1911 Encyclopædia Britannica/Tramway
TRAMWAY, a track or line of rails laid down in the public roads or streets (hence the American equivalent “street railway”), along which wheeled vehicles are run for the conveyance of passengers (and occasionally of goods) by animal or mechanical power; also a light roughly laid railway used for transporting coals, both underground and on the surface, and for other similar purposes. The word has been connected with the name of Benjamin Outram, an engineer who, at the beginning of the 19th century, was concerned in the construction of tram roads, and has been explained as an abbreviation for “Outram way.” But this is clearly wrong, since the word is found much earlier. It appears to be of Scandinavian origin and primarily to mean a beam of wood, cf. Old Swedish tråm, trum, which have that sense. In a will dated 1555 reference is made to amending a “higheway or tram” in Bernard Castle, where a log road seems to be in question. In Lowland Scottish “tram” was used both of a beam of wood and specifically of such a beam employed as the shaft of a cart, and the name is still often given in England to the wheeled vehicles used for carrying coal-in mining, “Tramway,” therefore, is primarily either a way made with beams of wood or one intended for the use of “trams” containing coal (see Railway).
Construction.—The first tramway or street railway designed for passenger cars with flanged wheels was built in New York in 1832. The construction of this tramway does not appear to have been a success, and it was soon discontinued. In 1852 tramways were revived in New York by a French engineer named Loubat, who constructed the track of flat wrought-iron rails with a wide, deep groove in the upper surface, laid on longitudinal timbers. The groove, which was designed for wheel flanges similar to those employed on railways, proved dangerous to the light, narrow-tired vehicles of the American type. To meet this difficulty a step-rail consisting of a flat plate with a step at one side raised about 7 in. above the surface was designed and laid at Philadelphia in 1855. When tramways were first introduced into England by G. F. Train in 1860 a rail similar to that laid at Philadelphia was adopted. This rail (fig. 1) was made of wrought iron and weighed 50 ℔ per yard. It was 6 in. wide and had a step 3 in. above the sole. The rails were spiked to longitudinal timbers, which rested on transverse sleepers, and they were laid to a gauge of 4 ft. 81 in. Tramways of this type were laid at Birkenhead in 1860, at London in 1861, and in the Potteries (North Staffordshire) in 1863. The English public, however, would not tolerate the danger and obstruction caused by the step-rail, with its large area of slippery iron surface, and the tramway laid in London had to be removed, while those at Birkenhead and the Potteries were only saved by being relaid with grooved rails. Thus, while the step-rail became the standard form used in the United States, the grooved-rail became generally adopted in Europe. From the tramway point of View the step-rail has many advantages. A groove collects ice and dirt, and on curves binds the wheel flanges, increasing the resistance to traction. A grooved rail is, however, far less of a nuisance to the ordinary vehicular traffic, and it has come to be largely used in the principal cities of America.
|(Figs. 2 and 3 from D. K. Clarke’s Tramways, their Construction and Working,|
by permission of Crosby Lockwood & Son.)
|Fig. 1. Fig. 2.Fig. 3.|
Early Tramway Rails.
After the passing of the Tramways Act of 1870 the construction of tramways proceeded rapidly in England. A flat grooved rail supported on a longitudinal timber and laid on a concrete bed was generally adopted. The paving consisted of stone setts from 4 to 6 in. in depth, laid on a thin bed of sand and grouted with cement, mortar or a bituminous mixture. With the exception of the design of the rail and the manner of supporting it on the concrete foundation, which has continually changed, this method of constructing the track has varied but little to the present day.
The flat section of rail which was wanting in vertical stiffness soon proved unsatisfactory. A fillet or flange was then added to each side, which, bedding into the supporting timber, not only increased the vertical strength but also prevented horizontal displacement of the rail. With the addition of the side flanges a greatly improved method of fixing the rail to the sleepers was adopted. The old vertical spike, which was a crude fastening, was replaced by a “dog” or double-ended side spike, one end of which was driven through a hole in the flange of the rail (fig. 2). This fastening was very strong and proved a great improvement.
The next change was the use of cast-iron chairs to support the rails, which were introduced by Kincaid in 1872. These led to a modification of the rail section, and instead of the two side flanges a rail with a central flange (fig. 3) which fitted into the cast-iron chairs was used. The chairs weighed about 75 ℔ each, and were spaced at intervals of about 3 ft. The Barker rail laid in Manchester in 1877 was somewhat similar to that shown in fig. 3, but a continuous cast-iron chair was used to support it.
The introduction of steam traction about 1880, with its heavier axle loads and higher speeds, was a severe test of the permanent way. The flat section laid on timber sleepers and the built-up rails of the Kincaid and Barker types began to be discarded in favour of the solid girder rail rolled in one piece. The solidity and depth of this section gave it great vertical stiffness, and its introduction materially assisted in solving the problem of providing a smooth and serviceable joint.
The merits of the girder rail soon caused it to be generally adopted, and although the design has been greatly improved it remains to-day the standard form of tramway rail used throughout the world. At first difficulty was experienced in rolling the heavier sections with thin webs and wide bases, but the introduction of steel and improvements in the rolling mills overcame these troubles. The early girder rails laid about 1880 usually weighed from 70 to 80 ℔ per lineal yard, and were 6 or 61 in. deep. The groove varied from 1 to 11 in., and the tread was about 13 in. in width. The fish-plates were not designed to give any vertical support, and were merely used to keep the rail ends in line. The girder rails were either bedded directly on the foundation or spiked to timber sleepers which were buried in the concrete.
The form of head adopted for tramway rails in Europe has almost universally been one with the groove on one side. With this section the wheel flange forces out the dirt clear of the tread. In a few isolated cases a centre grooved rail has been used. As with railways, the adoption of many different gauges has led to much inconvenience. This want of uniformity in the gauge is in some parts of the country a great obstacle to the construction of inter-urban lines. London and the larger provincial towns adopted the standard gauge of 4 ft. 81 in., but in many towns narrow gauges of 3 ft. or 3 ft. 6 in. were laid. Glasgow and a few other towns adopted the gauge of 4 ft. 73 in. with a view of making the narrow grooved grail of the tramways available for railway wagons, but without any real success.
With the introduction of electric traction the weight and speed of the cars greatly increased, and experience soon proved that only the most substantial form of permanent way was capable of withstanding the wear and tear of the traffic. The early electric lines were laid with girder rails weighing about 75 ℔ per lineal yard. These proved to be too light, and, at the present time, rails weighing from 95 to 110 ℔ per lineal yard are in general use. The large number of rail sections designed a few years ago gave considerable trouble to makers of rails. The issue in 1903 by the Engineering Standards Committee of a set of standard girder tramway rail sections was therefore generally welcomed. The sections comprise rails of five different weights. Modified sections for use on curves were also published, together with a standard form of specification. Fig. 4 shows the section of the 100 ℔. B.S. rail (No. 3).
|(Reproduced by permission of the Engineering Standards Committee.)|
Fig. 4.—British Standard Tramway Rail, No. 3.
Tramway rails are generally ordered in 45 ft. lengths. Rails 60 ft. long are sometimes used, but they are difficult to handle, especially in narrow streets. The rail joints still prove the weakest part of the track. Numerous patents have been taken out for fish plates and sole-plates of special design, but none has proved quite satisfactory. The “Dicker” joint, in which the head of the rail on the tread side is partly cut away and the fish-plate carried up so that the wheel runs on its top edge, and the “anchor” joint, in which a short piece of inverted rail is bolted or riveted to the undersides of the abutting rails, have been largely used. The latter makes a good stiff joint, but when buried in concrete it interferes with the bedding of the rail as a whole, often causing it to work loose in the centre. Various processes have also been introduced for uniting the ends of the rails by welding. Electric welding was first tried in the United States about 1893, and has since been considerably used in that country. In this process two specially prepared fish-plates are applied, one to each side of the joint. Each fish-plate has three bosses or projections, one in the centre opposite the joint and one near each end. By passing a heavy alternating current of low voltage between the opposite bosses the fish-plates are welded to the rail. The current is obtained from the line by means of a motor-generator and static transformer. Another process which has been used considerably in the United States, and at Coventry and Norwich in England, is the cast-welded joint. To make this joint the rail ends are enclosed in an iron mould filled with molten cast-iron, which makes a more or less perfect union with the steel rails. The great drawback to these two processes is the costly and cumbersome apparatus required. The “thermit” process (see Welding) does not require any large initial outlay, and has been applied to welding the joints on both old and new tracks. The cost of making each joint is about £1.
Points and crossings are used on a tramway to deflect a car from one road to another. In the days of horse traction no movable switch was used. the car being guided by making the horses pull the leading wheels in the required direction. With the introduction of mechanical traction a movable switch was fitted in one of the castings to act as a guide to the wheel flanges. On modern tramways the points consist of a pair of steel castings, one being a fixed or dummy point, and the other containing a movable switch. On a single track at passing places the cars in Great Britain always take the left-hand road, and a spring is fitted to hold the movable switch to lead in that direction. The bottom of the grooves at open points and crossings are raised so that the car wheel runs on its flange over the break in the tread of the rail. Double switch points in which the two tongues are connected are sometimes laid. In recent years the size and weight of the castings and the length of the movable switches have considerably increased. Manganese steel is very generally used for the tongues and sometimes for the whole casting. Ordinary cast steel with manganese steel inset pieces at the parts which wear most quickly are a feature of the later designs. At some junctions the points are moved by electric power.
While the form of concrete foundation remains the same as that laid at Liverpool in 1868, far greater care is now given to the bedding of the rails. After the excavation has been completed the rails are set up in the trench and carefully packed up to the finished level. The concrete is then laid and packed under the rail, generally for a depth of 6 in. When the surface is to be paved with stone setts bedded on sand the concrete may be left rough, but where wood is to be laid the surface must be floated with fine mortar and finished to a smooth surface. Both hard and soft wood blocks are used for paving. Wood should not be used unless the whole width of the carriage-way is paved. Many different qualities of stone setts have been laid. Hard granite such as that supplied from the quarries near Aberdeen is time most suitable.
In urban districts the road authorities almost always require the tramway surface, i.e. between the rails and for 18 in. on either side, to be paved. In country districts many tramways have been laid with only a sett edging along each rail, the remainder of the surface being completed with either ordinary or tarred macadam. This construction, however, is only suitable on roads with very light traffic. After a tramway is laid, especially in a macadamized road, the heavy vehicular traffic use the track, and the wear is very much greater than on other parts of the carriage-way.
(From T. Arnall's Permanent Way for Tramways and Street Railways, by permission of The Railway Engineer.)
Fig. 5.—Section Edinburgh Cable Conduit.
Steam and Cable Tramways.—Horse traction, especially in hilly districts, has many limitations, and early in the history of tramways experiments were made both with steam cars and cable haulage. Although experimental steam cars were tried in England in 1873 the first tramways which regularly employed steam engines were French, though the engines were supplied by an English firm. About 1880 many improvements were made in the design of the engines employed, and this form of traction was adopted on several tramways in England. Beyond requiring a better constructed track it does not necessitate any modifications in the general design of the permanent way. The first cable tramway was constructed at San Francisco in 1873. In England the first cable system was a short length at Highgate in 1884. Cable tramways were also laid down at Edinburgh, Birmingham, Matlock and Brixton (London). Cable traction, with the expensive track construction it necessitates, and the limited speed of haulage, belongs to the past. Only gradients too severe to be worked by ordinary adhesion will in the future justify its use. The construction of the conduit or tube in which the cable runs adds very considerably to the cost of the permanent way. On the Edinburgh system the conduit was formed of concrete, with cast-iron yokes spaced at intervals of 4 ft. to support the slot beams. The conduit was 19 in. deep by 9 in. wide. The slot was 3 in. wide. The running rails were of the ordinary girder type bedded in concrete. Fig. 5 shows a cross-section of the track at a yoke. This form of construction is very similar to that employed in forming the tube on a modern electric conduit tramway. At Edinburgh and other places where a shallow conduit is used the supporting pulleys are placed in pits sunk below the general level of the tube. On the Birmingham cable tramway, where the tube is 2 ft. 8 in. deep, pits are not required at the supporting pulleys. This reduces the difficulty of draining the conduit. The yokes in this case are made of steel T-bars spaced 4 ft. apart.
Electric Tramways.—Electricity is now the standard motive power for tramway service, and is applied in three main ways: (1) the overhead or trolley system; (2) the open conduit system; and (3) the surface contact or closed conduit system. (See also Traction.)
On a tramway worked on the overhead principle current is supplied to the cars by two overhead conductors or wires. Round copper wires varying in size from 0 (0.324 in.) to 0000 (0.40 in.) S.W. gauge are generally used. With feeding points at every mile, the 0 wire is electrically sufficient on most Overhead Trolley.roads, but from a mechanical point of view 00 wire is the smallest it is desirable to erect. Wires having figure 8 or elliptical grooved sections have been employed, and have the advantage of allowing the use of a mechanical clip ear which is clear of the trolley wheel. The ordinary round wire is usually supported by a gun-metal or gun-metal and iron ear grooved to fit the wire, which is soldered or sweated to it. In Great Britain the overhead conductors are required by the board of trade to be divided into half-mile sections. The wires on adjoining sections are connected by section insulators. These consist of gun-metal castings in two parts, insulated from each other. The line wires are clamped to the metal ends. The continuity of the path of the trolley wheel is provided for on the underside of the insulator by fixing a hardwood strip between the ends or by the ribs on the castings with air gaps. The trolley wires are supported by ears either from span wires which extend across the roadway between two poles or from bracket arms carried on a pole on one side only of the road. The span wires and short bracket suspension wires are also insulated, so that there is double insulation between the conductor and the pole. The overhead conductors are usually hung about 21 ft. above the rails. (For catenary suspensions see Traction.) The poles which carry the span wires and the Bracket arms are placed not more than 40 yds. apart and are generally placed at the edge of the kerb. They are built up of three sections of steel tubes, one overlapping the other; the joints are shrunk together while hot. A cast-iron case is used to improve the appearance of the pole, and cast-iron collars hide the joints. Standard specifications for poles have been issued by the Engineering Standards Committee.
When permission can be obtained the span wires are sometimes supported by rosettes attached to the walls of the houses on either side of the street. This method has been largely adopted in Germany, and by dispensing with the poles in the roadway it improves the appearance of the street.
Overhead conductors will not be tolerated in some cities, and to
avoid the use of them open conduit and surface contact tramways
have been introduced. In the conduit system the
conductors are carried in a conduit or tube beneath the
surface of the track, and the electric current is picked up
Conduit.by means of a plough carried by the cars. Modern conduit tramways are divided into two kinds: those which have the conduit at the side under one running rail, and those which have it under the centre of the track. The only example of the former to be found in England is at Bournemouth, but it is used at Vienna, Brussels, Paris, Berlin and Budapest. Centre conduit construction has been adopted in London, Nice, Bordeaux, New York, Washington, &c. The advantages of the side slot system are the reduction in the amount of metal in the roadway, less breaking up of the pavement, and slightly cheaper cost of construction. Its chief disadvantage is the difficulty it introduces in connexion with points and crossings. It is also objected that if the side slot is made the same width as the rail groove it becomes a danger to narrow-tired vehicles.
- (From The Tramway and Railway World.)
- Fig. 6.—Section of Side Conduit.
The difficulty in regard to points and crossings is overcome by bringing the slot into the centre of the track at junctions and turn-outs. Fig. 6 shows a section of the side slot track laid at Bournemouth. The width of the slot is 1 in., which is the least width possible.
- (From The Tramway and Railway World.)
- Fig. 7.—Section of Centre Conduit (London County Council type).
In London 3 in. was first adopted as the width of the centre slot, but later this was increased to 1 in., so that in this particular there is not much to choose between the two systems. Fig. 7 shows a section of the London County Council track at one of the cast-iron yokes. These are spaced 3 ft. 9 in. apart, every second yoke being now continued out under the running rail which is fastened to it. There is no doubt that the extended yoke greatly increases the strength of the track. The slot beams weigh 60 ℔ per yard. The conductor bars are of mild steel, T-shaped. They weigh 22 ℔ per yard and are supported on insulators at intervals of 15 ft. Each insulator is covered over in the roadway with a cast-iron frame and movable lid. There are two conductor rails—positive and negative—so that the whole circuit is insulated from earth. The conduit or tube is formed of cement concrete. The track between the rails is paved with granite setts in order that there may be no trouble with wood blocks swelling and closing the slot.
American practice in conduit construction has become fairly well standardized (fig. 8). The conduit is oval in shape, its major axis being vertical, and is formed of concrete. An excavation about 30 in. deep and 5 ft. wide is made, and in this are laid cast-iron yokes weighing 410 ℔ each, and spaced 5 ft. apart centre to centre. Every third yoke contains bearings for a hand-hole plate, and weighs about 600 ℔. These yokes surround the conduit proper and are provided with extensions on each side for the attachment of the rails. In the older construction the rails were laid directly upon the iron of the yokes, steel wedges and shims being used under them for the tinal alinemcnt of the rails. In the more recent construction, on the Third Avenue railroad in New York City, a wooden stringer, 6 in. by 43 in. in size, is, laid alon from yoke to yoke on the bearing surfaces, and the rail laid upon this. The rail is held down on the yoke by means of two bolts at each bearing-point, these bolts having turned-up heads which embrace the foot of the rail. The slot rails, or Z bars forming the two jaws of the 5 in. slot. are bolted to the upper part of the yokes. The weights of the metal used per linear yard of construction of this type are: castiron, including both type: of yokes, 500 ℔; track rails, 214 ℔; slot rails, 116 ℔; conductor rails 42 ℔; and conduit plate, 16 ℔—nearly 400 ℔ of rolled steel per yard After the rails, which are of a high girder type, are fastened in place thin plates of sheet steel are bent into the oval holes in the yoke: extending from yoke to yoke, and form the inner surface of the completed conduit. Around this is carefully laid a shell, 4 in. thick of Portland cement concrete. The yokes are furnished with lugs which serve to retain, temporarily, wooden boards forming a mould in which the concrete is rammed. Sectional wooden shapes serve to hold the thin steel lining in place while the Concrete is hardening, Around this concrete tube, and on each side of it, to form a basis for the street pavement, is laid a mass of coarser concrete. In each side of the special yokes is placed an insulator of porcelain, protected by a cast-iron shell and carrying a support for the conductor rail which is of T-shaped steel, weighing 21 ℔ per yard. It is in 30 ft. lengths and is supported every 15 ft. by the insulators, the ends of separate rails being matched at and held by an insulator support. This rail is, of course, bonded with copper bonds.
- Fig. 8.—Cross-section of Open Conduit Road (American type).
Two such conductor rails are installed in the conduit 6 in. apart, the flat faces corresponding to the upper surface of the T being placed towards each other. Elaborate provisions for drainage and inspection are also provided, depending upon the situation of the tracks and nature of the street. The current is fed to the conductor rails by heavy copper conductors of from 500,000 to 1,000,000 circular mils cross section, insulated and lead-covered, laid in duets alongside of or between the two tracks of double-track systems.
- (From J. H. Rider’s Electric Traction, by permission of Whittaker & Co.)
- Fig. 9.—Cross-section of Stud, Skates and Magnets. Lorain System.
Connexion is made between the cars and the conductor rails by means of a “plough,” carried by a hard steel plate, which is channelled to receive the insulated wires leading up to the controller on the car. The plough carries two cast-iron rubbing-blocks, which are pressed outward into contact with the conductor rails by springs, the two being, of course, very carefully insulated from each other and from the other metal-work of the plough. It has been found expedient in practice to reverse the polarity of the current used on these conduit roads from time to time, since electrolytic deposits, formed by small leakage currents in the vicinity of insulators, &c., are thus dissolved before they become a source of trouble.
Great difficulty is experienced with all conduits in keeping them clean and free from water. On the London tramways a sump has been formed at intervals of about 60 yds. into which the conduit drains. These sumps are connected with the sewers. The principal objection to the conduit system is its heavy first cost. The tracks alone in London are estimated to cost about £13,000 per mile of single track against about £8000 per mile for a track to be worked on the overhead system.
This high cost of construction has caused considerable attention to be directed by inventors to devising surface contact systems. surface Many of the designs which have been patented Gonna appear excellent in theory, but have been found untrustworthy under working conditions. Among those Worked commercially in England are (1) the Lorain system in operation Surface Contact. at Wolverhampton; (2) the Dolter system at Torquay, Hastings and Mexborough, and (3) the G.B. system at Lincoln. Of all these systems current is supplied from iron studs laid in the roadway between the rails of the track to a skate carried on the car. The studs are placed 10 ft. to 15 ft. apart and contain a movable switch or contact, which is operated by the influence of a magnet carried under the car. In the Lorain system (fig. 9) connexion. is made to the source of power through two carbon contact pieces. The lower carbon contact is carried on a soft iron strip which is connected to the supply cable by means of a flat copper ribbon spring. When the- magnet passes from over a stud the iron armature and the lower carbon contact, which has been magnetically attracted, falls vertically, assisted by the copper ribbon spring. In the Dolter system the contact box (fig. 10) contains a bell crank lever with a carbon contact at its lower end. The upper arm of this lever is of soft iron, which is attracted by the magnet carried under the car. When the lever is moved the carbon block at the lower end is brought into contact with the fixed carbon contact in the side of the box which is permanently connected to the supply cable. In the G.B. contact box (fig. 11) contact is made direct to a bare feeder cable carried in a pipe under the boxes.
(From J. H. Rider’s Electric Traction, by permission of Whittaker & Co.)
- Fig. 10.—Cross-section of Stud, Skates and Magnets. Dolter System.
The switch, consisting of a piece of galvanized iron, is suspended freely by means of an insulated phosphor bronze spring. At the lower end of this moving piece a carbon contact piece is attached. When the magnet carried by the car passes over a stud, the moving piece is magnetically attracted to the cable against the pull of the spring. In the Lorain and the Dolter systems the studs are raised slightly above the road surface—which is an objectionable feature—and the current is collected by a skate, suspended under the car, touching the project in surface. In the G.B. system the stud heads are kept flush with tie pavement, and the collector consists of iron links spring suspended. As the collector passes over the box the links are magnetically attracted, and move down, making contact with the stud.
In all surface contact systems, short circuiting devices are provided to detect any studs which may remain live after the skate has passed, either by blowing a fuse or by ringing a bell, but it is questionable how much reliance can be placed on their efficiency under all conditions. The collecting skate and magnets carried by the cars on a surface contact tramway are of considerable weight, and the skate requires renewal at frequent intervals.
From The Tramway and Railway World.
Fig. 11.—G. B. Stud.
An efficient system of street traction may be defined as one which, while giving a reasonable return on the capital invested, provides the public, without disfigurement of the highway, with a quick and frequent service of comfortable cars.
When tramways were first introduced the. surface, of the streets was often exceedingly rough. The tramcar running on rails was therefore a great advance in comfort of travelling on the old stage carriage. Horse traction, however, limited the weight of the car and the speed of travelling. The substitution Advantages of Different Systems.of steam traction for horse traction was a great advance. Higher speeds and quicker acceleration were obtained, and larger and more comfortable cars could be worked. The power, however, was limited, and the locomotives, built as light as possible, were expensive in first cost and maintenance. Cable traction, owing to the heavy first cost of the track, requires a great density of traffic to make it pay. The speed is limited both up and down hill to that of the cable; It has the advantage that it can be safely worked on severe gradients, and once installed the working costs are low.
Electric traction by accumulator cars was tried in Birmingham in 1890 and abandoned after some years of unsatisfactory working. The cars were costly to work and maintain. The storage batteries had to be recharged at frequent intervals, and they rapidly dropped in capacity. There was little reserve of power, and the cells added considerably to the weight of the car.
Those forms of electric traction in which the power is supplied to the cars from an outside source have many advantages. Only the weight of the. motors has to be carried. These are efficient over a wide range of speed, accelerate quickly, have a large reserve of power and are clean and silent. The electric conduit and surface contact tramways do not require any disfiguring overhead wires. They have, however, troubles of their own. The construction of the electric conduit is so expensive that its choice must necessarily be limited to large cities. The conductors are easily short-circuited. Gaps in the conductors must be left at the points and crossings. The cost of keeping the conduit clean is considerable. It has the advantage, however, of having both the positive and negative conductors insulated. Surface contact systems require studs or contact boxes to be placed in the road. In most systems these project above the surface of the street. The switches which they contain are hidden away from inspection. A failure of insulation or the sticking of a switch may allow a live stud to be unprotected in the roadway. The weight of the car and consequently the power required to move it is considerably increased by the skate, magnet and battery which have to be carried.
For simplicity of working the overhead system easily comes first. The conductors are out of reach, they can easily be doubly or trebly insulated, and with their insulators are open to inspection. The poles and wiring can be erected without closing or obstructing the street. The supply of power is not interfered with by heavy rain, snow or other climatic causes. Duplicate conductors are used, and repairs can be rapidly executed. The only objection is that of unsightliness, which, however, can be greatly reduced by good design.
The cost of establishing tramways to be worked on the various systems of traction mentioned above has varied considerably. The locality and the amount of street widening have considerable influence on the total. Horse tramways in the larger cities cost in the past about £15,000 per track mile complete with horses, cars, &c., tramways worked by steam power about £18,000 per track mile including locomotives and cars. The Edinburgh Corporation cable tramways cost £23,316 to establish complete with powerhouse, cars, &c. Of this figure, the cost of the permanent way construction amounted to £14,431. The construction and equipment of the' South London conduit tramways cost £25,106 per mile of single line; the permanent way, its electrical equipment and the distributing cables cost £15,895 per track mile. More recent estimates appear to show that the average cost in London will be between £26,000 and £30,000 per track mile. In Glasgow the total cost of constructing and equipping the electric tramways on the overhead system, including the provision of a power station, cost £19,787 per track mile, and at Leeds £13,206. At Manchester, where current is provided by the lighting station, the complete cost works out at £12,498. The cost of the permanent way, cables and electrical equipment per track mile varies from £6575 at Manchester to £9959 at Glasgow. The cost of laying down a surface contact electric tramway is about slightly more than that of constructing and equipping a track with overhead conductors. The cost of the permanent way and its electrical equipment together with the cables at Wolverhampton on the Lorain surface contact principle amounted to £8601 per track mile.
The working expenses of the various systems of traction are largely affected by the age of the tramway, the locality, and, in the case'of electric lines, by the cost at which power is obtained. In Birmingham in 1890–1891 horse traction cost 9-79d. per car mile, steam traction 10.99d. per mile, cable traction 6-33d. and electric accumulator traction 9.90d. per car mile. Modern electric trolley lines generating their own current work at from 5d. to 6d. per car mile. Nhere current is purchased the costs vary from 6d. to 71d. per car mile. The working costs of the London County Council conduit tramways worked on purchased current amounted to 8.02d. per car mile in the year 1905–1906.
Tramway Cars.—The modern tramway car is made up of two distinct parts, the body and the truck. The present type of double ended car with a platform at each end was first used on the American street railways about 1860. The car body was supported directly on axle-boxes through helical steel or rubber springs.
When the early pioneers were experimenting in the United States with electric traction they attached the motor to the car body. This proved unsatisfactory, and resulted in the development of the modern truck. The truck may be described as a carriage or frame supported on the axle-boxes by springs and supporting by another set of springs the car body. The truck carries the motors and in itself resists all the strains of the driving mechanism.
Modern car bodies are mounted either on a single four-wheeled truck, with a fixed or rigid wheel-base, or on two four-wheeled bogies or swivelling trucks. Four-wheeled radial trucks have been tried on several tramways, but they have not proved satisfactory. The wheel-base of the fixed or rigid truck usually varies from 6 to 7 ft. The length of the wheel-base should be determined by the radius of the sharpest curve. To obtain steady running it should be made as long as possible. Two motors are generally fitted on a car.
Of the bogie or swivelling trucks the greater number now in use are of the “maximum traction” type. This truck is used to obtain the greatest tractive effect from two motors when fitted to a car supported on eight wheels. Each bogie is a small four-wheeled
truck in itself. It has one pair of its wheels driven by the single motor and of the standard size—about 30 in.—while the guiding or “ pony ” wheels are of small diameter. The weight of the car body is supported eccentrically on the truck, so that about 70% to 80% is available for adhesion under the driving-wheels. While this form of truck has many merits, it also has many disadvantages. The small wheels easily leave the rails, while the adhesion of the driving-wheels compared with a four-wheeled car is considerably reduced. Quick acceleration is difficult, and on a greasy rail much energy is lost in slipping. The use of equal-wheeled bogies with a motor on every axle gets over the difficulty of the loss of adhesion but at a greatly increased cost. The current consumption is increased, the first cost is greater, and there are four instead of two motors to be maintained. Steel-tired wheels have largely replaced the castiron chilled wheel for many years used on tramcars. While the various forms of trucks are common both to British and American practice, car body construction differs in many points. The single-deck car is universal outside the United Kingdom, where, although many single-deck cars are worked, the greater number are of the double-deck type. It is claimed that with small single-deck cars a quicker service can be maintained, as they are easier to load and unload and generally handler. On the other hand, the double-deck car seats more than double the number of passengers, requires the same number of men to work it, and takes but little more power to drive it. Experience has proved that the 58-passenger—28 inside and 30 outside—double-deck car mounted on a four-wheeled truck is the type of rolling stock most suitable for British conditions. For heavy rush traffic or long distance travel the larger bogie cars are convenient. They are, however, slow to start and stop, and a 72-passenger car is too much for one conductor to work efficiently. Another difference is due to the width of the cars. In the United States car bodies vary from 8 ft. to 9 ft. 6 in. in width. In Great Britain the width is limited by the Tramways Act of 1870 to 11 in. beyond the outer edge of the wheels, which, on the standard gauge, allows the maximum width to be 6 ft. 10 in. This limit has governed the arrangement of the seating in the cars. Inside, the ordinary side seat is almost invariably adopted. Cross seats have been used, but they leave a very narrow gangway-a great disadvantage at times of overcrowding. On the top deck, where the available width is greater and standing is never permitted, cross seats are universally fitted.
On the old horse cars a straight type of stairway was used. The reserved stairway, brought in about 1902, gave greater protection from accident and increased the seating accommodation on the top deck. It had, however, two great disadvantages. The stairway shut out the motorman’s view on the left-hand side, and the stream of passengers descending met the stream of passengers leaving the inside of the car, causing delay. The reversed type of stairway has now been abandoned and the straight type, well protected by railings, is usually fitted.
In addition to the ordinary single-deck and double-deck types of cars which are in general use many other designs are to be found. Single-deck open cars of the “toast-rack” type with transverse seats are popular on many holiday lines. They have the advantage of being quickly filled and emptied. Centre vestibule cars are now seldom seen. It is inconvenient not to have the conductor at the back of the car where he can look out for passengers, and, if necessary, “nurse” the trolley. There is also danger of a passenger being struck by the axle-boxes of the rear bogie truck when leaving the car. The Californian type of car body, with the central part closed in and one or two double-sided transverse seats at each end, has been used on routes where low bridges do not allow of the use of double deck cars. The carrying capacity of this type in wet weather when the exposed seats cannot be used is small. A demi or one-man car has been worked in some towns. It saves the wages of one man, but the average speed of the service is reduced. Top deck covers have in recent years been largely fitted. Their use practically doubles the covered seating capacity of the car and provides accommodation for smokers, a difficult matter on a single-deck car.
In Great Britain the board of trade requires all cars to be fitted with an efficient form of lifeguard. The gate and tray pattern, in which anything striking the vertical gate drops the tray, is that principally employed. In addition to the ordinary hand-brake which operates shoes on all the wheels, and the electric reverse switch, a large number of cars are fitted with some form of electric brake (see Traction).
Legislative Conditions in Great Britain.—The first tramways constructed in Great Britain were promoted by private enterprise under powers conferred by private acts of parliament. Considerable opposition was offered to pioneer schemes, but after a few private acts had been passed, parliament, in 1870, passed a general act providing for the laying of rails upon roads, and specifying the procedure for tramway promotion and the main relations between tramway undertakers and local authorities. The Tramways Act 1870, which is still in force, enabled promoters to apply to the board of trade for a provisional order which, when confirmed by parliament, possesses all the force of an act of parliament. The procedure is therefore simpler and cheaper than private bill procedure. Under this act promoters are obliged to obtain, as a condition precedent to making application for a provisional order, the consent of local authorities in whose areas the proposed tramways are to run. This provision is referred to as the “veto clause.” Where a line is laid in two or more districts and two-thirds of the line are in districts where the local authorities do consent, the board of trade may dispense with the consent of the remainder. When procedure by private bill is adopted a similar “veto” provision is made by Standing Order 22, which requires the consent of the local authority (and of the road authority where there is one distinct from the local authority) before the bill goes to first reading; in this case also the consent of authorities for two-thirds of a continuous line are deemed sufficient. The powers granted under the Tramways Act are in perpetuity, subject to the right of the local authorities (under the 43rd section) to purchase, at the end of twenty-one years or each septennial period following (or within three months after the promoters have discontinued working the tramway or have become insolvent), so much of the undertaking as lies within their areas, on paying the then value of the properties suitable to and used for the undertaking, exclusive of any allowance for past or future profits or compensation for compulsory sale or any other consideration whatsoever, such value to be determined by an arbitrator appointed by the board of trade. Another part of the arrangement specified between the local authorities and the undertakers is that the undertakers shall pave the tramway track between the outer rails and for 18 in. beyond each outer rail. Mr G. F. Shaw-Lefevre (afterwards Lord Eversley), when introducing the bill in 1870, said that it “would give powers to the local authorities to construct tramways, but not, of course, to work them.” The idea apparently was that local authorities should retain full control of the roads by constructing the tramways, and would make arrangements with lessees on terms which would secure reasonable fares and other conditions for the benefit of the travelling public. It was not until 1896 that parliament permitted local authorities to work tramways as well as own them, except in cases where lessees could not be obtained. The precedents for municipal working were created by private acts at a time when public opinion was in favour of that policy; and after the first few bills for municipal tramway working had been successful, other municipalities found practically no difficulty in obtaining the desired powers, although parliament had never adequately discussed, as a specific reform, the departure from the principle laid down by Mr Shaw-Lefevre in 1870. The conditions in fact proved more favourable to municipal than company promoters, since the local authorities, as soon as they aspired to work tramways as well as own them, used the power of veto against the proposals of companies.
The situation entered a more acute phase when electric traction was introduced on tramways. The Tramways Act provides, by section 34, that all carriages shall be moved by the power prescribed by the special acts or provisional order, and where no such power is prescribed, by animal power only. The mechanical power used must be by consent of the board of trade, and subject to board of trade regulations. Owing to the capital expenditure involved in electric traction, undertakings nearing the end of their twenty-one years’ tenure found that it was not commercially feasible to carry out the change without an extension of tenure. The local authorities were reluctant to grant that extension, and they were also reluctant to give permission for the promotion of new lines.
The difficulties of the altered conditions created by the advent of electric traction were met to some extent by the Light Railways Act 1896. This act contains no dentition of a light railway, and it has been used largely for electric tramway purposes. Lord Morley, when piloting the bill through the Lords, said that “light railway” includes “not merely all tramways but any railway which the board of trade thinks may justly be brought within the scope.” It certainly includes tramways in towns, and it might include large trunk lines, throughout the country.” Accordingly it has been used for the construction of many miles of tram lines on the public streets and also in some cases for extensions where the track leaves the public road, and is laid on land purchased for the purpose. These tracks are generally constructed with grooved girder rails, having a wide groove and a high check, so that the shallow flanged tramcar wheels can run on them with safety at high speeds. The rails are laid on cross sleepers and ballasted in the ordinary railway fashion. Fencing is erected, but level-crossing gates are often omitted, and cattle guards only are used to prevent animals straying on the track. These sleeper tracks on private ground are cheap to maintain if well constructed in the first instance. Speeds of 20 to 25 m. an hour have been sanctioned on electric lines of this character, worked by ordinary tramway rolling stock. There is no purchase clause in the Light Railways Act, but arrangements for purchase of the undertaking were usually made with the local authorities and the terms embodied in the order. The act contains no veto clause, section 7 stating that the commissioners are to “satisfy themselves that all reasonable steps have been taken for consulting the local authorities, including road authorities, through whose areas the railway is intended to pass, and the owners and occupiers of the land it is proposed to take.” The Light Railway Commissioners, however, have interpreted the act in the spirit of the Tramways Act, so that for all practical purposes the veto remains. The new act differed from the Tramways Act in providing for the compulsory purchase of land under the Lands Clauses Acts—the Tramways Act expressly stating that the promoters should not be empowered to acquire land otherwise than by agreement. The board of trade has held that the act does not apply to tramways wholly within one borough. County, borough and district councils as well as individuals and companies are empowered to promote and work light railways.
The passing of the act gave a great impetus to the construction of tramways worked by electric traction. But owing to the practical retention of the veto, there was not so much progress as was anticipated. Another cause of restriction was section 9, sub-section 3, which provides that if the board of trade considers that “by reason of the magnitude of the proposed undertaking, or of the effect thereof on the undertaking of any railway company existing at the time, or for any other special reason relating to the undertaking, the proposals of the promoters ought to be submitted to parliament,” they should not confirm the order. In many cases railway companies, by pleading the competitive influence of proposed tramways promoted under the Light Railways Act, were able to force the promoters to apply to parliament or to drop the scheme. The latter alternative was frequently adopted, owing to the costs of parliamentary procedure being too heavy for the undertaking.
Commercial Results.—Interest in the commercial results of tramway enterprise is practically limited to electric traction, since other forms of traction have been almost entirely superseded owing to their economical inferiority. The main advantages of electric traction over horse traction lie in the higher speed, greater carrying capacity of cars, and the saving in power over a system in which only a small proportion of the power source is available at one time. Steam, compressed air and gas traction possess the disadvantages that each car has to carry the dead weight of power-producing machinery capable of maintaining speed up to the maximum grade. Cable traction has the disadvantages that the speed of the cars is limited by the speed of the cable, that the range and complexity of the system are restricted, and that construction is expensive. The electric system, in which power is generated at a central source and distributed to cars which take power in proportion to the work being done, possesses a higher degree of flexibility, convenience and economy than any other system. Electric tramways in Great Britain are mostly equipped on the overhead trolley system, though the conduit and the surface contact systems have been installed in a few instances. Roughly the capital expenditure required for the three systems is in proportion of 2, 11 and 1, and both the conduit and the surface contact systems are more costly to maintain than the overhead system. A fourth system of electric traction, in which the cars are fitted with storage batteries charged at intervals, has been tried frequently and as frequently abandoned. The great weight of the batteries, the serious initial cost and high rate of deterioration prevented the attainment of financial success.
The earliest development of electric road traction on a large scale took place in America and on the continent of Europe, and the estimates for British tramways were therefore prepared from American and continental results. The following figures summarize a number of estimates made at this period; the first table gives the figures for capital cost, and the second for operating expenses. The receipts were estimated at 10d per car mile.
per mile of
|Permanent way, including bonding||5050|
|Cars at £700 each||2100|
|Car sheds, sundries and contingencies||1200|
|Wages of drivers and conductors||1·10|
|Car shed expenses, wages an stores||0·55|
|Repairs and maintenance||1·25|
The estimates gave reason to expect that electric traction would mean cheaper fares and more frequent services at a higher speed, resulting in a considerable increase in traffic receipts permile and a substantial reduction of working expenses. The result of pioneer undertakings in South Staffordshire, Bristol and Coventry supported this expectation. Later experience, however, showed that the estimates were too optimistic. Taking the actual figures realized for the undertakings included in the above tables, the capital expenditure per mile of, single track was £12,000 and the wor ing expenses per car mile 6·3d. The expectations as to gross revenue have been generally realized, but the increase in capital expenditure and working expenses over the estimates is typical of electric tramways in Great Britain. In the matter of wear and tear the estimates have also been too low. The reasons for the larger capital expenditure are (1) superior track construction, (2) more elaborate overhead equipment, (3) use of larger cars, (4) higher cost of road paving and other im movements imposed upon tramway undertakings.
According to the official returns of tramways and light railways for the year 1905–1906, there were 312 tramway undertakings in the United Kingdom, and 175 of these belonged to local authorities. Out of the total of 1491 m. of line owned by local authorities, 1276 m. are worked by these authorities themselves, and the remaining 215 m. by leasing companies. Local authorities working as well as owning their tramways made a net profit of £2,52,752, applying £663,336 to the reduction of tramway debt and £205,981 to the relief of rates, while carrying £623,617 to reserve and renewal funds. The following table summarizes the amounts expended by local authorities on electric traction:—
The corresponding table for electric traction companies (including electric railways), detailing the amounts and proportions of ordinary preference and loan and debenture capital, is as follows:—
| Preference |
| Loan and|
The financial results achieved by electric traction, companies are summarized in the next table:—
|Year.|| Number of|
| Aggregate |
| Average loan|
The total expenditure on tramways and light railways (omitting railways—main, branch and suburban) was £15,195,993 in 1896 and £58,177,832 in 1906.
One effect of the increased cost of expenditure per mile of track is to discourage extensions of rural and inter-urban lines where the traffic is not heavy. Proposals have been made to adopt the “rail-less trolley” (used in some places on the continent of Europe) for such extensions. In this system the cars run on ordinary wheels and take power from overhead trolley wires, But so far no such arrangement has been put into practice in Great Britain, and outlying districts are generally dealt with by petrol or steam motor vehicles, running as feeders to the tramway sand railways. The future commercial development of tramways lies more in the economics in working than in growth of track mileage. Owing, to the enormous volume of traffic a very slight alteration in one, of the items of expense or revenue produces a large result in the aggregate. The addition of 1d. per car mile to revenue or a corresponding reduction in expenses would, on the 240 millions of car miles run in 1905–1906, result in a gain of about £500,000 per annum, which is equal to nearly 1% on the entire capital expenditure in respect of tramways and light railways. The tables given above show that the yield upon the capital invested in electric traction is not high. The effect of increased capital expenditure has been accentuated by reductions in fares. In 1886 the average fare per passenger was, 1·61d. and in 1896 it was 1·31d., falling in 1906 as low as 1·10d. Some systems carry passengers over 21 m. for one penny, workmen being carried twice the distance for the same sum. Halfpenny fares are represented as a boon to the working man, but they have been abandoned as a failure after several years’ trial on several systems, and in Glasgow it is found that halfpenny fares contribute only 20·4% of the early morning traffic, while the penny fare contributes 72·3% of that traffic. The general manager of the Birmingham Corporation tramways reported against halfpenny fares on-the basis of his experience as general manager of the London County Council tramways that all the halfpenny passengers there are carried at a loss. The adjustment of fares and stages to their proper value is a question now carefully studied by tramway managers along with many problems of economy in working. The close adjustment of the service to the fluctuations in traffic is one source of economy which is being more seriously considered. Many systems have adopted top covers to cars in order to carry more passengers during wet weather. The adoption of these covers is not popular in fine weather; it adds to the weight and wind-resistance of the cars, thus increasing current consumption, and it adds to the cost of construction and maintenance. Economy in electrical, energy is, in its broader aspects, secured by purchasing current from an outside source, in. preference to generating it at a special station. The average cost per unit of electricity for all tramway undertakings in the United Kingdom is 1·06., but one tramway company which purchases its energy from a large power company pays, only 0·85d. per unit. In its narrower aspects economy in current may be secured by reducing waste car mileage—that is to say, eliminating the running of cars at times and places where they are not required for an adequate service. Saving may also be effected by supervision of the driving of the cars, since the difference of as much, as 20% has been noted between different drivers. One tramway manager secured substantial improvement by merely marking on the trolley standards the position which, the controller handle should occupy in passing each point. The limitation of stops is another source of economy, the average cost per stop on a system having been found to be 0·17 d. A slight increase in the maximum speed of tramcars would also improve the net results by reducing the proportion of standing charges (wages, &c.) to the traffic capacity of the system without making the cost of maintenance or current more than slightly greater. A 15% increase in average speed means a saving of 1d. per car mile. The development of parcels traffic is a source of revenue, and additional receipts can be earned by the hiring-out of cars for picnics and other special purposes. An important point is the proper selection of the size of car. A small four-wheeled car is suitable to continual traffic of comparatively small volume, but when the traffic is heavy cars of larger capacity are advisable. A serious burden on tramways is the cost of insurance against accidents, although the number of serious accidents on electric tramways is exceedingly small in proportion to the number of passengers carried, the ratio of tramway accidents of all kinds being about one accident to every 15,000 passengers.
There are many adjoining towns having separate tramway undertakings which do not provide intercommunication. Experience has shown that a break of tramway facilities reduces the receipts by 20 to 50% on the lines which have been severed; and the terminal half-mile, except in populous districts, is the least remunerative section of a tramway route.
Statistics.—Each year the British board of trade issues a return of street and road tramways and light railways authorized by act or order, showing the amount of capital authorized, paid up and expended; the length of line authorized and the length open for public traffic; the gross receipts, working expenditures, net receipts and appropriation of net receipts; the number of passengers conveyed; the number of miles run by cars and the quantity of electrical energy used; together with the number of horses, engines and cars in use. The return published in January 1909 deals with the figures for local authorities up to the 31st of March 1908 and for companies up to the 31st of December 1907. The following comparative table summarizes the most important general figures for the United Kingdom provided by this official return:—
|Years ended June 30.||Year ending Dec. 31 (com-|
panies) and March 31 (local
|Total capital authorized.||£6,586,111||£17,640,488||£24,435,427||£51,677,471||£91,305,439|
|Total capital expended||£4,207,350||£12,573,041||£16,492,869||£31,562,267||£68,199,918|
|Length of route open (miles)||269||865||1,064||1,484||2,464|
|Number of horses||9,222||24,535||38,777||24,120||5,288|
|Number of locomotive engines||14||452||589||388||64|
|Number of cars||1,124||3,440||5,335||7,752||10,908|
|Total number of passengers carried||146,001,223||384,157,524||858,485,524||1,394,452,983||2,625,532,895|
|Quantity of electrical energy used, B.O.T units||—||—||—||—||431,969,119|
The total figures at the date of the return are summarized in the following table, which is accompanied by one showing the lengths of line worked by various methods of traction:—
on lines and works
open for traffic.
ture on capital
|Length open open for traffic.||No. of undertakings.|
|Tramways and light railways belonging to
|Tramways and light railways belonging to
companies and private individuals
|Total United Kingdom||51,619,858||68,199,918||1522||55||941||43||2464||18||305|
Table showing lengths worked by various methods of traction:—
|England and Scotland.||Ireland.||Total.|
The following table gives a few totals, ratios, and percentages for the last two years of what may be called a period of electric traction, in comparison with a typical “steam” period (i.e. a period in which the use of steam power in tramways was at its maximum) and a typical “horse” period:—
|Horse period, |
|Length of route open||2,464·22||1009||321·27|
|Total number of passengers carried||2,625,532,895||759,466,047||150,881,515|
|Percentage of net receipts to total capital outlay||6·81||6·88||3·97|
|Percentage of working expenditure to gross receipts||62·64||74·79||83·81|
|Passengers carried per mile of route open||1,065,462||752,691||469,641|
|Average fare per passenger||1·09d.||1·61d.||1·84d.|
From the above figures it will be noticed that the capital cost per mile has increased as a result of the adoption of electric traction, while at the same time the percentage of the return on the capital has been reduced notwithstanding that the rate of working expenditure has fallen and the number of passengers carried per mile has increased, the fares charged having been disproportionately reduced. (E. Ga.)
- See Tramways: Their Construction and Working, by D. K. Clarke.
- Proc. Inst. Civ. Eng. 156, p. 179.
- Tramway Accounts, year ended March 31, 1906.
- Ibid., year ended March 31, 1905.
- See Tramways: Their Construction and Working, by D. K. Clarke.
- Average reduced owing to inclusion of Metropolitan and Metropolitan District railways capital.
- These figures include cost of buildings and equipment in respect of certain local authorities’ lines worked in conjunction with other lines.