30 metre rail vehicles? Longest theoretical bodyshell?

[BogiePicker]

The ICE4 and upcoming Velaro Novo intermediate vehicles are of 28.75 m in length. This has allowed DB to achieve a 200m unit with only seven vehicles, a 12.5% reduction.

I have read that the former has 19.5 m bogie centres. Its end vehicles are even longer, at 29.1 m. To achieve this, it used a maximum 2.85 width, not much wider than what can be achieved in a British static gauge. I'm pretty sure that other European vehicles reach or exceed 20m in bogie centres.

In Britain, the relationship between bogie centres and width (centre throw) is a function of the radii at passing sixfoots curves and platforms.

The ICE4 and Velaro Novo must be cleared for an extensive network, since they must work all over Germany and Europe, but this need not be so for a 'HS2 classic compatible' UK stock, which could be gauged for a far more restrictive network (which in turn could also be suitably modified). The vehicles have to be narrow anyway, so why not stretch them as long as possible. As above, 28.75 m would be 'adequate' for a 7-car 200m unit, but for a 300m unit you would only need 10 cars, and a 390 m unit would need 13 rather than 16 for a 25 m body.

You would only be extending them one metre beyond what is already in operation.

To be fair, with all this trouble, one might as well articulate. Is there anything out there longer than an ICE4/Velaro Novo vehicle?

 

[Sorcerer]

Presently much of the Hitachi 80x units are uniquely tapered inwards at the end of each coach so it would fit within gauge, and these are with 26m long coaches (with the exception of the 810s at 24m). So stretching further than that will mean even further tapering that will inevitably cramp a lot of the interior, but for purely hypothetical reasons I'm sure you could probably engineer 30m coaches within the British loading gauge. In reality though it wouldn't do much good, because really what could you get from a seven 28.75m coach unit that you couldn't get from an eight 25m coach unit?

 

[edwin_m]

Most of the WCML platforms that will now be served by classic compatibles are fairly straight. But when they were ordered the intention was for them to serve places like York and Newcastle which decidedly aren't. As mentioned this will increase the taper at the ends, which results in larger stepping distances at straight platforms, and larger still at convex curved platforms. I guess the design could be changed but changing the spec in such a fundamental way after placing the order would carry a huge cost.

 

[Bevan Price]

I wonder if they could use some of the WCML diversionary routes, such as the sharp curves at Earlestown & Parkside ?

 

[Bletchleyite]

25m vehicles for an 8 car 200m unit seems to be the obvious plan. You do save a bit of money on bogies and corridor connections if you go for 7 longer coaches, but the need for very steep end tapering to stop them whacking platforms would probably be a compromise too far.

 

[30907]

Two comments:
1. DB have had 28.75m restaurant cars but the were prone to derail on paintwork IIRC and were early withdrawals.
2. My impression is that 26m hasn't worked brilliantly here - 24m fits better on a railway that works in multiples of 20m.

 

[Nottingham59]

2. My impression is that 26m hasn't worked brilliantly here - 24m fits better on a railway that works in multiples of 20m.

The 26m IET standard was chosen as the longest car length that would be compatible with GB loading gauge, but does seem to have stability problems. I assume these stem from the extra overhang at the ends of the carriages. If the bogies could be set further apart to reduce that overhang, then would it be possible to fit the loading gauge by tapering the centre of the carriages, so that the centre of the car was less wide than the cross section over the bogies?

 

[edwin_m]

If the bogies could be set further apart to reduce that overhang, then would it be possible to fit the loading gauge by tapering the centre of the carriages, so that the centre of the car was less wide than the cross section over the bogies?

In principle that could probably be done, but I'm not sure why anyone would want to. The ends of the coach can be used for toilets, vestibules and equipment compartments where less width doesn't matter so much, but reducing the width in the middle would mean making some seats narrower or removing one from each row. It would probably also add extra weight to maintain structural strength.

 

[Nottingham59]

In principle that could probably be done, but I'm not sure why anyone would want to.

To address the stability issues which appear to come from excessive overhangs.

Alternatively, articulated cars with Jacobs bogies might be the way to go

 

[43096]

25m vehicles for an 8 car 200m unit seems to be the obvious plan. You do save a bit of money on bogies and corridor connections if you go for 7 longer coaches, but the need for very steep end tapering to stop them whacking platforms would probably be a compromise too far.

The money saved on bogies is ongoing though - there's a saving at every bogie overhaul/wheelset change.

 

[Sorcerer]

To address the stability issues which appear to come from excessive overhangs.

Alternatively, articulated cars with Jacobs bogies might be the way to go

One disadvantage of Jacobs bogies is that they actually shorten the viable length of a train coach. If I'm not mistaken the Stadler FLIRTs all have ~20m coaches which is shorter compared to a Pendolino's ~23m coaches, and even shorter still than Hitachi's 26m coaches. I can see the network eventually opting for a standard lengths of 20m for articulated units or 25m for non-articulated units.

 

[AndrewE]

To address the stability issues which appear to come from excessive overhangs.

Alternatively, articulated cars with Jacobs bogies might be the way to go

except that with bogies at vehicle ends you have the problem of overhang in the coach centres which impacts on line spacing and the "6-foot"...

 

[BogiePicker]

Presently much of the Hitachi 80x units are uniquely tapered inwards at the end of each coach so it would fit within gauge, and these are with 26m long coaches (with the exception of the 810s at 24m). So stretching further than that will mean even further tapering that will inevitably cramp a lot of the interior, but for purely hypothetical reasons I'm sure you could probably engineer 30m coaches within the British loading gauge. In reality though it wouldn't do much good, because really what could you get from a seven 28.75m coach unit that you couldn't get from an eight 25m coach unit?

25m vehicles for an 8 car 200m unit seems to be the obvious plan. You do save a bit of money on bogies and corridor connections if you go for 7 longer coaches, but the need for very steep end tapering to stop them whacking platforms would probably be a compromise too far.

The idea is that you would have a corresponding increase in bogie centres, so wouldn't rely on end tapering to do all the compensation. As with ICE4 and Velaro Novo, longer bogie centres but still with some tapering. The wiki article on the IC250 is good and one of its articles presents a concept of a 25.5m vehicle with 18m+ bogie centres. With this, you're probably looking at 21-22m bogie centres.

However, considering the case of an infinite radius curve - straight line - it's clear that the shallower the curves, the less that the sixfoots cause problems for increasing bogie centre length and centre throw, and it may be that along intercity routes (WCML), there may be more generous allowances along curves. In any case, this would be a fully captive unit, I don't see where it would be cascaded to.

The money saved on bogies is ongoing though - there's a saving at every bogie overhaul/wheelset change.

Yes, the reasons for the increase in vehicle length would be the same as BR's reason for developing the IC250 and DB with the ICE4, namely, fewer carriages for the same unit length. With the ICE4, Siemens was also able to develop each carriage as an essentially independent vehicle. There may also be aerodynamic benefits.