A local signal box to me closes at night but the line remains open. I always thought that the last signal of the box needed a release from the next box to be able to clear this signal. Is there a lever in the box that is used to close the box and release the last signal?
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Signal boxes that close
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Signal boxes that can be "switched out" can literally do just that. A large multipole switch is provided and a set procedure is followed to clear the box's signals and then the switch is operated to directly connect the block instruments in the boxes each side to each other. Thus the signals are left at 'clear' all night and there is therefore no need for a 'Line Clear' release to allow the 'starter' signal controlling access to the next section to be cleared.
ralphchadkirk
Established Member
The lock allows signals to be released in both directions at the same time.
When a box is 'switched out', it just becomes a collection of distant and stop signals that are permanently set to 'off', thus creating one long signal section between the previous signal box, and the following one.
Examples I have seen with the boxes both 'in' and 'out' are Pontrilas on the Central Wales line, Henley-in-Arden (not anymore) on the Stratford-upon-Avon line, and Arley on the Severn Valley Railway.
Examples I have seen with the boxes both 'in' and 'out' are Pontrilas on the Central Wales line, Henley-in-Arden (not anymore) on the Stratford-upon-Avon line, and Arley on the Severn Valley Railway.
dk1
Veteran Member
Somerleyton Swing Bridge Box used to 'switch out' between 22.00-06.00 or whenever short staffed (much to the annoyance of river traffic). At these times ALL signals in both directions where cleared & the absolute block section then became Reedham Swing Bridge Box to Oulton Broad North Box.
A more detailed description about switching out can be found at http://www.signalbox.org/block/absolute10.htm where both the cases for signals needing 'Line Clear' and those that don't before being cleared are covered.
A 'line clear' release and a single beat on the block bell is given by the 'boxes in advance in either direction (say A and C) in response to the 5-5-7 bell signal from B, to allow the latter to clear his signals right through in each direction. Once B has done this, a single beat is returned to both A and C, who both then acknowledge the 5-5-7 bell signal by repetition and return the block indicator to normal. B then turns his block switch 'out', and A and C proceed to check that through communication has been established.
Other than, I understand, some earlier WR installations (not sure whether any remain in this manner), the block switch certainly doesn't release any signals directly.
--- old post above --- --- new post below ---
Further to my earlier post, an example of a block switch (the only example, in the double line context referred to here, in preservation!) can be seen in the eleventh photo on this page (the first 'internal' photo) - the block switch is positioned between the two sets of block instruments.
Incidentally, in this case at least, although the block phone is connected through between Loughborough and Rothley when the block switch is turned 'out', it's still possible for Quorn to partake in any conversation. The block indicators and bells are taken out of circuit completely though.
Old Timer
Established Member
The "Multipole" switch release you refer to is not a switch release.
The Block Switch merely serves to directly connect the block bells and the block indicator circuits between the signalboxes on each side.
Operating the BS will not of itself give any release to the electrical locking of the Section signal. If the Section signal was to be replaced to the On position with the BS in "Closed" then the Section signal would again become locked until a Line Clear Release was obtained.
The circuits for the Line Clear release require the adjoining signalbox to be open, the BS to be at "Open", and a Line Clear displayed on the Block Instrument.
There is a means of obtaining an illegal Line Clear Release of the Section signal but that shall not be divulged.
EWS 58038
Member
Why not close 80% of all boxes and build 25 big IECC's... Saves a lot of money.
It would be a massive, massive investment to resignal so much of the network, that's why- that's why we have such old technology still in use.
Why as many as 25 though- if you're going down that route, might as well concentrate control in even less locations, NATS style.
Though, going further, if were doing that full ERTMS ETCS level 2 roll out would be "better" than plain line side signalling, no?
But the anser is, mainly, money. RMT signallers would make some sort of safety-based argument in order to protect jobs (as, funnily enough, it is part of a union's role to fight job losses. This doesn't make them bad)
Why as many as 25 though- if you're going down that route, might as well concentrate control in even less locations, NATS style.
Though, going further, if were doing that full ERTMS ETCS level 2 roll out would be "better" than plain line side signalling, no?
But the anser is, mainly, money. RMT signallers would make some sort of safety-based argument in order to protect jobs (as, funnily enough, it is part of a union's role to fight job losses. This doesn't make them bad)
If it isn't broken, why fix it? In Cornwall the service is generally one train per hour and absolute block works well.
Indeed, where there's an intensive service over a complicated layout, a PSB or IECC could easily replace the workload a large number of 'boxes with a single workstation or two. Out in the rural areas, there's less cost savings to outweigh the investment. I'm sure it'll come eventually though.
7 on the GWML with 2 on the Newquay branch. Saltash to St Germans inclusive is controlled by Plymouth PSB. To have one person controlling all of Cornwall would require a resignalling scheme with very little benefit.
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