Four Injured in Alton Towers Smiler Crash

Edited: June 2, 2015, 10:32 AM

A crash between two trains on The Smiler roller coaster at Alton Towers in the United Kingdom has left four people seriously injured, according to a BBC report.

Park owner Merlin Entertainments said in a statement quoted by the BBC: "There has been an incident on the Smiler this afternoon involving two carriages coming together on a low section of the track. One of the carriages was empty and the other had 16 guests in. The Resort's fully qualified First Responders were on the scene immediately to assist with the evacuation which is ongoing, and the area has been closed to allow for access to emergency services vehicles."

The Smiler is a Gerstlauer Infinity Coaster with a record 14 inversions. It opened in May 2013.

The Smiler

Roller coaster physics 101 would suggest that "low sections" of a track are the ones where trains are running at their highest speed, thanks to the tradeoff of potential and kinetic energy. The reason why roller coaster trains sometime shut down during normal operation is due to the need to keep trains isolated in their own section of the track, to prevent these types of collisions. I'll defer to people with first-hand knowledge of The Smiler for further analysis.

Replies (16)

June 2, 2015, 8:50 AM

Reports now say that the four victims were teenagers and that they suffered leg injuries.

June 2, 2015, 9:01 AM

This coaster has been a lemon from the start. This is probably the worst event so far, but its by no means the only event that has put life and limb at risk. Stalls, Debris falling, cracks in the supports, guide wheels detatching....

Its time to pull the thing down.

June 2, 2015, 1:59 PM

The park has announced that it will be closed Wednesday, June 3, following the crash. Visitors with dated tickets may get a ticket for another date or a full refund.

June 3, 2015, 1:25 PM

One of the victims had their leg amputated below the knee, an empty car had gone off but then did not make the second loop on the cobra roll and then a nother car full of 16 people came through and crashed into the back of it. Hopefully though Alton Towers can fix the problems.

June 3, 2015, 6:24 PM

Horrible accident. Block break failure or human error? Hopefully the park is completely open and honest about how the accident took place.

Edited: June 3, 2015, 9:29 PM

I can't imagine how this could possibly be a human error without there also being a block zone failure in the ride system. The entire point of having block zones on a coaster is to prevent a human error at dispatch. The computer is supposed to be watching the position of the trains so that tower and dispatch don't have to bear full responsibility knowing when it is okay to send a train.

On every modern, multi-train coaster I've ever seen, the dispatch operators clear a train for dispatch once all riders are screened, on board and safely in their locked restraints. It's not the dispatch ops' job to *also* check the position of the other trains on the track. That's what the ride system does. Once the dispatch ops clear a train for dispatch, the ride system dispatches it when the zone ahead is clear and it is safe for the train to leave the station and move into that next zone.

The tower op is the backstop, who can throw an emergency stop or power disconnect whenever he or she sees a train moving where it shouldn't. But tower knows to do that only if camera monitors or sensor displays show something out of place. If that doesn't happen and tower doesn't have a clear view of the entire track, then tower won't know that there's a problem.

June 3, 2015, 9:40 PM

The only hypothetical I can think of that might explain this, save for a complete failure of the block zone software or deliberate sabotage, is if the first train valleys but somehow the sensor at the end of that block gets flagged within the expected time window, leading the system to believe that the stalled train has left the zone.

False sensor flags are actually somewhat common -- which is why coasters "break down" and stop during operation. Rain drops can do it, as can debris on the track. When the ride system sees these erroneous flags, it shuts down the system -- halting all the trains at the next lift, launch, or safety brake -- since it now believes a train to be out of position on the track. I can't imagine calculating the odds of a false sensor flag happening at the exact moment needed to make the ride system believe that a stalled train was actually moving through its proper position instead.

Edited: June 3, 2015, 11:56 PM

I've been thinking a lot about this incident since it happened and based on my knowledge of roller coasters here's what I've come up with. Note that I am not a roller coaster designer (yet) and that I don't have any specific knowledge of Smiler, but I am a mechanical engineer and have spoken with people who design/maintain/operate these attractions at various parks. While this is pure speculation, I think it sounds like a fairly likely scenario and would allow for an accident generally considered impossible.

Most modern multi-train roller coasters have at least three operating modes: normal/automatic, evacuation/reset/manual block, and maintenance/full manual. Any time a coaster is in normal operation, it will be running in automatic mode. In this mode, the operator has control over all station elements, but once the train has been dispatched it is 100% under the control of the computer until it parks in the station. The only thing an operator can do to affect a train on the track is initiate a stop, which will usually shut the whole ride down.

If there is a problem or a train gets too close to the one in front, the ride computer will stop trains on the course. In some cases (usually when it is simply a stacked train), this can be automatically resolved when the track is clear. In others (generally when a fault is detected), the ride must be manually reset by using the evacuation/reset/manual block mode. In this mode, all block devices are engaged until they are manually activated by the operator. Depending on the system, when a train is released it will proceed either to the next block or until the block before the next occupied block before stopping. If anyone has experienced a cascade reset at a Disney park, that is an example of manual block mode.

The third mode, maintenance/full manual, is rarely used unless the maintenance team is trying to fix a problem or is testing a component. In this mode, the computer is essentially deactivated and the operator has control of every single element on the coaster. While the computer will still give warnings when a dangerous situation may result, it will not prevent the operator from doing something like sending a train into an occupied block. Because of the risks of using this mode, it can typically only be accessed with a special key and/or code given only to maintenance personnel and should never, ever be used when guests are aboard the coaster.

Based on reports I have heard elsewhere, just before the accident occurred Smiler went down to add an additional train. At a Disney park, customized controls make this a simple procedure. However, at most other parks on most other roller coasters, adding a train requires maintenance personnel to perform the procedure and the ride typically must be put into manual block mode or full manual mode to do it. The train is usually then cycled empty before normal operation continues. This explains why the train that stalled was not loaded but the one behind it was. My belief is that after the train was added, the ride was left in one of these modes and not switched back to normal mode before resuming operation.

However, reports also state that the loaded train stopped on the lift hill for several minutes before the lift restarted and the train was sent into an occupied block. This means that the block system was still active at the time and something happened to cause the train to proceed. While it is possible that there was a false sensor reading while the train was stopped, the delay should have been long enough for the computer to consider the train lost and down the ride completely. Therefore, my guess is that an operator manually restarted the lift and ignored/overrode any warning received from the computer. How this was possible, however, I do not know.

When a ride is started, one of the checks the computer should do is verify the location of each train on the track. Whether the train is in the station, on the course, or parked in a maintenance bay, the computer needs to know where it is. If there is a discrepancy, the computer should down the ride and prohibit any action that would place a train in motion. For example, if a computer knows there are four trains on the coaster and only registers three occupied blocks, it needs to shut everything down immediately. This same check should occur anytime the coaster is reset or the operating mode is switched. Since sensors are typically located in block sections, but are not necessarily located on every section of track in a block, if the computer didn't register the stalled train it should have registered it as a lost train and locked out the operator when the ride was switched into manual mode.

Based on everything above, I think the most likely occurrence is this: Upon returning to operation, the operators were unaware that a train had stalled on the course. When the loaded train stopped on the lift, maintenance personnel were unable to restart it. Instead of evacuating the train, they chose to switch the ride into manual mode to get the train back to the station, and due to an issue with programming this action was permitted by the computer even though a train could not be located. Since no train was registered in the block, the computer assumed it was clear and did not give a warning when the lift was restarted. The loaded train then proceeded over the lift and crashed into the back of the stalled train. Depending on what procedures Alton Towers has in place, this could be ruled either a programming issue or a combination of a programming issue and operator error. The only other plausible scenario I can think of would be if the ride had been operating in full manual mode the entire time, in which case it would be 100% operator error. However, I find this highly unlikely for a variety of reasons, and any other situation I can think of is something that should have been discovered in testing and would need to be corrected in order for the coaster to be certified.

Again, this is all speculation as I have no specific knowledge of Smiler. I hope an answer is found and the problem is corrected. I do think Smiler will reopen, but I would not be surprised if it isn't until next season and I also wouldn't be surprised if other Gerstlauer coasters with similar programming are shut down until they can be thoroughly examined and it can be proven this type of accident couldn't occur again.

Lastly, I will say that while this accident is certainly bad, it could have been a whole lot worse. It sounds like loss of a leg is the worst permanent harm any of the riders will face. While that is a pretty serious injury, this is the type of accident that has the potential to kill people. It is fortunate that everyone survived this event and that most will make a full recovery. Finally, if this has made anyone doubt the safety of amusement rides, think of all the people in the world that enjoyed a ride without any problems on the same day. Even though they are rare, accidents that are the fault of neither the guest nor the operator do happen, but riding an amusement ride is still far safer than many activities people perform in their daily lives.

June 4, 2015, 3:51 AM

Getting to the Park is more risky!

Edited: June 4, 2015, 10:13 AM

Great stuff, AJ. I think it's always helpful and instructive to get to know more about how our favorite rides work, whether the information here turns out to be an explanation of this incident or not.

In today's news, Alton Towers has announced that the park will remain closed until the investigation in finished.

The BBC quoted Merlin CEO Nick Varney:

"We want to know if this issue is isolated to The Smiler. We can't open again until we're sure."

A total of 16 people were hurt, four seriously.

They were Joe Pugh, 18, and his girlfriend Leah Washington, 17, both from Barnsley, South Yorkshire, 27-year-old Daniel Thorpe from Buxton in Derbyshire, and 19-year-old Vicky Balch, who is believed to be from Leyland in Lancashire.

All four were airlifted to major trauma centres across the West Midlands.

June 5, 2015, 5:42 AM

This has gotten bigger now. Sister park Thorpe Park has closed SAW: The ride, and Chessington World of Adventures has closed Dragon's Fury and Rattlesnake as a result of ongoing investigations.

Merlin (Who operate all 3 parks) also operate the Legoland parks, and the Dungeons.

June 6, 2015, 6:15 AM

Alton towers looks like it may be closed into next week. If you are planning a Uk Coaster trip, I'd suggest putting it off for now with AT closed, and Saw at Thorpe Park presumably closed too.

The question is, is this going to spread to non-merlin operated coasters?

June 7, 2015, 10:41 AM

Partial reopen tomorrow. Smiler remains closed, as does Spinball and the effected rides at other parks. The government is talking about a sectorwide review of theme park operations.

June 10, 2015, 1:51 PM

One Guest has had their leg amputated, but apparently despite being on life support at one point, she is doing well.

Sky News (a subsidary of News Ltd, that owns Fox in the US) has had over 1000 complaints to the broadcasting regulator against them regarding their questioning of a Alton Towers/Merlin Exective whom had earlier refused to confirm the amputation on privacy grounds.

The Guardian is claiming the lawsuit will be in the seven figure range.

Edited: June 10, 2015, 3:34 PM

June 26, 2015, 5:52 PM

Small update, another passenger has had an amputation.

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