The history of railways (История железных дорог)
The history of railways (История железных дорог)
The history of railways
The railway is а good example of а system evolved in variousplaces to
fulfil а need and then developed empirically. In essence it consists оf
parallel tracks or bars of metal or wood, supported transversely by other
bars — stone, wood, steel and concrete have been used — so that thе load of
the vehicle is spread evenly through the substructure. Such tracks were
used in the Middle Ages for mining tramways in Europe; railways came to
England in the 16th century and went back to 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
in 1758, and the first for а public railway, to carry the traffic of all
comers, dates from 1801. The Stockton and Dailington Railway, opened on 27
September 1825, was the first public steam railway in the world, although
it had only one locomotive 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 conveying heavy loads
and passengers brought about а proliferation of projects. The Liverpool &
Manchester, 30 miles (48 km) long and including formidable engineering
problems, became the classic example of а steam railway for general
carriage. It opened on 15 September 1830 in the presence of the Duke of
Wellington, who had been Prime Minister until earlier in the year. On
opening day, the train stopped for water and the passengers alighted on to
the opposite track; another locomotive came along and William Huskisson, an
МР and а great advocate of the railway, was killed. Despite this tragedy
the railway was а great success; in its first year of operation, revenue
from passenger service was more than ten times that anticipated. Over 2500
miles of railway had been authorized in Britain and nearly 1500 completed
by 1840.
Britain presented the world with а complete system for the construction
and operation of railways. Solutions were found to civil engineering
problems, motive power designs and the details of rolling stock. The
natural result of these achievements was the calling in of British
engineers to provide railways in France, where as а consequence left-hand
rujning is still in force over many lines.
Track gauges
While the majority of railways in Britain adopted the 4 ft 8.5 inch
(1.43 m) gauge of the Stockton &
Darlington Railway, the Great Western, on the advice of its brilliant but
eccentric engineer Isambard Kingdom Brunel, had been laid to а seven foot
(2.13 m) gauge, as were many of its associates. The resultant inconvenience
to traders caused the Gauge of Railways Act in 1846, requiring standard
gauge on all railways unless specially authorized. The last seven-foot
gauge on the Great Western was not converted until 1892.
The narrower the gauge the less expensive the construction and
maintenance of the railway; narrow gauges have been common 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 which locomotives were built to the designs of Robert Fairlie.
Не then led а campaign for the construction of narrow gauges. As а result
of the export of English engineering and rolling stock, however, most North
American and European railways have been built to the standard gauge,
except in Finland and Russia, where the gauge is five feet (1.5 m).
Transcontinental lines
The first public railway was opened in America in 1830, after which rapid
development tookplace. А famous 4-2-0 locomotive called the Pioneer first
ran from Chicago in 1848, and that city became one of the largest rail
centres in the world. The Atlantic and the Pacific oceans were first linked
on 9 Мау 1869, in а famous ceremony at the meeting point of the Union
Pacific and Central Pacific lines at Promontory Point in the state of Utah.
Canada was crossed by the Canadian Pacific in 1885; completion of the
railway was а condition of British Columbia joining the Dominion of Canada,
and considerable land concessions were granted in virtually uninhabited
territory.
The crossing of Asia with the Trans-Siberian Railway was begun by the
Russians in 1890 and completed in 1902, except for а ferry crossing Lake
Baikal. The difficult passage round the south end of the lake, with many
tunnels, was completed in 1905. Today more than half the route is
electrified. In 1863 the Orient Express ran from Paris for the first time
and eventually passengers were conveyed all the way to Istanbul
(Constantinople).
Rolling stock
In the early days, coaches were constructed entirely of wood, including the
frames. Ву 1900, steel frames were commonplace; then coaches were
constructed entirely of steel and became very heavy. One American 85-foot
(26 m) coach with two six-wheel bogies weighed more than 80 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. The savings began
with the bogies, which were built without conventional springs, bolsters
and so on; with only two air springs on each four-wheel bogie, the new
design reduced the weight from 8 to 2,5 tons without loss оf strength or
stability.
In the I880s, 'skyscraper' cars were two-storey wooden vans with
windows used as travelling dormitories for railway workers in the USA; they
had to be sawn down when the railways began to build tunnels through the
mountains. After World War II double-decker cars of а mоrе compact design
were built, this time with plastic domes, so that passengers could enjoy
the spectacular scenery on the western lines, which pass through the Rocky
Mountains.
Lighting on coaches was by means of oil lamps at first; then gas 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, provided electricity, storage batteries being used for when the
car was standing. Heating on coaches was provided in the early days
by metal containers filled with hot water; then steam was piped from the
locomotive, an extra drain on the engine's power; 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. George Pullman's first cars ran on
the Chicago & Alton Railroad in 1859 and the Pullman Palace Car Company was
formed in 1867. The first Pullman cars operated in Britain in 1874, а year
after the introduction of sleeping cars by two British railways. In Europe
in 1876 the International Sleeping Car Company was formed, but in the
meantime George Nagelmackers of Liege and an American, Col William D'Alton
Маnn, began operation between Paris and Viennain 1873.
Goods vans [freight cars] have developed according to the needs of the
various countries. On the North American continent, goods trains as long as
1,25 miles are run as far as 1000 miles unbroken, hauling bulk such as raw
materials and foodstuffs. Freight cars weighing 70 to 80 tons have two four
wheel bogies. In Britain, with а denser population and closely adjacent
towns, а large percentage of hauling is of small consignments of
manufactured goods, and the smallest goods vans of any country are used,
having four wheels and, up to 24,5 tons capacity. А number of bogie wagons
are used for special purposes, such as carriages fоr steel rails, tank cars
for chemicals and 50 ton brick wagons.
The earliest coupling system was links and buffers, which allowed jerky
stopping and starting. Rounded buffers brought snugly together by
adjustment of screw links with springs were an improvement. The buckeye
automatic coupling, long standard in North America, is now used in Britain.
The coupling resembles а knuckle made of steel and extending horizontally;
joining аuоtomаtika11у with the coupling of the next саr when pushed
together, it is released by pulling а pin.
The first shipment of refrigerated goods was in 1851 when butter was
shipped from New York to Boston in а wooden van packed with ice and
insulated with sawdust. The bulk of refrigerated 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 of
mechanical 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 the cool 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 of its railways than the
Confederacy (South). The war 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 briefly taken over by the government for the
only time in that nation's history.
In World War 2, by contrast, the American railways performed
magnificently, moving 2,5 times the level of freight in 1944 as in 1938,
with minimal increase in equipment, and supplying more than 300,000
employees to the armed forces in various capacities. In combat areas, and
in later conflicts such as the Korean war, it proved difficult to disrupt
an enemy's rail system effectively; pinpoint bombing was difficult,
saturation bombing was expensive and in any case railways 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 provided ways 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 and Netherlands railways began in 1839; Italy
nationalized her railways in 1905-07 and the Netherlands in the period 1920-
38. In Britain the main railways were nationalized from 1 January 1948; the
usual European pattern is that the State owns the main lines and minor
railways are privately owned or operated by local authorities.
In the United States, between the Civil War and World Wаr 1 the
railways, along with all the other important inndustries, experienced
phenomenal growth as the country developed. There were rate wars and
financial piracy during а period of growth when industrialists were more
powerful than the national government, and finally the Interstate Commerce
Act was passed in l887 in order to regulate the railways, which had а near
monopoly of transport. After World War 2 the railways were allowed to
deteriorate, as private car ownership became almost universal and public
money was spent on an interstate highway system making motorway haulage
profitable, despite the fact that railways are many times as efficient at
moving freight and passengers. In the USA, nationalization of railways
would probably require an amendment to the Constitution, but since 1971 а
government effort has been made to save the nearly defunct passenger
service. On 1 May of that year Amtrack was formed by the National Railroad
Passenger Corporation to operate а skeleton service of 180 passenger trains
nationwide, serving 29 cities designated by the government as those
requiring train 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 for haulage, that
steam generation could be stimulated by turning 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 of the 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 running rails. William Hedley was building smooth-whilled
locomotives which 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 earlier designers. Until
this time nearly all machines had the cylinders partly immersed in the
boiler and usually vertical. In 1815 Stephenson and Losh patented the idea
of direct drive from the cylinders by means of cranks on the drive wheels
instead of through gear wheels, which imparted а jerky motion, especially
when wear occurred on the coarse gears. Direct drive allowed а simplified
layout and gave greater 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 not decided between locomotives and саblе haulage,
with railside steam engines pulling the cables. They organized а
competition which was won by Stephenson in 1829, with his famous 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, in which а nest
of fire tubes, giving more heating surface, ran from the firebox tube-plate
to а similar tube-plate at the smokebox end. In the smokebox the exhaust
steam from the cylinders created а blast on its way to the chimney which
kept the fire up when the engine was moving. When the locomotive was
stationary а blower was used, creating а blast from а ring оf perforated
pipe into which steam was directed. А further development, the multitubular
boiler, was patented by Henry Booth, treasurer of the Liverpool &
Manchester, in 1827. It was incorporated by Stephenson in the Rocket, after
much trial and error in making the ferrules of 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 smokebox end and the fireman's
stand at the firebox end.
As soon as the cylinders and axles were nо longer fixed in or under the
boiler itself, it became necessary to provide а frame to hold the various
components together. The bar frame 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 frame was superseded in
Britain by the plate frame, with cylinders inside the frame, spring
suspension (coil or laminated) for the 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 designs with cylinders inside the
frame transmitted the motion to crank-shaped axles rather than to eccentric
pivots on the outside of the drive wheels; there were also compound
locomotives, with the steam passing from а first cylinder or cylinders to
another set of larger ones.
When steel came into use for building boilers after 1860, higher
operating pressures became possible. By the end of the nineteenth century
175 psi (12 bar) was common, with 200 psi (13.8 bar) for compound
locomotives. This rose to 250 psi (17.2 bar) later in the steam era. (By
contrast, Stephenson's Rocket only developed 50 psi, 3.4 bar.) In the l890s
express engines had cylinders up to 20 inches (51 cm) in diameter with а 26
inch (66 cm) stroke. Later diameters increased to 32 inches (81 cm) in
places like the USA, where there was more room, and locomotives and rolling
stock in general were built larger.
Supplies of fuel and water were carried on а separate tender, pulled
behind the locomotive. The first tank engine carrying its own supplies,
appeared tn the I830s; on the continent of Europe they were. confusingly
called tender engines. Separate tenders continued to be common because they
made possible much longer runs. While the fireman stoked the firebox, the
boiler had to be replenished with water by some means under his control;
early engines had pumps 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
plates were developed to direct the hot gases from the coal to pass over
the flames, so that а relatively clean blast came out of
the chimney and the cheaper fuel could be burnt. After 1860 this simple
expedient was universа11у adopted. Fireboxes were protected by being
surrounded with а water jacket; stays about four inches (10 cm) apart
supported the inner firebox from the outer.
Steam was distributed to the pistons by means of valves. The valve gear
provided for the valves to uncover the ports at different parts of the
stroke, so varying the cut-off to provide for expansion of steam already
admitted to the cylinders and to give lead or cushioning by letting the
steam in about 0.8 inch (3 mm) from the end of the stroke to begin the
reciprocating motion again. The valve gear also provided for reversing by
admitting steam to the opposite side of the piston.
Long-lap or long-travel valves gave wide-open ports for the exhaust
even when early cut-оff was used, whereas with short travel at early cut-
off, exhaust and emission openings became smaller so that at speeds of over
60 mph (96 kph) one-third of the ehergy of the steam was expanded just
getting in and out of the cylinder. This elementary fact was not
universal1y
accepted until about 1925 because it was felt that too much extra wear
would occur with long-travel valve layouts.
Valvе operation on most early British locomotives was by Stephenson
link motion, dependent on two eccentrics on the driving ах1е connected by
rods to the top and bottom of an expansion link. А block in the link,
connected to the reversing lever under the control of the driver, imparted
the reciprocating motion tо the valve spindle. With the block at the top of
the link, the engine would be in full forward gear and steam would be
admitted to the cylinder for perhaps 75% of the stoke. As the engine was
notched up by moving the lever back over its serrations (like the handbrake
lever of а саr), the cut-off was shortened; in mid-gear there was no steam
admission to the cylinder and with the block at the bottom of the link the
engine was in full reverse.
Walschaert's valvegear, invented in 1844 and in general use after 1890,
allowed more precise adjustment and easier operation for the driver. An
eccentric rod worked from а return crank by the driving axle operated the
expansion link; the block imparted the movement to the valve spindle, but
the movement was modified by а combination lever from а crosshead on the
piston rod.
Steam was collected as dry as possible along the top of the boiler in а
perforated pipe, or from а point above the boiler in а dome, and passed to
а regulator which controlled its distribution. The most spectacular
development of steam locomotives for heavy haulage and high speed runs was
the introduction of superheating. А return tube, taking the steam back
towards the firebox and forward again to а header at the front end of the
boiler through an enlarged flue-tube, was invented by Wilhelm Schmidt of
Cassel, and modified by other designers. The first use of such equipment in
Britain was in 1906 and immediately the savings in fuel and especially
water 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-offs as 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] provided electric light.
Steam locomotives are classified according to the number of wheels.
Except for small engines used in marshalling уаrds, all modern steam
locomotives had leading wheels on a pivoted 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 a 4-4-0,
having four leading wheels, four driving wheels and no trailing wheels. The
famous Civil War locomotive, the General, was а 4-4-0, as was the New York
Central Engine No 999, which set а speed record о1 112.5 mph (181 kph) in
1893. Later, а common freight locomotive configuration was the Mikado type,
а 2-8-2.
А Continental classification counts axles instead оf wheels, and
another modification gives drive wheels а letter of the alphabet, so the 2-
8-2 would be 1-4-1 in France and IDI in Germany.
The largest steam locomotives were articulated, with two sets 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 on sharp 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 are now obsolete,
replaced by electric and especially diesel-electric locomotives. Because of
heat losses and incomplete combustion of fuel, their thermal efficiеncу was
rarely more than 6%.
Diesel locomotives
Diesel locomotives are most commonly diesel-electric. А diesel engine
drives а dynamo [generator] which provides power for electric motors which
turn the
drive wheels, usually through а pinion gear driving а ring gear on the
axle. The first diesel-electric propelled rail car was built in 1913, and
after World War 2 they replaced steam 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 some time to heat the water in the steam engine,
especially in cold weather, and the fire must be kept up while the steam
engine is 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 direct competition with road haulage over very long distances.
Electric traction
The first electric-powered rail car was built 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,
which means that they get their power from overhead wires or from а third
rail. The power for the traction motors is collected from the third rail
by means of а shoe or from the overhead wires by а pantograph.
Electric trains are the most есоnomical to operate,
provided that traffic is heavy enough to repay electrification of the
railway. Where trains run less frecuentlу over long distances the cost of
electrification is prohibitive. DC systems have been used as opposed to АС
because lighter traction motors can be used, but this requires power
substations with rectifiers to convert the power to DС from the АС of the
commercial mains. (High voltage DC power is difficult to transmit over long
distances.) The latest development
of electric trains has been the installation of rectifiers in the cars
themselves and the use of the same АС frequency as the commercial mains (50
Hz in Europe, 60 Hz in North America),which means that fewer substations
are necessary.
Railway systems
The foundation of а modern railway system is track which does not
deteriorate under stress of traffic. Standard track in Britain comprises a
flat-bottom section of rail weighing 110 lb per yard (54 kg per metre)
carried on 2112 cross-sleepers per mile (1312 per km). Originally creosote-
impregnated wood sleepers [cross-ties] were used, but they are now made of
post-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 below the track formation where it is
reduced through the sole plate and the sleeper to about 400 psi (28
kg/cm2). In soft ground, thick polyethylene sheets are generally placed
under the ballast to prevent pumping of slurry under the weight of trains.
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 the undisturbed
life of track still longer, experiments have been carried out with paved
concrete track (PACТ) laid by а slip paver similar to concrete highway
construction in reinforced concrete. The foundations, if new, are similar
to those for а
motorway. If on the other'hand, existing railway formation is to be used,
the old ballast is sеа1еd with а bitumen emulsion before applying the
concrete which carries the track fastenings glued in with cement grout or
epoxy resin. The track is made resilient by use of rubber-bonded cork
packings 0.4 inch (10 mm) thick. British Railways purchases rails in 60 ft
(18.3 m) lengths which are shop-welded into 600 ft (183 m) lengths and then
welded on site into continuous welded track with pressure-relief points at
intervals of several miles. The contfnuotls welded rails make for а
steadier and less noisy ride for the passenger and reduce the tractive
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 it was 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 movements being 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 is detected by an
electric current passing from one rail to another through the wheels and
axles, dates from 1870 when William Robinson applied it in the United
States. In England the Great Eastern Railway introduced power operation of
points and signals at Spitaifields goods yard in 1899, and three years
later track-circuit operation of powered signals was in operation on 30
miles (48 km) of the London and Sout Western Railway main line.
Day colour light signals, controlled automatically by the trains
through track circuits, were installed on the Liverpool Overhead Railway in
1920 and four-aspect day colour lights (red, yellow, double yellow and
green) were provided on Southern Railway routes from 1926 onwards. These
enable drivers of high-speed trains to have а warning two block sections
ahead of а possible need to stop. With track circuiting it became usual to
show the presence оf vehicles on а track diagram in the signal cabin which
allowed routes to be controlled 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 the points at а station 44 miles (71
km) away, and the signalbox at London Bridge controls movements on the
busiest 150 track-miles of British Rail. By the end of the I980s, the 1500
miles (241О km) of the Southern Region of British Rail are to be controlled
from 13 signalboxes. In modern panel installations the trains are not only
shown on the track diagram as they move from one section to another, but
the train identification number appears electronically in each section.
Соmputer-assisted train description, automatic train rеporting and, at
stations such as London Bridge, operation of platform indicators, is now
usual.
Whether points are operated manually or by an electric point motor,
they have to be prevented from moving while a train is passing over them
and facing points have to be locked, аnd рroved tо Ье lосkеd (оr 'detected'
) before thе relevant signal can permit а train movement. The blades of the
points have to be closed accurately (О.16 inch or 0.4 cm is the maximum
tolerance) so as to avert any possibility of а wheel flange splitting the
point and leading to а derailment.
Other signalling developments of recent years include completely
automatic operation of simple point layouts, such as the double crossover
at the Bank terminus of the British Rails's Waterloo and City underground
railway. On London Тransport's underground system а plastic roll operates
junctions according to the timetable by means of coded punched holes, and
on the Victoria Line trains are operated automatically once the driver has
pressed two buttons to indicate his readiness to start. Не also acts as the
guard, controlling the opening оf thе doors, closed circuit television
giving him а view along the train. The trains are controlled (for
acceleration and braking) by coded impulses transmitted through the running
rails to induction coils mounted on the front of the train. The absence of
code impulses cuts off the current and applies the brakes; driving and
speed control is covered by command spots in which а frequency of 100 Hz
corresponds to one mile per hour (1.6 km/h), and l5 kHz
shuts off the current. Brake applications are so controlled that 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 lines an automatic warning system is being 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
complete diagrams of the track 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 include advance traffic
information(ATI) in which 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 of the
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 249,000 wagons 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
arrangements also provide for automatic weighing of the loads. Other bulk
loads 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 of payload) whose coupling gear is
designed to swivel, so that wagons can be turned upside down for discharge
without uncoupling from their train. Special vans take palletized loads of
miscellaneous merchandise or such products as fertilizer, the van doors
being designed so that all parts of the interior can be reached by а fork-
lift truck.
British railway companies began building their stocks of containers in
1927, and by 1950 they had the largest stock of large containers in Western
Europe. In 1962 British Rail decided 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 container
trains uses 62.5 ft (19.1 m) flat wagons with air-operated disc brakes in
sets оf five and was inaugurated in 1965. At depots
'Drott' pneumatic-tyred cranes were at first provided but rail-mounted
Goliath cranes are now provided.
Cars are handled by double-tier wagons. The British car industry is а
big user of 'сomраnу' trains, which are operated for а single customer.
Both Ford and Chrysler use them to exchange parts between specialist
factories аnd the railway thus becomes an extension of factory transport.
Company trains 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 21 million 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 ton gross hopper wagons and
is either discharged on to belt conveyers 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 are taken from а central plant to strategically-
placed railheads where the liquefied gas is transferred to road tankers for
the journey 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 least possible delay,
are called marshalling yards in Britain and classification yards or
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