Part time signalling and tram-trains

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aformeruser

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Trams are able operate at line-of-sight while heavy rail needing proper signalling and an argument given in favour of light rail being saving the cost of signalling. Would it be possible for a line to have tram-trains on it all day, with provision for signalling for heavy rail at peak times only or just during diversions?
 
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142094

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Trams are able operate at line-of-sight while heavy rail needing proper signalling and an argument given in favour of light rail being saving the cost of signalling. Would it be possible for a line to have tram-trains on it all day, with provision for signalling for heavy rail at peak times only or just during diversions?

It probably would be possible somehow, although I think the major stumbling block would be how to run a heavy rail train on a track that is not grade separated, and also need to bear in mind some of the trackwork that a tram can get around (such as tight curves) would no doubt not be suitable for something bigger and heavier.
 

tsr

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The technology is there in the form of part-time road signals for various types of traffic, and of course the existing tram infrastructure copes, but I don't think the public would be too happy with heavy rail in areas accessible to pedestrians and road vehicles. The infrastructure would have to be rebuilt to NR standards, as has been said above. Look at the relative problems with using routes such as the one to Weymouth Quay.
 

swt_passenger

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I think you've both got the wrong end of jcollins' stick.

I reckon what he's really asking is if the 'heavy rail' signalling is needed when only tram trains are present for long periods on the heavy rail track.

Seems to me that once signalling for heavy rail is in place, then there are no real cost savings by switching it off.
 

tsr

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I think you've both got the wrong end of jcollins' stick.

I reckon what he's really asking is if the 'heavy rail' signalling is needed when only tram trains are present for long periods on the heavy rail track.

Seems to me that once signalling for heavy rail is in place, then there are no real cost savings by switching it off.

I see - thanks for (perhaps) clarifying. I think I agree with you.
 

WatcherZero

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The problem with signalling infrastructure is its pretty static, its there all the time. What you can do is not fit tram-trains with all the heavy rail signalling equipment if they have an absolute possession, for example freight only operated for 3 hours a day during the night. You would still need some way of controlling the points or signals for the trams but if it was a long straight line with just block signalling to keep the freight trains apart theres room to maneouver.
 

aformeruser

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I think you've both got the wrong end of jcollins' stick.

I reckon what he's really asking is if the 'heavy rail' signalling is needed when only tram trains are present for long periods on the heavy rail track.

Yes I'm thinking of using track already built for heavy rail not putting heavy rail on tracks built for light rail. For instance, instead of converting a line used only by occasional freight to light rail use and diverting the freight, letting tram-trains use the line alongside the freight but restricting the hours when heavy rail can use it.

I suppose the same question could already be asked about heavy rail lines that only see occasional freight and diverted services without bringing tram-trains in.

Seems to me that once signalling for heavy rail is in place, then there are no real cost savings by switching it off.

I know with the plan to move to regional control centres the saving made by staffing a signal box for shorter hours but would there not be any saving made by turning off equipment, both in terms of energy saving and lasting longer by being used less?
 

Joseph_Locke

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There are many conundra with light rail (tram-train) operation on an existing heavy rail line, and it all comes down to aligning the two safety cases.

If the light rail vehicle already operates on line-of-sight (i.e. no signals at all) then it doesn't actually matter what the rail vehicle ahead is, because our light rail vehicle is already approved. The other way round is more complex, but TPWS is the answer. TPWS could be fitted to every signal, effectively as a train stop, and appropriate controls applied that maintain a safe distance between our 2000t freight and the tram ahead.

The only issues are allowing line-of sight operation on Network Rail (or indeed any Railway, as distinct from a Light Railway or Tramway, as legally defined) and how you detect a vehicle that isn't designed to operate track circuits.

One could fit the light rail vehicle with TPWS, but low-floor trams don't have much spare space underneath and managing the activation and isolation of it introduces risks).

All that said, Mott MacDonald (who are currently employed to resolve these issues) must be getting there, as the DfT has committed to it.
 

142094

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Yes I'm thinking of using track already built for heavy rail not putting heavy rail on tracks built for light rail. For instance, instead of converting a line used only by occasional freight to light rail use and diverting the freight, letting tram-trains use the line alongside the freight but restricting the hours when heavy rail can use it.

As far as I am aware, when tram-trains use the heavy rail lines in Germany, they use the heavy rail signals and not tram signals.
 

DownSouth

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The only issues are allowing line-of sight operation on Network Rail (or indeed any Railway, as distinct from a Light Railway or Tramway, as legally defined) and how you detect a vehicle that isn't designed to operate track circuits.
Standard LRVs off the shelf do operate track circuits. This is an important requirement for effective operation if the network uses segments of both on-street running and dedicated alignments. This is common in many major light rail networks, some of which may be heavy rail lines no longer carrying freight or enough passengers to justify heavy or metro rail.
 
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