Should HS2 have a wider track gauge?

[MarkyT]

I recall that Russia is the only country currently running broad track gauge high speed rail (250kph) based off widened Velaro bodied stock. The seating layout if I recall when I traveled on it last year was still the standard 2+2, and 2+1 in Business class. Certainly roomy, but not particularly different.

Of course they've gone down that route due to the existing track infrastructure in Russia, which is broad gauge, but the costs of acquiring custom gauge stock will always be higher than standard gauge stock which can be bought off the shelf.

The Russian gauge is only 85mm greater, at 1520mm, than standard at 1435mm. Not that significant at approx. 106% of standard

Larger frontal CSA (cross sectional area) is significant for air resistance at very high speed. For wide body jet aircraft, that is a fairly minor concern in the thin air at 40 thousand feet. For a similar size vehicle at ground level, I think the thick air would cost a lot of drag at HS rail speeds. Probably better to go for the longest trains with traditionally profiled trains, i.e no bigger than typical European double decker HS stock. Note Japan with slightly larger possible loading gauge on the Shinkansen has moved away from DD stock in recent years as they speed up their network. The DDs were slower than some of the latest single deckers. I wonder whether part of that limitation was the the effect of the large CSA on aerodynamic drag with the power available.

 

[edwin_m]

Spain has the Euromed service that reaches 220km/h using what are essentially TGVs built for the broad gauge (so don't offer any extra internal space). There are also various gauge-changing sets but I'm not sure what speed they reach on the classic network.

https://en.wikipedia.org/wiki/Euromed_(train)

The Russian high speed trains would appear to be 330mm wider than the standard gauge Velaro they are based on:

https://en.wikipedia.org/wiki/Sapsan

Running gear for high speed trains is inevitably a very complex design and altering a key parameter such as track gauge will result in a lot of extra cost with the risk of poor running if the dynamics goes wrong. As the speed of the train is limited by factors other than track gauge, there is no reason to go for a non-standard gauge unless the local network of the country in question also uses that gauge.

 

[Foxhunter]

You are nowhere near the stability limits of standard gauge even with stock significantly wider than current.

fwiw on structure / track gauge relationship.

If you ever have the good fortune to travel on the Hanoi to Beijing train, on boarding in Hanoi you will find that the train is made up of a set of Chinese coaches to their standard design for inter-city loco hauled stock i.e. larger than anything we have in the UK. For the Vietnamese section of the route they are on metre gauge bogies.

At the border everyone alights, passes through customs/border control, and walks through to the station on the Chinese side to find an identical rake but on standard gauge bogies. Everyone takes the same seat/compartment as they had on the Vietnamese section and their journey continues.

Direct evidence for the proposition that structure and track gauges are only tenuously related.

 

[MarlowDonkey]

The wagons that are used to transport cars and lorries through the Channel Tunnel are much higher than anything else in the UK. Wider too possibly as well.

What standard was used for the loading gauge in the Tunnel? Presumably if larger than the French, stock would have had to have been delivered by road.

 

[Joseph_Locke]

The wagons that are used to transport cars and lorries through the Channel Tunnel are much higher than anything else in the UK. Wider too possibly as well.

What standard was used for the loading gauge in the Tunnel? Presumably if larger than the French, stock would have had to have been delivered by road.

HS1 and CT is, IIRC, UIC GC.

 

[edwin_m]

HS1 and CT is, IIRC, UIC GC.

The structure gauge in the Channel Tunnel is larger than on either side of it. IIRC none of the UIC gauges allow HGV shuttles with roofs, or double deck car carriers with level floors and height to stand up on each deck. Therefore the shuttle vehicles are "captive" and can only leave by road. The shuttle locomotives and HGV crew cars are to European gauge so are small enough to travel on the French network or even HS1, but they don't do so in service. I don't know if they do so to access overhaul facilities.

 

[DPWH]

AFAIK Local maintenance is done at Coquelles in France but for heavy overhauls the class 9 are returned to Brush Works in Loughborough, by road obviously since they couldn't get down the MML from St Pancras to Loughborough without incidents. This is apparently preferable to sending them via rail to a similar facility somewhere on the continent.

 

[suzanneparis]

That's interesting. What are the dimensions of the class 9 h l w ? Must be a big load to take to Loughborough.

 

[mr_jrt]

Could that change with a HS1-HS2 link and gauge enhancement of the MML between "East Midlands hub" (or thereabouts) and the brush works at Loughborough?

 

[najaB]

Could that change with a HS1-HS2 link and gauge enhancement of the MML between "East Midlands hub" (or thereabouts) and the brush works at Loughborough?

"Could?" Well anything is possible. "Will?" Can't see it happening, much cheaper to just put them on trucks when they need work.

 

[mr_jrt]

Well, yes for specifically those units. I was thinking if there was a euro-gauge route to a major works then they might be interested as it would open up a lot more work for them, the captive HS2 sets for a start, but in theory anything from the continent if the paths on HS2 were worth it.

 

[najaB]

Well, yes for specifically those units. I was thinking if there was a euro-gauge route to a major works then they might be interested as it would open up a lot more work for them, the captive HS2 sets for a start, but in theory anything from the continent if the paths on HS2 were worth it.

True. But the HS1-HS2 link has been ruled out so it would be a heck of a business case to try and make on the basis of the occasional bit of refurb work from the Continent.