195309 – Barnes – Liverpool Street Resignalling

When the Secretary approached me on the question of the presentation of a paper, the choice of the subject came easily, the problems arising when, with regard to the time avail- able, a decision had to be made whether to deal with the technical or practical aspects of the scheme.

After some consideration it was felt that more general interest to members might evolve around installation problems rather than actual circuiting or signalling technique.

In consequence, more attention will be paid tonight to installation methods, and the reasons for certain special arrangements having to be made. It should, however, be mentioned at this stage that the methods and system described are not necessarily standard to British Railways, there having been no attempt made as yet to standardize on a relay interlocking system on any one Region, let alone British Railways as a whole.

It is in fact worth noting that on the Great Eastern electrification scheme, of which the Liverpool Street Resignalling forms a part, three different types of relay interlockings were installed. This means that a relief signalman may, under certain circumstances, be called upon to operate three different types of panel on three consecutive turns of duty. That they are able to do so with complete facility and without any loss of efficiency speaks well for each of the systems concerned, and is surely a complete vindication of some of the earlier criticisms direct- ed at relay interlocking systems as compared with power frames.

No paper dealing with relay interlocking could do full justice to the subject without acknowledgment first of all being made to the amount of pioneer and development work undertaken by the late London and North Eastern Railway Company under the earlier direction of Mr. Tattershall was undoubtedly the first of the British Signal Engineers to see the possibilities in panel control of relay interlockings, and maintained close co-operation with the contracting firm who were responsible for the design and development of the special relays and other equipment concerned in the initial installation.

It must have called for considerable moral courage to pioneer an installation of this type in the face of some rather severe criticism from the more conservative members of the profession, several of whom, to say the least, adopted a somewhat tongue in cheek attitude towards these developments.

The first installation was brought into use at Thirsk in 1933 and was a logical development of the earlier route lever systems which had been applied for some years in all electric lever frames, for whilst revolutionary in concept, relay interlocking was not such a very great step from route locking in which functions rather than levers are interlocked.