Why were slam door trains still built so late on?

[AY1975]

Does anyone know why BR (and its predecessors) continued to build slam door trains (particularly in the case of suburban DMUs and EMUs) for so long after sliding door technology had become available and been proven to work?

I would guess that this was at least partly thanks to the influence of the Southern Region (and was maybe a legacy of Sir Oliver Bulleid?).

One could argue that slam door units built in the 1950s and '60s (and, in the case of the Class 312s and later batches of 4-VEPs, well into the '70s) were already out-of-date when built.

 

[Journeyman]

This has been done to death already. Watch out for some fairly predictable responses.

 

[30907]

For suburban services, I agree that the move to automatic doors was belated.
However, they were more complex operationally, I presume much more expensive, and also significantly slower to load and unload (remember that the SR operated with 20sec station stops whereas today 1 minute is the norm). I suspect that all of those were factors to be weighed against increased passenger safety.

As to main line stock, it was the mid 70s before fully automatic doors began to be widely used in mainland Europe - previously inward-opening hand-operated doors were typical, and the first step forward was a form of central locking or closing-and-locking (still common today, and just about as difficult to open as a Mk 3 door!). The Mk 3 was behind the game, yes, but only just.

PS Hope that doesn't count as predictable

 

[Journeyman]

For suburban services, I agree that the move to automatic doors was belated.
However, they were more complex operationally, I presume much more expensive, and also significantly slower to load and unload (remember that the SR operated with 20sec station stops whereas today 1 minute is the norm). I suspect that all of those were factors to be weighed against increased passenger safety.

As to main line stock, it was the mid 70s before fully automatic doors began to be widely used in mainland Europe - previously inward-opening hand-operated doors were typical, and the first step forward was a form of central locking or closing-and-locking (still common today, and just about as difficult to open as a Mk 3 door!). The Mk 3 was behind the game, yes, but only just.

PS Hope that doesn't count as predictable

Nah, that's reasonably sensible.

Mark 3s were constructed with manually operated slam doors mainly because at the time they were introduced, they had to operate with Mark 1s and Mark 2s, and power doors would have prevented them from doing so. Even in otherwise all-Mark 3 formations, it was common for a Mark 1 catering vehicle to be included until well into the eighties.

 

[Helvellyn]

502, 503 on Merseyside; 506 in Manchester; 306 on the Great Eastern; and 303, 311 on Clydeside all had sliding doors. However it could be argued slam doors allowed higher seating densities with a door opening into seating bays meaning no need for separate vestibules. Add in the number of EMUs with full width compartments and sliding doors would have been a big drop in capacity.

Mark 3s were constructed with manually operated slam doors mainly because at the time they were introduced, they had to operate with Mark 1s and Mark 2s, and power doors would have prevented them from doing so. Even in otherwise all-Mark 3 formations, it was common for a Mark 1 catering vehicle to be included until well into the eighties.

Whilst I sort of buy the loco-hauled argument I do wonder why HSTs didn't get sliding (or more likely swing plug) doors given they were conceived as fixed formation units. Especially given the APT had plug doors.

 

[CarltonA]

(and was maybe a legacy of Sir Oliver Bulleid?).

He was made CBE in the 1940s, which is the third rank of chivalry and does not count as a knighthood so he should not be referred to as "Sir".

 

[edwin_m]

The Mk1s converted for use with

Whilst I sort of buy the loco-hauled argument I do wonder why HSTs didn't get sliding (or more likely swing plug) doors given they were conceived as fixed formation units. Especially given the APT had plug doors.

Especially odd that the guard's door on the power cars was a sliding plug, having been changed from the traditional brake van double hinged door fitted to the prototypes.

Another reason for the conservatism on the Southern was that they were in the lucky position of having a fleet where everything would multiple with everything else (I think - possible exceptions for some of the older designs). The power door fitted units couldn't run in service with the older units and I presume couldn't even multiple with them.

 

[Journeyman]

Whilst I sort of buy the loco-hauled argument I do wonder why HSTs didn't get sliding (or more likely swing plug) doors given they were conceived as fixed formation units. Especially given the APT had plug doors.

Agreed, given that HST trailers were incompatible with loco hauled vehicles it would have been possible to do it, although I suppose construction of two different body designs would have increased complexity and expense.

 

[higthomas]

However it could be argued slam doors allowed higher seating densities with a door opening into seating bays meaning no need for separate vestibules. Add in the number of EMUs with full width compartments and sliding doors would have been a big drop in capacity.

Why could one not have the same layout with power doors though? Just cost?

 

[43096]

Agreed, given that HST trailers were incompatible with loco hauled vehicles it would have been possible to do it, although I suppose construction of two different body designs would have increased complexity and expense.

Don’t forget that originally the HST stock in the prototype was of loco-hauled configuration with HST through jumpers added. The plan was probably to have one common coach type. The advantages of the HST’s three phase train supply stopped that, but probably too late to change the body design.

 

[randyrippley]

Don’t forget that originally the HST stock in the prototype was of loco-hauled configuration with HST through jumpers added. The plan was probably to have one common coach type. The advantages of the HST’s three phase train supply stopped that, but probably too late to change the body design.

The original plan was for all the MkIII fleet to be capable of being dual powered - this idea was dropped at the same time as 41001/2 became 43000/1. At the same time as the blunt end driving cabs were stripped out, the conventional power lines on the prototype coaches were cut to simplify the cabling and connectors

 

[randyrippley]

Why could one not have the same layout with power doors though? Just cost?

multiple reasons
for one, take a look at a coach from a 4-VEP. Sliding doors would conflict with each other
secondly, sliding doors require a completely different construction method using a double skin: just where would the door slide into on a VEP? Plug doors weren't an option: they were too slow, and platform clearance was an issue. The plug doors fitted by Inchicore on the Irish MkIII fleet proved that.

 

[randyrippley]

Don't forget there's a fundamental reason why the Southern used slam doors for so long: Eastleigh was set up to build MkI coaches, often on recycled underframes. They didn't have the skills or engineering facilities to build newer designs. And there was no way BR was going to re-equip and retrain the staff there, when they had other works capable of newer designs.

 

[theageofthetra]

Nah, that's reasonably sensible.

Mark 3s were constructed with manually operated slam doors mainly because at the time they were introduced, they had to operate with Mark 1s and Mark 2s, and power doors would have prevented them from doing so. Even in otherwise all-Mark 3 formations, it was common for a Mark 1 catering vehicle to be included until well into the eighties.

Or even a pre BR catering vehicle.

 

[Journeyman]

Why could one not have the same layout with power doors though? Just cost?

London Transport built some mock-ups of a compartment vehicle with power doors once, as compartments were popular on longer Metropolitan Line services before the A Stock was developed. I've seen some photos - it looks monstrously complicated!

 

[Taunton]

I think the real answer is that it wasn't perceived as a problem, by operator or passenger.

 

[PeterC]

I think the real answer is that it wasn't perceived as a problem, by operator or passenger.

On suburban services I suspect that most passengers saw a slam door to each seating bay as an advantage.

 

[Cowley]

On suburban services I suspect that most passengers saw a slam door to each seating bay as an advantage.

Plus the extra few seconds you got from swinging the door open before the train had fully stopped and stepping off.

 

[MatthewRead]

What I would like to know is why the 150/1's have a hand worked door to the drivers cab like on the A stock despite being a good 20 years or so younger.

 

[DelW]

Much of the early MU rolling stock was based on loco-hauled coach designs. At that time there was generally no head-end power available from the loco, as both steam and early diesel locos heated the coaches using low-pressure steam. Electricity for lighting was produced by dynamos and batteries under each coach, but I'd guess it's unlikely that that would have been adequate to power door mechanisms reliably enough.

 

[AndrewE]

What I would like to know is why the 150/1's have a hand worked door to the drivers cab like on the A stock despite being a good 20 years or so younger.

Well, the crew can't get "locked out" of the train by accident, for a start!

 

[MatthewRead]

Well, the crew can't get "locked out" of the train by accident, for a start!

But other units of the same era all had automatic cab doors.

 

[Pigeon]

Electricity for lighting was produced by dynamos and batteries under each coach, but I'd guess it's unlikely that that would have been adequate to power door mechanisms reliably enough.

Memories of sitting waiting for the road for 15-20 minutes in Mk 1 stock with tatered batteries, the lights getting steadily dimmer and redder until you could hardly see, then suddenly brightening up again when we finally moved off and the dynamo kicked in...

As for the title question, I think it's backwards, especially with "so late on" apparently meaning the 60s. Sliding doors have their place - where the platforms are cramped and swarming and the trains accelerate hard straight into tunnels with fag-paper clearances, ie. the Underground. It is easy to imagine improperly-closed slam doors batting people aside all down the platform and then being torn off altogether at the tunnel mouth being a daily event in those conditions, and even more often, station stops being outrageously extended by waiting for platform staff to fight their way through the crowds to close doors, while passengers open them again behind them. But the conditions on BR lines are considerably different, and back in the 60s - when "safety" was still a matter for common sense, and had not yet become an overblown insistence on pandering to wet ninnies with no concept of personal responsibility for their actions - to fit sliding doors would have been seen as a large and pointless increment in expense and hassle to solve a problem that didn't exist.

There was an official report into untoward incidents with slam doors, dated late 80s I think, in which the actual data indicated that using sliding doors instead was indeed a grossly extravagant and unnecessary hassle and expense. Even though the design of the slam-door latch installation (which was described in detail) was a truly appalling piece of bodgery that seemed to be doing its best to guarantee improper alignment in fitting and failures in service for silly reasons, only one in eight incidents were actually down to the door mechanism itself, the other seven all being variations on the theme of people pratting about with it. The obvious and straightforward solution would have been simply to replace the existing latch design with a design that was actually half-way competent, which given that you could eat a handful of iron filings and puke a better design than the existing one would not have been at all difficult. But thanks to the rising trend of encouraging people to blame the consequences of their own stupidity on others for financial gain, the report mis-classified well over half the pratting-about failures as failures of the mechanism, and consequently came out in favour of the excessive solution.

 

[Killingworth]

I'm digressing a little but in my youth I used the North Tyneside electrics built for the LNER in 1937 with manually operated sliding doors. By the end of their lives in the 1960s some of them were becoming very stiff to operate and it can't have been uncommon for a train to start with a door partially open. If memory serves correctly the South Tyneside branch continued to use older NER stock from 1920-22 with inward opening end doors. They were replaced in the mid-1950s by Southern Region compartment units with slam doors which didn't seem to be an improvement, although it may have speeded loading and unloading. It's sad that the electric advances made by the NER and LNER in the north weren't carried further after nationalisation, but that's another story.

I'll slam the door as I leave, window raised, leather strap pegged back.

 

[Cowley]

I'm digressing a little but in my youth I used the North Tyneside electrics built for the LNER in 1937 with manually operated sliding doors. By the end of their lives in the 1960s some of them were becoming very stiff to operate and it can't have been uncommon for a train to start with a door partially open. If memory serves correctly the South Tyneside branch continued to use older NER stock from 1920-22 with inward opening end doors. They were replaced in the mid-1950s by Southern Region compartment units with slam doors which didn't seem to be an improvement, although it may have speeded loading and unloading. It's sad that the electric advances made by the NER and LNER in the north weren't carried further after nationalisation, but that's another story.

I'll slam the door as I leave, window raised, leather strap pegged back.

I bet your memories of travelling on those old machines are cherished now Killingworth?
Great post.

 

[Taunton]

Despite much observation, I never saw a door open on a moving train, and never was delayed by it. There are other accounts, but they seem to have been rare.

If you call non-slam doors "Power Doors", it becomes more apparent. There was no power on non-EMU rolling stock until the recent generation. Stock was commonly left at the terminus without a locomotive and people boarded, the only services needed was lighting from batteries, which if it failed was a nuisance but not a great one, as each carriage was separately fitted. Even when changing locos at an intermediate point, there was no power in the train to operate power doors.

When air-con came along in the 1970s, non operation when there was no loco attached was never an issue. But inability to opemn/close doors would be.

EMUs were different, there was a ready electrical supply, although it was still not reliable enough to operate doors, so until quite recently power doors, on the Underground and the few electric units so fitted, were by compressed air from the brake line. Trains could be left at the terminus unstaffed but quite reliant on passengers to use the open buttons. I recall the old Wirral units at West Kirby, press the button, a large hiss from the mechanism, doors open, and the underfloor reciprocating compressor starts up to recharge. Closure buttons were unknown until recent times, only the guard's panel could close them. Doors were normally held closed by a small air piston. To open, a larger piston overcame this and pushed them apart. Both driver and guard doors were generally still hand operated for times in the depot with no air, when the passenger doors could just be pushed open/closed at will.

 

[big all]

Don't forget there's a fundamental reason why the Southern used slam doors for so long: Eastleigh was set up to build MkI coaches, often on recycled underframes. They didn't have the skills or engineering facilities to build newer designs. And there was no way BR was going to re-equip and retrain the staff there, when they had other works capable of newer designs.

from what i remember the later batch off veps where delivered 70-71 and built in york
i can remember the door tread plates said somthing like made in br workshops and may have even said br york

 

[yorksrob]

from what i remember the later batch off veps where delivered 70-71 and built in york
i can remember the door tread plates said somthing like made in br workshops and may have even said br york

BREL was on there.

 

[Taunton]

from what i remember the later batch off veps where delivered 70-71 and built in York

All the Southern VEP/CIG/REP generation were built in York, starting in 1963, when Eastleigh production closed down with the last of the 4-CEP.

 

[hexagon789]

Whilst I sort of buy the loco-hauled argument I do wonder why HSTs didn't get sliding (or more likely swing plug) doors given they were conceived as fixed formation units. Especially given the APT had plug doors.

I believe both electric-plug doors and retention tanks were considered when the HST was in development (can't recall if that was for production or prototype as well) but ruled out on cost grounds IIRC.

Irish Rail did have their Mk3s all fitted with electric-plug doors (similar to the 442's) but not with retention tanks either.