Why were slam door trains still built so late on?

randyrippley said:

doors that were on the latch and shook loose
latches that failed
vibration causing coach bodies to flex and twist, with the door forced out of position
people opening doors at a platform when held at a signal rather than a scheduled stop
people mistaking their stop and trying to exit too late as the train is leaving the platform

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People leaning on doors combined with the first three above.
People ‘larking’ around.

JonathanH said:

Depends whether the door opens in the direction of travel or not. If a door was on the latch, the force of the displaced air down the side of the train was more than enough to open the door, more so as speed picked up.

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I thought the latch was actually a double one and the "outer" latch would hold the door even if the "inner" one had failed or it hadn't been closed completely. I think the fluorescent paint on the edge appeared about the same time as central locking, to make it more obvious if not fully latched.

Mk1 and early Mk2 doors would open right back against the bodywork but the later Mk2 and Mk3 doors were restrained to about 90 degrees by a strap (otherwise, being at the end of the coach, two adjacent ones would probably have touched each other). This arguably made them more dangerous than the older ones if opened before stopping, especially as they were larger so projected further, and heavier so harder for the person opening to control them. If someone had opened a trailing end door of this type at high speed, the airflow would probably have broken the strap but I'm not sure if the door would then have folded right back or just damaged/destroyed the hinges.

edwin_m said:

I thought the latch was actually a double one and the "outer" latch would hold the door even if the "inner" one had failed or it hadn't been closed completely. I think the fluorescent paint on the edge appeared about the same time as central locking, to make it more obvious if not fully latched.

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Yes, doors were on an outer latch and these mainly did 'hold' a partially open door. However, a passing train would cause a change in airflow which had more power than this safety latch feature could withstand.

I recall one journey on a VEP between Wokongham and Reading where a door did fly open unexpectedly (and as you note open right back against the body of the train). Rather than pull the emergency cord, a passenger reached out to close the door standing in the doorway with one hand on the luggage rack and the other pulling the door against the airflow. Clearly a very dangerous thing to do.

Bald Rick said:

Yes it happened all the time. It was one of the single biggest risks to passengers on the rail system. People fell out of trains, at speed, quite regularly (older readers may remember the ‘Tamworth Triangle’)

Introducing central door locking and (separately) TPWS significantly improved safety on the railway.

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Yeah I remember the Tamworth Triangle. Was it ever solved? There were many thoughts at the time including a serial pusher as it were pushing people out of moving trains.

GrimShady said:

Yeah I remember the Tamworth Triangle. Was it ever solved? There were many thoughts at the time including a serial pusher as it were pushing people out of moving trains.

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It was solved by central door locking.

I never heard of the Tamworth Triangle before but here is an interesting read relating to that topic:

https://1991-new-world-order.fandom.com/wiki/The_'Tamworth_Triangle'

This sentence is a bit confusing though: "A person also fell out of a North East England Class 158 Pacer unit and on to the platform as it left the station in 1993."

Bletchleyite said:

"Other units of the same era" = "Class 150/2 and 455". All others of that era didn't have dedicated cab doors at all, they just used the first passenger door, which caused obvious issues with getting out to use signal post telephones on full and standing trains. The Class 319 onwards did too, but aren't they a bit later and use a Networker-style semi-automatic plug door?

With those two classes, it might be to do with the fact that passengers can access that area when they are coupled, therefore the door needs to be on the interlock.

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Lack of a manual driver's door could be a problem on dmus. I was at Liverpool Lime Street once when the crew struggled to get into a dmu (150/2 or 156 - I can't remember which) - because the train's batteries were almost flat, and the power-operated doors refused to open.....

JonathanH said:

Yes, doors were on an outer latch and these mainly did 'hold' a partially open door. However, a passing train would cause a change in airflow which had more power than this safety latch feature could withstand.

I recall one journey on a VEP between Wokongham and Reading where a door did fly open unexpectedly (and as you note open right back against the body of the train). Rather than pull the emergency cord, a passenger reached out to close the door standing in the doorway with one hand on the luggage rack and the other pulling the door against the airflow. Clearly a very dangerous thing to do.

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To be honest, many a time you would leave a station and notice a door on the first catch. It was no big deal as they would never open; you would simply make a point of walking back, or the guard walking forward at the next station if the door was still on the first catch .

We used to have a trick on 4-car SUBs or EPBs when all doors left open on empty coaching stock into reverse for about 2ft then into forward without stopping for about 4ft. The jolt would shut most - if not all - doors. It didn't work on 2car EPBs, trailers or 63 stock such as VEPs or CIGs, as they have fibreglass doors, so no weight to shut fully.

Yes I know, health and safety.

Bevan Price said:

Lack of a manual driver's door could be a problem on dmus. I was at Liverpool Lime Street once when the crew struggled to get into a dmu (150/2 or 156 - I can't remember which) - because the train's batteries were almost flat, and the power-operated doors refused to open.....

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But if the batteries were almost flat they wouldn't have been able to start it anyway, so probably no urgent need to get on board. I think there's always some means of releasing a door mechanically from outside.

edwin_m said:

But if the batteries were almost flat they wouldn't have been able to start it anyway, so probably no urgent need to get on board. I think there's always some means of releasing a door mechanically from outside.

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Emergency release tin opener.

edwin_m said:

But if the batteries were almost flat they wouldn't have been able to start it anyway, so probably no urgent need to get on board. I think there's always some means of releasing a door mechanically from outside.

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I had a turbo middle coach once with completely flat batteries and I think a tripped MCB or two and the only way to enter the coach was to fully remove all air from the main reservoir and push the doors open and reset the MCBs.