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The Permanent Way—Reports of Mr. Nicholas Wood and Mr. John Hawkshaw, 1838

In addition to the question of gauge, another important matter referred to the consideration of Mr. Wood and Mr. Hawkshaw was the construction of the permanent way. [1] On the Great Western a construction had been introduced by Mr. Brunel differing materially from that ordinarily used; and as defects had shown themselves after the opening of the railway, some anxiety was felt in reference to it by many of the shareholders.

The subject of the permanent way adopted on the Great Western Railway does not necessarily belong to the gauge question, and would, perhaps, have been more properly considered in the chapter on Mr. Brunel’s railway works; but, as a matter of fact, the controversy concerning it became so interwoven with that of the broad gauge, that in a historical account it would be difficult to separate them.

It appeared to Mr. Brunel that, with a view of applying the engine power to the greatest advantage, particularly in attaining high speed, more attention ought to be paid to the construction of the permanent way. He says, in a report dated February 1837:—

It appears to be frequently forgotten that although lofty embankments and deep cuttings, bridges, viaducts, and tunnels are all necessary for forming the level surface upon which the rails are to be laid, yet they are but the means for obtaining that end; and the ultimate object for which these great works are constructed, and for which the enormous expenses consequent upon them are incurred, consits merely of four level parallel lines, not above two inches wide, of a hard and smooth surface; and upon the degree of hardness, smoothness, and parallelism (which last has hitherto been very much neglected) of these four lines depend the speed and cost of transport, and in fact the whole result aimed at….

In forming all my plans I have looked to the perfection of the surface on which the carriages are to run, as the great and ultimate desideratum; and in the detail of construction of this last operation, without which all the previous labour is comparatively wasted, I have always contemplated introducing all the perfection of materials and workmanship of which it is capable.

With a view to improvement on this point, Mr. Brunel considered it would be advantageous if two important changes were made. He proposed, in the first place, to abolish the use of stone blocks for the rails to rest on, and to substitute timber; and, secondly, to apply the support uniformly and continuously along the whole length of the rails, instead of only at intervals.

The first of these changes, namely, the substitution of timber for stone, was not wholly new, for transverse wood sleepers were often used in exceptional situations; but it was the general opinion that stone, where it could be applied, formed the best support for the rails, [2] and the exclusive employment of timber was considered a great innovation.

The other principle, that of ‘continuous bearing,’ was similar to that of the old wooden and stone tramways; and, even as applied to iron rails it had been extensively used before, as Mr. Brunel mentions in his report of August 1838 (see Appendix I)

Mr. Brunel designed for this continuous bearing a peculiar shape of rail, which, from the form of its section, acquired the name of the ‘bridge rail.’ The rail was bolted down to the longitudinal timbers, and the timbers of the two rails were connected together at intervals by cross-pieces, called transoms, bolted to them; these served to keep the two rails at a proper distance apart. The longitudinal timbers lay on gravel or other ‘ballast,’ which had been found to form the best foundation, as being firm and solid, easy of adjustment, and allowing free drainage. [3]

Mr. Brunel, however, thought there would be difficulty in giving the longitudinal baulks a sufficiently solid bearing on the gravel below them.

A similar difficulty had already been experienced with the heavy stone blocks used on other railways. As a remedy for this, Mr. Stephenson caused each block to be lifted and dropped several times on its place, so as to consolidate the ballast below.

The same thing could not be done with a long wooden baulk, and Mr. Brunel therefore contrived another mode of overcoming the difficulty. Piles were driven into the ground between the rails, and their heads bolted to the cross-transoms, the object being to hold the timber framework firmly down. The gravel was then rammed hard under the longitudinal baulks, to give the consolidation desired. The result, however, of this mode of construction was far from successful, and the state of the road, when run over by the trains, was in many places very defective. [4]

In the course of his enquiry Mr. Wood tried a large number of experiments on the Great Western and other lines. He was of opinion that stone blocks afforded a permanently firmer base, and so caused less resistance to the train, but that there was less noise with continuous timber bearings, and that they gave a smoother and a more perfect road for high rates of speed. He thought, however, that the piles were objectionable, and that the weight of the trains would in the course of time sufficiently consolidate the foundation. Mr. Brunel accepted Mr. Wood’s conclusions and abandoned the piling, adopting at the same time larger timbers and heavier rails.

The experience of the permanent way, as thus altered, fully justified the favourable anticipations Mr. Brunel had formed of the continuous timber bearing. [5]

[1] In the course of constructing the earth-works of a railway, the contractors were accustomed to lay down temporary ways or lines of rail, for the earth waggons to travel upon. When these were done with, the proper road for the trains was laid down; and this, to distinguish it from the former one, was called the permanent way.

[2] See Wood On Railways, 3rd. edit. 1838, p. 151.

[3] A full description of the original road of the Great Western Railway, communicated by Mr. Brunel, will be found in Wood’s Treatise on Railroads, 3rd edit. 1838, p. 708.

[4] At this time Mr. Brunel was confined to the house by the effects of his accident on board the Great Western steam-ship. Had he been on the spot, he would have been able to give the work careful consideration during its progress, and to judge of the expediency of proceeding with the plan.

[5] The continuity of the timbers diminishes the risk of trains leaving the line from small imperfections in the permanent way. And, should a train leave the rails, the injury to the carriages and to the road is generally less serious than it is when the wheels of a carriage off the rails come into repeated and violent contact with the cross sleepers. Instances have frequently occurred where carriages which have left the rails have run considerable distances on the longitudinal timbers without injury.

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