Railway Construction

by William Hemingway Mills

The railway system spread rapidly, and the constantly increasing traffic of all kinds soon necessitated heavier rails. Various sections were devised and tried on different lines, one of the main objects in view being to obtain a steady road for the increasing speeds, as well as one of durability. Some of these sections are shown in [Figs. 236 to 258].

Sections [236 to 248] all required chairs to attach them to the sleepers. The flange rails, [249 to 253], and bridge rails, [254 to 256], also rail [257], were designed to rest direct upon the sleepers without the necessity of chairs; and the Barlow rail, [258], with its great width of 11 or 12 inches, was intended to be used without sleepers of any kind, the gauge being secured by means of angle iron tie-bars.

Rails were rolled heavier and longer, and more care was bestowed on the fastenings; but, notwithstanding these improvements, the rail-joints still continued to be the weak point in the road. Even with an extra large joint-chair and stout wooden key, there was much vertical play at the ends of the rails, producing objectionable noise and vibration in the running, and acting detrimentally on all the fastenings. The introduction of fish-plates at the rail-joints, as shown in [Fig. 259], effected an improvement which cannot be overrated, as by their adoption such security, speed, and smoothness became attainable as were not before possible. With a pair of simple rolled wrought-iron fish-plates, or splices, and four bolts—two through the end of each rail—a better, smoother, and more effectual joint was obtained than had ever been produced by the heavy cast-iron joint-chairs. The system of fishing, or splicing, was at once admitted to be the simplest and most direct method of joining the rails; and, although minor detailed improvements have since been made, the arrangement, as a principle, has never been superseded. Many miles of fished rails were laid down with a chair, or support, placed immediately under the joint, forming the method termed the supported fish-joint; but experience proved that this mode of application did not give such a good result as the suspended fish-joint, and the latter plan has now been adopted on almost all railways.

The experience obtained year after year in the wear of rails under heavy traffic, led to continued improvements both in the method of rolling and in the selection of the iron to form the rail-pile; one description of iron was found more suitable for the head, or running surface, and another for the vertical web; but, even with the best machinery and most carefully assorted materials, high-class wrought-iron rails were liable to lamination, and long thin strips of iron became detached from the upper, or wearing, surface. The rail was composed of many layers of iron, and it was not always possible to ensure that they were all thoroughly welded, or incorporated together. As early as 1854 a few experimental solid steel rails were laid down on some of the principal railways, and gave excellent results as to evenness of wear and durability, but their cost of manufacture rendered their extended use almost prohibitory.

Compound rails of steel and wrought-iron, as in [Fig. 260], were also tried on several railways, but the practical results were not such as to lead to a very extended adoption. In preparing the pile for a compound rail, suitable wrought-iron bars were placed to form the lower member or flange, the web, and part of the head, and a slab of steel was placed on the top to form the upper portion of head, or wearing surface of the rail. It was intended that in the process of rolling these distinct layers were to be incorporated together, to form the section shown in [Fig. 260]. Doubtless many good wearing rails were manufactured on this system, but the inherent difference of the two materials, steel and iron, rendered it very difficult to ensure such uniform incorporation as would withstand the constant pounding under heavy, fast traffic. It was not until some years later that the process of the Bessemer Converter was discovered and perfected, by means of which steel can be produced in large quantities far more rapidly and at much less cost than by any other method hitherto adopted. The introduction of this process for making steel caused a complete revolution in the material for rails. Steel which had previously been excluded on account of its cost, could now be supplied at a moderate price, and, from its compact and homogeneous character, promised a very much longer wearing life than the best wrought-iron rails that had ever been rolled. Experience has shown that these promises have been fully verified; wrought-iron rails are things of the past, steel rails have taken their place, and can now be

purchased at a less price per ton than the iron rails of twenty years ago.

It is interesting to note that out of the many varied sections that have been designed, some of which are shown in the sketches described, only two have practically survived—the bullhead rail and the flange rail. The bull-head rail, [Fig. 261], has grown out of the original double-head rail, which had both the top and bottom members made to the same section and weight, with the object that, when the upper table had become so much worn as to be unfit for further use, then the rail could be turned, and the other table, or head, brought into service. Experience, however, proved that turned rails formed a most uneven and unsatisfactory road, the long contact with the cast-iron chairs resulted in serious indentations at the rail-seats, rendering the rails totally unfitted for smooth running. In practice, therefore, it has been found better to restrict the running wear to one head only, and to give increased sectional area to that head, and, at the same time to diminish the sectional area of the lower member to a corresponding extent, but to retain the same width, so as to obtain a full bearing surface on the cast-iron chair. Steel bull-head rails are now adopted on nearly all the principal lines at home, and on several of the leading lines abroad.

The flange rail, [Fig. 265], was designed to give a broad, direct bearing on the sleepers, and thus avoid the necessity of using chairs. Rails of this section have been laid down on many of our lines at home, and are very largely used on the Continent, in the United States of America, and in our colonies generally. This section is, also, nearly always adopted for narrow-gauge railways. Having fewer parts, it makes a cheaper road than the bull-head rail, but is not considered so strong or suitable for heavy and fast traffic. Comparing the two rails shown in [Figs. 261 and 265], each having exactly the same size and sectional area in the head, it will be seen that there is more material in the lower member, or flange, of the one rail than there is in the lower member of the other; the weight per lineal yard being 79 lbs. for the former and 75 lbs. for the latter. But this small excess in the weight and cost of the flange rail falls very short of the cost of the cast-iron chairs and wooden keys necessary for the bull-head rail.