aftermath

The train car had ruptured the building’s sprinkler-system as it had crashed through the wall, automatically sending a fire-alarm to the local emergency center. The first manual call to emergency services was placed by one of the guards a minute after the accident, explaining that a train had derailed and struck the building at the station and that he couldn’t tell if or how many people had been injured. The first medical responders on site were met by the conductor and steward, who had evacuated the stricken train themselves, and were taken to the ambulances outside the station to be checked out while further responders walked the length of the train and, after assisting the restaurant car worker in his evacuation, ensured that nobody else was onboard. Due to the chaotic situation a major accident had been declared, sending dozens of firefighters, medical responders and police officers to the site only to find that most of them, especially the medical responders, had very little to do.

Since there was supposed to be another conductor onboard the area around the wreckage was extensively searched until, by 9:00am, word got through that he was safe and sound at Ilmala depot and hadn’t been on the train as it crashed. Investigators examined the train and found a properly working brake-system which had been manually released, which matched the statement by the conductor. They also found that the couplers at the northern end of car 4 were completely intact rather than torn off, but showed a significant buildup of snow and ice. The same situation, if slightly less severe, was found on the southern end of car 5 when investigators went to meet the train at Ilmala depot.

The southern end of car 5, where the train split in two, photographed a few hours after the accident. The ice-covered coupling-hook is covered in solid ice. The buffers can be seen to the left and right.

At this point it might be worth quickly explaining the couplers used on the Intercity cars by the Finnish railway. There are several different coupling-systems in use around the world, with the Finnish railway using the buffers-and-chain system (also known as “screwlink”-couplers) which is most common in Europe. Each car has a steel hook in the middle of each end, which has a short hinged steel rod attached to it. When coupling train car A to train car B this rod is connected to another hinged rod, forming a three-piece articulated connection which is then hung from the hook of car B. Alternatively, the articulated connection can originate from car B and connect to car A’s hook. The articulation at 4 points ensures that the train cars stay connected even if the train cars are slightly pulled apart (acceleration) or compressed (deceleration). The steel buffers on either side of the hook ensure that the cars cannot move so close together that the connection detaches from the hook. A threaded section in the middle of the connection allows adjustment of the connection’s length since different train cars may require different spacing. With the coupler properly adjusted and installed the connection won’t slip off the hook on compression before the buffers stop the tightening of the gap, while the hook itself keeps the train cars connected when the gap is widened under acceleration.

A coupling-system identical to the one used by the Finnish railways

The train cars involved in the accident had covered over 1200km/746mi the day before the accident, requiring a full examination to ensure service-ready condition along with a check of the braking-system. The examination involved workers checking all screwed connections between the cars. The guideline for this check was to use the locomotive and a buffer-stop to compress the train, using the buffers to hold all couplers at minimum distance before adjusting the coupler to “proper tension”. What exactly that “proper tension” is isn’t defined, an expert consulted by the investigation explained that once the buffers touch the threaded section of the connection should be tightened another ~30mm.

A graphic from the report showing how the couplers are designed to act when the train is compressed, using the articulation to curve down and maintain connection.

Investigators found that the ice and snow accumulated on the 1200km/746mi trip the prior day made it very difficult to see the threaded section of the connection, along with a significant ice-buildup on the threads and hooks. The report notes that the ice on the hooks reduced their inside space, meaning the connections sat higher in the hook than intended. Measurements taken after the accident revealed that the couplers had not been adjusted correctly, being set much tighter than intended before getting covered in ice, taking away the articulation.

Photos from the report showing the significant buildup of ice on and around the hook on car 5.

The train’s data-logger recorded some traction-difficulties as the train departed Ilmala depot. This meant that the locomotive, which was pushing the train cars, briefly slowed down or at least accelerated less strongly, causing the train cars to “pull away” from it and each other, lengthening the train by a few inches. When the locomotive gained traction again it “caught up”, compressing the train by similar few inches. Being frozen rock-solid and sitting in ice-covered hooks this allowed the connection between cars 4 and 5 to slip up and out of the hook as it couldn’t articulate downwards to accommodate the reduced distance. Following the compression that unhooked the connection the train stretched again as the locomotive slowed on further traction-issues, allowing the unhooked connector to fall past the hook and remain unhooked.

A sketch from the report showing the frozen stiff connector slipping out of the hook on car 5.

From this point onwards the train was held together in its middle by the 1500V-cable and the pneumatic line, with the former straining under the load and finally coming undone far enough to cause the locomotive to shut down. The investigators concluded that the conductor failed to spot the disconnected coupler between the cars, on either stop due too the amount of snow both on the ground and around the coupler along with the crammed situation between the train cars. The stress of falling behind schedule and having to crawl around between the train cars out in the open next to an active rail line likely aided in missing the detached connection. Lastly it was noted that the sink from the fifth car’s onboard bathroom (which had an enclosed toilet-system but an open sink) had added further to the ice and snow present between the two cars.

The coupler-area from car 5 photographed after the accident, the arrow points to where water from the sink’s drainage had run down.

With the coupler apart and the cable and pneumatic line disconnecting the manual release of the brakes by the conductor just about doomed the train. He should have ensured that the train cars were properly connected before releasing the brakes, just assuming that they should be is insufficient.

With the train cars disconnected and in motion there was no way for the train driver or dispatch-center to stop them on the remaining 2km/1.25mi remaining until they reached Helsinki central station. The report notes that quick action by the dispatch center made a big difference in the outcome of the unavoidable derailment, quickly setting a new path that sent the train into shorter tracks away from the most populated area and the historic main building. At the time of the accident track 13 featured a hydraulicly dampened buffer stop designed to compress when faced with forces comparable to the impact of a 120 metric ton train at 6kph/3.7mph. The buffer stop is placed ahead of a 153cm/60in high 79cm/31in thick concrete barrier separating the track from the platform. In this accident those measures proved completely insufficient, with the incoming train crushing the buffer stop before mounting the barrier, lifting it clear above the platform itself ahead of hitting the building.

Another perspective of the wreckage, the concrete barrier can be seen to the right of the firefighters.

The rear two train cars were recovered during the night after the accident, with the leading two cars being dragged out of the wreckage the next day once the building had been inspected, deeming it structurally sound enough to not collapse upon removal of the train. The height of the train car had caused it to demolish both a ground-floor conference room as well as first floor offices used by the financial advisory company. Following the recovery of the train cars engineers closely examined the building and concluded that the train had managed to barely miss important structural components, limiting damage to a degree that allowed the building to be repaired rather than requiring demolition. It’s unknown what happened to the train cars involved in the accident, but the leading car, which suffered severe damage, was likely retired and scrapped.

The gash in the building left behind as the train car was dragged away. The old style buffer stop can be seen in the foreground.

After the accident new and improved buffer stops were gradually installed at Helsinki central station, starting with tracks 13 and 14. The new stops have a longer compression-distance and sit several meters away from the concrete barrier, allowing them to slide back when struck by a train while resistence from their mounts slows them and the train. They are designed to stop a train at up to 35kph/22mph without injury to the passengers, as investigators had noticed that speed to be the maximum a runaway train could reach on the downhill approach to Helsinki station without derailing on the points ahead of the platforms.

One of the new buffer stops as shown in the report, the spare stopping-distance behind it is clearly visible.

In further steps taken to avoid a repetition of the accident glycol-sprayers were installed at Ilmala depot, preventing a buildup of ice and snow to conceal the couplers, and releasing the brakes on train cars was banned unless a locomotive is present between the train cars and Helsinki central station. The signaling- and train control system was also upgraded so approaching locomotives and multiple-units/rail cars can’t approach the station at more than 20kph/12.5mph without triggering an emergency stop. Lastly, several emergency stop devices were installed on the tracks between Ilmala depot and Helsinki central station. These devices, if not purposely deactivated for an incoming train, act like wheel chocks and bring trains to a safe stop within a short distance.

One of the emergency stop devices installed along the rail line, in this case the train would approach from the left. When deactivated the red pieces fold down between the rails.

With all these measures a repetition of the accident is extremely unlikely, making operations at the station a lot safer. Beyond those improvements nothing else has changed at the station since the accident, apart from the Intercity-services changing their livery from red to green.

An intercity similar to the one involved in the accident waiting for passengers at Helsinki central station in 2019, the short commuter-platforms can be seen on the right (by the purple train).

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