Single doors

[EJD799]

Why were London Underground trains built with two double doors and two single doors instead of 3 double doors like most trains?

 

[AndyPJG]

Can't have double doors at gthe end of the coach...no where for one door leaf to go?

 

[smashing68]

Weren't A and C stock mostly three double doors?

 

[edwin_m]

At a guess, two single doors at the ends of adjacent coaches are moreorless equivalent to a double door and result in a roughly equal distribution of doors along the length of the train - unless it's one of those with an intermediate cab. As well as the issue of it having nowhere to slide to, a double door at a coach end is somewhat pointless, as passengers can only go to/from one direction. At a double door separate lines of people can exit and enter, one for the saloon in each direction.

It may also have something to do with the historic situation where the guard was positioned by the single door at the non-driving end of the last coach. Having a double door here would increase the risk of them falling out.

 

[PeterC]

At a guess, two single doors at the ends of adjacent coaches are moreorless equivalent to a double door and result in a roughly equal distribution of doors along the length of the train - unless it's one of those with an intermediate cab. As well as the issue of it having nowhere to slide to, a double door at a coach end is somewhat pointless, as passengers can only go to/from one direction. At a double door separate lines of people can exit and enter, one for the saloon in each direction.

It may also have something to do with the historic situation where the guard was positioned by the single door at the non-driving end of the last coach. Having a double door here would increase the risk of them falling out.

If the guard's panel is at the end of a car then I imagine that it's easier to use a consistent pattern and have end doors on all cars.

 

[bramling]

Why were London Underground trains built with two double doors and two single doors instead of 3 double doors like most trains?

Don’t forget that on older Tube stocks the wheels protrude up through the floor, hence why the outer ends of Tube cars have always had longitudinal seating. This would presumably restrict the door positions as well. I don’t think it’s an issue on more recent stocks, however the layout stuck no doubt simply out of tradition. To be fair I’m not convinced there’s anything wrong with having single end doors.

 

[EJD799]

Weren't A and C stock mostly three double doors?

I think so. Also, the S Stock is too.

 

[bramling]

I think so. Also, the S Stock is too.

S stock yes, and A stock trailer cars. C stock, rather amazingly, had four double doorways per car.

I think the reason why A stock had single doors on DM cars was to accommodate a guards position, and perhaps to make it more logical in relation to the driver’s cab as well.

 

[Lucan]

the historic situation where the guard was positioned by the single door at the non-driving end of the last coach. Having a double door here would increase the risk of them falling out.

I had not thought of them falling out, but a single door was more effective at stopping passengers using the guard's door because his bulk was filling it. There was a bar the guard could put across the entry to his vestibule area that deterred passengers from trying to exit that way, but guards did not always bother using it.

 

[edwin_m]

I had not thought of them falling out, but a single door was more effective at stopping passengers using the guard's door because his bulk was filling it. There was a bar the guard could put across the entry to his vestibule area that deterred passengers from trying to exit that way, but guards did not always bother using it.

Also they would have to keep passengers out of this area so they could get to the opposite door when the platform was on the other side.

From checking a few images, there seems to have been a grab handle next to the control panel but on the other side there was just a partition with the normal pole on the end furthest from the door. But they could probably lean on this partition to provide a bit of bracing against the motion of the train.

 

[Ian79]

Why were London Underground trains built with two double doors and two single doors instead of 3 double doors like most trains?

Most mainline trains (in the UK anyway) have two double doors per vehicle not three. The only one I can think of with three double doors is the Class 345 on the Elizabeth Line, which also has articulated bogies and walk-through access so is a different beast in terms of passenger loading/unloading.
It's also worth pointing out that tube trains have shorter carriages than mainline, and there is very little space left on the side of the train which isn't either door, or the space a sliding door opens into.

 

[MotCO]

The D78 stock only had single doors, albeit they were wider than a normal single door.

 

[stuu]

Most mainline trains (in the UK anyway) have two double doors per vehicle not three. The only one I can think of with three double doors is the Class 345 on the Elizabeth Line, which also has articulated bogies and walk-through access so is a different beast in terms of passenger loading/unloading.

They don't, they have standard bogies under each carriage

 

[edwin_m]

The D78 stock only had single doors, albeit they were wider than a normal single door.

As did the short-lived 1983 tube stock, which looked a bit like a chopped-down D78. Ran on the Jubilee line until replaced by the current fleet for the extension.

 

[Somewhere]

Weren't A and C stock mostly three double doors?

Surface stock is mainline-size, so can fit the door leafs into the body-sides without getting in the way of the wheels

 

[61653 HTAFC]

As did the short-lived 1983 tube stock, which looked a bit like a chopped-down D78. Ran on the Jubilee line until replaced by the current fleet for the extension.

Always quite liked the 1983 stock, though the single doors were completely unsuitable for work in zones one and two. In a parallel universe they might still be working, but on the Isle of Wight!

 

[etr221]

My understanding is that all tube stock has had wheels that protude above passenger floor level - hence having to have longtitudinal seats (with wheels underneath them) over the bogies - which also precludes having doorways in those positions. Hence 'narrow' (single leaf) doorways at the car ends - and, once power operated doors came in the 1920s, intermediate (normally double leaf) doorways between the bogies.

In short you can't have doorways where the bogies are, only where they aren't...

On the 'early' electric surface stock, there were 'gatemen' operated doors (AIUI) at car ends, a feature brought over (with much else) from American practice by Mr Yerkes - and once established, old habits die hard. And for many years the single door at the car end was the best place for the guard and his door controls - it wasn't until the C69 Circle stock that they (car end doors) were finally done away with. I can't remember whether the C69 were always OPO, or originally had guards riding in the rear cab.

 

[Taunton]

If I'm not mistaken the first "Standard" tube trains, built from the early 1920s and lasting into the 1960s (and for the Isle of Wight even longer), were built with just the two mainstream double doors. It was only after quite a period, and dwell time issues with them, that the single end doors were added
.

 

[AM9]

If I'm not mistaken the first "Standard" tube trains, built from the early 1920s and lasting into the 1960s (and for the Isle of Wight even longer), were built with just the two mainstream double doors. It was only after quite a period, and dwell time issues with them, that the single end doors were added
.

Yes the 'Standard' tube stock originally had a single pair of doors on each side at the centre of the cars. Also on some of the Central Line motor cars, those doorways seemed to be wider and they had a centre pillar between the two sliding doors. I think that designs post 1927 had changed to a conventional 'pillarless' two-door aperture in the body structure.

For more detailed information on the development of the Standard tube stock, see here.

 

[TT-ONR-NRN]

The D Stock, of course, was highly successful and lived long entirely with single leaf doors. I think they looked very smart indeed, but of course they must have been far less practical than double doors. They were always quite an outlier on the network compared to other stock for this reason.

 

[Dstock7080]

And for many years the single door at the car end was the best place for the guard and his door controls - it wasn't until the C69 Circle stock that they (car end doors) were finally done away with. I can't remember whether the C69 were always OPO, or originally had guards riding in the rear cab.

C Stock were crew operated from introduction until OPO in 1984 (Circle H&C), 1985 (District).

 

[Somewhere]

My understanding is that all tube stock has had wheels that protude above passenger floor level - hence having to have longtitudinal seats (with wheels underneath them) over the bogies - which also precludes having doorways in those positions. Hence 'narrow' (single leaf) doorways at the car ends - and, once power operated doors came in the 1920s, intermediate (normally double leaf) doorways between the bogies.

In short you can't have doorways where the bogies are, only where they aren't...

On the 'early' electric surface stock, there were 'gatemen' operated doors (AIUI) at car ends, a feature brought over (with much else) from American practice by Mr Yerkes - and once established, old habits die hard. And for many years the single door at the car end was the best place for the guard and his door controls - it wasn't until the C69 Circle stock that they (car end doors) were finally done away with. I can't remember whether the C69 were always OPO, or originally had guards riding in the rear cab.

And of course, C69 stock wasn't tube stock, it was surface stock, so didn't have the issue

 

[100andthirty]

Summarising:

Surface stock: District, C&H, Met - trains are more or less full size, so there is no restriction on where doors can be located along the length of the cars. As a detail point, cab doors can't be too close to the first set of passenger doors so that they don't clash when open. That's why the first sets of double doors on S stock driving motor cars are non standard.

Tube stock: all other lines. Since the very beginning wheels/bogies have always penetrated the floor/saloon so door openings can't be placed in those locations. In the beginning, there were platforms with gates at the ends of what were quite short cars. Later designs replaced the gates with doors between the bogies. As designers worked to improve boarding and alighting times they added single doors in the overhang beyond the bogies. Careful analysis showed that boarding and alighting rates through end doors were lower than double doors even when taken as pairs across car ends. And single doors make providion of platform screen doors more complex - see Jubilee line extension.

Given the success of four double doors of C stock and the anticipated (now realised) success of the three sets of double doors on S stock, LU was determined to specify an equivalent for the next generation of tube trains. Hence, all double doors (with through gangways and air conditioning) was a key specification requirement that, probably more than any other requirement, drove the configuration of the 2024 tube stock, the first of which is being tested in Germany

 

[Purple Train]

Most mainline trains (in the UK anyway) have two double doors per vehicle not three. The only one I can think of with three double doors is the Class 345 on the Elizabeth Line, which also has articulated bogies and walk-through access so is a different beast in terms of passenger loading/unloading.
It's also worth pointing out that tube trains have shorter carriages than mainline, and there is very little space left on the side of the train which isn't either door, or the space a sliding door opens into.

The other issue with having three sets of doors per vehicle is that they have issues at stations on sharp bends in either direction, as opposed to, say, the Stadlers (obviously if you ignore the step), which would have no issue on a left-hand curve with the platform on the left (and vice versa). This is less of a problem on the Tube, but there will of course be the odd place with certain horrible gaps, such as Bank on the Central Line.

 

[MasterSpenny]

The other issue with having three sets of doors per vehicle is that they have issues at stations on sharp bends in either direction, as opposed to, say, the Stadlers (obviously if you ignore the step), which would have no issue on a left-hand curve with the platform on the left (and vice versa). This is less of a problem on the Tube, but there will of course be the odd place with certain horrible gaps, such as Bank on the Central Line.

And it also reduces the space for seats onboard.

 

[Taunton]

And it also reduces the space for seats onboard.

I don't think any rolling stock design nowadays could care less about providing seats.

 

[Bletchleyite]

Most mainline trains (in the UK anyway) have two double doors per vehicle not three. The only one I can think of with three double doors is the Class 345 on the Elizabeth Line, which also has articulated bogies and walk-through access so is a different beast in terms of passenger loading/unloading.

345s are not articulated (nor is S-stock for that matter), and the walk-through design is standard on Aventras.

 

[Purple Train]

And it also reduces the space for seats onboard.

It only really loses six seats per carriage on the 345s, which is immaterial considering the low-density layout.

 

[AM9]

It only really loses six seats per carriage on the 345s, which is immaterial considering the low-density layout.

Surely they are high density in terms of passenger accommodation layout, - maybe "low density" as in seats, i.e. relatively sparse.

 

[Purple Train]

Surely they are high density in terms of passenger accommodation layout, - maybe "low density" as in seats, i.e. relatively sparse.

Of course, sorry , I'm having an unmitigated disaster with terminology today...