Derby 23rd Febuary 2011

[Jerry1237]

Derby 23rd Febuary 2011

Agenda is:
Scheme design, exam technique, M1/7 discussion where appropriate

16:20 for a 16:30 start at DeltaRail, 2 St Christopher's Way, Derby.

All welcome from any background, company or with level of knowledge but. We are looking for regular attendees. Please let us know if you want to come in advance if possible.

See you there,
Jerry

PS: Networking afterwards in local establishment (even though the Harvester cannot reliably produce a single pint of Pedi!)

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Group studied signal placement on M2 2009 mainline plan based upon the headway calcs previously derived. Several questions raised:

1) Does a signal that can display only a single red (exit to a main route) require an overlap?
2) How can a 3-asp signals be applied through station B when the braking distances don't support such?
3) Could a 3-asp head (green blanked) be used to exit from the spur with a R/G 2-asp starter?
4) What options are there when transitioning from 3-asp to 4-asp and vice versa?
5) Where do you start on the plan?

[PJW]

Derby 23rd Febuary 2011

Agenda is:
Scheme design, exam technique, M1/7 discussion where appropriate

16:20 for a 16:30 start at DeltaRail, 2 St Christopher's Way, Derby.

All welcome from any background, company or with level of knowledge but. We are looking for regular attendees. Please let us know if you want to come in advance if possible.

See you there,
Jerry

PS: Networking afterwards in local establishment (even though the Harvester cannot reliably produce a single pint of Pedi!)

---

Group studied signal placement on M2 2009 mainline plan based upon the headway calcs previously derived. Several questions raised:

1) Does a signal that can display only a single red (exit to a main route) require an overlap?
2) How can a 3-asp signals be applied through station B when the braking distances don't support such?
3) Could a 3-asp head (green blanked) be used to exit from the spur with a R/G 2-asp starter?
4) What options are there when transitioning from 3-asp to 4-asp and vice versa?
5) Where do you start on the plan?

1. Yes, the signal in rear must prove train detection clear to the extent of the overlap. Whether it actually needs an IRJ at the signal (i.e. rather than a combined berth and overlap TC) is more debatable. Basically my view is that you'd risk assess- if it would be important to detect a SPAD at that fixed red (I am assuming here that no associated PL, a signal just imiting the extent of a wrong road move to allow bi-di use of a platform for terminating and reversing a train service for example) then provide, otherwise may get away with a combined TC. If there is a fixed red and associated PL then I'd expect separate TCs; apart from anything else there are likely to be points within that overlap length.
2. Haven't got access to plan at present (in Eire) so comments here purely generic. Potentially could use "modified 3 aspect" sequence, by approach releasing a signal with inadequate distance for braking if following signal at red. Not often a good solution though. What about imposing a speed restriction through the relevant area that then would give enough braking distance; you can get away with this IF it doesn't actually impact the train service (i.e. if all trains due to stop anyway). Otherwise might need just a few 4 aspect signals in the area.
3-5. Think I need to see the plan for these.......