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.