Construction and Maintenance of the Railroad
EVERY FOOT OF TRACK IN BRITAIN that carries passenger trains is patrolled daily to detect possible flaw.
OF all the varied and innumerable constituents that go to make up the railway, the so-
Rails gradually wear away, owing to the constant abrasive action of the wheels on their upper surfaces; in tunnels corrosion still further reduces their life. Other track constituents similarly wear out; sleepers, in the course of time, rot or split; the ballast gets dirty and fails to give efficient drainage. Periodic renewal of the permanent way, either in part or as a whole, is always, therefore, in progress.
Long before the advent of the first locomotive, pioneer railway tracks had come into existence. The lines of parallel, flat-
But the wagon wheels gradually indented and destroyed the timber, and the next logical step, early in the eighteenth century, was that of laying iron plates over the upper surface of the timber. The business of keeping the wagons on the tracks was at first left to the dexterity of the horse drivers, and the next development, therefore, need occasion no surprise.
On a tram-
But the surface of such lines as these, from the running point of view, was still far from perfect, and it is to William Jessop, the engineer of a tram-
MAN POWER. Laying a new 60 ft rail, which weighs over 17 cwt. Assistance in manipulation is afforded by the rail-
It is to this transfer from the plate-
As the first locomotives sent to America were of British origin, America also standardized 4 ft 8½ in as its railway gauge; the same figure also obtains generally on the continent of Europe, and explains why it has been possible for the British locomotive “Cock o’ the North” of the LNER, to run trials on the French railways; also why wagons can be run direct from Great Britain to destinations abroad by way of the Harwich-
The Gauge Muddle
In Great Britain, Isambard Brunel departed from the standard by laying a gauge of 7 ft, but ultimately it had to be abandoned, at enormous expense, because of the impossibility of running through coaches or wagons between the GWR and any other system.
It is in Australia, probably, that this break of gauge difficulty is seen in its most acute form. Each State began to lay its railways on the gauge best suited to its own needs, with the result that the railways of Western Australia and Queensland are of the 3 ft 6 in gauge; those of New South Wales and the Trans-
In India, and also in Argentina, a gauge of 5 ft 6 in is in use on all the principal lines and is of considerable value, permitting more ample development of rolling stock -
To revert to early developments, we find that before the nineteenth century had dawned -
As soon as any appreciable weights came to be imposed on the tracks, it was found that cast-
Then, as the weight and speed of traffic increased, it was found that wrought iron could not stand up to the work. Fort-
The question is often asked as to how long a rail may be expected to “last”, but it is a question that does not admit of a precise answer. To a certain extent the reply depends on the rail itself, and whether or not it contains special toughening alloys or has been subjected to heat treatments designed to increase its wearing capacity.
Beyond this, however, everything depends on the nature of the traffic passing over the stretch of line in which the rails are laid -
Rails in some sections of line, where a comparatively light and infrequent traffic is carried, have remained in use from forty to over fifty years; at some suburban locations in a city such as London the life may vary from two or three years to a matter of only months. It is in electrically-
There are various ways of measuring the extent to which rails have worn, and one of these is shown in an illustration below. “Plasticine” is used for this purpose, in a special hinged frame, which is closed round the rail, head and foot; when the frame is withdrawn, an exact impression of the rail is left in the “Plasticine”. The mould is then inserted in a kind of printing-
Another development of importance has been that of section. Few British travellers on the continent of Europe can have failed to notice that the type of track in use differs entirely from that in Great Britain. There is a certain appearance of solidity about the British “bull-
STEEL SLEEPERS. Experiments in the use of steel sleepers are being carried out on an extensive scale by the British railways. The success of these experiments depends largely on the resistance of the sleepers to corrosion.
The idea was gladly seized upon by the railway pioneers in undeveloped countries, for the use of the Vignoles rail meant that no more material had to be transported to the rail-
The result has been that, in every country other than Great Britain (with the exception of a few individual railways) the flat-
To protect the timber by spreading the weight of the trains over a larger area of its surface, steel sole plates are used between the rails and the sleepers. Then the dog-
A HALLADE TRACK-
MEASURING WORN RAILS by an ingenious appliance which consists of a frame holding a piece of “Plasticine”. The frame divides, and when removed from the rail, the impression obtained reveals any defects. Each impression is photographed and recorded.
As to weight, the rails used on certain Continental and most American main lines considerably exceed the heaviest rails used in Great Britain. The Pennsylvania Railroad of America, for example, has now standardized for main-
There are various kinds of wear. The worst with which the engineer must contend is that of the outside, or “high rail” on a curve, which gets cut away at an angle of 45 degrees or so by the horizontal pressure of the wheel flanges, resulting from centrifugal force as the trains round the curve.
As better methods of handling have been devised, both at the manufacturers’ works and at the railway depots and the line-
The Germans also do a great deal in these days in the matter of welding rails together into long continuous lengths. Hitherto it has always been considered essential to keep the lengths of rails down to a reasonable figure; and to leave between them an expansion space at a normal temperature of ¼ in, to allow for the expansion of the rails in hot weather. When temp-
But it has long been the practice to weld tram rails together in continuous lengths; tram rails, of course, are buried, only the top of the head showing above the road metal, so that they do not respond to temperature changes so much as the rail-
The same principle is therefore being applied to railway rails in Germany, and welded continuous lengths up to 90 metres (295 ft) are becoming common. The most startling experiment in welding has been carried out in the Brandleite Tunnel, where the rails have been welded together in both tracks throughout practically the whole length of the tunnel, which is all but two miles long.
The Weakest Point
At a central depot the 30-
Welding the rails together reduces the number of fishplates, but this is not the only reason that rails are being lengthened. The rail-
The principal weakness of the joint is that the rail-
Lately in Great Britain the problem of the joints has been simplified by cutting the fishplates (which join the rails together) from 18 in in length down to 10 in, and securing the rails by one bolt at each rail-
Between two upstanding jaws the rail stands, with its foot securely housed under the lower one, while between the “web” of the rail (which joins head and foot together) and the outer jaw of the rail, a key of compressed oak or teak is tightly driven. Every now and then keys work out of position, and fall on to the ballast; and the surfaceman, driving them in with his hammer, is a familiar sight on the railway track.
Many ingenious patents have been devised to produce keys which will not drop out in this way, but the patentees have overlooked one important fact. It is that in any event every mile of railway track over which passenger trains run must be “walked” daily, in order to ensure that every detail is in perfect order for the safe running of trains.
TIMBER ALLEY. Sleepers are stacked at railway creosoting depots to be seasoned before the creosoting takes place.
The line is divided into sections, and each section has its gang of men responsible for this supervision. Driving a key here and there in the course of these perambulations is a minor matter, and, in effect, costs nothing, whereas most of these patent keys would be very expensive, and the users would be no better off in consequence. Incidentally, in some country areas where traffic is not dense and the gangs of surfacemen have considerable lengths of line to supervize, they are provided with motor-
The rail seat of the chair is rounded to a radius corres-
The flat base of the chair helps to distribute the weight of the trains over as large an area of the sleeper as possible, and the life of the sleeper is further preserved, and the running of the trains is quietened, by the interposition of a felt pad between the chair and the timber. Three large galvanized screws, each weighing 1½ lb, secure each chair to the sleeper, except on the Great Western Railway, which uses two bolts passing through the sleeper, and held on the underside by fanged washers that bite into the timber,
The supply of timber for sleepers is a problem. Most of the sleepers used on British lines come from the countries bordering on the Baltic, and are of fir, 9 ft long by 10 in wide by 5 in deep. Before use they require creosoting as a protection against rot, and for this purpose each sleeper is made to absorb from three to six gallons of creosote oil.
The depots at which this creosoting is done are, with their huge piles of sleepers, familiar sights to travellers; they may be seen on the GWR at Hayes, in Middlesex; on the LNER at Boston, Lowestoft, and West Hartlepool; on the LMS at Beeston (Nottingham), Northampton, and Ditton Junction (Widnes); and on the Southern Railway at Redbridge, near Southampton.
The seasoned sleepers are run on trolleys into long cylindrical tanks, which are then tightly closed, after which the air in the tank is exhausted and creosote is pumped in under pressure until the desired quantity has been absorbed. At the same depots the sleepers are now “chaired” by automatic machinery. One machine shapes two flat seats on the timber to receive the chairs, and at the same time bores the six holes for the chair-
Various substitutes for timber sleepers have been tried; in some countries they are essential. The voracity of the white ant, for example, would soon terminate the life of wooden sleepers laid in countries where this hungry pest is found. The commonest substitute for timber is the steel sleeper, pressed while hot out of a steel plate into the shape of an inverted pea-
The controlling factor in a country with a climate like that of Great Britain depends on how the thin steel sleeper will stand up to corrosion, especially when laid in such ballast as broken blast-
Experiments are being carried out in Great Britain with steel sleepers, and in the course of time much more information about these latest experiments will available. Concrete sleepers have been tried, but with unsatisfactory results; they are very cumbersome to handle, and cannot stand up to their work without cracking as a result of vibration.
Ballast is an important component of the railway track. By the way in which it is packed under the sleepers it governs the level of the rails, and has a strong influence on the relative smoothness of riding. It maintains the sleepers in position, especially on curves, and on it the permanent way depends for support as well as for “line”. Most important of all, it serves to drain away the surface water from the track. The gravel and cinders of earlier days have given place largely to granite and to broken slag. The latter has been obtained in enormous quantities by crushing the contents of the vast slag-
ON THE CPR SYSTEM. Flat-
For one mile of modern British mainline track the following materials are needed:
To these figures it is necessary to add the ballast, of which roughly 3,500 tons are needed for every mile of double track.
Relaying of railway tracks in need of renewal proceeds each year according to an ordered programme. When relaying is in progress signs are erected at the side of the line to warn drivers that they must reduce speed. First comes a horizontal board, painted green, which is pointed at one end and fish-
A CHAIRED TRACK. The rails rest in cast-
The old track is stripped with the utmost speed; no time is wasted in unscrewing old fish bolts, but the heads are knocked off, the plates are removed, the rails are lifted out, and the old sleepers are dragged from their places. Then the new chaired sleepers are pulled into place, the rails dropped into position, the fish-
In these days a certain amount of track relaying, and much pioneer track-
These new units are stored on flat wagons behind the track-
Last of all, mention must be made of the method adopted for testing the condition in which any given length of track is being maintained. This is done by means of the Hallade machine, which is carried in an ordinary coach, and by a system of damped pendulums causes a pen to inscribe on a roll of paper, which is being slowly rotated by clockwork, an exact picture of the oscillations of the coach during the test journey. These records enable the engineers to see exactly where joints require packing up, or curves re-
The Great Western Railway goes even farther than this. A special bogie coach has been adapted for this track-
[From part 11, published 12 April 1935]