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The New Zealand Railways Magazine, Volume 4, Issue 1 (May 1, 1929)

Twenty Years of Automatic Signalling — Present Day Installations

page 34

Twenty Years of Automatic Signalling
Present Day Installations

The increasing adoption of the automatic system of train signalling by the world's leading railways, and the conspicuous success of this system in securing greater efficiency and greater safety in train operation, is indicated in the following article.

It has been freely stated of late, by those perhaps who do not acquaint themselves with the trend of events throughout the Railway world, that the extension of automatic signalling installations is not only at a standstill, but that the existing systems are being taken out. Nothing could be further from the truth. The statement, however, prompts me to broadcast through the medium of our excellent New Zealand Railways Magazine, some facts which, I think, should dispel the idea that such a retrograde step is taking place. Let me say at the outset that it is always the aim and object of the Signal Engineer to instal a signalling system which he knows has been proved, not only by experiment, but by actual service conditions, and which, at the same time, will prove economical in operation.

With reference to signalling improvements and railway efficiency, considerable interest and importance attaches to the record established in the United States of America last year through the installation of modern signalling equipment. Mr. Julius H. Parmelee, Director of the Bureau of Railway Economics, Washington, D.C., has compiled a composite index of railway efficiency which incorporates thirteen performance factors. It was found that seven of these factors were influenced either directly, or indirectly, by the methods of signalling in vogue. Modern signalling facilities increased car miles per car day, ton miles per car day, gross tons per train, net tons per train, gross ton miles per train hour, net ton miles per train hour, and the percentage of serviceable freight cars in service. To arrive at a comparison, a five year average performance was computed for the period 1920 to 1924 inclusive, as a basis upon which to determine the subsequent improvement in each of the thirteen efficiency factors.

It was found that in 1928 a four per cent. improvement in freight train speed had been obtained, as compared with a similar period in 1927. The improvement in this factor was undoubtedly due to signalling improvements, as it is a well known fact that a greater tonnage can often be handled after a signal installation is in service, owing to the elimination of many undesirable train stops.

With this improved factor, there is a decided tendency to favour the authorisation of signalling installations which will reduce operating costs. Advantage is being taken of the many developments which have been made in signal equipment during recent years, developments which make for more flexible operation without sacrificing safety, and which warrant the more extensive use of signal and interlocking facilities.

For example, the Texas and Pacific have completed the installation of a 567 miles section of colour light Absolute Permissive Block automatic signals, on single line. (Prior to 1925, this railway had practically no automatic signals.) In 1926–1927, 125 miles were put in, which, with the 1928 programme, make the total mileage 692. The signalling was extended in this instance to relieve the congestion brought about by extra trains running, and, because of the urgent need, the 567 miles were completed in six months.

On the Aitcheson, Tapeka and Santa Fe, the length of track equipped with Absolute Permissive Block automatic signalling apparatus will, by the end of 1929, aggregate 5,466 track miles. This will leave only 57 miles to be completed to finish the shortest through route from Chicago to the Pacific Coast. (This company has also placed an order for the largest amount of automatic signalling material which has been ordered for years.)

page 35

On the Southern Pacific there has been installed a further 40 miles out of the 800 mile Absolute Permissive Block automatic signalling programme authorised.

On the Louisville and Nashville a gauntlet track across the Cumberland River has been equipped with Absolute Permissive Block automatic signalling. This installation is entirely controlled by train operation, and it effects a saving of over £1,000 annually.

The Louisville, Henderson and St. Louis has recently completed its first installation of Absolute Permissive Block automatic signals (covering 60 miles of single track), the signals being installed to improve the safety of train operation, and to increase the track capacity.

On the West Coast of the South Island. Westport Railway Station and surroundings.

On the West Coast of the South Island.
Westport Railway Station and surroundings.

In addition to these installations I also give a list of some of the construction contracts let for Absolute Permissive Block automatic signalling systems on single lines:—

The Aitcheson, Topeka, and Santa Fe (Eastern lines), 91 miles. (Western), 375 miles. (Gulf), 41 miles. (Coast), 25 miles.

The Paducah and Illinois, 15 miles; and the Louisville and Nashville, 88 miles.

The installations on single line system only have been mentioned. The double line systems run into large mileages, as also do the installations of electric of electric and electro-pneumatic power interlocking.

It may be as well to quote the figures; they speak for themselves.

The yearly construction in miles has steadily increased from 546 in 1920, to 5,127 in 1927, which was the peak year.

In 1928, 3,121 miles were installed comprising 1,940 arm signals, and 3,740 light signals, and these were spread over lines controlled by 42 railway companies. This exceeded the annual average for the last ten years by 752 miles.

The cause for the drop in the construction mileage for the latter year was due to impending action on the part of the Interstate Commerce Commission (which body controls the installation of safety devices), with reference to a decision concerning the installation of automatic train control. The question, however, was not the enforcement of train control installations, as the Commission considered that its previous orders had accomplished their purpose in the direction of extending the development of automatic train control. This left the companies free to proceed with signalling installations which had been held in abeyance. page 36 A hint from one of the Commissioners that “the records indicate that the railways may be expected to make satisfactory progress in extending the use of such signals, especially as they tend to promote efficiency of operation as well as safety,” had, I think, a very significant meaning.

The electric interlocking plants installed during 1928 totalled 1,570 working levers, 471 electro-pneumatic, whilst 209 and 283 respectively, were under construction at the end of December of that year.

In January of the present year it was contemplated that 2,359 miles of track (comprising 978 arm signals and 1,324 light signals), on 23 railways would be equipped with automatic signalling apparatus.

The number of separate installations it was hoped, in January, 1929, to complete for the current year, totalled 773 electric, and 49 electro pneumatic. These contemplated estimates for 1929 were not complete, however, as companies had not formulated their signalling programmes.

It is interesting to note that the total mileage of tracks equipped with this modern signalling system since 1908 (the birth year of the proved Absolute Permissive Block automatic signalling), amounts to 51,713 miles. The approximate total mileage of all railways is 216,000 (including branch and unimportant lines), which means that just less than one-fourth of the world's railways are equipped with the most up-to-date of all our signalling systems. However, each year sees vast extensions of the modern system.

As mentioned in a previous article, the Southern Railway of Great Britain is embarking upon an extensive programme for colour light signalling.

Sufficient has now been said, I think, in defence of this latest system of signalling, which has done so much during the past twenty years, not only to promote efficiency in railway operation, but the safety of the travelling public.

As far as New Zealand is concerned, the Absolute Permissive Block system of signalling (recently declared by a visiting signal engineer of distinction to be the most up-to-date system in the signalling world), functions with mathematical precision, and a large measure of our operating efficiency (and safety), is due to it. In the words of the slogan, “Automatic Signalling Keeps the Wheels Moving.”

A view of the sub-station at Woolston (Christchurch-Lyttelton electrified line), South Island.

A view of the sub-station at Woolston (Christchurch-Lyttelton electrified line), South Island.