Papers.] GRINLING ON PERMANENT WAY. 333 (Students’ Paper, No. 555.)’ (Abridged.) ‘‘ Permanent Way ; its Constructionand Maintenance.” By ARTHURJOHN GRINLINO, Stud. Inst. C.E. PERMANENTway consists of rails, sleepers, andthe necessary fastenings, andthe term is used todistinguish the finished and permanentrailroad from temporary lines laid down duringits construction, for the carriage of materials. It willbe assumed thatthe necessaryearthwork has been completed, and the banks and cuttings finished to the proper width at formation-level, depending, of course, on the number of lines of way to be constructed. It is important that the formation should be 2 incheshigher inthe centre thanat the sides, to allow of efficient drainage ; and in cuttings provision must be made, either bymeans of open ditches, where there is sufficient width, or by pipes of sufficiently large section, for carrying off any water they are likely to collect. Bottom Ballast.-The bottom ballast is spread directly over the formation and constitutes the foundation for the permanent way. It should consist of hard, rough stone pitching, where this is avail- able, not more than 9 inches in width on any face, laid on edge, and hand-packedas closely as possible. Where it is difficult to obtain stone,broken brick or slag forms an efficient substitute. In soft clay cuttings, a layer of clinker or coarse gravel is sometimes spread over the formation to prevent the large stone bottom-ballast from squeezing intothe clay, andin a wet cuttingthis aids the drying up of the formation. It is also an excellent plan to spread 2 or 3 inchesthickness of good ashesimmediately on the top of the bottom ballast, as this helps to keep the road dry. The total depth of the bottom ballast is usually about 12 inches. Top Ballast.-A large variety of materials may be used for this 1 Paper read and discussed before a meeting of the Birminghanl Association of Students of the Institution, on 11 May, 1905. Downloaded by [ University Of Wollongong] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. 334 GRINLING ON PERMANENT WAY. [Selected purpose, and the material adoptedis usually that which can be most readily and economically obtained. The points to be aimed at are an easy-running road,good drainage, and a materialin which the sleepers can be properly packed ; absence of dust is also an important matter, in respect of both the life of the rolling-stock and the comfort of the passengers, and it is desirable that the material adopted should be one in which weeds will not easily grow. The principalmaterials used fortop ballast are : (1) granite chippings, (2) slag, (3) screened and unscreened gravel, (4) hard, well-burnt ashes, (5)burnt clay, and (6) broken stone. (1) Screened granite chippings form an excellent material for top ballast,as the sleepers can be evenlypacked, good drainageis obtained, there is hardly any dust, and weeds will not grow in it; but except in the case of a railway running through the neighbour- hood of granite quarries thecost is against its extensive adoption. (2) Slag is now very extensively used for ballasting, and presents many advantages, but there is considerable difference of opinion as to how small it should be broken. A usual specification is that it mustpass freely througha 2-inchring. If it is too large, the sleepers, instead of being supported over their entire area, tend to rest on a few large lumps ; and it is also difficult to pick up slack joints.Many inspectors say that a road packed withlarge slag tends to get out of line, as the sharp edges form a kind of rocker- bearing for the sleepers to slide on. (3) Gravel, both screened and unscreened, is extensively used for top ballast. Thereshould be sufficient sandpresent to render it compact, but not enough to interfere with the efficient drainage of the road. (4) Ashes are frequently used for lines in the neighbourhood of collieries. Theyform a very elastic road-bed and affordexcellent drainage, but they are scarcely heavy enough to steady a road for heavyexpress traffic. Caremust be takenthat ashes arenot placed in contact with steel-work, such as the flooring of bridges, on account of thesulphur which theycontain. The same rule applies to slag. (5) Where economy has to be studied, and nothing more suitable can be obtained, burnt clay is frequently used for ballasting, but great care must be taken that it is sufficiently burnt, otherwise it will tend to consolidate into hard lumps under the influence of the weather. In the construction of a new line it is not true economy to cut down the estimate for ballast, as the outlay on a sufficient supply of good ballast will be amplyrepaid inthe subsequent maintenance of the line. Downloaded by [ University Of Wollongong] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. Papers.] GRINLING ON PERMANENT WAY. 335 (6) Broken stone, like slag, if broken small enough and free from dust, forms a good material for top ballast, but stone that weathers rapidly should be avoided for ballasting. Sleepers.-The purpose of sleepers is todistribute the weight supportedby the railsover the face of the ballast. Wood is the material used for sleepers in this country. Baltic red-wood is the timber most generally used, although some Companies use memel, Scotch fir, and red pine. Foreign hard woods, such as Australian karri-wood, are now being experimented with. Beech has also been recommended as avery suitable timber forsleepers, and has been used with good results onseveral Continental railways. Sleepers are usually 8 feet 10 inches in length, 10 inches in width and 5 inches in depth. They should consist of thoroughly seasoned wood, as far as possible free from sap, large or loose knots, cracks, shakes, or other defects. There are several methodsof treating sleepers before placing them in the road, so as to increase their life. In this country they are creosoted, the operation being carried out in the following manner. The sleepers, havingbeen sawn totheir properdimensions, are placed in a hermetically-closed cylinder; the air is then pumped out, and creosote is allowed to flow in, and is finally forced in by pumps until the fibre of the wood is saturated with it. Section and Weight of Rails.-Hitherto the rails used by different Railwaycompanies have been of slightly different weights and sections, but in future renewals these differences will be abolished by theintroduction of BritishStandard sections. The following are general dimensions and weights of British Standard rails:- No. of "B.S."I Height of Width of Nominal l Section. Rail. Head. Weight of Rail. I 1 Inches. 1 Inches. 1 Lbs. per Yard. I I 85 ~ 595 ~ 24$ 85 Chairs.-On all English railways using bull-headed and double- headed rails, the rails are supported in cast-iron chairs, fastened to transverse sleepers by means of various kinds of fastenings which will be described later. The iron must be of good quality, so that in atransverse bending-test a bar 1 inch in widthand 2 inches in depth, placed on bearings 3 feet apart, shall bear a load of 30 cwts. in the centre without breaking, and show a deflection of at least 4 inch. The castings should be sharp and clean, and free from all blow-holes, sponginess, and broken surfaces. In designing a chair Downloaded by [ University Of Wollongong] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. 336 GRINLING ON PERMANENT WAY. [Selected for heavy traffic it is essential to give it a large bearing-area, so as todistribute the weight as much as possible over thesleeper; otherwise the chairs will tend to sink into thesleeper and damage it. The bearing-area and the weight of the chair vary considerably on differentrailways; the latter should be not less than 40 lbs. for heavy trafEic. TheGreat Northern Railway, intheir recent renewals of permanent way, have introduced a new form of chair on either side of therail-joint, in order tostrengthen it. These are known as inter-joint chairs. They are similar tothe ordinary chairs so far as the jaw is concerned, and hold the rail in exactly the same way ; but the rail-seatis cast with a projection onwhich the rail rests,thus considerablyreducing the unsupported length at the joint. This chair is designed to reduce the risk of fractured fish- plates, but at the same time it has the advantage of not interfering with the elasticity of the road, as the ends of the rails are left free. On the main line a 12-inch by 6-inch sleeper is placed under these chairs. Fa&enings.-The fastenings which are used to connect the chairs to the sleepers are of various kinds, comprising solid oak treenails, spikes, coach-screws, andfang-bolts. The Board of Tradereqnire- ment is that at least one fastening of each chair must be an iron spike or bolt. A veryusual method of securing a chair tothe sleeper is by means of two wrought-iron spikes and two compressed oak treenails, placed diagonally. Spikes are usually about 6 inches in length and $ inch to inch in diameter. The spike is considered to be strong enough to resist any shearing-stress that may occur, and the treenail, which is not considered to be so strong, is supposed to swell underthe influence of the weather andto fill up the hole completely, thustending to keep thechair perfectly tightand prevent it having any lateralmotion. Rail-Joints.-The form of joint almost universally adopted in this country is of the " suspended " type, the rails being connected by two fish-plates bolted together through the rails by four fish-bolts.