Tri-state Banner Repeater Installs

[TheEdge]

Is there a new rule that NR are now only allowed to install tri-state Banner repeaters in new signalling installs?

6 tri-state repeaters have gone in along the Felixstowe branch since it was resignalled. 4 repeat 2 aspect signals and the two that do actually repeat a 3 aspect signal don't seem to have any useful benefit in being three state rather than two.

 

[The Planner]

Possibly it allows just the one thing to be bought and a standard item to replace/fix?

 

[ComUtoR]

I prefer them but they don't seem to be installed in logical locations. We have had a load of new signalling schemes recently and I haven't seen any Three State ones installed. I was hoping they would be the new standard.

 

[Aictos]

What is a tri state banner repeater?

 

[hwl]

Is there a new rule that NR are now only allowed to install tri-state Banner repeaters in new signalling installs?

6 tri-state repeaters have gone in along the Felixstowe branch since it was resignalled. 4 repeat 2 aspect signals and the two that do actually repeat a 3 aspect signal don't seem to have any useful benefit in being three state rather than two.

Makes a big difference for defensive freight driving in general so the policy seems to be install 3 aspect even if the rest of the signalling isn't there yet.

 

[edwin_m]

What is a tri state banner repeater?

One that shows a sloping black bar on a green background for a green signal, same on a white background for yellows, and a horizontal bar on a white background for red. "Normal" banners show the same for all non-red aspects of the main signal.

 

[TheEdge]

Makes a big difference for defensive freight driving in general so the policy seems to be install 3 aspect even if the rest of the signalling isn't there yet.

I understand that freight needs more defensive driving. But I still don't understand why they have been used to repeat a two aspect signal, all put in as part of the same new installation.

And even the ones that do repeat three aspect seem to be rather redundant given linespeed and distance and visibility of the next signal.

 

[Aictos]

One that shows a sloping black bar on a green background for a green signal, same on a white background for yellows, and a horizontal bar on a white background for red. "Normal" banners show the same for all non-red aspects of the main signal.

Ahh, I know I've seen some banner repeaters that show a sloping black bar on a green background only and some banner repeaters that show a sloping black bar on a white background but I didn't know the industry had banners repeaters being able to show three aspects???

 

[John Webb]

Have a look at http://www.railsigns.uk/sect7page3/sect7page3.html right at the bottom of the page. Tri-state banners were first trialled in 2007.

 

[edwin_m]

I understand that freight needs more defensive driving. But I still don't understand why they have been used to repeat a two aspect signal, all put in as part of the same new installation.

And even the ones that do repeat three aspect seem to be rather redundant given linespeed and distance and visibility of the next signal.

I think it's about presenting consistent information to the driver - a green banner always means a green aspect. However a white banner won't always mean a non-green aspect for several decades until the last of the conventional banners is replaced.

A lot of banners were installed as part of XC linespeed enhancement, when the required 7s sighting time of the signal itself wasn't achieved at the higher speed. Someone pointed out that two-state banners weren't addressing the hazard because when approaching at full speed the signal would always be showing a proceed aspect (except in cases of failure or emergency) so the banner would always be showing the same "off" indication - in effect a very expensive "signal ahead" warning sign. The thing the driver needs to know in that situation is whether the signal is green or not. If the train had already encountered a cautionary aspect then it would be going more slowly and the driver would have 7s of sighting time for the signal itself.

 

[Joseph_Locke]

My answer is similar to edwin_m's - whay wouldn't you give a driver all the information you could about the signal round the corner? The third state would be wasted on a 2-aspect signal, but as someone else said, standardisation?