Double decker trains

[najaB]

From what i have always heard (and whether it is true i do not kjnow) is that the tunnels on your island are too low to get 2 level trains running.

It's not just the tunnels. All the infrastructure is built to a smaller gauge than on the continent.

 

[jopsuk]

From what i have always heard (and whether it is true i do not kjnow) is that the tunnels on your island are too low to get 2 level trains running.

One of the restrictions is that the loading gauge "cuts in" below our (quite high) platform level. So whereas on most european networks you can carry width to quite a low level - eg these French units are full width to bascially axle level, british stock typically tapers from above even floor level - it's a significant feature of stock design here.

This is a major issue, as it means that available floor width for a lower deck is impinged on, access stairs are forced more central and basically the extra capacity would be much reduced to the point that it may not actually add capacity.

 

[Phil.]

Why not think laterally and build double deck stations to go with double deck trains? In effect a double deck train would have separate doors for each deck allowing entry and exit just as on conventional trains. Safety of lemming like passengers on the upper platform can be assured by sliding doors a la Jubilee line. Drivers would of course have to become accustomed to stopping at precise points as per the Jubilee line but if Japanese drivers can do it I'm sure drivers here could too.
All you'd have to do then would be to rebuild all of the commuter lines to UIC gauge and Robert's your father's brother.

 

[D365]

Why not think laterally and build double deck stations to go with double deck trains?

So many shades of no...

 

[Phil.]

You missed the smiley then.....

 

[Hophead]

April 1st appears to have come around early, if this news item from Rail Magazine is to be believed:

Parry People Movers Ltd, the successor to the company that built the two Class 139 vehicles which operate on the Stourbridge branch, is putting forward the idea of double-deck trams based on the ‘139s’.
​

I am, for now, unconvinced.

 

[3141]

April 1st appears to have come around early, if this news item from Rail Magazine is to be believed:

Parry People Movers Ltd, the successor to the company that built the two Class 139 vehicles which operate on the Stourbridge branch, is putting forward the idea of double-deck trams based on the ‘139s’.
​

I am, for now, unconvinced.

But it would be feasible for street running or on a specially-constructed reserved track, and with low tram platforms the cutting-in of the railway loading gauge would not be an issue. After all, we ran thousands of double-deck trams in the past.

Whether Parry People Movers are the ones to do it is another question.

 

[jopsuk]

I agree there's nothing daft about double decker trams. But really, you need to be using a low-floor technology platform.
The last few pages of this Parry newsletter expand

I'm not convinced that the expanded diagram and the exterior concept shots can actually be related...

 

[100andthirty]

Trams usually run on infrastrucfure that has very sharp curves and our forefathers rapidly discovered the benefits of bogies. Anyone who has used a pacer would sympathise with anyone condemned to ride on thectop deck of a four wheeler.

UK benefits from a general headroom under structured on ROAD of 4.5m.

On RAIL, as the same Parry document shows, the typical UK train can't be much more than 3.6m tall with the body having to be significantly narrower than the normal 2.8m below a height above rail of about 1100mm. This means that any DD train has so many compromises that I would be surprised whether there was any increase in capacity.

Now if theg could provide something like 4.5m height to top of gauge (more if 25kV) and increased the lower gauge, then it all becomes doable......but the dwell time issue (larger volumes of people using the same number of doors) remain.

 

[tranzitjim]

One of the restrictions is that the loading gauge "cuts in" below our (quite high) platform level. So whereas on most european networks you can carry width to quite a low level - eg these French units are full width to bascially axle level, british stock typically tapers from above even floor level - it's a significant feature of stock design here.

This is a major issue, as it means that available floor width for a lower deck is impinged on, access stairs are forced more central and basically the extra capacity would be much reduced to the point that it may not actually add capacity.

For the British system, what is the maximum width permissible at platform height, and what is the maximum width that is permissible above platform height?

Also, what would you define as platform height too please?

 

[Trog]

Also, what would you define as platform height too please?

Three feet above the plane of the rails heads.

 

[jopsuk]

For the British system, what is the maximum width permissible at platform height, and what is the maximum width that is permissible above platform height?

Also, what would you define as platform height too please?

if every platform was straight, or every item of rolling stock was the same length with the bogie centres in the same position, maximum width could be defined as a single number. Because of curved platforms, limited clearance structures on curves and different length stock having different overhang on curves trhe number is not fixed and not the same across the network. VERY roughly "go anywhere" dimensions are about 23m long and 2.7m wide or 20m long and 2.8m wide. Classes 165, 166 and 323 benefit from enhanced clearance and are about 23m long by 2.8m wide

 

[61653 HTAFC]

if every platform was straight, or every item of rolling stock was the same length with the bogie centres in the same position, maximum width could be defined as a single number. Because of curved platforms, limited clearance structures on curves and different length stock having different overhang on curves trhe number is not fixed and not the same across the network. VERY roughly "go anywhere" dimensions are about 23m long and 2.7m wide or 20m long and 2.8m wide. Classes 165, 166 and 323 benefit from enhanced clearance and are about 23m long by 2.8m wide

332/333s also, I believe.

 

[Bald Rick]

Three feet above the plane of the rails heads.

Or, more metrically, (so our antipodal cousin understands) 915mm

 

[Blamethrower]

What if platform overhangs were eliminated?

Take a pilot route (great Western), chop off the protruding edges and introduce full accessible stock which can be wider down to wheel level.

Then perhaps there would be more scope for double deckers being introduced. Even though overhangs exist, on most trains and platforms you have to step up and out to get on the train. Do we over compensate with loading gauges?

 

[najaB]

What if platform overhangs were eliminated?

Take a pilot route (great Western), chop off the protruding edges and introduce full accessible stock which can be wider down to wheel level.

Quite a logistical exercise to chop off all the platform overhangs and introduce new stock in one weekend possession.

 

[AM9]

What if platform overhangs were eliminated?

Take a pilot route (great Western), chop off the protruding edges and introduce full accessible stock which can be wider down to wheel level.

Then perhaps there would be more scope for double deckers being introduced. Even though overhangs exist, on most trains and platforms you have to step up and out to get on the train. Do we over compensate with loading gauges?

Gaps larger than that specified in the specification for platform-train interface are only available on a grandfather rights basis. Any new train or station would need to comply with the current requirements.
The problem isn't just with the platform. There are many obstructions below solebar level of passenger stock that would require major infrastructure changes e.g the truss structures of many underbridges, especially around London.
There is no cost effective method of changing the UK railway's victorian structure gauge to enable double deck trains to run. Given that the difference in passenger capacity between a double deck service and an intensive service using conventional stock would probably be minimal, in particular taking the extended dwells required and the effect on capacity of meeting the DDA requirements, I doubt that there will ever be such a conversion here. Dedicated lines built to something like GB+ or GC would be possible for a commuter line, but that would mean captive stock so it would involve a complete duplicate network that covered a large area with many lines.

 

[RobShipway]

Gaps larger than that specified in the specification for platform-train interface are only available on a grandfather rights basis. Any new train or station would need to comply with the current requirements.
The problem isn't just with the platform. There are many obstructions below solebar level of passenger stock that would require major infrastructure changes e.g the truss structures of many underbridges, especially around London.
There is no cost effective method of changing the UK railway's victorian structure gauge to enable double deck trains to run. Given that the difference in passenger capacity between a double deck service and an intensive service using conventional stock would probably be minimal, in particular taking the extended dwells required and the effect on capacity of meeting the DDA requirements, I doubt that there will ever be such a conversion here. Dedicated lines built to something like GB+ or GC would be possible for a commuter line, but that would mean captive stock so it would involve a complete duplicate network that covered a large area with many lines.

Could you do as has been done with the tunnel prior to Bath going west along the GWML and lower the ground level in the area with the Underbridges?

 

[TheEdge]

Could you do as has been done with the tunnel prior to Bath going west along the GWML and lower the ground level in the area with the Underbridges?

Remember right away a lot of the original GWML was built to broad gauge loading gauge so there is a lot more space on the infrastructure than there even is in Europe. Saying that quite a lot of "smaller" stuff, platforms and the like have been changed accordingly but bridges, tunnels etc have not. Look at the size of Box Tunnel for example.

 

[AM9]

Remember right away a lot of the original GWML was built to broad gauge loading gauge so there is a lot more space on the infrastructure than there even is in Europe. Saying that quite a lot of "smaller" stuff, platforms and the like have been changed accordingly but bridges, tunnels etc have not. Look at the size of Box Tunnel for example.

Actually, the track through Box Tunnel is having to be lowered. The grand portal size isn't carried right through the tunnel.

 

[Trog]

Track lowering under bridges can be problematic as you may well have to do a formation dig so as to also lower the blanketing layer between the bottom of the ballast and the underlying ground, which does not come cheap. There may also be under track structures, where lowering the track would give shallow ballast. The dip put into the track can cause drainage problems, and it has been known for such dips to be lifted out by staff who see them as a top defect.

 

[jopsuk]

Remember right away a lot of the original GWML was built to broad gauge loading gauge so there is a lot more space on the infrastructure than there even is in Europe. Saying that quite a lot of "smaller" stuff, platforms and the like have been changed accordingly but bridges, tunnels etc have not. Look at the size of Box Tunnel for example.

Brunel's loading gauge wasn't much more than anyone else's. In fact, this was the point. He built to a broader track gauge for similar width vehicles, in order to benefit from stability in order to run faster

 

[Peter Mugridge]

I agree there's nothing daft about double decker trams. But really, you need to be using a low-floor technology platform.
The last few pages of this Parry newsletter expand

I'm not convinced that the expanded diagram and the exterior concept shots can actually be related...

Why the lift? Surely for access compliance you only need to be able to get wheelchairs onto the lower deck? The lift just adds cost and complexity for no real purpose and reduces capacity slightly? A staircase will do.

 

[swt_passenger]

...and lower the ground level in the area with the Underbridges?

In this context 'under bridges' are where roads or watercourses pass under the railway. Track lowering doesn't really come into it.

The point AM9 was making concerns the typical sort of girder bridge where each track of the multi-track railway is passing between parallel girders, effectively each track has its own bridge 'trough'.

Track lowering generally only applies to overbridges and tunnels.

 

[AM9]

In this context 'under bridges' are where roads or watercourses pass under the railway. Track lowering doesn't really come into it.

The point AM9 was making concerns the typical sort of girder bridge where each track of the multi-track railway is passing between parallel girders, effectively each track has its own bridge 'trough'.

Track lowering generally only applies to overbridges and tunnels.

Thanks for clarifying that. I'm not sure whether an 'overbridge' is where the railway passes over something or under it. I suppose it depends on where you are standing/sitting!
As far as the bridges that we are both talking abnout, the area with the biggest passenger demands (south London) probably has more tracks with trusses enforcing the below-solebar loading gauge than the rest of the country in total. So infrastructure changes for the lines that some might propose as the most needing of DD trains woud be prohibitively expensive and disruptive for decades.

 

[jopsuk]

Why the lift? Surely for access compliance you only need to be able to get wheelchairs onto the lower deck? The lift just adds cost and complexity for no real purpose and reduces capacity slightly? A staircase will do.

Because they're mad as a box of frogs, I think.

 

[janplomer]

Hello,

I feel concern about use of double deck trains. Technical issues are evidently known (gauge height, gauge width up to platform level etc.), but economical and capacity benefits are supposed only for universally designed vehicles, derived from european DD cars. I tried to design a double-deck trainset especially for use in UK. It respect the width limitation (also in curves). Please look at the picture below and give me a feedback, what do you mean about it.

Thank You

Jan

 

[LexyBoy]

Welcome Jan!

I won't claim much about train design - I'm just an interested passenger - but there are a few things that look problematic to me:
- The carriages are long (24 m) with bogies at the far ends: existing 23 m Intercity stock has bogie centres 16 metres apart, and the new IEP trains are 17 m and require significant infrastructure changes to accomodate this. I think you'd have huge problems with overhang on curves.
- Less significantly, 2 doors per coach with 136 seats per coach will make them very slow to load/unload.
- What is the "patented bogie design"? I'd be interested to read the patent, they look curious. How do they help with the "platform offset"?
- 2.6 metres up to 1000 mm seems still very wide, much UK stock is only ~2.7 maximum width and just by judgement I'd say it's 2-300 mm narrower on each side than this going down to bogie level, so around 2.2 m.
- The height is significantly more than current stock, but this would be comparatively easy to fix. The doors look quite low down too, maybe this is due to the increased height though. UK platform height is nominally 915 mm.

 

[450.emu]

Hello,

I feel concern about use of double deck trains. Technical issues are evidently known (gauge height, gauge width up to platform level etc.), but economical and capacity benefits are supposed only for universally designed vehicles, derived from european DD cars. I tried to design a double-deck trainset especially for use in UK. It respect the width limitation (also in curves). Please look at the picture below and give me a feedback, what do you mean about it.

Thank You

Jan

Looks great! I wish we had these in the UK

 

[jopsuk]

These are (average) 24.27m long vehicles with no taper- indeed, with over 20m between bogie centres. There's not a slightly convex curved platform in the country this train could get along.

If the bogies are patented (or even patent pending) please tell us the patent number- or better, link us directly to the patent.

I notice the inter-car bogies are unusually 6-wheel