125-469: Station distances are from Orpington, which is 13 mi 65 ch (22.23 km) from London Charing Cross . The Southern Heights Light Railway (SHLR) was to have been a speculative London area suburban electric railway between Orpington , Kent and Sanderstead , Surrey . It was authorised in 1928 under the Light Railways Act 1896 , but ultimately not constructed. The engineer
250-649: A plotland development, of which many examples sprang up in countryside around major cities in the first half of the 20th century. The process involved speculative developers buying up failed country farms or estates, and dividing the land into portions or plots of about an acre which were then sold off to individuals to do with as they pleased. This was before the existence of laws governing planning permission . The results were usually settlements of poor quality residences lacking utilities and social services, accessed by unmade tracks. The Aperfield Court Estate at Biggin Hill
375-532: A 750 V DC third-rail system. The section from Vuosaari to Vuosaari harbour is not electrified, as its only purpose is to connect to the Finnish rail network, whose gauge differs only by a couple of millimetres from that of the metro. The route has been previously used by diesel shunting locomotives moving new metro trains to the electrified section of the line. The new tramway in Bordeaux (France) uses
500-457: A British Class 442 EMU . In the event of a collision with a foreign object, the beveled end ramps of bottom running systems can facilitate the hazard of having the third rail penetrate the interior of a passenger car. This is believed to have contributed to the death of five passengers in the Valhalla train crash of 2015. Modern systems, such as ground-level power supply (first used in
625-423: A cap and linear welded along the centre line of the rail. Because aluminium has a higher coefficient of thermal expansion than steel, the aluminium and steel must be positively locked to provide a good current collection interface. A third method rivets aluminium bus strips to the web of the steel rail. As with overhead wires, the return current usually flows through one or both running rails, and leakage to ground
750-498: A changeover to third rail made at Drayton Park railway station . A third rail is still used in the tunnel section of the route, because the size of the tunnels leading to Moorgate station was too small to allow for overhead electrification. The North Downs Line is not electrified on those parts of the line where the North Downs service has exclusive use. The electrified portions of the line are: The Helsinki Metro uses
875-476: A high traffic density. Because of mechanical limitations on the contact to the third rail, trains that use this method of power supply achieve lower speeds than those using overhead electric wires and a pantograph . Nevertheless, they may be preferred inside cities as there is no need for very high speed and they cause less visual pollution . The third rail is an alternative to overhead lines that transmit power to trains by means of pantographs attached to
1000-615: A less stable train vehicle. Nevertheless, it was sometimes used at the beginning of the development of electric trains. The oldest electric railway in the world, Volk's Railway in Brighton, England, was originally electrified at 50 volts DC using this system (it is now a three-rail system). Other railway systems that used it were the Gross-Lichterfelde Tramway and the Ungerer Tramway . The third rail
1125-496: A level crossing at the Kedzie station in an apparent attempt to urinate. The end ramps of conductor rails (where they are interrupted, or change sides) present a practical limitation on speed due to the mechanical impact of the shoe, and 161 km/h (100 mph) is considered the upper limit of practical third-rail operation. The world speed record for a third rail train is 175 km/h (109 mph) attained on 11 April 1988 by
1250-734: A loop service from the former South Eastern Railway London termini, running Lewisham - Woodside - Sanderstead - Orpington - Lewisham and vice versa. Despite the SR's abandonment of support in 1931, electrification works already in hand were allowed to go ahead, and electric trains from London termini to Sanderstead via Woodside began in 1935. They were to continue until 1983, latterly as a very poorly patronised peak-hours shuttle service. The proposed line would have served eight stops between Orpington and Sanderstead , three of which were to be full stations with goods services. The other five were to be "halts", for passengers only. The scheme's proposed route
1375-410: A novel system with a third rail in the centre of the track. The third rail is separated into 10 m (32 ft 9 + 3 ⁄ 4 in) long conducting and 3 m (9 ft 10 + 1 ⁄ 8 in) long isolation segments. Each conducting segment is attached to an electronic circuit which will make the segment live once it lies fully beneath the tram (activated by a coded signal sent by
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#17327806038731500-584: A number of territories with less than a million inhabitants, most of which are UK or US territories, or have close historical ties with the UK or US: American Samoa, Bahamas, Belize, British Virgin Islands, Cayman Islands, Dominica, Falkland Islands, Grenada, Guam, The N. Mariana Islands, Samoa, St. Lucia, St. Vincent & The Grenadines, St. Helena, St. Kitts & Nevis, the Turks & Caicos Islands, and
1625-634: A result, a new LRO was applied for and authorisation was sought to deviate from the authorised route in an effort to reduce construction costs by £17,245. The line was to have taken a different route in the parishes of Cudham , Tatsfield and Titsey , on the Kent/Surrey border. The scheme faded away in the 1930s, after Colonel Stephens died in October 1931 and the scheme lost its main promoter. The death blow had already been given in July of that year, when
1750-407: A segmented ground-level power supply , where each segment is electrified only while covered by a vehicle which is using its power. The third-rail system of electrification is not related to the third rail used in dual-gauge railways. Third-rail systems are a means of providing electric traction power to trains using an additional rail (called a "conductor rail") for the purpose. On most systems,
1875-438: A smooth engagement of the train's contact shoes. The position of contact between the train and the rail varies: some of the earliest systems used top contact, but later developments use side or bottom contact, which enabled the conductor rail to be covered, protecting track workers from accidental contact and protecting the conductor rail from frost, ice, snow and leaf-fall. Because third-rail systems, which are located close to
2000-640: A third rail (current feed, outside the running rails) and fourth rail (current return, midway between the running rails), is used by a few steel-wheel systems; see fourth rail . The London Underground is the largest of these (see railway electrification in Great Britain ). The main reason for using the fourth rail to carry the return current is to avoid this current flowing through the original metal tunnel linings which were never intended to carry current, and which would suffer electrolytic corrosion should such currents flow in them. Another four-rail system
2125-515: A thousand paces as measured by every other step—as in the total distance of the left foot hitting the ground 1,000 times. When Roman legionaries were well-fed and harshly driven in good weather, they thus created longer miles. The distance was indirectly standardised by Agrippa 's establishment of a standard Roman foot (Agrippa's own) in 29 BC , and the definition of a pace as 5 feet. An Imperial Roman mile thus denoted 5,000 Roman feet . Surveyors and specialised equipment such as
2250-508: A train from an external source was by using both rails on which a train runs, whereby each rail is a conductor for each polarity, and is insulated by the sleepers . This method is used by most scale model trains ; however, it does not work as well for large trains as the sleepers are not good insulators. Furthermore, the electric connection requires insulated wheels or insulated axles, but most insulation materials have poor mechanical properties compared with metals used for this purpose, leading to
2375-710: Is U+3344 ㍄ SQUARE MAIRU , after マイル mairu . The international mile is precisely equal to 1.609 344 km (or 25146 / 15625 km as a fraction). It was established as part of the 1959 international yard and pound agreement reached by the United States, the United Kingdom, Canada, Australia, New Zealand, and the Union of South Africa , which resolved small but measurable differences that had arisen from separate physical standards each country had maintained for
2500-404: Is a power surge or a break in the wires. Depending on train and track geometry, gaps in the conductor rail (e.g., at level crossings and junctions) could allow a train to stop in a position where all of its power pickup shoes are in gaps, so that no traction power is available. The train is then said to be "gapped". Another train must then be brought up behind the stranded train to push it on to
2625-465: Is away to the south). Here, the line would have turned west to the second true station at Tatsfield . The fact that two out of three of the true stations proposed for the line were so close together is an indication that the focus of the scheme was very much on the Biggin Hill - Tatsfield suburban development. Beyond Tatsfield would have been the route's summit, at Botley Hill (the highest point on
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#17327806038732750-538: Is based upon the length of a meridian of latitude . The German geographical mile ( geographische Meile ) was previously 1 ⁄ 15 ° of latitude (7.4127 km). The informal term "metric mile" is used in some countries, in sports such as track and field athletics and speed skating , to denote a distance of 1,500 metres (0.932 miles). The 1500 meters is the premier middle distance running event in Olympic sports . In United States high-school competition,
2875-635: Is defined by the First International Extraordinary Hydrographic Conference in Monaco as exactly 1,852 metres (which is 1.151 miles or 6,076.12 feet). In the United States, the nautical mile was defined in the 19th century as 6,080.2 feet (1,853.24 m), whereas in the United Kingdom, the Admiralty nautical mile was defined as 6,080 feet (1,853.18 m) and was about one minute of latitude in
3000-515: Is from Rome. The Italian mile ( miglio , pl. miglia ) was traditionally considered a direct continuation of the Roman mile, equal to 1000 paces, although its actual value over time or between regions could vary greatly. It was often used in international contexts from the Middle Ages into the 17th century and is thus also known as the "geographical mile", although
3125-523: Is line M1 of the Milan Metro , where current is drawn by a lateral, flat bar with side contact, with return via a central rail with top contact. Along some sections on the northern part of the line an overhead line is also in place, to allow line M2's trains (that use pantographs and higher voltage, and have no contact shoes) to access a depot located on line M1. In depots, line M1 trains use pantographs because of safety reasons, with transition made near
3250-659: Is not considered serious. Where trains run on rubber tyres, as on parts of the Lyon Metro , Paris Métro , Mexico City Metro , Santiago Metro , Sapporo Municipal Subway , and on all of the Montreal Metro and some automated guideway transit systems (e.g. the Astram Line ), a live rail must be provided to feed the current. The return is effected through the rails of the conventional track between these guide bars ( see rubber-tyred metro ). Another design, with
3375-398: Is used in radar -related subjects and is equal to 6,000 feet (1.8288 kilometres). The radar mile is a unit of time (in the same way that the light year is a unit of distance), equal to the time required for a radar pulse to travel a distance of two miles (one mile each way). Thus, the radar statute mile is 10.8 μs and the radar nautical mile is 12.4 μs. The geographical mile
3500-459: Is usually located outside the two running rails, but on some systems it is mounted between them. The electricity is transmitted to the train by means of a sliding shoe , which is held in contact with the rail. On many systems, an insulating cover is provided above the third rail to protect employees working near the track; sometimes the shoe is designed to contact the side (called "side running") or bottom (called "bottom running" or "under-running") of
3625-666: The Sjællandske miil , for instance, had been 11.13 km. The Germans also used a longer version of the geographical mile . The Breslau mile , used in Breslau , and from 1630 officially in all of Silesia , equal to 11,250 ells , or about 6,700 meters. The mile equaled the distance from the Piaskowa Gate all the way to Psie Pole ( Hundsfeld ). By rolling a circle with a radius of 5 ells through Piaskowa Island , Ostrów Tumski and suburban tracts, passing eight bridges on
3750-510: The Commonwealth of Nations and the United States by an international agreement in 1959 , when it was formally redefined with respect to SI units as exactly 1,609.344 metres . With qualifiers, mile is also used to describe or translate a wide range of units derived from or roughly equivalent to the Roman mile (roughly 1.48 km ), such as the nautical mile (now 1.852 km exactly),
3875-461: The Exchequer , which thereafter verified local standards until its abolition in the 19th century. New brass standards are known to have been constructed under Henry VII and Elizabeth I . Arnold's c. 1500 Customs of London recorded a mile shorter than previous ones, coming to 0.947 international miles (5,000 feet) or 1.524 km. The English statute mile
Southern Heights Light Railway - Misplaced Pages Continue
4000-671: The Italian mile (roughly 1.852 km ), and the Chinese mile (now 500 m exactly). The Romans divided their mile into 5,000 pedēs ("feet") , but the greater importance of furlongs in the Elizabethan-era England meant that the statute mile was made equivalent to 8 furlongs or 5,280 feet in 1593. This form of the mile then spread across the British Empire , some successor states of which continue to employ
4125-630: The New York metropolitan area ; the SEPTA Market–Frankford Line in Philadelphia ; and London's Docklands Light Railway . Electric traction trains (using electric power generated at a remote power station and transmitted to the trains) are considerably more cost-effective than diesel or steam units, where separate power units must be carried on each train. This advantage is especially marked in urban and rapid transit systems with
4250-814: The Pyrenees also features a third rail. Many suburban lines that ran out of the Paris Saint Lazare station used third-rail (bottom contact) feed. To mitigate investment costs, the Rotterdam Metro , basically a third-rail-powered system, has been given some outlying branches built on surface tracks as light rail (called sneltram [ nl ] in Dutch), with numerous level crossings protected with barriers and traffic lights. These branches have overhead wires. The RandstadRail project also requires Rotterdam Metro trains to run under wires along
4375-501: The South Eastern Railway , with the hope that this would encourage interest in suburban development. The Orpington, Cudham and Tatsfield Light Railway Company (OCTR) was therefore incorporated in 1898, with Colonel Holman Fred Stephens as the engineer. The company obtained a Light Railway Order in 1902, authorising construction of a 7.5 mile (12 km) line which was to be completed in four years. Authorised capital
4500-466: The decempeda and dioptra then spread its use. In modern times, Agrippa's Imperial Roman mile was empirically estimated to have been about 1,618 yards (1,479 m; 4,854 ft; 0.919 mi) in length, slightly less than the 1,760 yards (1,609 m; 5,280 ft) of the modern international mile. In Hellenic areas of the Empire, the Roman mile ( ‹See Tfd› Greek : μίλιον , mílion )
4625-409: The geographical mile is now a separate standard unit. The Arabic mile ( الميل , al-mīl ) was not the common Arabic unit of length ; instead, Arabs and Persians traditionally used the longer parasang or "Arabic league ". The Arabic mile was, however, used by medieval geographers and scientists and constituted a kind of precursor to the nautical or geographical mile . It extended
4750-446: The international mile and international foot . In the United States, the term statute mile formally refers to the survey mile, but for most purposes, the difference of less than 1 ⁄ 8 inch (3.2 mm) between the survey mile and the international mile (1609.344 metres exactly) is insignificant—one international mile is 0.999 998 US survey miles—so statute mile can be used for either. But in some cases, such as in
4875-483: The loading gauge . There is also a risk of pedestrians walking onto the tracks at level crossings and accidentally touching the third rail, unless grade separation is fully implemented. In the United States, a 1992 Supreme Court of Illinois decision affirmed a $ 1.5 million verdict against the Chicago Transit Authority for failing to stop an intoxicated person from walking onto the tracks at
5000-425: The nominal ellipsis form of mīlle passus 'mile' or mīlia passuum 'miles', the Roman mile of one thousand paces . The present international mile is usually what is understood by the unqualified term mile . When this distance needs to be distinguished from the nautical mile, the international mile may also be described as a land mile or statute mile. In British English , statute mile may refer to
5125-452: The tramway of Bordeaux in 2003), avoid the safety problem by segmenting the powered rail, with each segment being powered only when fully covered by the vehicle which utilizes its power. Third-rail systems using top contact are prone to accumulations of snow, or ice formed from refrozen snow, and this can interrupt operations. Some systems operate dedicated de-icing trains to deposit an oily fluid or antifreeze (such as propylene glycol ) on
Southern Heights Light Railway - Misplaced Pages Continue
5250-543: The " ban mile" ( banska milja ), had been the Austrian mile given above. The Ottoman mile was 1,894.35 m (1.17709 mi), which was equal to 5,000 Ottoman foot. After 1933, the Ottoman mile was replaced with the modern Turkish mile (1,853.181 m). The CJK Compatibility Unicode block contains square-format versions of Japanese names for measurement units as written in katakana script. Among them, there
5375-474: The 10th century, the nominal prototype physical standard of English length was an arm-length iron bar (a yardstick) held by the king at Winchester ; the foot was then one-third of its length. Henry I was said to have made a new standard in 1101 based on his own arm. Following the issuance of Magna Carta in 1215, the barons of Parliament directed John and his son to keep the king 's standard measure ( Mensura Domini Regis ) and weight at
5500-488: The A2022, and would have been substantially nearer the old village of Sanderstead than the SR station of the same name. Mitchley Wood survives mostly intact as a semi-natural ancient woodland . From there, the route would have hugged the slope of Purley Downs, cutting through the golf course to descend to the junction with the SR's Oxted line . The actual junction was to have been at the bridge carrying Purley Downs Road over
5625-677: The Belgian high-speed section and Brussels Midi station or 1.5 kV DC on the railway lines in the south of France for seasonal services. As originally delivered, the Class 373 units were additionally fitted with 750 V DC collection shoes , designed for the journey in London via the suburban commuter lines to Waterloo . A switch between third-rail and overhead collection was performed while running at speed, initially at Continental Junction near Folkestone, and later on at Fawkham Junction after
5750-483: The Brighton main line near Sanderstead. So, the railway was envisaged entirely as a suburban commuter route to the London termini. Given this, it is noticeable that the proposed stops were quite widely spaced compared to the Southern Railway's London suburban lines in general. The topography added a further complication, this being the need to avoid crossing the several steep-sided narrow valleys which dissect
5875-686: The NAD27, is defined in metres. State Plane Coordinate Systems were then updated, but the National Geodetic Survey left individual states to decide which (if any) definition of the foot they would use. All State Plane Coordinate Systems are defined in metres, and 42 of the 50 states only use the metre-based State Plane Coordinate Systems. However, eight states also have State Plane Coordinate Systems defined in feet, seven of them in US survey feet and one in international feet. State legislation in
6000-601: The North Downs). The route would then have followed the Croydon Road (the present B269) to Chelsham for Warlingham Halt around Chelsham Road -this was a long stretch without any stop proposed. The third true station would have been at Hamsey Green , where the line would have crossed the Limpsfield Road (B269). Mitchley Wood Halt would have been around the west end of Mitchley Hill, near the junction with
6125-474: The Oxted line, and unlike at Orpington this junction would have been on the level. Mile The mile , sometimes the international mile or statute mile to distinguish it from other miles, is a British imperial unit and United States customary unit of length; both are based on the older English unit of length equal to 5,280 English feet , or 1,760 yards . The statute mile was standardised between
6250-409: The Roman computations of the mile as 5,000 feet, 1,000 paces , or 8 longer divisions, which they equated with their " furrow 's length" or furlong . The origins of English units are "extremely vague and uncertain", but seem to have been a combination of the Roman system with native British and Germanic systems both derived from multiples of the barleycorn . Probably by the reign of Edgar in
6375-538: The Roman mile is the milestone . All roads radiated out from the Roman Forum throughout the Empire – 50,000 (Roman) miles of stone-paved roads. At every mile was placed a shaped stone. Originally, these were obelisks made from granite, marble, or whatever local stone was available. On these was carved a Roman numeral , indicating the number of miles from the centre of Rome – the Forum. Hence, one can know how far one
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#17327806038736500-670: The Roman mile to fit an astronomical approximation of 1 arcminute of latitude measured directly north-and-south along a meridian . Although the precise value of the approximation remains disputed, it was somewhere between 1.8 and 2.0 km. The " old English mile " of the medieval and early modern periods varied but seems to have measured about 1.3 international miles (2.1 km). The old English mile varied over time and location within England. The old English mile has also been defined as 79,200 or 79,320 inches (1.25 or 1.2519 statute miles). The English long continued
6625-482: The SR board decided not to support the application for a new LRO and the scheme was deleted from SR publicity. The only construction that started was south of Orpington station on the east side of the line; some excess spoil was delivered to the site during the 1930s ready for construction. The SR had to electrify a connection to the proposed western junction at Sanderstead , and chose the previously failed Woodside and South Croydon Joint Railway . This would have allowed
6750-593: The Southern Region third rail network from Farringdon southwards and on overhead line northwards to Bedford , Cambridge and Peterborough . The changeover is made whilst stationary at Farringdon when heading southbound, and at City Thameslink when heading northbound. On the Moorgate to Hertford and Welwyn suburban service routes, the East Coast Main Line sections are 25 kV AC, with
6875-506: The US State Plane Coordinate Systems (SPCSs), which can stretch over hundreds of miles, the accumulated difference can be significant, so it is important to note that the reference is to the US survey mile. The United States redefined its yard in 1893, and this resulted in US and Imperial measures of distance having very slightly different lengths. The North American Datum of 1983 (NAD83), which replaced
7000-562: The US Virgin Islands. The mile is even encountered in Canada, though this is predominantly in rail transport and horse racing, as the roadways have been metricated since 1977. Ireland gradually replaced miles with kilometres, including in speed measurements; the process was completed in 2005. The US survey mile is 5,280 US survey feet , or 1,609.347 metres and 0.30480061 metres respectively. Both are very slightly longer than
7125-451: The US is important for determining which conversion factor from the metric datum is to be used for land surveying and real estate transactions, even though the difference (2 ppm ) is hardly significant, given the precision of normal surveying measurements over short distances (usually much less than a mile). Twenty-four states have legislated that surveying measures be based on the US survey foot, eight have legislated that they be based on
7250-465: The US survey foot and US survey mile, as permitted by their 1959 decision, with effect on January 1, 2023. The nautical mile was originally defined as one minute of arc along a meridian of the Earth. Navigators use dividers to step off the distance between two points on the navigational chart, then place the open dividers against the minutes-of-latitude scale at the edge of the chart, and read off
7375-509: The United Kingdom, road signs use "m" as the abbreviation for mile though height and width restrictions also use "m" as the symbol for the metre, which may be displayed alongside feet and inches. The BBC style holds that "there is no acceptable abbreviation for 'miles ' " and so it should be spelled out when used in describing areas. The Roman mile ( mille passus , lit. "thousand paces"; abbr. m.p. ; also milia passuum and mille ) consisted of
7500-461: The actual spacing depends on the carrying capacity, maximum speed, and service frequency of the line. One method for reducing current losses (and thus increase the spacing of feeder/substations, a major cost in third rail electrification) is to use a composite conductor rail of a hybrid aluminium/steel design. The aluminium is a better conductor of electricity, and a running face of stainless steel gives better wear. There are several ways of attaching
7625-457: The conductor rail is placed on the sleeper ends outside the running rails, but in some systems a central conductor rail is used. The conductor rail is supported on ceramic insulators (known as "pots"), at top contact or insulated brackets , at bottom contact, typically at intervals of around 10 feet (3.0 m). The trains have metal contact blocks called collector shoes (also known as contact shoes or pickup shoes) which make contact with
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#17327806038737750-420: The conductor rail to prevent the frozen build-up. The third rail can also be heated to alleviate the problem of ice. Unlike overhead line equipment, third-rail systems are not susceptible to strong winds or freezing rain , which can bring down overhead wires and hence disable all trains. Thunderstorms can also disable the power with lightning strikes on systems with overhead wires , disabling trains if there
7875-465: The conductor rail, or a jumper cable may be used to supply enough power to the train to get one of its contact shoes back on the live rail. Avoiding this problem requires a minimum length of trains that can be run on a line. Locomotives have either had the backup of an on-board diesel engine system (e.g., British Rail Class 73 ), or have been connected to shoes on the rolling stock (e.g. Metropolitan Railway ). The first idea for feeding electricity to
8000-556: The conductor rail. The traction current is returned to the generating station through the running rails. In North America, the conductor rail is usually made of high conductivity steel or steel bolted to aluminium to increase the conductivity. Elsewhere in the world, extruded aluminium conductors with stainless steel contact surface or cap, is the preferred technology due to its lower electrical resistance, longer life, and lighter weight. The running rails are electrically connected using wire bonds or other devices, to minimise resistance in
8125-672: The context, such as a discussion of the 2nd-century Antonine Itinerary describing its distances in terms of miles rather than Roman miles . The mile has been variously abbreviated in English—with and without a trailing period—as "mi", "M", "ml", and "m". The American National Institute of Standards and Technology now uses and recommends "mi" to avoid confusion with the SI metre (m) and millilitre (ml). However, derived units such as miles per hour or miles per gallon continue to be abbreviated as "mph" and "mpg" rather than "mi/h" and "mi/gal". In
8250-627: The definition of the foot in the Mendenhall Order of 1893, with 1 foot = 1200 / 3937 (≈0.304800609601) metres and the definition was retained for data derived from NAD27, but renamed the US survey foot to distinguish it from the international foot. Thus a survey mile = 1200 / 3937 × 5280 (≈1609.347218694) metres. An international mile = 1609.344 / ( 1200 / 3937 × 5280) (=0.999998) survey miles. The exact length of
8375-743: The depots away from revenue tracks. Third rail electrification is less visually obtrusive than overhead electrification . Several systems use a third rail for part of the route, and other motive power such as overhead catenary or diesel power for the remainder. These may exist because of the connection of separately owned railways using the different motive systems, local ordinances, or other historical reasons. Several types of British trains have been able to operate on both overhead and third-rail systems, including British Rail Class 313 , 319 , 325 , 350 , 365 , 375/6 , 377/2 , 377/5 , 377/7 , 378/2 , 387 , 373 , 395 , 700 and 717 EMUs, as well as Class 92 locomotives. Network Rail claims to run
8500-454: The dip slope, and which would have required viaducts. This put serious constraints on the choices for the route. At Orpington station there was to have been a diving junction, so that the SHLR down trains would not have to cross the main line here. South of Orpington station on the east side of the line some excess spoil was delivered to the site during the 1930s ready for construction and in 2023
8625-515: The discrepancy with latitude measurement to less than 2%). The metric system was introduced in the Netherlands in 1816, and the metric mile became a synonym for the kilometre, being exactly 1,000 m. Since 1870, the term mijl was replaced by the equivalent kilometer . Today, the word mijl is no longer used, except as part of certain proverbs and compound terms like mijlenver ("miles away"). The German mile ( Meile )
8750-456: The distance in nautical miles. The Earth is not perfectly spherical but an oblate spheroid , so the length of a minute of latitude increases by 1% from the equator to the poles, as seen for example in the WGS84 ellipsoid , with 1,843 metres (6,046 ft) at the equator, 1,862 metres (6,108 ft) at the poles and average 1,852 metres (6,076 ft). Since 1929 the international nautical mile
8875-410: The east side of Berry's Green before turning due west to Biggin Hill station on the present A233 road , about the south end of Aperfield Road. It then ran south-east and south to cross Tansfield Lane, then paralleled that road westwards to its terminus of Tatsfield station where Tatsfield Primary School used to be, by the crossroads at the top of Church Hill. The OCTLR was defunct after 1906. However,
9000-401: The electric circuit. Contact shoes can be positioned below, above, or beside the third rail, depending on the type of third rail used: these third rails are referred to as bottom-contact, top-contact, or side-contact, respectively. The conductor rails have to be interrupted at level crossings , crossovers , and substation gaps. Tapered rails are provided at the ends of each section to allow
9125-623: The fact that there are already overhead electric wires on part of the route for freight and Regional Eurostar services, led to the change. Also in London, the West London Line changes power supply between Shepherd's Bush and Willesden Junction , where it meets the North London Line. South of the changeover point, the WLL is third rail electrified, north of there, it is overhead . The cross-city Thameslink service runs on
9250-460: The ground, present electric shock hazards, high voltages (above 1500 V) are not considered safe. A very high current must therefore be used to transfer adequate power to the train, resulting in high resistive losses , and requiring relatively closely spaced feed points ( electrical substations ). The electrified rail threatens electrocution of anyone wandering or falling onto the tracks. This can be avoided by using platform screen doors , or
9375-671: The international foot, and eighteen have not specified which conversion factor to use. SPCS 83 legislation refers to state legislation that has been passed or updated using the newer 1983 NAD data. Most states have done so. Two states, Alaska and Missouri , and two jurisdictions, Guam and Puerto Rico , do not specify which foot to use. Two states, Alabama and Hawaii , and four jurisdictions, Washington, DC , US Virgin Islands , American Samoa and Northern Mariana Islands , do not have SPCS 83 legislation. In October 2019, US National Geodetic Survey and National Institute of Standards and Technology announced their joint intent to retire
9500-455: The international mile continues to be used in some countries, such as the United Kingdom, the United States, and a number of countries with fewer than one million inhabitants, most of which are UK or US territories or have close historical ties with the UK or US. The modern English word mile derives from Middle English myle and Old English mīl , which was cognate with all other Germanic terms for miles . These derived from
9625-429: The land mile varied slightly among English-speaking countries until the international yard and pound agreement in 1959 established the yard as exactly 0.9144 metres, giving a mile of exactly 1,609.344 metres. The US adopted this international mile for most purposes, but retained the pre-1959 mile for some land-survey data, terming it the U. S. survey mile . In the United States, statute mile normally refers to
9750-412: The latitudes of the south of the UK. Other nations had different definitions of the nautical mile. The nautical mile per hour is known as the knot . Nautical miles and knots are almost universally used for aeronautical and maritime navigation, because of their relationship with degrees and minutes of latitude and the convenience of using the latitude scale on a map for distance measuring. The data mile
9875-554: The length of an ell was not standardised, so that the length of a mile could range between 3,280 m and 4,280 m. In the sixteenth, the Dutch had three different miles: small ( kleine ), medium ( middelbaar/gemeen ), and large ( groote ). The Dutch kleine mile had the historical definition of one hour's walking ( uur gaans ), which was defined as 24 stadia, 3000 paces, or 15,000 Amsterdam or Rhineland feet (respectively 4,250 m or 4,710 m). The common Dutch mile
10000-517: The length of the rod by 1 ⁄ 11 would have amounted to a significant tax increase. Parliament instead opted to maintain the mile of 8 furlongs (which were derived from the rod) and to increase the number of feet per mile from the old Roman value. The applicable passage of the statute reads: "A Mile shall contain eight Furlongs, every Furlong forty Poles, and every Pole shall contain sixteen Foot and an half." The statute mile therefore contained 5,280 feet or 1,760 yards. The distance
10125-453: The line in return for 75% of the gross receipts. Also, approval was given for the SR to invest in the scheme, and to have the option to purchase at cost price within five years of completion. In return, two of the SHLR directors were to be nominated by the SR board. A subsequent meeting of the board, in the same month, fixed the SR investment at £150 000, which was intended to pay for the cost of electrification. The Light Railway Order (LRO)
10250-495: The main lines to serve north and mid Kent. As a consequence, these trains are dual-voltage enabled, as the majority of the routes along which they travel are third-rail electrified. In London, the North London Line changes from third rail to overhead electrification between Richmond and Stratford at Acton Central . The entire route originally used third rail, but several technical electrical earthing problems, plus
10375-419: The mile was changed as with improved calculations of the circumference of the Earth. In 1617, Willebrord Snellius calculated a degree of the circumference of the Earth at 28,500 Rijnlantsche Roeden (within 3.5% of the actual value), which resulted in a Dutch mile of 1900 rods. By the mid-seventeenth century, map scales assigned 2000 rods to the common Dutch mile, which equalled around 7,535 m (reducing
10500-475: The mile. The US Geological Survey now employs the metre for official purposes, but legacy data from its 1927 geodetic datum has meant that a separate US survey mile ( 6336 / 3937 km) continues to see some use, although it was officially phased out in 2022. While most countries replaced the mile with the kilometre when switching to the International System of Units (SI),
10625-680: The most accepted equivalencies are 1,976 Imperial yards (1.123 statute miles or 1.81 km). It was legally abolished three times: first by a 1685 act of the Scottish Parliament , again by the 1707 Treaty of Union with England, and finally by the Weights and Measures Act 1824 . It had continued in use as a customary unit through the 18th century but had become obsolete by its final abolition. The Irish mile ( míle or míle Gaelach ) measured 2,240 yards: approximately 1.27 statute miles or 2.048 kilometres. It
10750-550: The opening of the first section of the Channel Tunnel Rail Link . Between Kensington Olympia railway station and North Pole depot , further switchovers were necessary. The dual-voltage system did cause some problems. Failure to retract the shoes when entering France caused severe damage to the trackside equipment, causing SNCF to install a pair of concrete blocks at the Calais end of both tunnels to break off
10875-404: The present international mile or to any other form of English mile since the 1593 Act of Parliament , which set it as a distance of 1,760 yards . Under American law , however, statute mile refers to the US survey mile. Foreign and historical units translated into English as miles usually employ a qualifier to describe the kind of mile being used but this may be omitted if it is obvious from
11000-638: The previous standards was 2 ppm , or about 3.2 millimetres ( 1 ⁄ 8 inch) per mile. The US standard was slightly longer and the old Imperial standards had been slightly shorter than the international mile. When the international mile was introduced in English-speaking countries, the basic geodetic datum in America was the North American Datum of 1927 (NAD27). This had been constructed by triangulation based on
11125-516: The proposed line was held at Orpington , Kent . It was to have been a single track railway constructed across the North Downs from Orpington to Sanderstead . In a departure from Stephens' usual practice, there were to have been no level crossings at all on the line, which would have required 23 bridges to have been built. Construction of the line would have required the excavation of 631,000 cubic yards (482,000 m) of material. The line
11250-399: The rails of a railway track . It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost fully segregated from the outside environment. Third-rail systems are usually supplied from direct current electricity. Modern tram systems with street-running avoid the risk of electrocution by the exposed electric rail by implementing
11375-401: The risk can be reduced by placing the conductor rail on the side of the track away from the platform, when allowed by the station layout. The risk can also be reduced by having a coverboard , supported by brackets , to protect the third rail from contact, although many systems do not use one. Where coverboards are used, they reduce the structure gauge near the top of rail. This in turn reduces
11500-399: The scheme in its publicity, notably on its system maps. A revised estimate of the cost of purchasing land and erecting necessary buildings (that is, excluding that of building the actual railway line) was given as £575 000. Only three of the proposed stops were to be built as full stations, and the company requested that level crossing be allowed "where necessary" (this was in contradiction to
11625-608: The scheme was revived in a more ambitious form when the Southern Heights Light Railway was proposed in the mid 1920s. Colonel H. F. Stephens was the engineer again, forming a personal link between the two schemes, and he was also to be a major promoter in his own right despite calling himself the "Agent to the Promoters". The SHLR scheme first drew wider public attention in March 1925, when an inquiry into
11750-472: The scheme's behalf in February 1926, just before the application for a Light Railway Order . The total cost he estimated to be £800 000, so it was proposed that the capital applied for was to be £900 000. £600 000 of this was to be in ordinary shares and £300 000 to be in guaranteed interest debentures . Sir Herbert obtained the board's approval for the SR to guarantee the interest on the latter, and to work
11875-541: The scheme's original publicity). The provisional nature of the LRO involved certain conditions: The authorised capital was to be raised, and the land purchased, within two years, which meant that the authorisation would lapse at the end of 1930. In that year, Colonel Stephens made a fund-raising trip to the United States, with no success. The LRO lapsed in December 1930, as the capital could not be raised. In January 1931, as
12000-415: The stainless steel to the aluminium. The oldest is a co-extruded method, where the stainless steel is extruded with the aluminium. This method has suffered, in isolated cases, from de-lamination (where the stainless steel separates from the aluminium); this is said to have been eliminated in the latest co-extruded rails. A second method is an aluminium core, upon which two stainless steel sections are fitted as
12125-413: The survey mile, about 3.219 mm ( 1 ⁄ 8 inch) longer than the international mile (the international mile is exactly 0.0002% less than the US survey mile). While most countries abandoned the mile when switching to the metric system , the international mile continues to be used in some countries, such as Liberia , Myanmar , the United Kingdom and the United States. It is also used in
12250-491: The term is sometimes used for a race of 1,600 metres (0.994 miles). The Scandinavian mile ( mil ) remains in common use in Norway and Sweden, where it has meant precisely 10 km since metrication in 1889. It is used in informal situations and in measurements of fuel consumption, which are often given as litres per mil . In formal situations (such as official road signs) only kilometres are given. The Swedish mile
12375-450: The third rail shoes if they had not been retracted. An accident occurred in the UK when a Eurostar driver failed to retract the pantograph before entering the third-rail system, damaging a signal gantry and the pantograph. On 14 November 2007, Eurostar's passenger operations were transferred to St Pancras railway station and maintenance operations to Temple Mills depot, making the 750 V DC third rail collection equipment redundant and
12500-560: The third rail shoes were removed. The trains themselves are no longer fitted with a speedometer capable of measuring the speed in miles per hour (the indication used to automatically change when the collector shoes were deployed). In 2009, Southeastern began operating domestic services over High Speed 1 trackage from St Pancras using its new Class 395 EMUs. These services operate on the High Speed line as far as Ebbsfleet International or Ashford International , before transferring to
12625-444: The third rail, allowing the protective cover to be mounted directly to its top surface. When the shoe slides along the top surface, it is referred to as "top running". When the shoe slides along the bottom surface, it is less affected by the build-up of snow, ice, or leaves, and reduces the chances of a person being electrocuted by coming in contact with the rail. Examples of systems using under-running third rail include Metro-North in
12750-570: The train) and switch it off before it becomes exposed again. This system (called Alimentation par Sol (APS), meaning 'current supply via ground') is used in various locations around the city but especially in the historic centre: elsewhere the trams use the conventional overhead lines (see also ground-level power supply ). In summer 2006 it was announced that two new French tram systems would be using APS over part of their networks. These will be Angers and Reims , with both systems expected to open around 2009–2010. The French Culoz–Modane railway
12875-480: The trains. Whereas overhead-wire systems can operate at 25 kV or more, using alternating current (AC), the smaller clearance around a live rail imposes a maximum of about 1200 V, with some systems using 1500 V ( Line 4, Guangzhou Metro , Line 5, Guangzhou Metro , Line 3, Shenzhen Metro ), and direct current (DC) is used. Trains on some lines or networks use both power supply modes (see § Mixed systems below). All third-rail systems throughout
13000-608: The way, the standard Breslau mile was determined. The Saxon post mile ( kursächsische Postmeile or Polizeimeile , introduced on occasion of a survey of the Saxon roads in the 1700s, corresponded to 2,000 Dresden rods , equivalent to 9.062 kilometres. The Hungarian mile ( mérföld or magyar mérföld ) varied from 8.3790 km to 8.9374 km before being standardised as 8.3536 km. The Portuguese mile ( milha ) used in Portugal and Brazil
13125-437: The world are energised with DC supplies. Some of the reasons for this are historical. Early traction engines were DC motors, and the then-available rectifying equipment was large, expensive and impractical to install onboard trains. Also, transmission of the relatively high currents required results in higher losses with AC than DC. Substations for a DC system will have to be (typically) about 2 kilometres (1.2 miles) apart, though
13250-546: The world's largest third-rail network. On the southern region of British Rail, freight yards had overhead wires to avoid the electrocution hazards of a third rail. The locomotives were fitted with a pantograph as well as pick-up shoes. The Class 373 used for international high-speed rail services operated by Eurostar through the Channel Tunnel runs on overhead wires at 25 kV AC for most of its journey, with sections of 3 kV DC on Belgian lines between
13375-683: The yard. As with the earlier statute mile , it continues to comprise 1,760 yards or 5,280 feet. The old Imperial value of the yard was used in converting measurements to metric values in India in a 1976 Act of the Indian Parliament. However, the current National Topographic Database of the Survey of India is based on the metric WGS-84 datum , which is also used by the Global Positioning System . The difference from
13500-494: Was 2.0873 km prior to metrication. The Russian mile ( миля or русская миля , russkaya milya ) was 7.468 km, divided into 7 versts . The Croatian mile ( hrvatska milja ), first devised by the Jesuit Stjepan Glavač on a 1673 map, is the length of an arc of the equator subtended by 1 / 10 ° or 11.13 km exactly. The previous Croatian mile, now known as
13625-687: Was 24,000 German feet. The standardised Austrian mile used in southern Germany and the Austrian Empire was 7.586 km; the Prussian mile used in northern Germany was 7.5325 km. Following its standardisation by Ole Rømer in the late 17th century, the Danish mile ( mil ) was precisely equal to the Prussian mile and likewise divided into 24,000 feet. These were sometimes treated as equivalent to 7.5 km. Earlier values had varied:
13750-410: Was 32 stadia, 4,000 paces, or 20,000 feet (5,660 m or 6,280 m). The large mile was defined as 5000 paces. The common Dutch mile was preferred by mariners, equating with 15 to one degree of latitude or one degree of longitude on the equator . This was originally based upon Ptolemy 's underestimate of the Earth's circumference. The ratio of 15 Dutch miles to a degree remained fixed while the length of
13875-416: Was bought by a London speculator called Frederick Dougal in 1889,. He divided up the land into plots which he sold off for £10 each with a £1 deposit (£1300 in 2020 values, £130 down). However, interest was limited by the remoteness of the locality. Such plotlands only became popular with the arrival of private road vehicles. The answer here was the promotion of a speculative branch railway from Orpington on
14000-636: Was electrified with 1500 V DC third rail, later converted to overhead wires at the same voltage. Stations had overhead wires from the beginning. The French branch line which serves Chamonix and the Mont Blanc region ( Saint-Gervais-le-Fayet to Vallorcine ) is third rail (top contact) and metre gauge. It continues in Switzerland, partly with the same third-rail system, partly with an overhead line. The 63 km (39 mi) long Train Jaune line in
14125-474: Was established by a Weights and Measures Act of Parliament in 1593 during the reign of Queen Elizabeth I . The act on the Composition of Yards and Perches had shortened the length of the foot and its associated measures, causing the two methods of determining the mile to diverge. Owing to the importance of the surveyor's rod in deeds and surveying undertaken under Henry VIII , decreasing
14250-399: Was granted provisionally on 29 December 1928. Instead of the expected share capital of £600 000, only £500 000 was authorised. Simultaneously, the SHLR and SR signed a working agreement. Notably, this specified that the line was to be single, but was to be engineered to allow for future double track. Also, timetabling and fares were to be the responsibility of the SR. The latter began to include
14375-439: Was not uniformly adopted. Robert Morden had multiple scales on his 17th-century maps which included continuing local values: his map of Hampshire , for example, bore two different "miles" with a ratio of 1 : 1.23 and his map of Dorset had three scales with a ratio of 1 : 1.23 : 1.41 . In both cases, the traditional local units remained longer than the statute mile. The English statute mile
14500-488: Was on the dip slope of the North Downs , so the roughly S-shaped route entailed continuous ascending gradients from Orpington to the summit on the crest of the Downs near Tatsfield, then similarly continuous descending gradients to Sanderstead . The circuitous nature of the route meant that the proposed railway would not have attracted through traffic, especially since there was no direct passenger connection allowed for to
14625-673: Was said to have been codified under Dyfnwal the Bald and Silent and retained unchanged by Hywel the Good . Along with other Welsh units, it was discontinued following the conquest of Wales by Edward I of England in the 13th century. The Scots mile was longer than the English mile, as mentioned by Robert Burns in the first verse of his poem " Tam o' Shanter ". It comprised 8 (Scots) furlongs divided into 320 falls or faws (Scots rods ). It varied from place to place but
14750-406: Was standardised as 36,000 Swedish feet or 10.6884 kilometres (6.6415 miles) in 1649; before that it varied by province from about 6 to 14.485 km. Third rail A third rail , also known as a live rail , electric rail or conductor rail , is a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between
14875-739: Was still in situ. Green Street Green Halt would have been around the junction between Shire Lane and Farnborough Hill, west of the station site proposed for the earlier OCTR. This was because the SHLR proposed a different, longer route to Tatsfield via the valley up which Shire Lane runs. This valley curves south to the east of Leaves Green and Biggin Hill Airport , and Downe and Keston Halt would have been around New Hill Road. Cudham and Biggin Hill would have been around Jail Lane. The first true station with goods services, Westerham Hill , would have been in South Street (the actual hill
15000-443: Was superseded in 1959 by the international mile by international agreement. The Welsh mile ( milltir or milldir ) was 3 statute miles and 1,470 yards long (6.17 km). It comprised 9,000 paces ( cam ), each of 3 Welsh feet ( troedfedd ) of 9 inches ( modfeddi ). (The Welsh inch is usually reckoned as equivalent to the English inch.) Along with other Welsh units , it
15125-481: Was to have been Colonel Holman Fred Stephens , heavily involved in the promotion of light railways . The context of the scheme lay in the suburban development of a remote rural area near the crest of the North Downs on the Kent-Surrey border, comprising the tiny hamlet of Biggin Hill in the former together with the small but ancient village of Tatsfield in the latter. This locality was an early example of
15250-473: Was to have been electrified by the third rail system, and was to have been operated by the Southern Railway as part of its suburban electric railway network. Passenger trains would have been operated by electric multiple units , with steam locomotives handling goods trains. The Southern Railway involvement was vital. That company's chairman, Sir Herbert Ashcombe Walker , addressed its board on
15375-593: Was used beside the native Greek units as equivalent to 8 stadia of 600 Greek feet . The mílion continued to be used as a Byzantine unit and was also used as the name of the zero mile marker for the Byzantine Empire , the Milion , located at the head of the Mese near Hagia Sophia . The Roman mile spread throughout Europe, with its local variations giving rise to the different units. Also arising from
15500-468: Was used in Ireland from the 16th century plantations until the 19th century, with residual use into the 20th century. The units were based on " English measure " but used a linear perch measuring 7 yards (6.4 m) as opposed to the English rod of 5.5 yards (5.0 m). The Dutch mile ( mijl ) has had different definitions throughout history. One of the older definitions was 5,600 ells . But
15625-539: Was £70 000, and the South Eastern Railway was to work the line once completed. Unfortunately, investment was not forthcoming and construction did not begin. The 1902 proposal involved a line running due south of Orpington to a station at Green Street Green , just south of the road called Farnborough Hill and west of High Street. It then turned south-west to run up the valley occupied by Cuckoo Wood to Cudham station at Hang Grove Hill. From there hugged
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