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California high speed rail


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#61 MattW

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Posted 11 November 2016 - 03:56 PM

Here is a nice explanation and rebuttal to an LA Times article on this from the CAHSRBLOG:

 

 

The argument Vartabedian, Ibbs, and other critics are making is that shorter stations make it harder to operate a “double” train set, as systems like Japan’s Shinkansen often do. But you could just as easily operate two single-sets with shorter headways. That would maintain your capacity.

Here’s an example. Sometimes the Shinkansen operates a single trainset:

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And sometimes it operates a double set:

GYuFR3.gif

(Both gifs come from this video.)

Many European systems commonly operate single sets, such as Eurostar, the TGV, the AVE, and so on. So the CHSRA isn’t doing anything significant here in terms of capacity. But the savings is significant and welcome.

The same is true of tunneling. Lowering the tunnel speed from 220 to 200 mph provides a big cost savings on the cost of tunneling, but at a minor time penalty – that will likely be made up by other time savings elsewhere, including going almost directly from Palmdale to Burbank under the mountains rather than going via Santa Clarita.

So the CHSRA’s decision is sensible, as is often the case. But HSR critics will find something to criticize no matter what they do.

I would hope that even if platform length is limited to one trainset now, that provisions are kept to allow doubled trainsets later. I wouldn't imagine much would be required, just making sure there's enough space off each end of the platform kept clear to allow future extension.


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#62 west point

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Posted 13 November 2016 - 05:39 PM

As well as leaving space for future platform extension provision must be made for utility connections. Duct work for each kind of utility is capped at the end of each platform. For drains they must be low enough for future extensions.

#63 cirdan

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Posted 14 November 2016 - 10:21 AM

I would hope that even if platform length is limited to one trainset now, that provisions are kept to allow doubled trainsets later. I wouldn't imagine much would be required, just making sure there's enough space off each end of the platform kept clear to allow future extension.

 

 

 

 

Actually, platforms themselves are not that expensive to build. In Spain I was once at a station where the platforms were much longer than actually required, but the extra section was fenced off and there were no lights or seats. I've also seen something similar on the metro in Brussels.

 

Building something like a platform edge alongside an operational and heavily used main line track causes all sorts of extra costs due to the provisions for safe working that may require work to stop as trains pass or trains to be suspended as work proceeds. It may actualkly work out cheaper in the long run to just build for the maximum length, fence it off and forget all about it until such a time as you may need it..






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