Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 22, 2009 21:12:31 GMT
I've been out of touch with the signalling works on the Met Main recently, so I'm curious to know if the Met Main lines between Mantles Wood and Harrow South will be wired up with 3- or 4-aspect MAS w/ATP, or if it will be 2-aspect w/ATO and ATP and the Chiltern units so equipped.
If 3- or 4-aspect MAS w/ATP is used, will electric trainstops be used to take advantage of the existing tripcocks on Chiltern units, or will the Chiltern units also be equipped with SSL ATP, alongside their Chiltern ATP, AWS, and TPWS?
|
|
|
|
Post by 100andthirty on Oct 23, 2009 5:28:01 GMT
Current plan is to use colour light signals (probably 3 aspect) with Chiltern ATP. But things can change!
|
|
Ben
fotopic... whats that?
Posts: 4,282 
|
Post by Ben on Oct 23, 2009 17:59:37 GMT
Why is 3 aspect favoured about the current 4?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 23, 2009 18:30:26 GMT
Why is 3 aspect favoured about the current 4? Because the presence of ATP makes 4-aspect signalling unnecessary for S8 trains, and the low speed (<70mph) makes 4-aspect signalling unnecessary for NR/Chiltern trains. |
|
mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
|
Post by mrfs42 on Oct 23, 2009 23:16:02 GMT
Depends how closely the signals are spaced, plus the braking rates. I *could* show you plenty of lines signalled with 4 aspect signalling that rarely get above 40mph.  |
|
|
|
Post by Harsig on Oct 24, 2009 9:11:31 GMT
Why is 3 aspect favoured about the current 4? Because, despite appearances to the contrary, the Met Main Lines north of Harrow is already predominately only three aspect signalling, with four aspect signalling in and on the approach to controlled areas where the signals tend to be closer together. (A quick count shows that between Harrow and Amersham there are 21 four aspect signals and 31 three aspect signals) |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 25, 2009 12:24:06 GMT
The choice between 2, 3 or 4 aspect signalling is more to do with headway (the time between successive trains) than line speed. 4 aspect signalling comes into its own when you have a mix of different maximum train speeds and braking rates (i.e. a mixed traffic railway). Thats why most LT lines are 2 aspect.
|
|
