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Coventry double block

Current and future British signalling (UK except Northern Ireland)

Coventry double block

Unread postby Train approaching » Wed Oct 26, 2016 7:47 pm

I know when the 2007 signalling was commissioned at Coventry, following closure of the PSB, that double blocking (where trains on the down main were held at the preceding signal to the signal protecting the Leamington branch) was in use, but wondered if this arrangement is still in use and if anyone knows anywhere else on the network where such an arrangement exists.
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Re: Coventry double block

Unread postby Mike Hodgson » Wed Oct 26, 2016 7:52 pm

Was this a precaution because TPWS was not a 100% secure way of stopping conflicting movements?
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Re: Coventry double block

Unread postby Train approaching » Wed Oct 26, 2016 8:05 pm

It was just something one of the senior signalling engineers involved in the scheme told me.
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Re: Coventry double block

Unread postby Train approaching » Wed Oct 26, 2016 8:53 pm

Just found this:
http://www.opentraintimes.com/maps/signalling/rugbhm_1

It looks as if DB is in operation on both main approaches to the station.
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Re: Coventry double block

Unread postby S&TEngineer » Thu Oct 27, 2016 8:51 am

You will find this arrangement all over the NR network where high to low approach speeds or junction conflicts are involved. In this case TPWS is not effective enough if only one signal is fitted hence the outer signal is approach released from red if the inner signal is at red.

A few years ago I designed one arrangement at Colwich Junction on the West Coast Main Line that had four consecutive signals held at red and approach released in turn due to the Enhanced Permitted Speed of 125mph on approach and two consecutive junction conflicts ahead. In that case the outer two signals were automatics and the inner two signals were controlled. I can tell you the risk assessment for that lot was quite involved....... :shock:
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Re: Coventry double block

Unread postby The Planner » Fri Oct 28, 2016 10:20 am

Aren't there "ghost" overlaps at Cov too? I'm sure there is some sort of odd arrangement on the down on platform 3.
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Re: Coventry double block

Unread postby S&TEngineer » Fri Oct 28, 2016 5:07 pm

The Planner wrote:Aren't there "ghost" overlaps at Cov too? I'm sure there is some sort of odd arrangement on the down on platform 3.

Do you mean 'Phantom Overlaps'?
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Re: Coventry double block

Unread postby The Planner » Sat Oct 29, 2016 10:20 am

That's them.
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