The history of railways (История железных дорог)

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The history of railways

The railway is а good example of а system evolved in variousplaces to fulfil а need and then developed empirically. Inessence it consists оf parallel tracks or bars of metal or wood,supported transversely by other bars — stone, wood, steel andconcrete have been used — so that thе load of the vehicle isspread evenly through the substructure. Such tracks wereused in the Middle Ages for mining tramways in Europe;railways came to England in the 16th century and went backto Europe in the 19th century as an English invention.

English railways

The first Act of Parliament for а railway,giving right of way over other people's property, was passed

in1758, and the first for а public railway, to carry the trafficof all comers, dates from 1801. The Stockton and DailingtonRailway, opened on 27 September 1825, was the first publicsteam railway in the world, although it had only onelocomotive and relied on horse traction for the most part,with stationary steam engines for working inclined planes.

The obvious advantages of railways as а means of conveyingheavy loads and passengers brought about а proliferation ofprojects. The Liverpool & Manchester, 30 miles (48 km) longand including formidable engineering problems, became theclassic example of а steam railway for general carriage. Itopened on 15 September 1830 in the presence of the Duke ofWellington, who had been Prime Minister until earlier in theyear. On opening day, the train stopped for water and thepassengers alighted on to the opposite track; another locomotive came along and William Huskisson, an МР and а greatadvocate of the railway, was killed. Despite this tragedy therailway was а great success; in its first year of operation,revenue from passenger service was more than ten times thatanticipated. Over 2500 miles of railway had been authorizedin Britain and nearly 1500 completed by 1840.

Britain presented the world with а complete system for theconstruction and operation of railways. Solutions were foundto civil engineering problems, motive power designs and thedetails of rolling stock. The natural result of these achievementswas the calling in of British engineers to provide railwaysin France, where as а consequence left-hand rujning isstill in force over many lines.

Track gauges

While the majority of railways in Britainadopted the 4 ft 8.5 inch (1.43 m) gauge of the Stockton &

Darlington Railway, the Great Western, on the advice of itsbrilliant but eccentric engineer Isambard Kingdom Brunel,had been laid to а seven foot (2.13 m) gauge, as were many ofits associates. The resultant inconvenience to traders causedthe Gauge of Railways Act in 1846, requiring standard gaugeon all railways unless specially authorized. The last seven-footgauge on the Great Western was not converted until 1892.

The narrower the gauge the less expensive the constructionand maintenance of the railway; narrow gauges have beencommon in underdeveloped parts of the world and in mountainous areas.In 1863 steam traction was applied to the 1 ft 11.5 inch (0.85 m) Festiniog Railway 1n Wales, for whichlocomotives were built to the designs of Robert Fairlie. Неthen led а campaign for the construction of narrow gauges.As а result of the export of English engineering and rollingstock, however, most North American and Europeanrailways have been built to the standard gauge, except inFinland and Russia, where the gauge is five feet (1.5 m).

Transcontinental lines

The first public railway was openedin America in 1830, after which rapid development tookplace. А famous 4-2-0 locomotive called the Pioneer firstran from Chicago in 1848, and that city became one of thelargest rail centres in the world. The Atlantic and the Pacificoceans were first linked on 9 Мау 1869, in а famous ceremonyat the meeting point of the Union Pacific and Central Pacificlines at Promontory Point in the state of Utah. Canada wascrossed by the Canadian Pacific in 1885; completion of therailway was а condition of British Columbia joining theDominion of Canada, and considerable land concessions weregranted in virtually uninhabited territory.

The crossing of Asia with the Trans-Siberian Railway wasbegun by the Russians in 1890 and completed in 1902, exceptfor а ferry crossing Lake Baikal. The difficult passage roundthe south end of the lake, with many tunnels, was completedin 1905. Today more than half the route is electrified. In 1863the Orient Express ran from Paris for the first time andeventually passengers were conveyed all the way to Istanbul(Constantinople).

Rolling stock

In the early days, coaches were constructedentirely of wood, including the frames. Ву 1900, steel frameswere commonplace; then coaches were constructed entirelyof steel and became very heavy. One American 85-foot(26 m) coach with two six-wheel bogies weighed more than80 tons. New lightweight steel alloys and aluminium began

to be used; in the 1950s the Budd company in America was

building an 85-foot coach which weighed only 27 tons. Thesavings began with the bogies, which were built withoutconventional springs, bolsters and so on; with only two airsprings on each four-wheel bogie, the new design reduced theweight from 8 to 2,5 tons without loss оf strength or stability.

In the I880s, 'skyscraper' cars were two-storey woodenvans with windows used as travelling dormitories for railwayworkers in the USA; they had to be sawn down when therailways began to build tunnels through the mountains.After World War II double-decker cars of а mоrе compactdesign were built, this time with plastic domes, so that passengers could enjoy the spectacular scenery on the westernlines, which pass through the Rocky Mountains.

Lighting on coaches was by means of oil lamps at first; thengas lights were used, and each coach carried а cylinder оf gas,which was dangerous in the event of accident or derailment.Finally dynamos on each car, driven by the axle, providedelectricity, storage batteries being used for when the car wasstanding.Heating on coaches was provided in the early days

by metal containers filled with hot water; then steam waspiped from the locomotive, an extra drain on the engine'spower; nowadays heat as well as light is provided electrically.

Sleeping accommodations were first made on the Cumberland Valley Railroad in the United States in 1837. GeorgePullman's first cars ran on the Chicago & Alton Railroad in1859 and the Pullman Palace Car Company was formed in1867. The first Pullman cars operated in Britain in 1874, аyear after the introduction of sleeping cars by two Britishrailways. In Europe in 1876 the International Sleeping CarCompany was formed, but in the meantime GeorgeNagelmackers of Liege and an American, Col WilliamD'Alton Маnn, began operation between Paris and Viennain 1873.

Goods vans [freight cars] have developed according to theneeds of the various countries. On the North Americancontinent, goods trains as long as 1,25 miles are run as far as1000 miles unbroken, hauling bulk such as raw materials andfoodstuffs. Freight cars weighing 70 to 80 tons have two fourwheel bogies. In Britain, with а denser population andclosely adjacent towns, а large percentage of hauling is ofsmall consignments of manufactured goods, and the smallestgoods vans of any country are used, having four wheels and,up to 24,5 tons capacity. А number of bogie wagons are usedfor special purposes, such as carriages fоr steel rails, tank carsfor chemicals and 50 ton brick wagons.

The earliest coupling system was links and buffers, whichallowed jerky stopping and starting. Rounded buffers broughtsnugly together by adjustment of screw links with springswere an improvement. The buckeye automatic coupling, longstandard in North America, is now used in Britain. Thecoupling resembles а knuckle made of steel and extendinghorizontally; joining аuоtomаtika11у with the coupling of thenext саr when pushed together, it is released by pulling а pin.

The first shipment of refrigerated goods was in 1851 whenbutter was shipped from New York to Boston in а woodenvan packed with ice and insulated with sawdust. The bulk ofrefrigerated goods were still carried by rail in the USA in the,1960s, despite mechanical refrigeration in motor haulage;because of the greater first cost and maintenance cost ofmechanical refrigeration, rail refrigeration is still mostly

provided by vans with ice packed in end bunkers, four to six inches (10 to 15 cm) of insulation and fans to circulate thecool air.

Railways in wartime

The first war in which railwaysfigured prominently

was the American Civil War (1860-65), in which the Union

(North) was better able to organize andmake use ofits railways than the Confederacy (South). Thewar was marked by а famous incident in which а 4-4-0 locomotive

called the General was hi-jacked by Southern agents.

The outbreak of World War 1 was caused in part by the

fact that the mobilization plans of the various countries,including the use оf railways and rolling stock, was planned to the last detail, except that there were nо provisions for stopping the plans once they had been put into action until the armies were facing each other. In 1917 in the United States, the lessons of the Civil War had been forgotten, and freight vans were sent to their destination with nо facilities for unloading, with the result that the railways were brieflytaken over by the government for the only time in thatnation's history.

In World War 2, by contrast, the American railways performed magnificently, moving 2,5 times the level of freightin 1944 as in 1938, with minimal increase in equipment, andsupplying more than 300,000 employees to the armed forcesin various capacities. In combat areas, and in later conflictssuch as the Korean war, it proved difficult to disrupt anenemy's rail system effectively; pinpoint bombing wasdifficult, saturation bombing was expensive and in any caserailways were quickly and easily repaired.

State railways

State intervention began in England withpublic demand for safety regulation which resulted in Lord

Seymour's Act in 1840; the previously mentioned Railway

Gauges Act followed in 1846. Ever since, the railways havebeen recognized as one of the most important of nationalresources in each country.

In France, from 1851 onwards concessions were granted for a planned regional system for which the Government providedways and works and the companies provided track and roiling stock; there was provision for the gradual taking over of the lines by the State, and the Societe Nationale des Chemins de Fer Francais (SNCF) was formed in 1937 as а company in which the State owns 51% of the capital and theompanies 49%.

The Belgian Railways were planned by the State from the outset in 1835. The Prussian State Railways began in 1850; bу the end of the year 54 miles (87 km) were open. Italian andNetherlands railways began in 1839; Italy nationalized herrailways in 1905-07 and the Netherlands in the period1920-38. In Britain the main railways were nationalized from1 January 1948; the usual European pattern is that the State owns the main lines and minor railways are privately ownedor operated by local authorities.

In the United States, between the Civil War and World Wаr 1 the railways, along with all the other importantinndustries, experienced phenomenal growth as the countrydeveloped. There were rate wars and financial piracy duringа period of growth when industrialists were more powerfulthan the national government, and finally the InterstateCommerce Act was passed in l887 in order to regulate therailways, which had а near monopoly of transport. AfterWorld War 2 the railways were allowed to deteriorate, asprivate car ownership became almost universal and publicmoney was spent on an interstate highway system makingmotorway haulage profitable, despite the fact that railwaysare many times as efficient at moving freight and passengers.In the USA, nationalization of railways would probablyrequire an amendment to the Constitution, but since 1971 аgovernment effort has been made to save the nearly defunctpassenger service. On 1 May of that year Amtrack was formedby the National Railroad Passenger Corporation to operate аskeleton service of 180 passenger trains nationwide, serving29 cities designated by the government as those requiringtrain service. The Amtrack service has been heavily used, but

not adequately funded by Congress, so that bookings,

especially for sleeper-car service, must be made far in

advance.

The locomotive

Few machines in the machine age have inspired so much affection as railway locomotives in their 170 years of operation. Railways were constructed in the sixteenth century, but the wagons were drawn by muscle power until l804. In that year an engine built by Richard Trevithick worked on the Penydarren Tramroad in South Wales. It broke some cast iron tramplates, but it demonstrated that steam could be used forhaulage, that steam generation could be stimulated byturning the exhaust steam up the chimney to draw up the fire, and that smooth wheels on smooth rails could transmit motive power.

Steam locomotives

The steam locomotive is а robust and

simple machine. Steam is admitted to а cylinder and by

expanding pushes the piston to the other end; on the return stroke а port opens to clear the cylinder of the now expanded steam. By means of mechanical coupling, the travel ofthe piston turns the drive wheels of the locomotive.

Trevithick's engine was put to work as а stationary engine at Penydarren. During the following twenty-five years, а limited number of steam locomotives enjoyed success on colliery railways, fostered by the soaring cost of horse fodder towards the end of the Napoleonic wars. The cast iron plateways,which were L-shaped to guide the wagon wheels, were not strong enough to withstand the weight of steam locomotives,and were soon replaced by smooth rails and flanged wheels on the rolling stock.

John Blenkinsop built several locomotives for collieries, which ran on smooth rails but transmitted power from а toothed wheel to а rack which ran alongside the runningrails. William Hedley was building smooth-whilled locomotiveswhich ran on plateways, including the first to have the popular nickname Puffing Billy.

In 1814 George Stephenson began building for smooth rails at Killingworth, synthesizing the experience of the earlierdesigners. Until this time nearly all machines had thecylinders partly immersed in the boiler and usually vertical.In 1815 Stephenson and Losh patented the idea of directdrive from the cylinders by means of cranks on the drivewheels instead of through gear wheels, which imparted аjerky motion, especially when wear occurred on the coarsegears. Direct drive allowed а simplified layout and gavegreater freedom to designers.

In 1825 only 18 steam locomotives were doing useful work.One of the first commercial railways, the Liverpool & Manchester, was being built, and the directors had still notdecided between locomotives and саblе haulage, with railsidesteam engines pulling the cables. They organized а competitionwhich was won by Stephenson in 1829, with hisfamous engine, the Rocket, now in London's Science Museum.

Locomotive boilers had already evolved from а simple

flue to а return-flue type, and then to а tubular design, inwhich а nest of fire tubes, giving more heating surface, ranfrom the firebox tube-plate to а similar tube-plate at thesmokebox end. In the smokebox the exhaust steam from thecylinders created а blast on its way to the chimney whichkept the fire up when the engine was moving. When thelocomotive was stationary а blower was used, creating аblast from а ring оf perforated pipe into which steam wasdirected. А further development, the multitubular boiler,was patented by Henry Booth, treasurer of the Liverpool &Manchester, in 1827. It was incorporated by Stephenson inthe Rocket, after much trial and error in making the ferrulesof the copper tubes to give water-tight joints in the tube

plates.

After 1830 the steam locomotive assumed its familiar form,with the cylinders level or slightly inclined at the smokeboxend and the fireman's stand at the firebox end.

As soon as the cylinders and axles were nо longer fixed inor under the boiler itself, it became necessary to provide аframe to hold the various components together. The barframe was used on the early British locomotives and exported to America; the Americans kept со the bar-frame design,which evolved from wrought iron to cast steel construction,with the cylinders mounted outside the frame. The bar framewas superseded in Britain by the plate frame, with cylindersinside the frame, spring suspension (coil or laminated) forthe frames and axleboxes (lubricated bearings) to hold the

axles.

As British railways nearly all produced their own designs,а great many characteristic types developed. Some designswith cylinders inside the frame transmitted the motion tocrank-shaped axles rather than to eccentric pivots on theoutside of the drive wheels; there were also compoundlocomotives, with the steam passing from а first cylinder orcylinders to another set of larger ones.

When steel came into use for building boilers after 1860,higher operating pressures became possible. By the end ofthe nineteenth century 175 psi (12 bar) was common, with200 psi (13.8 bar) for compound locomotives. This rose to250 psi (17.2 bar) later in the steam era. (By contrast,Stephenson's Rocket only developed 50 psi, 3.4 bar.) In thel890s express engines had cylinders up to 20 inches (51 cm)in diameter with а 26 inch (66 cm) stroke. Later diametersincreased to 32 inches (81 cm) in places like the USA, wherethere was more room, and locomotives and rolling stockin general were built larger.

Supplies of fuel and water were carried on а separatetender, pulled behind the locomotive. The first tank enginecarrying its own supplies, appeared tn the I830s; on thecontinent of Europe they were. confusingly called tenderengines. Separate tenders continued to be common becausethey made possible much longer runs. While the firemanstoked the firebox, the boiler had to be replenished withwater by some means under his control; early engines hadpumps running off the axle, but there was always the difficulty that the engine had to be running. The injector was invented in 1859. Steam from the boiler (or latterly, exhaus steam) went through а cone-shaped jet and lifted the water into the boiler against the greater pressure there through energy imparted in condensation. А clack (non-return valve)

retained the steam in the boiler.

Early locomotives burned wood in America, but coal in Britain. As British railway Acts began to include penalties for emission of dirty black smoke, many engines were built after 1829 to burn coke. Under Matthetty Kirtley on the Midland Railway the brick arch in the firebox and deflector plateswere developed to direct the hot gases from the coal to passover the flames, so that а relatively clean blast came out of

the chimney and the cheaper fuel could be burnt. After 1860this simple expedient was universа11у adopted. Fireboxeswere protected by being surrounded with а water jacket;stays about four inches (10 cm) apart supported the innerfirebox from the outer.

Steam was distributed to the pistons by means of valves.The valve gear provided for the valves to uncover the portsat different parts of the stroke, so varying the cut-off toprovide for expansion of steam already admitted to thecylinders and to give lead or cushioning by letting the steamin about 0.8 inch (3 mm) from the end of the stroke to beginthe reciprocating motion again. The valve gear also providedfor reversing by admitting steam to the opposite side of thepiston.

Long-lap or long-travel valves gave wide-open ports for theexhaust even when early cut-оff was used, whereas with shorttravel at early cut-off, exhaust and emission openings becamesmaller so that at speeds of over 60 mph (96 kph) one-third ofthe ehergy of the steam was expanded just getting in and outof the cylinder. This elementary fact was not universal1y

accepted until about 1925 because it was felt that too muchextra wear would occur with long-travel valve layouts.

Valvе operation on most early British locomotives was byStephenson link motion, dependent on two eccentrics on thedriving ах1е connected by rods to the top and bottom of anexpansion link. А block in the link, connected to the reversing lever under the control of the driver, imparted thereciprocating motion tо the valve spindle. With the block atthe top of the link, the engine would be in full forward gearand steam would be admitted to the cylinder for perhaps75% of the stoke. As the engine was notched up by movingthe lever back over its serrations (like the handbrake leverof а саr), the cut-off was shortened; in mid-gear there was nosteam admission to the cylinder and with the block at thebottom of the link the engine was in full reverse.

Walschaert's valvegear, invented in 1844and in general useafter 1890, allowed more precise adjustment and easier operation for the driver. An eccentric rod worked from а returncrank by the driving axle operated the expansion link; theblock imparted the movement to the valve spindle, but themovement was modified by а combination lever from аcrosshead on the piston rod.

Steam was collected as dry as possible along the top of theboiler in а perforated pipe, or from а point above the boilerin а dome, and passed to а regulator which controlled itsdistribution. The most spectacular development of steamlocomotives for heavy haulage and high speed runs was theintroduction of superheating. А return tube, taking thesteam back towards the firebox and forward again to а headerat the front end of the boiler through an enlarged flue-tube, was invented by Wilhelm Schmidt of Cassel, and modified byother designers. The first use of such equipment in Britain was in 1906 and immediately the savings in fuel and especiallywater were remarkable. Steam at 175 psi, for example, was generated 'saturated' at 371'F (188'С); by adding 200'F (93'C) of superheat, the steam expanded much more readily in the cylinders, so that twentieth-century locomotives were able to work at high speeds at cut-offsas short as 15%. Steel tyres, glass fibre boiler lagging, long-lap piston valves, direct steam passage and superheating all contributed to the last

phase of steam locomotive performance.

Steam from the boiler was also for other purposes.

Steam sanding was introduced for traction in 1887 on th

Midland Railway, to improve adhesion better than gravity

sanding, which often blew away. Continuous brakes were

operated by а vacuum created on the engine or by соmpressed air supplied by а steam pump. Steam heat was piped to the carriages, arid steam dynamos [generators] providedelectric light.

Steam locomotives are classified according to the numberof wheels. Except for small engines used in marshalling уаrds,all modern steam locomotives had leading wheels on apivoted bogie or truck to help guide them around сurves.The trailing wheels helped carry the weight of the firebox.For many years the 'American standard' locomotive was a4-4-0, having four leading wheels, four driving wheels and notrailing wheels. The famous Civil War locomotive, theGeneral, was а 4-4-0, as was the New York Central EngineNo 999, which set а speed record о1 112.5 mph (181 kph) in1893. Later, а common freight locomotive configuration wasthe Mikado type, а 2-8-2.

А Continental classification counts axles instead оf wheels,and another modification gives drive wheels а letter of thealphabet, so the 2-8-2 would be 1-4-1 in France and IDI inGermany.

The largest steam locomotives were articulated, with twosets of drive wheels and cylinders using а common boiler.The sets оf drive wheels were separated by а pivot; otherwise such а large engine could not have negotiated curves. The largest ever built was the Union Pacific Big Вoу, а 4-8-8-4,used to haul freight in the mountains of the western United States. Even though it was articulated it could not run onsharp curves. It weighed nearly 600 tons, compared to less than five tons for Stephenson's Rocket.

Steam engines could take а lot of hard use, but they arenow obsolete, replaced by electric and especially diesel-electric locomotives. Because of heat losses and incompletecombustion of fuel, their thermal efficiеncу was rarely morethan 6%.

Diesel locomotives

Diesel locomotives are most commonly diesel-electric.А diesel engine drives а dynamo [generator]whichprovides power for electric motors which turn the

drive wheels, usually through а pinion gear driving а ringgear on the axle. The first diesel-electric propelled rail car was built in 1913, and after World War 2 they replacedsteam engines completely, except where electrification of railways is economical.

Diesel locomotives have several advantages over steam engines. They are instantly ready for service, and can be shut down completely for short рeriods, whereas it takes sometime to heat the water in the steam engine, especially in coldweather, and the fire must be kept up while the steam engineis on standby. The diesel can go further without servicing, as it consumes nо water; its thermal efficiency is four times as high, which means further savings of fuel. Acceleration and

high-speed running are smoother with а diesel, which means less wear on rails and roadbed. The economic reasons for turning to diesels were overwhelming after the war, especially in North America, where the railways were in directcompetition with road haulage over very long distances.

Electric traction

The first electric-powered rail car wasbuilt in 1834, but early electric cars were battery powered,and the batteries were heavy and required frequent recharging. Тоdау е1есtriс trains are not self-contained, whichmeans that they get their power from overhead wires orfrom а third rail. The power for the traction motors iscollected from the third rail

by means of а shoe or from theoverhead wires by а pantograph.

Electric trains are the most есоnomical to operate,

provided that traffic is heavy enough to repay electrificationof the railway. Where trains run less frecuentlу over longdistances the cost of electrification is prohibitive. DCsystems have been used as opposed to АС because lightertraction motors can be used, but this requires powersubstations with rectifiers to convert the power to DС fromthe АС of the commercial mains. (High voltage DC power isdifficult to transmit over long distances.) The latest development

of electric trains has been the installation of rectifiersin the cars themselves and the use of the same АС frequencyas the commercial mains (50 Hz in Europe, 60 Hz in NorthAmerica),which means that fewer substations are necessary.

Railway systems

The foundation of а modern railway system is track whichdoes not deteriorate under stress of traffic. Standard track inBritain comprises a flat-bottom section of rail weighing 110lbper yard (54 kg per metre) carried on 2112 cross-sleepers permile (1312 per km). Originally creosote-impregnated woodsleepers [cross-ties] were used, but they are now made ofpost-stressed concrete. This enables the rail to transmit the

pressure, perhaps as much as 20 tons/in2(3150 kg/cm2) fromthe small area of contact with the wheel, to the ground belowthe track formation where it is reduced through the soleplate and the sleeper to about 400 psi (28 kg/cm2). In softground, thick polyethylene sheets are generally placed underthe ballast to prevent pumping of slurry under the weight oftrains.

The rails are tilted towards one another on а 1 in 20 slоре.Steel rails tnay last 15 or 20 years in traffic, but to prolong theundisturbed life of track still longer, experiments have beencarried out with paved concrete track (PACТ) laid by а slippaver similar to concrete highway construction in reinforcedconcrete. The foundations, if new, are similar to those for а

motorway. If on the other'hand, existing railway formation isto be used, the old ballast is sеа1еd with а bitumen emulsionbefore applying the concrete which carries the track fastenings glued in with cement grout or epoxy resin. The track ismade resilient by use of rubber-bonded cork packings0.4 inch (10 mm) thick. British Railways purchases rails in60 ft (18.3 m) lengths which are shop-welded into 600 ft(183 m) lengths and then welded on site into continuouswelded track with pressure-relief points at intervals ofseveral miles. The contfnuotls welded rails make for а

steadier and less noisy ride for the passenger and reduce thetractive effort.

Signalling

The second important factor contributing to safe rail travel is the system of signalling. Originally railways relied on the time interval to ensure the safety of a succession of trains, but the defects rapidly manifested themselves,and a space interval, or the block system, was adopted, although itwas not enforced legally on British passenger lines until the

Regulation of Railways Act of 1889. Semaphore signals

became universally adopted on running lines and the interlocking оf points [switches] and signals (usually accomplished mechanically by tappets) to prevent conflicting movementsbeing signalled was also а requirement of the 1889 Асt. Lock-and-block signalling, which ensured а safe sequence of movements by electric checks, was introduced on the London, Chatham and Dover Railway in 1875.

Track circuiting, by which the presence of а train isdetected by an electric current passing from one rail to another through the wheels and axles, dates from 1870 whenWilliam Robinson applied it in the United States. In Englandthe Great Eastern Railway introduced power operation of points and signals at Spitaifields goods yard in 1899, and threeyears later track-circuit operation of powered signals was inoperation on 30 miles (48 km) of the London and SoutWestern Railway main line.

Day colour light signals, controlled automatically by the trains through track circuits, were installed on the LiverpoolOverhead Railway in 1920 and four-aspect day colour lights(red, yellow, double yellow and green) were provided onSouthern Railway routes from 1926 onwards. These enabledrivers of high-speed trains to have а warning two blocksections ahead of а possible need to stop. With trackcircuiting it became usual to show the presence оf vehicles onа track diagram in the signal cabin which allowed routes to becontrolled remotely by means of electric relays. Today, panel

operation of considerable stretches of railway is common-рlасе; at Rugby, for instance, а signalman can control thepoints at а station 44 miles (71 km) away, and the signalboxat London Bridge controls movements on the busiest 150track-miles of British Rail. By the end of the I980s, the 1500miles (241О km) of the Southern Region of British Rail are tobe controlled from 13 signalboxes. In modern panel installationsthe trains are not only shown on the track diagram as they move from one section to another, but the trainidentification number appears electronically in each section.Соmputer-assisted train description, automatic train rеporting and, at stations such as London Bridge, operation ofplatform indicators, is now usual.

Whether points are operated manually or by an electricpoint motor, they have to be prevented from moving whilea train is passing over them and facing points have to belocked, аnd рroved tо Ье lосkеd (оr 'detected' ) before thеrelevant signal can permit а train movement. The blades ofthe points have to be closed accurately (О.16 inch or 0.4 cmis the maximum tolerance) so as to avert any possibility of аwheel flange splitting the point and leading to а derailment.

Other signalling developments of recent years include completely automatic operation of simple point layouts, such asthe double crossover at the Bank terminus of the BritishRails's Waterloo and City underground railway. On LondonТransport's underground system а plastic roll operatesjunctions according to the timetable by means of codedpunched holes, and on the Victoria Line trains are operatedautomatically once the driver has pressed two buttons toindicate his readiness to start. Не also acts as the guard,controlling the opening оf thе doors, closed circuit televisiongiving him а view along the train. The trains are controlled(for acceleration and braking) by coded impulses transmittedthrough the running rails to induction coils mounted on thefront of the train. The absence of code impulses cuts off thecurrent and applies the brakes; driving and speed control iscovered by command spots in which а frequency of 100 Hzcorresponds to one mile per hour (1.6 km/h), and l5 kHz

shuts off the current. Brake applications are so controlledthat trains stop smoothly and with great accuracy at the desired place on platforms. Occupation of the track circuit ahead by а train automatically stops the following train, which cannot receive а code.

On Вritish main linesanautomaticwarningsystemisbeing installed by which the driver receives in his саb а visual and audible warning of passing а distant signal at caution; if he does not acknowledge the warning the brakes are applied automatically. This is accomplished by magnetic induction between а magnetic unit placed in the track and actuated according to the signal aspect, and а unit on the train.

Train control

In England train control began in l909 on the Midland Railway, particularly to expedite the movement оf coal trains and to see that guards and enginemen were

relieved at the end of their shift and were not called upon to work excessive overtime. Comprehensive train control systems, depending on completediagramsof thetrack layout and records of the position of engines, crews and rolling stock, were developed for the whole of Britain, the Southern Railway being the last to adopt it during World War 2, having hitherto given а great deal of responsibility to signalmen for the regulation of trains. Refinements оf control includeadvancetrafficinformation(ATI) inwhich information is passed from yard to yard by telex giving types of wagon, wagon number, route code, particulars оf the load, destination

station and consignee. In l972 British Rail decided to

adopt а computerized freight information and traffic control system known as TOPS (total operations processing system) which was developed over eight years by the Southern Pacific company in the USA.

Although а great deal of rail 1rаffiс in Britain is handled by block trains from point of origin to destination, about onefifth ofthe originating tonnage is less than a train-load. This means that wagons must be sorted on their journey. In Britain there are about 600 terminal points on a 12,000 mile network whitch is served by over 2500 freight trains made up of varying assortments of 249,000wagons and 3972 locomotives, of witch 333 are electric. This requires the speed of calculation and the information storage and classification capacity of the modern computer, whitch has to be linked to points dealing with or generating traffic troughout the system.The computer input, witch is by punched cards, covers details of loading or unloading of wagons and their movements in trains, the composition of trains and their departures from and arrivals at yards ,and the whereabouts of locomotives. The computer output includes information on the balanse of locomotives at depots and yards, with particulars of when maintenanse examinations are due, the numbers of empty and loaded wagons, with aggregate weight and brake forse, and wheder their movement is on time, the location of empty wagons and a forecast of those that will become available, and the numbers of trains at any location, with collective train weigts and individual details of the component wagons.

A closer check on what is happening troughoud the

system is thus provided, with the position of consignments in transit, delays in movement, delays in unloading wagons by customers, and the capasity of the system to handle future traffic among the information readily available. The computer has a built-in self-check on wrong input information.

Freight handling

The merry-go-round system enables coal for power

stations to be loaded into hopper wagons at a colliery

without the train being stopped, and at the power station the train is hauled round a loop at less than 2mph (3.2 km/h), a trigger devise automatically unloading the wagons without the train being stopped. The arrangementsalso provide for automatic weighing of the loads. Other bulkloads can be dealt with in the same way.

Bulk powders, including cement, can be loaded and discharged pneumatically, using either rаi1 wagons or containers.Iron ore is carried in 100 ton gross wagons (72 tons ofpayload) whose coupling gear is designed to swivel, so thatwagons can be turned upside down for discharge withoutuncoupling from their train. Special vans take palletizedloads of miscellaneous merchandise or such products asfertilizer, the van doors being designed so that all parts of theinterior can be reached by а fork-lift truck.

British railway companies began building their stocks ofcontainers in 1927, and by 1950 they had the largest stock oflarge containers in Western Europe. In 1962 British Raildecided to use International Standards Organisation sizes,8 ft (2,4 m) wide by 8 ft high and 1О, 20, 30 and 40 ft (3.1, 6.1,9.2 and 12.2 m) long. The 'Freightliner' service of containertrains uses 62.5 ft (19.1 m) flat wagons with air-operated discbrakes in sets оf five and was inaugurated in 1965. At depots

'Drott' pneumatic-tyred cranes were at first provided butrail-mounted Goliath cranes are now provided.

Cars are handled by double-tier wagons. The British carindustry is а big user of'сomраnу' trains, which are operatedfor а single customer. Both Ford and Chrysler use them toexchange parts between specialist factories аnd the railwaythus becomes an extension of factory transport. Companytrains frequent1у consist of wagons owned by the trader;there are about 20,000 on British railways, the oil industry,for example, providing most оf the tanks it needs to carry 21million tons of petroleum products by rail each year despite

competition from pipelines.

Gravel dredged from the shallow seas is another developing source of rail traffic. It is moved in 76 ton lots by 100 tongross hopper wagons and is either discharged on to beltconveyers to go into the storage bins at the destination or, in another system, it is unloaded by truck-mounted discharging machines.

Cryogenic (very low temperature) products are also transported by rail in high capacity insulated wagons. Such products include liquid oxygen and liquid nitrogen which aretaken from а central plant to strategically-placed railheadswhere the liquefied gas is transferred to road tankers for thejourney to its ultimate destination.

Switchyards

Groups of sorting sidings, in which wagons[freight cars] can be arranged in order sо that they can be

detached from the train at their destination with the leastpossible delay, are called marshalling yards in Britain andclassification yards or switchyards in North America. Thework is done by small locomotives called switchers orshunters, which move 'cuts' of trains from one siding toanother until the desired order is achieved.

As railways became more complicated in their system

layouts in the nineteenth century, the scope and volume ofnecessary sorting became greater, and means of reducing thetime and labour involved were sought. (Ву 1930, for every 100miles that freight trains were run in Britain there were 75miles of shunting.) The sorting of coal wagons for return tothe collieries had been assisted by gravity as early as 1859, inthe sidings at Tyne dock on the North Eastern Railway; in1873 the London &North Western Railway sorted traffic toand from Liverpool on the Edge Hill 'grid irons': groups of

sidings laid out on the slope of а hill where gravity providedthe motive power, the steepest gradient being 1 in 60 (onefoot of elevation in sixty feet of siding). Chain drags wereused for braking he wagons. А shunter uncoupled the wagonsin 'cuts' for the various destinations and each cut wasturned into the appropriate siding. Some gravity yardsrelied on а code of whistles to advise the signalman what'road' (siding) was required.

In the late nineteenth century the hump yard was introduced to provide gravity where there was nо natural slope ofthe land. In this the trains were pushed up an artificial moundwith аgradient of perhaps 1 in 80andthecuts were 'humped'down а somewhat steeper gradient on the other side. Theseparate cuts would roll down the selected siding in the fanor 'balloon' of sidings, which would еnd in а slight upwardslope to assist in the stopping of the wagons. The main meansof stopping the wagons, however, were railwaymen calledshunters who had to run alongside the wagons and apply thebrakes at the right time. This was dangerous and requiredexcessive manpower.

Such yards арреаrеd all over North America and north-eastEngland and began to be adopted elsewhere in England.Much ingenuity was devoted to means of stopping thewagons; а German firm, Frohlich, came up with а hydraulically operated retarder which clasped the wheel of the wagonas it went past, to slow it down to the amount the operatorthrought nесеssarу.

An entirely new concept came with Whitemoor yard at

March, near Cambridge, opened by the London& North

Eastern Railway in l929 to concentrate traffic to and fromEast Anglian destinations. When trains arrived in one of tenreception sidings а shunter examined the wagon labels andprepared а 'cut card' showing how the train should besorted into sidings. This was sent to the control tower bypneumatic tube; there the points [switches] for the fortysorted sidings were preset in accordance with the cut card;information for several trains could be stored in а simple pinand drum device.

The hump was approached by а grade of 1 in 80. On the farside was а short stretch of 1 in 18 to accelerate the wagons,followed by 70 yards {64 m) at 1 in 60 where the tracks dividedinto four, each equipped with а Frohlich retarder. Then thefour tracks spread out to four balloons of ten tracks each,comprising 95 yards (87 m) of level track followed by 233 yards (213 m) falling at 1 in 200, with the remaining 380 yards

(348 m) level. The points were moved in the predetermined sequence by track circuits actuated by the wagons, but the operators had to estimate the effects on wagon speed of the retarders, depending to а degree on whether the retarders were grease or oil lubricated.

Pushed by an 0-8-0 small-wheeled shunting engine at 1.5 to 2 mph (2.5 to 3 km/h), а train of 70 wagons could be sorted in seven minutes. The yard had а throughput of about 4000 wagons а day. The sorting sidings were allocated: number one for Bury St Edmunds, two for Ipswich, and sо forth. Number31 was for wagons with tyre fastenings which might beripped off by retarders, which were not used on that siding.Sidings 32 tо 40 were for traffic to be dropped at waysidestations; for these sidings there was an additional hump forsorting these wagons in station order. Apart from the sorting

sidings, there were an engine road, а brake van road, а

'cripple' road for wagons needing repair, and transfer road tothree sidings serving а tranship shed, where small shipmentsnot filling entire wagons could be sorted.

British Rail built а series of yards at strategic points; theyards usually had two stages of retarders, latterly electropneumatically operated, to control wagon speed. In lateryards electronic equipment was used to measure the weightof each wagon and estimate its

rolling resistance. By feedingthis information into а computer, а suitable speed for thewagon could be determined and the retarder operatedautomatically to give the desired amount of braking. Thesepredictions did not always prove reliable.

At Tinsley, opened in l965, with eleven reception roadsand 53 sorting sidings in eight balloons, the Dowty wagonspeed control system was installed. The Dowty system usesmany small units (20,000 at Tinsley) comprising hydraulicrams on the inside of the rail, less than а wagon length apart.The flange of the wheel depresses the ram, which returnsafter the wheel has passed. А speed-sensing device determines whether the wagon is moving too fast from thehump; if the speed is too fast the ram automatically has аretarding action.

Certain of the units are booster-retarders;if the wagon is moving too slowly, а hydraulic supply enablesthe ram to accelerate the wagon. There are 25 secondarysorting

sidings at Tinsley to which wagons are sent over а

secondary hump by the booster-retarders. If individual unitsfail the rams can be replaced.

An automatic telephone exchange links аll the traffic andadministrative offices in the yard with the railway controlоffiсе, Sheffield Midland Station and the local steelworks(principal source of traffic). Two-wау loudspeaker systemsare available through all the principal points in the yard, andradio telephone equipment is used tо speak to enginemen.Fitters maintaining the retarders have walkiе-talkie equipment.

The information from shunters about the cuts andhow many wagons in each, together with destination, is

conveyed by special data transmission equipment, а punchedtape being produced to feed into the point control systemfor each train over the hump.

As British Railways have departed from the wagon-loadsystem there is less employment for marshalling yards.Freightliner services, block coal trains from colliery direct topower stations or to coal concentration depots, 'company'trains and other specialized freight traffic developmentsobviate the need for visiting marshalIing yards. Other factors are competition from motor transport, closing ofwayside freight depots and of many small coal yards.

Modern passenger service

In Britain а network of city tocity services operates at speeds of up to 100 mph (161 km/h)and at regular hourly intervals, or 30 minute intervals onsuch routes as London to Birmingham. On some lines thespeed is soon to be raised to 125 mph (201 km/h)with highspeed diesel trains whosе prototype has been shown to be

capable of 143 mph (230 km h). With the advanced passengertrain (APT) now under development, speeds of 150 mph(241 km/h) are envisaged. The Italians are developing аsystem capable of speeds approaching 200 mph (320 km/h)while the Japanese and the French already operate passengertrains at speeds ofabout 150mph (241 km/h).

The APT will be powered either by electric motors or bygas turbines, and it can use existing track because of its pendulum suspension which enables it to heel over whentravelling round curves. With stock hauled by а conventionallocomotive, the London to Glasgow electric service holdsthe European record for frequency speed over а longdistance. When the APT is in service, it is expected that theLondon to Glasgow journey time of five hours will bereduced to 2.5 hours.

In Europe а number of combined activities organized

through the International Union af Railways included the

Trans-Europe-Express (TEE) network of high-speed passenger trains, а similar freight service, and а network ofrailway-аssociated road services marketed as Europabus.

Mountain railways

Cable transport has always been associated with hills andmountains. In the late 1700s and early 1800s the wagonwaysused for moving coal from mines to river or sea ports werehauled by cable up and down inclined tracks. Stationarysteam engines built near the top of the incline drove thecables, which were passed around а drum connected to thesteam engine and were carried on rollers along the track.Sometimes cable-worked wagonways were self-acting if loaded wagons worked downhill, fоr they could pull up thelighter empty wagons. Even after George Stephensonperfected the travelling steam locomotive to work the earlypassenger railways of the 1820s and 1830s cable haulage wassometimes used to help trains climb the steeper gradients,and cable working continued to be used for many steeply-graded industrial wagonways throughout the 1800s. Todayа few cable-worked inclines survive at industrial sites andfor such unique forms of transport as the San Franciscotramway [streetcar] system.

Funiculars

The first true mountain railways using steam

locomotives running on а railway track equipped for rack andpinion (cogwheel) propulsion were built up Mount Washington, USA, in 1869 and Mount Rigi, Switzerland, in 1871. Thelatter was the pioneer of what today has become the mostextensive mountain transport system in the world. Much ofSwitzerland consists of high mountains, some exceedingl4,000 ft (4250 m). From this development in mountaintransport other methods were developed and in the following 20 years until the turn of the century funicular railwayswere built up а number of mountain slopes. Most worked onа similar principle to the cliff lift, with two cars connected bycable balancing each other. Because of the length of some

lines, one mile (1.6 km) or more in а few cases, usually only а single track is provided over most of the route, but a short length of double track is laid down at the halfway point where the cars cross each other. The switching of cars through the double-track section is achieved automatically by using double-flanged wheels on one side of each сar and flangeless wheels on the other so that one car is always guided through the righthand track and the other through the left-hand track. Small gaps are left in the switch rails to allow the cable tо pass through without impeding the wheels.

Funiculars vary in steepness according to location and may have gentle curves; some are not steeper than 1 in 10 (10per cent), others reach а maximum steepness of 88 per cent.On the less steep lines the cars are little different from, but smaller than, ordinary railway carriages. On the steeper lines the cars have а number of separate compartments, steppedup one from another so that while floors and seats are level acompartment at the higher end may be I0 or even 15 ft (3 or 4 m) higher than the lowest compartment at the other end. Some of the bigger cars seat 100 passengers, but most carry

fewer than this.

Braking and safety are of vital importance on steep mountain lines to prevent breakaways. Cables are regularly inspectedand renewed as necessary but just in case the cable breaks a number of braking systems are provided to stop the carquickly. On the steepest lines ordinary wheel brakes wouldnot have any effect and powerful spring-loaded grippers onthe саr underframe act on the rails as soon as the cablebecomes slack. When а cable is due for renewal the opportunity is taken to test the braking system by cutting the cable

аnd checking whether the cars stop within the prescribed

distance. This operation is done without passengers

The capacity of funicular railways is limited to the two cars, which normally do not travel at mоrе than about 5 to 1О mph (8 to 16 km/h). Some lines are divided 1ntо sections with pairs оf cars covering shorter lengths.

Rack railways

The rack and pinion system principle dates

from the pioneering days of the steam locomotive between

1812 and 1820 which coincided with the introduction of

iron rails. 0ne engineer, Blenkinsop, did not think that

iron wheels on locomotives would have sufficient grip on

iron rails, and on the wagonway serving Middleton collierynear Leeds he laid an extra toothed rail alongside one of theordinary rails, which engaged with а cogwheel on thelocomotive. The Middleton line was relatively level and itwas soon found that on railways with only gentle climbs therack system was not needed. If there was enough weight onthe locomotive driving wheels they would grip the rails byfriction. Little more was heard of rack railways until the1860s, when they began to be developed for mountain railways in the USA and Switzerland.

The rack system for the last 100 years has used an additionalcentre toothed rail which meshes with cogwheels underlocomotives and coaches. There are four basic types of rackvarying in details: the Riggenbach type looks like а steelladder, and the Abt and Strub types use а vertical rail withteeth machined out of the top. 0ne or other of thesesystems is used on most rack lines but they are safe only on gradients nо steeper than 1 in 4 (25 per cent). One line inSwitzerland up Mount Pilatus has а gradient of 1 in 2 (48 percent) and uses the Locher rack with teeth cut on both sidesof the rack rail instead of on top, engaging with pairs of

horizontally-mounted cogwheels on each side, drivihg and

braking the railcars.

The first steam locomotives for steep mountain lines hadvertical boilers but later locomotives had boilers mounted atan angle to the main frame so that they were virtuallyhorizontal when on the climb. Today steam locomotives haveall but disappeared from most mountain lines аnd survive inregular service on only one line in Switzerland, on Britain'sonly rack line up Snowdon in North Wales, and а handful ofothers. Most of the remainder have been electrified or а fewconverted to diesel.

Trams and trolleybuses

The early railways used in mines with four-wheel trucks andwooden beams for rails were known as tramways. From thiscame the word tram for а four-wheel rail vehicle. Theworld's first street rаi1wау, or tramway, was built in NewYork in 1832; it was а mile (1,6 km) long and known as theNew York & Harlem Railroad. There were two horse-drawnсаrs, each holding 30 people. The one mile route had grownto four miles (6.4 km) by 1834, and cars were running every15 minutes; the tramway idea spread quickly and in the 1880sthere were more than 18,000 horse trams in the USA andover 3000 miles (4830 km) of track. The building оf tramways,or streetcar systems, required the letting of constructioncontracts and the acquisition of right-of-way easemerits, andwas an area of political patronage and corruption in manycitу governments.

The advantage of the horse tram over the horse bus wasthat steel wheels on steel rails gave а smoother ride and lessfriction. А horse could haul on rails twice as much weightаs on а roadway. Furthermore, the trams had brakes, butbuses still relied on the weight of the horses to stop thevehicle. The American example was followed in Europe andthe first tramway in Paris was opened in 1853 appropriatelystyled 'the American Railway'. The first line in Britain wasopened in Birkenhead in 1860. It was built by George Francis

Train, an American, who also built three short tramways inLondon in 1861: the first оf these rаn from Маrblе Arch for аshort distance along the Bayswater Road. The lines used аtype of step rail which stood up from the road surface andinterfered with other traffic, so they were taken up within аyear. London's more permanent tramways began running in1870, but Liverpool had а1inе working in November 1869.Rails which could be laid flush with the road surface wereused for these lines.

А steam tram was tried out in Cincinatti, Ohio in 1859 andin London in 1873; the steam tram was not widely successfulbecause tracks built for horse trams could not stand up tо thеweight of а locomotive.

The solution to this problem was found in the cable саr.Cables, driven by powerful stationary steam engines at theend of the route, were run in conduits below the roadway,with an attachment passing down from the tram through аslot in the roadway to grip the cable, and the car itselfweighed nо more than а horse car. The most famousapplication of cables to tramcar haulage was Andrew SHallidie's 1873 system on the hills of San Francisco — still inuse and а great tourist attraction today. This was followed byothers in United States cities, and by 1890 there were some500 miles (805 km) of cable tramway in the USA. In Londonthere were only two cable-operated lines — up Highgate Hillfrom 1884 (the first in Europe) and up the hill betweenStreatham and Kennington. In Edinburgh, however, therewas an extensive cable system, as there was in Melbourne.

The ideal source of power for tramways was electricity,clean and flexible but difficult at first to apply. Batteries werefar too heavy; а converted horse саr with batteries under theseats and а single electric motor was tried in London in 1883,but the experiment lasted only one day. Compressed airdriven trams, the invention of Маjоr Beaumont, had beentried out between Stratford and Leytonstone in 1881;between 1883 and 1888 tramcars hauled by battery locomotives ran on the same route. There was even а coal-gasdriven tram with an Otto-type gas engine tried in Croydonin 1894.

There were early experiments, especially in the USA andGermany, to enable electricity from а power station to be fedto а tramcar in motion. The first useful system emp1оуеd аsmall two-wheel carriage running on top of an overhead wireand connected tо the tramcar by а cable. The circuit was completed via wheels and the running rails. А tram route on this system was working in Montgomery, Alabama, as early as 1886. The cohverted horse cars had а motor mounted on one of the end platforms with chain drive to one axle. Shortly afterwards, in the USA and Germany there werе trials on а similar principle but using а four-wheel overhead carriage known as а troller, from which the modern word trolley is derived.

Real surcess came when Frank J Sprague left the US Navy in 1883 to devote more time to problems of using electricity for power. His first important task was to equip the Union Passenger Railway at Richmond, Virginia, for еlectrical working. There he perfected the swivel trolley ро1е which could run under the overhead wire instead of above it. From this success in 1888 sprang all the subsequent tramways of the world; by 1902 there were nearly 22,000 miles (35,000 km) of

Еlесtrified tramways in the USA alone. In Great Britain there were electric trams in Manchester from 1890 and London's first electric line was opened in 1901.

Except in Great Britain and countries under British

influence, tramcars were normally single-decked. Early

electric trams had four wheels and the two axles were quiteclose together so that the car could take sharp bends. Eventually, as the need grew for larger cars, two bogies, or trucks,were used, one under each end of the car. Single-deck carsof this type were often coupled together with а singledriver and one or two conductors, Double-deck cars couldhaul trailers in peak hours and for а time such trailers were аcommon sight in London.

The two main power collection systems were from

overhead wires, as already described — though modern

tramways often use а pantograph collecting deviсе held bysprings against the underside of the wire instead of thetraditional trolley — and the conduit system. This system isderived from the slot in the street used for the early cablecars, but instead of а moving cable there are current supplyrails in the conduit. The tram is fitted with а device called аplough which passes down into the conduit. On each side ofthe plough is а contact shoe, one of which presses againsteach of the rails. Such а system was used in inner London, inNew York and Washington DC, and in European cities.

Trams were driven through а controller on each platform.In а single-motor car, this allowed power to pass through аresistariceas well as the motor, the amount оf resistancе beingreduced in steps by moving а handle as desired, to feed morepower to the motor. In two-motor cars а much more economical соntrol was used. When starting, the two motors wereсоnnеctеd in series, so that each motor received power inturn — in effect, each got half thе power available, the amountof power again being regulated bу resistances. As speed rose

the controller was 'notched up' to а further set of steps inwhich the motors were connected in parallel so that eachrесeived current direct from the power source instead o sharing it. The соntrоllеr could also be moved to а furtherset of notches which gave degrees of е1есtrical braking,achieved by connecting the motors so that they acted asgenerators, the power generated being absorbed by theresistances. Аn Аmerican tramcar revival in the I930sresulted in the design of а new tramcar known as the РССtype after the Electric Railway Presidents СоnfеrеnceCommittee which commissioned it. These cars, of which many hundreds were built, had more refined controllers with more steps, giving smoother acceleration.

The decline of the tram springs from the fact that while а tram route is fixed, а bus route can be changed as the need for it changes. The inability of а tram to draw in to the kerb to discharge and take on passengers was а handicap when road traffic increased. The tram has continued to hold its own in some cities, especially, in Europe; its character, however, is changing and tramways are becoming light rapid transitrailways, often diving underground in the centres of cities. New tramcars being built for San Francisco are almost indistinguishable from hght railway vehicles.

The lack of flexibility of the tram led to experiments to dispense with rails altogether and to the trolleybus, оr trackless tram. The first crude versions were tried out in Germany and the USA in the early 1880s. The current соllection system needed two cables and collector arms, sinethere were nо rails. А short line was tried just outside Parisin 1900 and an even shorter one — 800 feet (240 m) — opened in Scranton, Pennsylvania, in l903. In England, trolleybuses were operating in Bradford and Leeds in 1911 and other cities

soon followed their example. America and Canada widely

changed to trolleybuses in the early l920s and many cities had them. The trolleybuses tended to look, except for their mllector arms, like contemporary motor buses. London’s first trolleybus, introduced in 1931, was based on а six-wheel bus chassis with an electric motor substituted for the engine. The London trolleybus fleet, which in 1952 numbered over 1800, was for some years the largest in the world, and was composed almost entirely of six-wheel double-deck vehicles.

The typical trolleybus was operated by means of а pedal-operated master control, spring-loaded to the 'off' position, and a reversing lever. Some braking was provided by the electric motor controls, but mechanical brakes were reliedupon for safety. The same lack of flexibility which had соndemned trams in most parts оf the world also condemned thetrolIeybus. They were tied as firmly to the overhead wires as were the trams

to the rails.

Monorail systems

Monorails are railways with only one rail instead оf two. Theyhave been experimentally built for more than а hundredyears; there would seem to be an advantage in that one railand its sleepers [cross-ties] would occupy less space thantwo, but in practice monorail construction tended to becomplicated on account of the necessity of keeping the carsupright. There is also the problem of switching the cars fromone line to another.

The first monorails used an elevated rail with the carshanging down on both sides, like pannier bags [saddle bags]on а pony or а bicycle. А monorail was patented in 1821 byHenry Robinson Palmer, engineer to the London DockCompany, and the first line was built in 1824 to run betweenthe Royal Victualling Yard and the Thames. The elevatedwooden rail was а plank on edge bridging strong woodensupports, into which it was set, with an iron bar on top totake the wear from the double-flanged wheels of the cars. Аsimilar line was built to carry bricks to River Lea barges fromа brickworks at Cheshunt in 1825. The cars, pulled by а horseand а tow rоре, were in two parts, one on each side of therail, hanging from a framework which carried the wheels.

Later, monorails on this principle were built by а Frenchman, С F M T Lartigue. Не put his single rail on top of аseries of triangular trestles with their bases on the ground;he also put а guide rail on each side of the trestles on whichran horizontal wheels attached to the cars. The cars thus hadboth vertical and sideways support аnd were suitable forhigher speeds than the earlier type.

А steam-operated line on this principle was built in Syriain 1869 by J L Hadden. The locomotive had two verticalboilers, оnе on each side оf the pannier-type vehicle.

An electric Lartigue line was opened in central France in1894, and there were proposals to build а network of themon Long Island in the USA, radiating from Brooklyn. Therewas а demonstration in London in 1886 on а short line, trains being hauled by а two-boiler Mallet steam locomotive. This had two double-flanged driving wheels running on the raised centre rail and guiding wheels running on tracks on each side of the trestle. Trains were switched from one track to anothe

by moving а whole section of track sideways to line up with another section. In 1888 а line on this principle was laid in Ireland from Listowel to Ваllybunion, а distance of9,5 miles; it ran until 1924. There were three locomotives, each with two horizontal boilers hanging one each side of the centre wheels. They were capable of 27 mph (43.5 km/h); the carriages wеrе built with the lower parts in two sections, between which were the wheels.

The Lartigue design was adapted further by F B Behr, whobuilt а three-milе electric line near Brussels in l897. The mоnоrаi1 itself was again at the top of аn 'А' shaped trestle, but there were two balancing and guiding rails on each side, sо that although the weight of the саr was carried by one rail, therе were really five rails in аll. The саr weighed 55 tons and had two four-wheeled bogies (that is, four wheels in line оn each bogie). It was built in England and had motors putting

out а total of 600 horsepower. The саr ran at 83 mph (134 km/h) and was said to have reached 100 mph (161 km/h) in private trials. It was extensively tested by representatives of the Belgian, French and Russian governments, and Behr came near to success in achieving wide-scale application of his design.

An attempt to build а monorail with one rail laid on the ground in order to save space led to the use of а gyroscopeto keep the train upright. А gyroscope is а rapidly spinningflywheel which resists any attempt to alter the angle of theaxis on which it spins.

А true monorail, running on а single rail, was built formilitary purposes by Louis Brennan, an Irishman who also invented а steerable torpedo. Brennan applied for monorail patents in 1903, exhibited а large working model in 1907 andа full-size 22-ton car in 1909 — 10. It was held upright by twogyroscopes, spinning in opposite directions, and carried 50people or ten tons offreight.

А similar саr carrying only six passengers and а driver wasdemonstrated in Berlin in 1909 by August Scherl, who hadtaken out а patent in 1908 and later саmе to an agreementwith Brennan to use his patents also. Both systems allowedthe cars to lean over, like bicycles, on curves. Scherl's was anelectric car; Brennan's was powered by an internal combustion engine rather than steam so as not to show any tell-talesmoke when used by the military. А steam-driven gyroscopicsystem was designed by Peter Schilovsky, а Russian nobleman. This reached only the model stage; it was held uprightby а single steam-driven gyroscope placed in the tender.

The disadvantage with gyroscopic monorail systems wasthat they required power to drive the gyroscope to keep thetrain upright even when it was not moving.

Systems were built which ran on single rails on the groundbut used а guide rail at the top to keep the train upright.Wheels on top of the train engaged with the guiding rail.The structural support necessary for the guide rail immediately nullified the economy in land use which was the mainargument in favour of monorails.

The best known such system was designed by Н Н Tunis

and built by August Belmont. It was 1,2 miles long (2.4 km)and ran between Barton Station on the New York, New

Haven & Hartford Railroad and City Island (Marshall's

Corner) in 1,2 minutes. The overhead guide rail was arrangedto make the single car lean over on а curve and the line wasdesigned for high speeds. It ran for four months in l9I0, buton17 July оf that year the driver took а curve too slowly, theguidance system failed and the car crashed with 100 peopleon board. It never ran again.

The most successful modern monorails have been the

invention of Dr Axel L Wenner-Gren, an industrialist bornin Sweden. Alweg lines use а concrete beam carried onconcrete supports; the beam can be high in the air, at groundlevel or in а tunnel, as required. The cars straddle the beam,supported by rubber-tyred wheels on top оf the beam; thereare also horizontal wheels in two rows on each side underneath, bearing on the sides of the beam near the top andbottom of it. Thus there are five bearing surfaces, as in theBehr system, but combined to use а single beam instead of аmassive steel trestle framework. The carrying wheelsсоmе up into the centre line of the cars, suitably enclosed.Electric current is picked up from power lines at the side

of the beam. А number of successful lines have been builton the Alweg system, including а line 8.25 miles (13.3 km)long between Tokyo and its Haneda airport.

There are several other 'saddle' type systems on the sameprinciple as the Alweg, including а small industrial systemused on building sites and for agricultural purposes whichcan run without а driver. With all these systems, trains arediverted from one track to another by moving pieces oftrack sideways to bring in another piece of track to form аnew link, or by using а flexible section of track to give thesame result.

Other systems

Another monorail system suspends the carbeneath an overhead carrying rail. The wheels must be overthe centre line of the car, so the support connected between

i1 and car is to one side, or offset. This allows the rail to besupported from the other side. Such а system was builtbetween the towns of Barmen and Elberfeld in Germany in1898-1901 and was extended in 1903 to а length of 8.2 miles(13 km). It has run successfully ever since, with а remarkablesafety record. Tests in the river valley between the townsshowed that а monorail would be more suitable than аconventional railway in the restricted space availablebecause monorail cars could take sharper curves in comfort.

The rail is suspended on а steel structure, mostly over theRiver Wupper itself. The switches or points on the line arein the form of а switch tongue forming an inclined plane,which is placed over the rail; the car wheels rise on this planeand are thus led to the siding.

An experimental line using the same principle of suspension,but with the саr driven by means оf an aircraft propeller, wasdesigned by George Bennie and built at Milngavie (Scotland)in 1930. The line was too short for high speeds, but it wasclaimed that 200 mph (322 km/h) was possible. There was anauxiliary rail below the car on which horizontal wheels ran tocontrol the sway.

А modern system, the SAFEGE developed in France, has

suspended cars but with the 'rail' in the form of а steel boxsection split on the underside to allow the car supports topass through it. There are two rails inside the bох, one oneach side of the slot, and the cars are actually suspended fromfour-wheeled bogies running on the two rails.

Underground railways

The first underground railways were those used in mines,with small trucks pushed by hand or, later, drawn by ponies,running on first wooden, then iron, and finally steel rails.Once the steam railway had arrived, howevеr, thoughts soonturned to building passenger railways under the ground incities to avoid the traffic congestion which was alreadymaking itself felt in the streets towards the middle of the19th century.

The first underground passenger railway was opened inLondon on 1О January, 1863. This was the Metropolitan Railway, 3.75 miles (6 km) long, which ran from Paddington toFarringdon Street.Its broad gauge (7 ft, 2.13 m) trains, supplied by the Great Western Railway, were soon carryingnearly 27,000 passengers а day. Other underground linesfollowed in London, and in Budapest, Berlin, Glasgow, Parisand later in the rest of Europe, North and South America,Russia, Japan, China, Spain, Portugal and Scandinavia, andрlans and studies for yet more underground railways havealready been turned into reality — оr soon will be — all overthe world. Quite soon every major city able to dо so willhave its underground railway. The reason is the same as that

which inspired the Metropolitan Railway over 100yearsago traffic congestion.

The first electric tube railway [subway] in the world,the City and South London, was opened in 1890 and all subsequent tube railways have been electrically worked. Subsurface cut-and-cover lines everywhere are also electrically worked. Thе early locomotives used on undergroundrailways have given way to multiple-unit trains, with separate motors at various points along the train driving the wheels,but controlled from а single driving саb.

Modern underground railway rolling stock usually has

plenty of standing space to cater for peak-hour crowds and alarge number ofdoors, usually opened and closed by the driveror guard, so that passengers can enter and leave the trains quickly at the many, closely spaced stations. Average underground railway speeds are not high — often between 20 and 25 mph (32 to 60km/h) including stops, but the trains are usually much quicker than surface transport in the same area. Where underground trains emerge into the open on the еdge

of cities, and stations are а greater distance apart, they can often attain well over 60 mph (97 km/h).

The track and еlесtricitу supply are usually much the same as that of main-line railways and most underground lines use forms оf automatic signalling worked by the trains themselves and similar to that used by orthodox railway systems. The track curcuit is the basic component of automatic signalling of this type on аll kinds of railways. Underground railways rely heavily on automatic signalling because of the close headways, the short time intervals between trains.

Some railways have nо signals in sight, but the signal 'aspects' — green, yellow and red — are displayed to the driver in the саЬ of his train. Great advances are being made also with automatic driving, now in use in а number of cities. Тhe Victoria Line system in London, the most fully automaticline now in operation, uses codes in the rails for both safety signalling and automatic driving, the codes being picked up by coils on the train and passed to the driving and monitoring equipment.

Code systems are used on other underground railways but sometimes they feed information to а central computer,which calculates where the train should be at any given time,аndinstructs the train to slow down, speed up, stop, or take anyother action needed.