"Paul Scott" wrote in message
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wrote in message
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"Paul Scott" wrote in message
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Yes - as discussed here in the past, the District renewals towards
Upminster
appear to use identical rail and sleepers to recent NR track renewals -
the
same 'mainline' firms are involved albeit in a Metronet led consortium.
Eventually the whole SSR is supposed to get the same treatment...

What will the sleepers be made of?

Concrete - obviously the fittings for the fourth rail are additional, but
the same rail securing, with pandrol clips, as on the big railway...

I'm no concrete expert but, AIUI, water gets into concrete. This causes the
sleeper to crack and disintegrate. Plastics also don't work out, I
understand, because polymers can start to crack, which could negatively
impact the roadbed.

Are they also planning to upgrade signalling system on the Metropolitan
line?