Okay, so today’s entry is going to be a bit different. It’s purely speculation, based on my own opinion and only formulated from what I know (about electromechanical design) and what I’ve seen and heard in news broadcasts. (Apart from that today was fairly dull, with mainly shit weather and nothing really much happened).
So today there was an accident. And no it wasn’t in a helicopter. It was in a theme park. One which I’ve attended on numerous occasions. Alton Towers. Been running for what now, thirty years, never with a ‘major’ accident. The ride in question was ‘The Smiler’ and £18 million pound state of the art roller coaster, launched in 2013 and has been continually plagued with problems.
First I’ll just say that my thoughts are with the sixteen people involved and with their families, you do not go to a theme park and expect to possibly loose your limbs.
Okay, so now follows my analysis. This is just my opinion, but I’ve got a bit of an interest in how things work and are designed, so know a reasonable amount about electromechanical engineering and have worked in this very industry.
This ride as I said has been plagued with problems. On its press launch it left a bunch of journalists stuck on the lift hill, bits have fallen off it and it’s had numerous closures for ‘technical’ problems. I’ll hazard a guess at what these ‘technical’ problems are and it’s all down to one device, proximity sensors. Now these are ‘hall-effect’ devices and to be honest are a major pain in the ass. In a nice clean industrial setting on a conveyer belt they work fine. But you stick them out in the nice British weather and they become very unreliable. They work on the theory that when a magnet passes the front it operates a switch. The design is very good, the problem then comes with weather proofing and mechanical stability, you have all the cabling and everything else. These coasters are usually designed with triple redundant systems. That is, there are three separate circuits that all have to agree. I’ll explain. You have a car going down the track, before it you have a brake and before the next section you have three hall-effect sensors. The brake is applied (and it’s fail safe pneumatic, so if power or air fails, brake is on), this will stop any car entering this section of the track. All three sensors have to be triggered before the brake is released. Perfect safety system, triple redundancy. Now what happens if one of those sensors is a bit dodgy? That brake isn’t going to release, the ride then breaks down and everyone gets pissed off. £18 million quids worth of scrap. So what are the options? Well, replace or adjust the sensor is of course the correct option. This requires a mechanic, possibly a new sensor. And the most important point for a park like this….time. It’s going to take a mechanic probably an hour to find the dodgy sensor, possibly another one to change it and then this being a critical system would need to be checked by a second mechanic (this is standard procedure on any mission critical system, this is why in this country we have very few planes falling out of the sky because someone failed to put all the bolts in). That’s about three hours down the pan due to a faulty sensor and this ride probably has around two hundred of the things.
So what happens instead? Well operators get complacent. They work out that if the brake jams a car on a section of the track that they can just reset the system and off it will go. They just need to send round an empty car to make sure it gets through all the sensors and all will be okay.
So what happened this time? They got unlucky, well the people on the car got unlucky. From what I can gather, the ride suffered yet another ‘technical failure’. They sent an empty car round. Due to the weight of an empty car it didn’t make it round one of the loops. No one noticed this. Blokie in operations box gets yet another bloody sensor error. Shuts the system down and restarts it. The ride computer now has no idea that it has a car stuck on a section of track. They send a car round now with people on it. All the sensors work correctly, remember it has no idea a car is on track because the system has been reset. The car then ploughs clean into the back of the stalled one and bang. Game over for sixteen people, four of them seriously.
So who’s to blame? Is it the manufacturer for producing a technically advanced ride with lots of safety systems that could cause too many false positives and then cause issues for the operators due to excessive downtime? Is it maintenance for possibly bypassing some safety systems or perhaps not doing routine maintenance properly? Or is it the operators for becoming too complacent and possibly working out ways to bypass these systems?
One things for certain, those sixteen people are certainly not to blame. Alton Towers is closed tomorrow. Health and safety executive are of course involved, there will be a full investigation. That ride will probably be closed for at least the rest of the year and may indeed never operate again. It cost £18 million, but if the ambulance chaser lawyers get involved then that £18 million will be a drop in the ocean to what they will be paying out in compensation. The Merlin group have already dropped 3% on FTSE, I can see them plummeting a lot further in coming days.
I don’t think it will be the end of Alton Towers, but ‘The Smiler’ certainly isn’t smiling anymore.