How does "line of sight" work on metrolink?

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luke1420

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Hi all,

Was just wondering if anyone can explain exactly how line of site work on metrolink. It seems easy enough in the city when the trams are only moving say 15mph as when they see a tram infront they can come to a complete stop. But what about on lines where it is faster such as the line of site section between old Trafford and Brooklands, trams rattle down that section at 50mph. Say if there was a tram stopes at sale and another tram heading between Dane road and sale would the driver be able to see the tram in front and make a safe stop?

Cheers Luke
 
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Bletchleyite

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Yes, it's the same as a road vehicle, basically. You drive such that you can stop in the distance you can see to be clear. If you feel this may not be the case, for example due to a blind bend, you slow down until it is.
 

luke1420

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Thanks for the reply!

To be fair the trams acceleration a deceleration seem pretty good so even if you are slowing below the speed limit it won't delay it much at all.
 

Bletchleyite

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The tram track brakes can stop a tram far more quickly than is safe for those travelling in it. Indeed, if an emergency braking occurs, the driver has then to walk through the tram and check if anyone is injured.
 

edwin_m

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Before opening each section, or converting the signalled sections to line of sight, the operator does some thorough checks and sets the speed limits so that the tram can stop short of any obstruction using the service brake. This has resulted in some reductions in speed, notably going under the railway and road between Cornbrook and Trafford Bar where the tight curve means sightlines are quite poor. Lineside vegetation also has to be kept under control so it doesn't restrict the sightlines.

The hazard brake is then available for unforeseen circumstances such as misjudging speed or pedestrians/vehicles unexpectedly going onto the track in front of the tram.

No different really from driving a road vehicle at similar speeds.
 

snowball

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There's a current discussion on Skyscrapercity about speed reductions on the curvaceous Bury line resulting from the conversion from block signalling to line of sight.

To alleviate the problem a variable speed limit was introduced at one location, Heaton Park Tunnel, driven by detection of a tram in the tunnel.
 

Shrimper

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The tram track brakes can stop a tram far more quickly than is safe for those travelling in it. Indeed, if an emergency braking occurs, the driver has then to walk through the tram and check if anyone is injured.

We don't have to walk through; we do have to make a PA asking anyone who has suffered an injury to make themselves known as we have to fill in a report.

At 50mph, hazard brake isn't all that violent - at lower speeds in the city centre it certainly feels it and unfortunately that is where we tend to have to use it!

To alleviate the problem a variable speed limit was introduced at one location, Heaton Park Tunnel, driven by detection of a tram in the tunnel.

The Heaton Park variable speed limit isn't yet active; we do have one in another location though - Collyhurst Tunnel, between Victoria and Queens Road.
 
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