RMweb Premium PhilJ W Posted June 18, 2021 RMweb Premium Share Posted June 18, 2021 4 hours ago, Wickham Green too said: I see nobody's mentioned air bags ................. ! I know of a few of the human variety. 2 Link to post Share on other sites More sharing options...
Wickham Green too Posted June 18, 2021 Share Posted June 18, 2021 Yeah - but they're the sort of distraction you DON'T want in the cab ! 2 Link to post Share on other sites More sharing options...
Hobby Posted June 18, 2021 Share Posted June 18, 2021 Nor an ejector seat, just think if you pressed the wrong button to cancel the alarm!! 1 Link to post Share on other sites More sharing options...
Popular Post lather Posted June 18, 2021 Popular Post Share Posted June 18, 2021 6 hours ago, meil said: Remember also that most ejection seats do not work on the ground i.e. they don't eject far enough for the parachute to work. So train drivers would be subject to far higher stresses than fighter pilots who are younger, and considerably fitter and far more highly trained. The risk analysis simply does not stack up. As someone who's studied the history of "bang seats", and even been strapped into a couple, I can maybe clear up a few misconceptions. While the very early seats were very definitely high-altitude only, the great majority of modern seats are what is known as "zero-zero" rated - i.e zero feet and zero speed. And those that aren't are still rated as things like "zero-70 knots" or similar (zero feet and 70 knots forward speed). As for the question of how high the seat would need to go for parachute deployment, the parachutes deploy very quickly in modern seats. In the early seats, the parachute was either the classic British seat-pack parachute like you see in the Battle of Britain, or a backpack parachute separate to the seat. In both of these cases, the pilot needed to get clear of the seat before manually opening the parachute. Later, they standardised on the backpack type (built into the seat for the RAF, or a stand-alone one worn by the pilot for the US). This was then linked to the seat, so that when it fell away from the pilot after ejection, it opened automatically. This was better, but still not great for low level. So, eventually, the parachute became an integral part of the seat as standard, and migrated upwards into the headrest, placing it closest to where the pilot needs it when required. This allows it to open effectively even in a zero-feet ejection. In the very first "zero-zero" ejection, done by Martin-Baker's test parachutist W.T.H. "Doddy" Hay, the parachute deployed fast enough that he went upwards pulling the fully-inflated parachute behind him for several hundred feet before he swung "right side down" to come down to land. Modern seats are very clever bits of kit, and can sense the altitude when fired. Some even have thrust-vectoring on the rocket pack which can flip the seat upright if it senses the plane is inverted and at low altitude, which helps prevent the pilot being fired straight down into the ground! So what happens when a seat is fired? Well, the first thing is that pulling the "loud handle" fires small explosive charges that retract the harness, pulling the pilot tightly into the seat in the correct posture to try and avoid injury. At the same time, the plane starts to think about what to do with the canopy. Here, the difference in approaches tends to be along national lines. The Russian preference is to physically jettison the canopy, even though this may create a post-ejection collision hazard as its behaviour is hard to predict. The British preference is to use "Miniature Detonating Cord" (MDC), which is basically a thin tube full of explosive, to blow a hole in the canopy. The Americans, on the other hand, tend to prefer a more brute force approach. While they have used canopy jettison and, occasionally, MDC, their preferred method is to use small horns called "canopy breakers" on the top of the seat to smash the canopy as the seat rises during ejection. A few hundredths of a second later, the "ejection gun" fires. This is basically a telescopic tube behind the seat, pushing against a bracket on the back of the headrest - think of something looking like a giant shock absorber from a car and you're on the right lines. As the propelling charge in the gun burns, it rapidly expands into gas, extending the tube upwards. This propels the seat up out of the cockpit at a velocity of 60 to 80 feet per second. In some cases, this is enough on its own to get the pilot clear of the plane, but usually a little extra help is needed. This comes in the form of a rocket pack under the seat, which fires as the seat clears the cockpit (about half a second after pulling the handle), and burns for only around half to one second. This provides the extra velocity needed to get to a safe enough height for successful parachute deployment. This is the point at which modern seats get very clever, as they can sense both the altitude and speed as they exit the cockpit, and some can also sense the attitude as well. So as the seat exits the cockpit, the on-board computer checks the conditions and instantly decides which sequence to use for the rest of the ejection. If it senses a high-altitude environment, where extreme cold and oxygen deprivation are the main hazards, it will go into the high-altitude mode, while a low-altitude environment where impact with the ground is the main danger will trigger one of the low-altitude modes. In some seats, this is the point where the thrust-vectoring kicks in, to help steer the seat away from danger as much as possible. Some seats also have a second stage to the rocket pack, which can be initiated if required to get a bit of extra height. Regardless of which mode the seat goes into, the next thing to happen, around one to one and a half seconds after the seat fires, is that the "drogue gun" fires. This is placed in or just behind the headrest, and fires out a small but heavy metal rod with an eyelet on the top. This drags out a small parachute about two feet or so across called the "drogue parachute". The line from this is attached to the main parachute via a large metal buckle, which is held in a pair of very strong jaws. This small parachute has enough drag to align the seat so that it places the pilot feet-down into the airflow. (Some seats use a "two-stage drogue" system, with the gun deploying a small drogue, which then pulls out a larger one.) In a high-altitude mode, the seat pauses the sequence at this point to allow the seat, which is feeding oxygen to the pilot from a small internal bottle, to fall to a lower height where the supplementary oxygen is no longer required. However, in the low-altitude modes, it will continue to progress through the sequence as quickly as possible. Once the computer decides that the time and altitude is right and the seat is stable enough (i.e. not tumbling wildly). the signal is sent to open the jaws and release the large buckle. This allows the "drogue parachute" to pull the main parachute out of its storage in the headrest. The main parachute is specially designed to inflate as quickly as possible, and often has a more conical shape than the classic "mushroom" style. As soon as the seat senses the pull of the parachute through the rigging lines, which are attached to the seat harness so that it does double duty as the parachute harness, it severs the connections between the harness and the seat, allowing the pilot to be pulled clear of the seat. As the seat falls away, a line attached to the harness also pulls out the survival pack, which is usually stored in the seat cushion and also contains the one-person dingy. Job done, the seat then free-falls to destruction while the pilot descends fairly gently on his parachute. The above may take a long time to read. (Sorry, but as you can no doubt appreciate, it IS a complex process...) However, in reality, the time from pulling the "loud handle" to being under a parachute which is deployed enough to enable a survivable (if a little painful) landing can be as little as two and a half seconds. You can see this in probably the most famous piece of footage of an ejection by searching for "MiG 29 crash Paris 1989" - in this case, the ejection took place at just a couple of hundred feet with the plane heading almost vertically down to the ground. Not only did the pilot survive, it really was a case of "and he walked away", despite ejecting at extreme low level, low speed and just two seconds from impact with a flight-path heading straight for the ground. And was he shaken by it? Of course not! In fact, the first thing he did after landing was pull a pack of smokes out of his pocket, light up and wander over to see the mess he'd made... But that's not the lowest you can go. Although I can't remember the exact details, I do remember hearing about one pilot who survived an inverted ejection at just 100 feet with only minor injuries. From the purely technical point of view, it would be possible to give train drivers "zero-zero"-capable ejection seats. Even things like tunnels and OHLE could be addressed and avoided via linking the seat to GPS or trackside transponders so that it knows when there's a bridge or tunnel, and using thrust vectoring to give lateral separation from the OHLE wires. (And, don't forget, unless he's in a central seat, he's already slightly to the side of the wire anyway.) The issues really are the physiological, as pointed out by others, and the ethical. Physiologically, ejection exposes the body to rapid acceleration which can result in spinal compression and fractures. However, contrary to popular belief, it isn't the peak "g" that's the issue, as that's only around 12g, but the rate at which it is applied - which can be 40g per second or more. THAT'S what causes the injuries, along with flailing of unrestrained limbs in a high-speed airflow and injuries sustained on landing. While a physically fit pilot may be able to handle that, the average train driver may well struggle and end up with quite bad spinal injuries. As for the ethical issue, the question is if it's right to give the driver a way out, but deny it to the others on board the train. This was a dilemma that the RAF had to face in the 1950s with the introduction of the "V-Force", as the Vulcan, Victor and Valiant only had ejection seats for the pilot and co-pilot - the other three crew sat facing rearwards in ordinary seats as it was thought at the time that rear-facing ejection wasn't possible (even though Martin-Baker's proved it was with a live ejection from the back of a Valiant). As a result, their only option was to attempt a manual bale-out through the entry hatch in the same way as their predecessors in the Lancaster, Halifax and Stirling. In reality, many of the front-seat crew refused to abandon their crew-mates to their fate and continued to try and save the plane right up to impact. And so the RAF ended up losing entire crews when it would have been technically possible to give them all ejection seats that would have enabled them all to survive. So, while it may be a technical possibility, unless a way could be found to get everyone else out of the train before impact, it's highly unlikely that any train operator would be able to justify giving the driver an ejection seat. Much better to try and improve the crashworthiness of the loco instead. 3 1 26 6 Link to post Share on other sites More sharing options...
RMweb Premium PhilJ W Posted June 18, 2021 RMweb Premium Share Posted June 18, 2021 (edited) 2 hours ago, lather said: The above may take a long time to read. (Sorry, but as you can no doubt appreciate, it IS a complex process...) However, in reality, the time from pulling the "loud handle" to being under a parachute which is deployed enough to enable a survivable (if a little painful) landing can be as little as two and a half seconds. You can see this in probably the most famous piece of footage of an ejection by searching for "MiG 29 crash Paris 1989" - in this case, the ejection took place at just a couple of hundred feet with the plane heading almost vertically down to the ground. Not only did the pilot survive, it really was a case of "and he walked away", despite ejecting at extreme low level, low speed and just two seconds from impact with a flight-path heading straight for the ground. And was he shaken by it? Of course not! In fact, the first thing he did after landing was pull a pack of smokes out of his pocket, light up and wander over to see the mess he'd made... Also explains the cause of the crash, flame out of right engine. Edited June 18, 2021 by PhilJ W 3 Link to post Share on other sites More sharing options...
Michael Hodgson Posted June 19, 2021 Share Posted June 19, 2021 Thanks for that detailed update on ejector technology lather, that's why my post suggesting it said that an ejector seat be designed for rather than fitted for a train driver. I was aware of issues when flying inverted and that modern seats are considerably more sophisticated than the early ones, just as other equipment like aircrew helmets are rather more elaborate (and costly) than what we make the kiddies wear when riding a bike. Your ethical point about V-bombers and everybody else on board may apply to passenger workings, but these days there is often only one person on board a freight train, and I suppose you'd have to make provision to fitting another one for an inspector travelling with him. I'm not sure that the situation with a V-bomber crew is comparable, as the pilot who chooses to remain on board is still using the control surfaces that are still available in an attempt to keep the aircraft stable long enough for his crew to bale out conventionally or is trying to make a crash landing that they might be able to survive even if he doesn't. After he's put the brakes into full emergency a train driver has no controls he can usefully manipulate when a collision is obvious. In any case, where a train is loco-hauled, there is a greater risk to the bloke at the front in a collision than there is to a passenger two thirds of the way down the train. Unlike a car he isn't expected to remain seated and he doesn't have a seat belt, indeed he probably prefers being able to go to the bar for a beer! I think there is a slightly different ethical issue about ejecting from trains - I suspect there is greater risk to people on the ground than there is from an aircraft. All the same, anybody unfortunate enough to be standing too near the line when a train is derailing has a problem anyway, even if he is beyond the threshold required to meet PTS rules. 1 Link to post Share on other sites More sharing options...
PatB Posted June 19, 2021 Share Posted June 19, 2021 Realistically, though, whilst still too frequent, fatal collisions with obstacles are, thankfully, quite rare events. As such, resources may be better spent on projects to improve road/rail separation (elimination of level crossings, basically), and improving crash worthiness of locos and stock. Indeed, in this day and age, how critical is it for the driver to be right at the pointy end? If looking at aircraft tech to improve driver safety, maybe the sort of VR gear that makes drones feasible would be a better option. Indeed, AIUI, driverless train technology is already able to achieve exactly this. 3 Link to post Share on other sites More sharing options...
Michael Hodgson Posted June 19, 2021 Share Posted June 19, 2021 Yes, we've already moved the signalmen from Kings Cross to York, and we could take the next logical step and run the entire railway from a call centre in Bombay, saving a fortune in drivers' wages. I seem to recall when the Victoria Line was opened that it had been designed to be driverless but the powers that be thought the public wouldn't feel safe travelling in unmanned trains so they retained the motorman and he's still there some half a century later. Of course he could become a "Train Captain" whose job is to lead survivors away after a smash. Not that London Transport has much trouble with low loaders on level crossings of course. 2 Link to post Share on other sites More sharing options...
Wickham Green too Posted June 19, 2021 Share Posted June 19, 2021 6 hours ago, PatB said: ....... AIUI, driverless train technology is already able to achieve exactly this. ..... and we'll soon have driverless cars on the level crossings too - GAWD 'ELP US ! 1 3 Link to post Share on other sites More sharing options...
RMweb Premium boxbrownie Posted June 19, 2021 RMweb Premium Share Posted June 19, 2021 6 hours ago, PatB said: Realistically, though, whilst still too frequent, fatal collisions with obstacles are, thankfully, quite rare events. As such, resources may be better spent on projects to improve road/rail separation (elimination of level crossings, basically), and improving crash worthiness of locos and stock. Indeed, in this day and age, how critical is it for the driver to be right at the pointy end? If looking at aircraft tech to improve driver safety, maybe the sort of VR gear that makes drones feasible would be a better option. Indeed, AIUI, driverless train technology is already able to achieve exactly this. Careful there are a few drivers on the forum who might not like sitting in a portacabin in Leeds driving the train with VR strapped to their noggin 2 Link to post Share on other sites More sharing options...
RMweb Gold Bucoops Posted June 19, 2021 RMweb Gold Share Posted June 19, 2021 Even airport control towers aren't "safe" - London City Airport's control tower is now at NATS in Swanwick. 1 2 Link to post Share on other sites More sharing options...
RMweb Premium petethemole Posted June 19, 2021 RMweb Premium Share Posted June 19, 2021 11 hours ago, Michael Hodgson said: In any case, where a train is loco-hauled, there is a greater risk to the bloke at the front in a collision than there is to a passenger two thirds of the way down the train. Unlike a car he isn't expected to remain seated and he doesn't have a seat belt, indeed he probably prefers being able to go to the bar for a beer! But in a loco-hauled train, unlike an MU, the driver can't get to the bar. (Sorry, blame the way I was taught grammar) 1 Link to post Share on other sites More sharing options...
Michael Hodgson Posted June 19, 2021 Share Posted June 19, 2021 2 hours ago, Wickham Green too said: ..... and we'll soon have driverless cars on the level crossings too - GAWD 'ELP US ! At least those could be programmed not to park on crossings! The satnavs might want some sort of database of such hazards 1 Link to post Share on other sites More sharing options...
RMweb Premium jamie92208 Posted June 19, 2021 RMweb Premium Share Posted June 19, 2021 It's not just drivers. I believe that at both Hatfield and Great Heck, catering staff were amongst the casualties. I seem to remember that catering containers were involved. Jamie 1 Link to post Share on other sites More sharing options...
RMweb Gold Dunsignalling Posted June 19, 2021 RMweb Gold Share Posted June 19, 2021 (edited) In any major impact, a refreshment trolley would potentially create absolute mayhem. I wouldn't want even to be responsible for trying to keep one under control in an emergency braking situation. John Edited June 19, 2021 by Dunsignalling 2 Link to post Share on other sites More sharing options...
Michael Hodgson Posted June 19, 2021 Share Posted June 19, 2021 2 hours ago, boxbrownie said: Careful there are a few drivers on the forum who might not like sitting in a portacabin in Leeds driving the train with VR strapped to their noggin At least they'd be in Leeds - meeting one of the Govenrnment's objectives of levelling up by creating jobs in the frozen North! I think the logic behind ATO on the Victoria Line had more to do with ASLEF strikes irritating the voters in commuterland. It was before Thatcher's time, but she would have been happy for the railways to go the same way as the pits, and our incumbent great Leader is in favour of driverless trains https://www.bbc.co.uk/news/uk-england-london-53314197 Somebody ought to tell him diggers could be driverless too. Link to post Share on other sites More sharing options...
RMweb Premium newbryford Posted June 19, 2021 RMweb Premium Share Posted June 19, 2021 Man charged with Rossington Azuma incident. 4 1 Link to post Share on other sites More sharing options...
Michael Hodgson Posted June 19, 2021 Share Posted June 19, 2021 8 minutes ago, Dunsignalling said: In any major impact, a refreshment trolley would potentially create absolute mayhem. I wouldn't want even to be responsible for trying to keep one under control in an emergency braking situation. John Surely that's a design issue - fit the thing with its own brakes and an accelerometer to apply them in such a situation. Maybe even a sort of deadman's that the steward just has to let go of. Link to post Share on other sites More sharing options...
RMweb Premium jamie92208 Posted June 19, 2021 RMweb Premium Share Posted June 19, 2021 1 minute ago, Michael Hodgson said: Surely that's a design issue - fit the thing with its own brakes and an accelerometer to apply them in such a situation. Maybe even a sort of deadman's that the steward just has to let go of. I'm not sure that it was the trolleys. I think that it was the wheeled containers that the restaurant car supplies come in. They are normally secured by what look like a set of dog clips. Jamie 1 Link to post Share on other sites More sharing options...
RMweb Premium JDW Posted June 19, 2021 RMweb Premium Share Posted June 19, 2021 14 minutes ago, Michael Hodgson said: Surely that's a design issue - fit the thing with its own brakes and an accelerometer to apply them in such a situation. Maybe even a sort of deadman's that the steward just has to let go of. Unfortunately that probably wouldn't do much - if the force of the train stopping is hard enough to throw the trolley forwards at any great rate, then it'll likely be thrown, tipped or just skid with locked wheels, as there's only a limited amount of friction between smooth trolley wheels and the carpet. A push-down handle like on airport baggage trolleys that released the brakes might help stop it at slow speed - maybe they already have them to keep them steady, I don't know - but at anything like a higher speed the lack of friction between the trolley and carpet would be the bigger problem. 2 Link to post Share on other sites More sharing options...
RMweb Gold Dunsignalling Posted June 19, 2021 RMweb Gold Share Posted June 19, 2021 15 minutes ago, Michael Hodgson said: Surely that's a design issue - fit the thing with its own brakes and an accelerometer to apply them in such a situation. Maybe even a sort of deadman's that the steward just has to let go of. Possibly, but they are tall, narrow, and quite heavy. I'd think whatever brakes they have would be rendered ineffective by them toppling over, at which point they could slide about anywhere. John 2 Link to post Share on other sites More sharing options...
Wickham Green too Posted June 19, 2021 Share Posted June 19, 2021 17 minutes ago, Dunsignalling said: ........ at which point they could slide about anywhere. ........ spewing boiling water as they go ! 1 2 Link to post Share on other sites More sharing options...
Fat Controller Posted June 19, 2021 Share Posted June 19, 2021 26 minutes ago, Dunsignalling said: Possibly, but they are tall, narrow, and quite heavy. I'd think whatever brakes they have would be rendered ineffective by them toppling over, at which point they could slide about anywhere. John You should try moving one from the upper deck to the lower (or vice versa) of a Eurotunnel Shuttle...We did, but just the once. 2 Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted June 19, 2021 RMweb Premium Share Posted June 19, 2021 4 hours ago, Wickham Green too said: ..... and we'll soon have driverless cars on the level crossings too - GAWD 'ELP US ! Like the Teslas that needed the real drivers to stop it driving onto the railway, instead of following the tarmac. And this one that thought it was a plane: https://interestingengineering.com/video/watch-this-tesla-model-s-catch-air-after-hitting-train-tracks 2 2 Link to post Share on other sites More sharing options...
Talltim Posted June 19, 2021 Share Posted June 19, 2021 (edited) 2 hours ago, Wickham Green too said: ........ spewing boiling water as they go ! Spewing luke warm water as they go! Edited June 19, 2021 by Talltim 5 Link to post Share on other sites More sharing options...
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