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| 3 Aspect > 4 aspect 02/12/2019 at 08:59 #122031 | |
jem771
102 posts 
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If a train is running on 3 aspect signals and its moving into a 4 aspect zone if the first 4 aspect signal is showing single yellow what would the preceeding 3 aspect signal show? Green or Single yellow? Jezz Log in to reply |
| 3 Aspect > 4 aspect 02/12/2019 at 09:57 #122032 | |
jc92
3689 posts |
Green. The aspect sequence works as normal so the previous signal would be sited braking distance from the signal in question then the signal in question will be able to display YY and so won't be sited breaking distance from the following signal.
"We don't stop camborne wednesdays" Log in to reply |
| 3 Aspect > 4 aspect 02/12/2019 at 14:40 #122037 | |
Late Turn
699 posts |
The current preference seems to be to insert a three-aspect distant signal (Y/YY/G) before the first four-aspect signal, the last three-aspect stop signal then being capable of showing R/YY/G instead. Most older installations seem to have full braking distance from the first four-aspect signal to the second, the downside being that the distance from a YY at that first signal to a R at the third is significantly greater than the braking distance required. Either way, the last three-aspect stop signal can show a green with the first four-aspect stop signal showing one yellow. There's probably an exception somewhere, where the first four-aspect stop signal is approach released from red if the next signal is at danger... Log in to reply |
| 3 Aspect > 4 aspect 02/12/2019 at 18:27 #122040 | |
GeoffM
6376 posts |
In addition, two consecutive signals displaying Y at the same time is non-preferred. There are exceptions.
SimSig Boss Log in to reply |
| 3 Aspect > 4 aspect 04/12/2019 at 00:52 #122057 | |
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bill_gensheet
1413 posts |
Not 3 to 4 aspect, but Chelmsford has Y on to Y with 715 and 725, as they are so close. 715 then goes straight to G when 725 is YY Cannot recall if 711 is Y with 715 Y and 725 R, or if 715 and 725 both sit R until both go to Y. https://www.opentraintimes.com/maps/signalling/geml3#T_CHLMSFD Bill Log in to reply |