It is proposed to cover some phases of the application of electricity to signalling, particularly as it applies to the New South Wales railways. Prior to 1885 electricity was mainly confined to the Morse telegraph and to telephones, and up to that year the Railway Department was wholly dependent on the Postmaster General's Department for all its communication lines, and many Railway 0fficers carried out combined Postal and Railway work. In country districts, on both main and branch lines, the Post Office in many cases was on the Railway station, and the Station Master was also the Post Master. There was comparatively very little double line in operation - none outside the Sydney to Parramatta area, and train movement over the single line was operated by train staff and ticket, the trains being reported in and out by Morse telegraph of the closed circuit type, operated by Meidinger (Bluestone) batteries. The invention of the Morse telegraph over 100 years ago marked the first great advance in Railway signalling on the communication and train despatching side. The telephone followed. In New South Wales, the Morse is now being rapidly superseded by printing telegraph and the carrier telephone systems, the latter providing so many additional circuits, and the fact that the quality of these derived circuits is a great improvement over physical circuits. Mr. Eddy's appointment as Commissioner for Railways in 1889 marked the first stage in a progressive programme of signalling both for double and single line wording. On double tines, block instruments, electrically operated, were introduced, and on single lines the token system with electric train tablet and electric train staff. All these instruments were operated by primary batteries of the Leclanche type and, with the exception of one form of block instrument, they were all of the open circuit type, current only being used when signals were exchanged between the stations or signal boxes. The token instruments for single line working still remain in service. As indicated above, the Morse instrument, except on trunk lines, has largely been superseded by the telephone, whilst the block instruments on double lines are being rapidly replaced by automatic signalling.
When the Federal Constitution was framed and the Commonwealth came into being, provision was made for the Railways of Australia to have their own communication systems as required for Railway operation, and the New South Wales Railways took advantage of this and proceeded on a progressive programme of pole line construction for both safe working and communication circuits. An agreement between the Postal and Railway Departments provides under rental conditions for the joint use of poles, and in country areas the Postal Department takes full advantage of this by getting the Railway Department to erect and maintain, on Railway poles, lines for Postal purposes.
The signalling system, as distinct from the communication side, prior to 1885 was in keeping with the period and consisted of signals operated mechanically from an interlocking machine at the station or in the signal box. There were no electrical safeguards. The points were operated by throwover ball lever on the ground. Increasing traffic and greater speeds of trains soon called for additional equipment, particularly in the direction of ensuring that signals could not be cleared unless the points were correctly set for the route. This protection took the form of a mechanical interlocking machine, with points and signal levers interlocked. Over the years the interlocking machine has not changed to any great extent. The machines have grown in size, the largest mechanical interlocking machine in New South Wales having a total of 80 levers, covering points, facing point locks and signal levers. The introduction of electricity to safe working has made it possible to combine both electrical and mechanical controls in such a way as to meet all the requirements of the signalling system in a large yard and thus keep down the size of the controlling machine. Unfortunately this is not the case in at least one other State where a mechanical interlocking machine with over 180 working levers is in use.
The application of power, both electrical and electro-pneumatic, for the operation of points and signals has done a great deal to reduce the size of the operating machine and confine the controlling functions within the compass of the operation by a minimum of Signalmen. Sydney Yard has the largest electro-pneumatic signalling installation in the State. Station West has a controlling machine of 400 levers which Control the electrical and the electro-pneumatic equipment operating the switches and route indicator systems. The signals are mainly electrically operated. Of recent years new installations have dispensed altogether with the interlocking machine and the whole of the locking is done electrically. Instead of pulling over a lever the Signalman turns a small key which sets up the controlling circuit by energising the controlling relays. These are designated 'Relay Interlockings' and their application to signalling justifies some special reference. Relay interlockings have been in use on the New South Wales Railways since 1957, in which year a small interlocking was installed, controlling interlocked, power-operated, boom gates protecting a level crossing in the Newcastle district. Since that date a number of large installations have been put into service, and the results obtained, both from an operating and maintenance point of view, justify the conclusion that relay interlockings will supersede the conventional type employing mechanical interlocking in the control machine. From information available, this bears out, in general, the experience of Railways overseas. New systems always pass through a developmental stage during which modifications are made. Some methods, maybe, are discarded, others altered as the result of experience but, fundamentally the basic principles remain. This has been none the less true in the case of the introduction of all-relay interlockings in New South Wales. From an operating point of view, the outstanding advantage is the compactness of the control machine. The controls for upwards of 100 functions and all telephone facilities are within easy reach of a control position. The Signalman can deal with train movements more expeditiously and can even conduct telephone business whilst in the act of routing trains. Furthermore, as there is no delay in waiting for indication locks on points or signal levers, the time saved in setting up or altering routes is sufficient, frequently, to avoid trains coming to a stand.
No difficulty has been experienced in teaching Signalmen of all grades how to operate an all-relay machine, and in a surprisingly short space of time they become familiar with all its features. They have been quick to appreciate the many advantages from their point of view.
Special features of an all-relay interlocking are the lever lights which indicate the interlocking circuits, a light being provided for each lever or key, and a comprehensive indicator diagram which includes in addition to the usual track lights, all signal repeaters and lights indicating the lie of each set of points. This information is invaluable, not only to Signalmen, but also to the Electrician who, in the event of a failure, can usually determine the section of the circuit at fault by glancing at the machine and the diagram.
The logical development of the circuits renders a seemingly complicated set-up a comparatively simple matter, for each control circuit is made up of a number of individual sections, each with its own particular function and significance. These sections may be followed, step by step and, for the purposes of testing or finding faults, may be isolated and examined as separate units. In this respect, it may be said that a relay interlocking machine bears some resemblance to a conventional power frame with its separate units, such as catch rod contacts, lever rotary contacts, electric indication locks and mechanical locking boxes. There, however, the comparison ends for, whereas in the case of the latter various mechanical and electrical adjuncts are an inseparable part of the machine to enable it to fulfil its purpose, in the ease of relay interlockings, apart from the actual control key contacts, only relay contacts are involved. Standardisation in this respect makes for improved maintenance and facilitates the location of faults.
From an economic standpoint, relay interlockings have proved extremely valuable in cases of additions to existing mechanical machines brought about by new and altered yard layouts. Specific cases are those which have called for an extension to a mechanical machine and a consequent addition to the signal box. So avoid these expensive additions, it has been found expedient to superimpose a small relay unit to control electric signals and points, and transfer the interlocking by means of electric locks on the mechanical levers. This has proved of considerable advantage in several respects. The overall size of the mechanical machine is reduced and during stage work in large interlockings an old existing machine can continue to function without extension, and on completion of the work the relay control panel can be recovered, together with the associated relays, and used elsewhere. It has been found convenient to have in stock a number of small relay units ready for such purposes.
Relay interlockings lend themselves to remote control and a number of such installations have been, or are being, installed in New South Wales.
Railway Signal Engineers are loath to emphasise the safety of any particular design or arrangement of equipment, for experience teaches that unforeseen circumstances can arise which negative all precautions which have been taken. In the case of relay interlockings as designed and installed in New South Wales, it is claimed that no safety measures have been sacrificed. As a matter of principle, once a route has been set up, no conflicting route can be cleared and, further, although there is no mechanical interlocking between keys or levers, the movement of any key will not throw to Stop any signal controlled by another key. There are no separate indication circuits insofar that the detector relays, which prove that the points are in position and locked, are utilised for interlocking as well as for signal control circuits. Detector relays, normal and reverse, are cross- checked and each is proved and de-energised in the appropriate point controller. Thus, before a point movement takes place, the detector relay must be down. Instantaneous point operation after the passage of a train has been delayed in certain installations by imposing a time delay on the local track in the points control. Interlockings in hand at the moment differ in this respect, in that 'pre-conditioning' is prevented and, preparatory to throwing a point lever, the latter must be in phase with the points when track conditions permit a point operation.
The use of relay interlockings has enabled large additions to Railway yards to be signalled by modern methods without having to build new signal boxes or to dispense with existing interlockings. Relay units are constructed to the required size and installed in the signal box over the existing interlocking machine. The locking is done by relays instead of the mechanical interlocking machine.
Much has been done to eliminate Traffic Staff from signalling duties by the introduction of automatic signalling. Where power supply is available from a reliable source the automatic signals are operated by alternating current, power being taken at 2200 volts and transformed where required down to 110 volts and 14 volts for the operation of points and signals, and to 6 volts for the track circuits. Outside the areas where power supply is not available, primary batteries of 500- ampere hour capacity are used, the signal motors being 20 volt or 10 volt. The life of these primary batteries is prolonged where any commercial or street lighting supply can be tapped by the use of rectifiers which are floated across the battery, the output from the rectifier being set to take the normal load of the circuit, and the battery to carry the peak which occurs when a signal is clearing. In operation, primary battery operation is reliable and economical. Approximately 12,000 signal movements are obtained from one 500-ampere hour unit. With a rectifier floating across the battery, the number of signal movements per recharge approximates 60,000.
Radio
Radio is not entirely a new development in Railway work. In New South Wales, the first step has been taken in obtaining suitable radio frequencies to meet the needs of Railway operation. Having established these frequencies, we are looking forward to making good use of this means of communication. Already we have provided the Department of Road Transport and Tramways with a system for communicating from the Head Office in Macquarie Street to mobile vehicles moving Around the tram and bus routes, and in cases of emergency and during the recent Royal Agricultural Society's Show good use was made of the facilities by movement of the vehicles around the various bus and tram routes, and arranging the bus and tram movement to meet the various conditions of loading.
In addition, the Investigation Section of the Railway Department has had equipped a number of fast moving motor cars with radio equipment as a means of checking, along the Railway routes the activities of train robbers.
The main transmitter for these radio installations is located at the Sydney Harbour Bridge and both stations work on a common aerial, which is connected from the transmitter by means of an air-dielectric coaxial feeder which is carried to the highest point of the Bridge.
Apart from an isolated radio installation in use at Enfield Marshalling Yards, no further application has been made up to the present Time. It is, however, contemplated that radio will be applied to train movement at an early date, in a limited form. It is not suggested that the simple application of radio to train operation will prevent all train accidents. It can, however, be applied to supplement our present signalling systems and safety devices, in that it will be possible to give advance warning to Enginemen whenever there is some irregular condition which has to be guarded against by prompt action.
Radar
Radar in its present state of development is too directional to have any direct application to Railway signalling, but there is every probability that there will be great improvement in radar and we are keepiag ourselves actively posted in the progress made. Radar principle has already been applied with success to the location of faults on open wire communication circuits and this application will be extended.
Cathode Ray Fault Locator
At this stage, it will be interesting to refer to the cathode ray fault locator which is being used for the purpose of locating and detecting faults, thus enabling the supervising and maintenance staff promptly to determine the location of a fault and to remove the cause.
The cathode ray fault locator is an instrument which employs a cathode ray electronic tube to show visibly the location and nature of line faults. The electrical condition of the line is shown on the cathode ray screen. The principle of the apparatus is as follows - Pulses of direct current are sent into the line under test 50 times each second. Part of the energy from these pulses is reflected from electrical irregularities in the line and returns to the instrument where it is amplified and applied to a cathode ray tube, causing a vertical line to appear. The position of this vertical line along a horizontal axis is a measure of the distance from the testing point to the fault. In order readily to read off the mileage to a fault, other vertical lines are made to appear on the screen at intervals representing ten miles. The nature of the fault is shown immediately by the phase of the reflection which affects the apparatus in such a way that 'Open Circuit' faults produce an initial upward vertical line, and short circuit or crosses give downward directions.
Two instruments have been in experimental use and have proved very useful and accurate. The mileage of faults has always been found within plus/minus 1% up to distances of 130 miles, and generally the accuracy is within 0.5%. It is known that greater precision can be obtained when the instruments are calibrated against individual lines as, up to date, the distance to a fault has been assumed to be track mileage in spite of the fact that short lengths of cable reduce the velocity of propagation and thus tend to falsify, to a small degree, the true mileage.
Training of Staff
No address on the Application of Electricity to Signalling would be complete without some reference to the training of staff for signalling and communication work, and an outline of the practice in this regard on the New South Wales Railways is as under -
Cadets
Cadet Assistant Engineers are employed through the Employment Officer in response to advertisements in the local press calling for applicants, whose education is up to the Leaving Certificate standard set by the Department of Education, which would permit of them entering immediately into the Diploma Course in Electrical Engineering at the Sydney Technical College. The cadets are required, as far as possible, to be under the age of 18 years, and arrangements are made for them to be appointed at the beginning of each year in order that they will be available to commence their training at the Technical College Diploma Course, at the commencement of the training year, which is usually about the middle of February of each year. They are employed on all phases of signalling and communication work and are transferred from one section to another in accordance with a set programme.
The age limit of 18 years automatically fixes the minimum period of four years for the cadetship, and if a Cadet were appointed prior to attaining the age of 18 years the lad would require to serve the number of years between his age on employment and his arriving at the age of 22 years, at which age he is required to be qualified for appointment as an Assistant Engineer, Class 4.
In connection with the training of Cadets, they are allowed leave with pay to permit them to have four hours' class instruction per week, which usually involves one morning or one afternoon per week. In addition, a Cadet is required to attend certain evening classes which are provided for in his curriculum at the Technical College. In cases where a Cadet is required to attend such evening classes, leave is granted to ensure that he has a period of 30-minutes for a meal, plus any necessary travelling time to enable him to arrive at the class room prior to the commencement of the class.
Authority is held for the employment in the Branch of two cadets each year.
Apprentices are employed under two classifications, namely - Apprentice Signal Electrician and Apprentice Electrical Fitter, and prior to appointment are required to have educational qualifications up to the Intermediate Certificate standard, as set by the Department of Education, and must have obtained a pass in Mathematics 1, Mathematics 2 and Physics.
On appointment, Apprentices are directed to the Railways Institute in respect of the technical training that they will be required to undertake during their apprenticeship. This involves attendance at the Electrical Trades Course for a period of five years, embracing a Lower Trades Certificate which is issued after three years, and a Higher Trades Certificate covering the final two years of technical training.
The number of Apprentice Signal Electricians employed each year has been set at 15, but in order to provide for wastage which occurred during the war years this number was increased as from 1-1-1947 to 25.
During training, the Apprentice is required to serve in the various sections of the Branch, and experience is obtained in the following-

• Metropolitan power signalling. (Maintenance and construction).
• Signalling Workshops.
• Communications
  • Workshops.
  • Metropolitan telephone maintenance.
  • Telephone trunk line equipment.
  • Automatic exchanges.
• Country signalling and communication maintenance.
• Drawing office experience.

Metropolitan Power signalling
The Apprentice is assigned to a Signal Electrician in the Metropolitan area and assists him in the maintenance of points motors, train stops, relays, signal motors and all electrical equipment associated with power signalling. At monthly Intervals the Apprentice is interviewed by the District Engineer and questiond regarding his experience and progress. Provision is made that the Apprentice is not employed on any one class of work in one section, and he is transferred from one section to another at six-monthly intervals. A period of training on construction work is given, dependent on the works in progress.
Signalling Workshops
Approximately six months of the apprenticeship is spent at the Signalling Workshops, where the training is devoted mainly to dismantling, repairing and assembling various units associated with the signalling system, i.e. train stops, impedance bonds, relays, signal motors, safe working instruments, etc.
Communications
Training in this section is devoted to Workshops, automatic telephone maintenance, trunk line equipment, switchboards, teleprinters, carrier telephone and carrier telegraph equipment, Morse equipment, public address systems and telephone train control installations.
A period is spent on each section of the work, and the Apprentice is assigned to assist a Telegraph Electrician in the course of his duties. Instruction is given on the methods of fault finding and operation of the various systems, and this instruction is supplement by the issue of maintenance circulars which deal with the theory and operation of the various types of equipment.
Country Signalling and Communications Maintenance
During the period of the Technical College recess, Apprentices in the 4th and 5th year are assigned to various country districts where they assist generally in the maintenance of communication equipment, safe working instruments, and general signalling apparatus.
Drawing Office
A short period is devoted to Drawing Office work, which may be spent in either the signalling circuit design section, mechanical design, or communications. Whilst the Apprentice is not required to design any circuits or appliances, the training is devoted to general drawing practice, i.e. drafting, miscellaneous circuits, and mechanical components.

During the whole of the period of apprenticeship, considerable attention is given by the Supervising Officers in each section of the Branch to instruction in the rudiments of safe working and its application to the signalling system. The use of testing instruments of various types is included in the training, together with the application of the instruments to fault finding in all signalling and communication circuits.
Monthly Report Sheets received from the Technical College and the Supervising Officer are analysed, and suitable action taken in respect of Apprentices who show aptitude and adaptability. At monthly meetings of all Apprentices, the Supervising Officer instructs in routine procedure and the general operations of the Branch.
Every twelve months all Apprentices are called together and addressed by the Signal and Telegraph Engineer. The address usually deals with the functions of the Branch in its relation to the Department and the work of the Apprentice as a unit of the Branch.
On completion of his Apprenticeship an Apprentice is required to pass a Departmental Board examination covering his practical training and a certificate is issued by the Board of Examiners as to his fitness for the particular grade in which he served his apprenticeship. The Technical College, at the Higher Trades examination, which is held at the end of the 5th year of their training, issues Certificates in various passes, namely 'A' (Honours), 'Credit' and 'C' Passes.
The Commissioner for Railways has approved of those Apprentices who obtain an 'A' (Honours) Pass in the 5th year examination being found a permanent position in the grade in which the apprenticeship was served. This is given as an incentive to the Apprentice to make full use of the technical training facilities which are provided gratis by the Department.
A number of Apprentice Electrical Fitters also are employed each Year. The Apprentice Mechanical Fitter in his 3rd year is taken from the Signalling Workshops, Chullora, and specially trained on interlocking work, and on completion of his apprenticeship is employed as an Interlocking Fitter on outside signalling work.
The complement of Electrical Apprentices in the Signal and Telegraph Branch going through their apprenticeship is maintained at a total of 89. Since 1956, we have been able to absorb as a journeyman every Apprentice who desires to remain in the service and has qualified.
The Railway Demonstration Room, which is fitted up as a School of Signalling, is used for the purpose of instructing the Apprentices during the course of their apprenticeship, in the technical details of the work. A series of lectures is given by the Technical Officers who are specialists in respect of the following:-

1. Mechanical locking
2. Circuit design
3. Railway safe working, ehich includes block, electric train staff and tablet instruments.
4. Communication work, which includes automatic telephone exchanges; radio communication; carrier channel telegraphy.

Each tear, at the termination of these lectures, an examination of the Appprentices is conducted, and first, second and third. monetary prizes are awarded to the Apprentices obtaining the highest number of marks.