Wilkinstown wrote:"Madscientist" You refer to an accident at Manulla Junction in the mid 1960s - do you have any more details ?
Wilkinstown wrote:If you look at the signalling diagram for Manulla Junction at http://catalogue.nli.ie/Record/vtls000306641, you can see that the subsidiary signal (No 26) sited to the left of the up home signal (confirmed by the photograph at http://catalogue.nli.ie/Record/vtls000306950) actually reads to the loop despite this being geograpically to the right.
I am now inclined to think that the arrangement of the up home signals at Claremorris (as in the early 1960s) is similar to that which applied at Manulla around the same time. The subsidiary signal simply read to the lower speed route. At Claremorris, I now suspect that the subsidiary home signals at the west end of Claremorris read to the slower route only. This is different to the arrangement which applied at crossing points on the former double line segments of the midland main line where, post singling, the subsidiary signal could read to either the main or loop lines. As I mentioned before the main home signals at these stations could not be lowered unless the main starter had already been lowered. The main starter in turn could not be lowered unless the section token had been released.
John Hinson wrote:It might be worth remembering that a subsidiary signal indicates the line is only clear as far as can be seen,
Wilkinstown wrote:I don't understand the confusion.
At Claremorris and Manulla Junction, main home cleared, road set for straight route. Subsidiary cleared, route set for subsidiary road (i.e not the straight road). The only unusual feature is that the position of the subsidiary signal does not correspond geographically - not the way I would have done it but I don't see the big deal as the subsidiary signal tells the driver he is not taking the main route. Basic route knowledge provides the remaining relevant information.
The arrangement was different at the former double track MGWR stations which were re-signalled in the 1920s when the lines concerned were reduced to single track. In this case the subsidiary home signal could read to either main or loop depending on the lie of the points. Either way the driver will have been cautioned by the subsidiary signal and should therefore have his train well under control passing the home signals.
As for checking trains, the main home at danger is fairly effective, once the signalman is happy the train is under control he can then call the train forward. Don't see any issue. At Manulla and Claremorris, in the up direction, the signal cleared will be the main arm for the straight road and the subsidiary for the secondary route. At some other stations, as described in the preceding paragraph, there was an additional control which prevented the main home being cleared unless the main starter was also cleared. At such stations the subsidiary read to either main or loop depending on circumstances.
Mike, the arrangements are so simple even the Irish had no problem understanding it !
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