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S&DJR Block Working
S&DJR Crest Somerset & Dorset Joint Railway
Block Working
S&DJR Crest
Introduction Crossing Orders Block Telegraph Staff&Ticket Electric Tablet Double Line Control


This page provides an outline history of the various methods of Block Working used on the former Somerset and Dorset Joint Railway (S&DJR). Other pages in RailWest provide more detailed information about the different methods and types of block equipment used for working S&DJR single-line and double-line sections, as well as details about the various examples of S&DJR 'shunting' and 'bank engine' staffs. There is also a Register of all S&DJR single-line sections from the 1880s onwards, with details of the various types of block equipment used and their configurations.

These pages concentrate on providing a general overview of the subject of S&DJR Block Working, with a basic chronology of the introduction of the different types of equipment. It is not intended to describe the finer details of the actual Block Regulations or the specific methods of operation of the various types of instruments. (General information about railway signalling can be found at The Signal Box website.) Signalling information for the early years of the S&DJR is still very scarce and so the starting point for these notes is the year 1874, which marks the opening of the 'Bath Extension' from Evercreech Junction to Bath and the expansion of the S&DJR to almost its fullest extent.

Block Telegraph & Crossing Orders

In 1874 the S&DJR was single-line virtually throughout and the railway was worked purely by 'block telegraph' without any form of physical 'train staff'. A system of 'crossing orders' was in use, controlled by a 'crossing agent' located in the S&DJR offices at Glastonbury (subsequently moved to Bath), but this system existed mainly to regulate the movements of trains (eg those crossing out-of-course) and was not part of the actual block system. Contemporary S&DJR Block Regulations show that the method of use of the block telegraph instruments was akin to the single-needle 'speaking telegraph' (with a single-needle indicator and a drop-handle to work the commutator) and did not involve the use of block bells. The block instruments were located usually in the station buildings and operated by a telegraph clerk, who acted under the instruction of the Station Agent (the S&DJR term for Station Master), as did the signalman himself. Minute 3114 of the S&DJR Officers' meeting on 27-January-1885 recorded that "the new Railway Clearing House code of block signalling" would be implemented with effect from 1-March-1886, but it is clear from the subsequent revision of the Regulations that, although bell codes had been introduced, the needle of the block instrument was used still to convey 'dial signals' as well. It is believed that the instruments were maintained by JB Saunders & Co of Cardiff, who listed the S&DJR as one of the railway companies with whom they had contracts, but little specific information is available.

Train Staff & Ticket

The 1876 disaster at Foxcote (near Radstock) made horribly obvious the danger of lax working of single-lines, but surprisingly the subsequent Accident Report by the Board of Trade contained no strong recommendations for changes in the method of working the single-line sections. The S&DJR continued to be worked mainly by block-telegraph for a further ten years, but there began to be a move towards better methods of control. The first change was the introduction of 'Train Staff and Ticket' (TS&T) working, where the use of a physical train staff in addition to the block instruments, rather than relying just on instruments alone, certainly provided a more secure system of working. One section was converted to TS&T working in 1877 and another in 1879, and then several more during 1886, but this did not have a great impact on the S&DJR in the long term because it was soon overtaken by a further change to the Electric Train Tablet system.

Electric Train Tablet

The most significant change for block working on the S&DJR was the introduction of the Electric Train Tablet (ETT) system in 1885-86. This method of working was introduced initially only on the main line from Bath Junction to Wimborne Junction and Broadstone, but in due course it was extended to cover almost all of the single-line sections and superseded almost all the TS&T working. ETT working became a feature of the S&DJR that existed right up until the closure of the railway to passenger traffic in 1966, although during the British Railways era some ETT sections were equipped with the alternative Electric Key Token system. More detailed information about the various methods and changes of single-line equipment on the S&DJR is contained in the specific RailWest pages on S&DJR single-line block working and the Register of S&DJR single-line sections.

Double Line Control

By the mid-1880s the S&DJR had embarked on a programme on doubling many of its single-line sections, eventually having continuous double-track all the way from Midford to Templecombe No 2 Junction, with a further section from Blandford to Corfe Mullen Junction. It appears that, as various sections of the S&DJR were doubled, the existing equipment and regulations for the 'block telegraph' method of single-line working were applied to double-line use with very little alteration.

Block Telegraph Regulations and Instrument Dials
An extract from the S&DJR Working Time Table Appendix No 7 dated 1- March-1886

The S&DJR Block Regulations introduced in 1886 were still in use in 1889, but thereafter unfortunately there is a gap in available material until 1905. By that time the bell codes had changed to more modern versions and the 'dial signals' appear no longer to form an integral part of block working, although they were still used for some purposes - even as late as 1914 the S&DJR Working Time Table Appendix contained the following Regulation:

"3(f). Where Dial signals are used to indicate the direction in which a train requires to run, the direction from which a train is approaching or for any other purpose, they must, when used with the Is Line Clear? signal, be given immediately after that signal, and when used with the Train Entering Section signal, the Block Indicator, before being placed to Train On Line, must be placed in the normal position, and when the Dial signal has been given and correctly acknowledged, and the signal Signal correctly repeated (one beat of the Block Indicator to the Right) has been received, the Block Indicator must be placed to Train On Line".

More specific information about the various types of block instruments used on the S&DJR is contained in the separate RailWest page on S&DJR double-line block working.


This page, and the other associated RailWest pages, deals with S&DJR Block Working only until the complete closure of the S&DJR system to passenger traffic in 1966. Some sections of the line remained opened for freight traffic after that date for a few more years. It is not clear whether these were worked under "One Train Working" regulations, with or without some form of Train Staff, or simply "under signalman's control". Additional information on any aspect or period of S&DJR block working is always welcome and should be sent to RailWest by e-mail please.

© CJL Osment 2001-18


Introduction Crossing Orders Block Telegraph Staff&Ticket Electric Tablet Double Line Control