Part IV

THE TRACK CIRCUIT IN GREAT BRITAIN AND ON THE CONTINENT

By T. S. Lascelles

No satisfactory records appear to have been kept as to the origin and development of track circuiting outside the United States, which renders it very difficult to arrive at any conclusions that could serve as a basis for a real historical sketch upon this interesting subject. In view of the fact that the Signal Section of the American Railway Association proposes to publish a memorial to the late Dr. William Robinson, generally regarded as the inventor of the closed track circuit and certainly the first to utilize it in the control of an automatic block system, the following brief remarks may prove of interest to the writer's fellow members of the Signal Section. It is not suggested that they are in any sense complete, as to make a complete survey would require considerable investigation. They really represent the writer's present general understanding of the subject and are open to such criticism and correction as anyone may be able to offer to them, in England or elsewhere.

There is no doubt but that track circuits were thought of and actually experimented with in England a great many years ago--probably as far back as the earliest American attempts--but the want of satisfactory records make it very difficult to decide on what actually took place. However, it is certain that the late W. R. Sykes, well-known throughout the railway world for his controlled manual block and other inventions, endeavored to use the track circuit in the sixties and that Bull, the inventor of the bull-headed rail employed in England for the chaired track universally found there, clearly had the idea of a track circuit in his mind, for he refers to it in a patent obtained in 1860. It was apparently in the early part of the sixties that W. R. Sykes fixed a track circuit experimentally at Briseton on the old London, Chatham and Dover Railway, and shortly after also at the Crystal Palace Station on the same line. The apparatus employed must necessarily have been rather primitive. In the seventies, track circuit was installed by him at St. Paul's station, also on the Chatham Railway. At that time very little was known about the track circuit theoretically and the construction of the relay was very different from our modern types. Sykes' relay completed the control circuit by the insertion of a contact point into a mercury trough. It was also, the writer believes, built on the solenoid principle. So far as is known it was not suggested at this time and at all events not attempted to make an automatic block system controlled by track circuits, such schemes for signaling of this type as were put forward being always based on the intermittent or track instrument control plan.

It must be remembered that the conditions obtaining in England, widely different from those seen in the United States, were not such as to give much encouragement to the development of automatic signaling, while over and above this, the English conservative nature always looked askance at automaticity in railway apparatus. Automatic signals, worked on a track instrument plan, were put into regular work on the Liverpool Overhead Railway in 1893, but it was not till 1902 that automatic signals controlled by continuous closed track circuits were to be seen in operation on an English main line railway. Before this, however, track circuits had made some progress, though not very much; the most important instance of its application was in the Kings Cross tunnels, just outside the London terminal of the Great Northern Railway, in the early nineties. This installation, which was used under none too favorable circumstances from the point of view of successful operation, proved to the English what the track circuit could do and heralded the day when its place in the safe working of railways should be better appreciated. By this time in the United States, largely under the influence of the pioneer work of Dr. Robinson, automatic signaling had made quite considerable progress and the potentialities of the track circuit had been fairly realized.

It may occur to Americans to ask why it was that progress in England was so slow and this is a question which cannot be answered by a single reason since a combination of circumstances was the cause. In the first place the older type of English signal officer was extraordinarily conservative regarding signaling practice of other countries as he had that peculiar type of contempt which generally comes from want of knowledge. Anyone who, like the writer, listened for instance to the objections brought forward by some of these men to controlled manual block, will know to what absurd lengths they could go in resisting improvements in working. Although this spirit, which has markedly diminished during the last 15 years, must have accounted to some extent for the slow development of the track circuit in England, there were yet some reasons of a more sensible kind which must be borne in mind. The English light weight four-wheeled freight car without air brakes was and still is a bother to the track circuit engineer because of the difficulty of getting a satisfactorily low shunt under all circumstances. Then again the Mansell disc wheel made it necessary to resort to bonding between the tire and the hub before a vehicle would shunt the track circuit at all and this was an expense to which the companies were loath to go, especially if they had or contemplated very few track circuits, though the use of even one circuit really necessitated the whole of these wheels being so treated. There was no great demand for automatic signaling, as the manual system was giving good results and was also cheap at that time, owing to the low wages paid to railway men. This and the other reasons just given combined to render the progress in England extremely slow.

Some of the First Installations

Nevertheless, in 1902 the British Pneumatic Railway Signal Company, who had in the previous year installed its first low pressure pneumatic interlocking at Grateley, on the London and South Western Railway, brought into use between that station and Andover an automatic block system controlled by continuous track circuits, the distance being about six miles. The signals were worked by low pressure air. The success of these systems led to the adoption of them shortly afterwards on the widened four-track main line between Woking and Basingstoke on the South Western, a distance of 24 miles. The Grateley-Andover installation has now been removed, not because it was at all unsatisfactory, but because it was felt traffic and other circumstances did not warrant its further employment. In 1905, Hall electro-gas automatic signals were brought into use on the North Eastern main line between Alne and Thirsk, a distance of 11 miles. In 1907, semi-automatic signals were installed between Pangbourne and Goring, a distance of 2-3/4 miles, four track, by the Great Western Railway to divide up a long manual block section and a few similar installations have been made on the Midland, the Great Central, the Belfast and County Down and other roads.

By this year, track circuiting had begun to be extensively used in England. The British Pneumatic Signal Company had installed a series of low-pressure plants near Manchester on the Great Central and track circuits were used throughout while the same thing had been done at Clapham Junction on the South Western. The Westinghouse Company had supplied the District Railway, London, with automatic signals and were actively engaged in fitting similar apparatus to the tube lines; they soon afterwards commenced work on the Metropolitan Railway.

The main steam lines began to apply track circuits at various places in conjunction with ordinary manual signaling and this process received an added impetus from the terrible disaster which befell the Midland Company's Scotch Express near a station called Hawes Junction, when, in emerging from a tunnel it crashed into two light engines that had been forgotten and had entered the block under the signals set for the express. Several other bad accidents, notably one at Pontypridd, on the Taff Vale Railway, due to trains and engines being overlooked by signalmen while standing at adverse signals, emphasized the necessity for paying serious attention to the question of track circuiting and for undertaking a really earnest study of the matter to see whether the difficulties due to the light freight car, etc., could not be overcome or at least considerably minimized.

Considerable progress had been made by the time the war broke out and quite a number of track circuits had come into existence on all the principal roads, although no extension work worth noticing was made to purely automatic block systems on steam roads, this class of work being confined to the suburban electric lines. Unfortunately, in this as in so many things the war had a retarding effect and caused the postponement of many plans. The increased price of wages and materials has hampered progress a great deal and it will be some time yet before any great improvement is noticeable. On the other hand, the great increase in wages has caused a demand on the railways for a reduction of operating costs with the result that signal engineers are endeavoring to produce schemes which will enable signal towers to be abolished or closed at intervals where they were formerly kept continuously in service and in this and other ways to dispense with unnecessary staff. It is in this that the track circuit will help very considerably. Its further extension on English lines is a certainty and simply a question of time and money. Since the inception of the Institution of Railway Signal Engineers a great amount of work has been done in discussing and studying requisites and so on for track circuit work, both of the direct current and alternating current types. All this has resulted in increased confidence on the part of the traffic officers in track circuit and allied apparatus and caused them to look more and more to the signal engineer to help them in their work and to accord him the respect and credit he deserves.

The writer is aware that these lines can only convey a very imperfect idea of the actual state of affairs, but he prefers to write them now as a preliminary account, not yet being in a position to furnish the figures which the Signal Section desires.

Track Circuits on the Continent

Turning to the continent, the writer must necessarily speak in very general terms since there is less published on this subject by continental journals than by English and, of course, the field is rather a wide one, embracing so many lands and tongues. The track circuit is, of course, known there fairly well, but there are no very great installations of automatic block to be found. In the case of France, the Paris, Lyons & Mediterranean had, before the war, an installation between Larsche and Auperre, 24 miles, and some semi-automatic sections in various places. The Midi Railway had also the Hall disc system from Bordeaux to Langon, 26 miles, and the writer believes extensions to this have since been made. The Est Railway began trials before the war and during the war, owing to shortage of staff and having greatness of traffic to the eastern military area, installed automatic signaling on the Paris-Nugent line. The writer has been told that it is under consideration to equip the whole line to Avricourt, where it connects with the Alsace-Lorraine system. The writer is not aware whether the other companies in France have any automatic blocks, but he believes not. They all have, however, track circuits installed at various places in connection with the ordinary signaling. Owing to the lower standard of living and the employment of women operators at many points, there is not so great an incentive to the adoption of automatic devices, as in some other countries. French engineers, however, know what Americans have done in this way and some very complete accounts of American systems have appeared in "La Revue generale des chemins de fer." The Paris Metropolitan line is automatically signaled by an intermittent contact system without track circuit.

In Germany, the track circuit for steam lines is not looked on with much favor, as owing to the extensive employment of the Siemen's controlled manual and the peculiar station masters' system of control, called "Station Block," always used in that country (with, it must be admitted, a very high record for safety,) the Germans think they would not gain much by any great use of track circuit or automatic signals. The writer has just had this view confirmed by a friend returned from visiting the important works of the German Railway Signal Company at Bruchsal, Baden. Automatic signaling is used on certain important sections of the Berlin Elevated and Underground Road, installed before the war by the Westinghouse Company, of London, with a.c. double rail track circuits and this will be extended eventually to cover the remaining sections still worked by the Siemen's controlled manual. Dr. Kemmann, a member of the General Railway Direction, Berlin, published last year a very interesting book describing his work with accounts also of the London Underground and New York Subway installations, showing that foreign systems are studied in Germany. But for steam roads the writer believes from what he has studied of German methods and ideas on the subject that the manual system will remain in use and that the track circuit will not be much adopted.

The same remarks apply generally to Austria, Holland and Scandinavia, though in the latter case English ideas are more in evidence and it is probable that the track circuit, already in use to some extent, will be developed as time goes on. In Austria automatic signaling was certainly tried on a small scale on the Southern Railway, but with what results the writer cannot say. In Switzerland the extended use of iron ties is against the track circuit. In Belgium the Hall system was at one time in use between Ghent and Wondelgem, but as the course of the line was changed, these signals were removed. The section was about 3-1/4 miles long. Automatic signals do not exist there now but the track circuit is used at certain stations, notably throughout the all-electric power installation at and close to Brussles Nord. The writer does not believe it likely that automatic signaling will be used on the steam roads in Belgium, at all events for some time yet. With regard to Italy, Spain and Portugal, the writer does not possess details, but believes it likely that the track circuit is only in use, if at all, at a few important stations. The new Metropolitan line in Madrid is equipped with an intermittent contact system, probably copied from the Paris Metropolitan.

Although a little outside the scope of these notes, the writer would emphasize that in the English colonies and in South America (especially, however, the former) the track circuit is being much used and its value appreciated. Automatic signaling is in use in Victoria, Queensland, South Australia and New South Wales. The operating conditions in these countries no doubt much resemble American circumstances and the adoption of automatic signals is a natural development.

Summing up, the writer would say, that the earliest experiments of W. R. Sykes in England are probably as old as those of Dr. Robinson, but owing to the different circumstances in which the former inventor was placed, he had little encouragement to continue them and thus American development at first went on far ahead of English, while owing to the vastness of the American continent it must always present a larger field to the signal engineers' ingenuity and activity. In later years, however, the English signalmen awoke to the importance of the question and installations were constructed which, if smaller, showed as great a degree of technical perfection as any in America. The future will doubtless see more such installations.

It is not known to the writer whether anyone on the continent had the idea of a track circuit as far back as Sykes' or Robinson's experiments or when the first attempts were made. It would require much investigation to find this out. Track circuit possibilities are now well known there and no doubt its use will extend, but in certain countries, notably Germany and Switzerland, there are local circumstances which act rather strongly against it at present. The writer cannot give statistics on the subject now. There are some figures which he possesses, but they should be verified and amplified before being used by the Signal Section for publication. The preceding notes are, he is too fully aware, very incomplete and general, but he hopes they may be of some present use.