Loading gauge

utilises differing loading gauges: a Metropolitan line S Stock sub-surface train (left) passes a Piccadilly line 1973 Stock tube train (right). The loading gauge governs the size of passenger carriages, goods wagons (freight cars) and shipping containers that can travel on the relevant section of railway track. It varies between rail systems around the world and can even vary within a single railway system. Over time, there has been a trend towards less restrictive loading gauges and greater standardization of them. Some older systems and lines have had their structure gauges expanded by raising bridges, increasing the height and width of tunnels and making other necessary alterations. Containerisation, and a trend towards larger shipping containers, has led rail operators to increase loading and structure gauges to compete with road haulage. The term "loading gauge" can also refer to a physical structure, sometimes using electronic detectors using light beams on an arm or gantry placed over the exit lines of goods yards or at the entry point to a restricted part of a network. The devices ensure that loads stacked on open or flat wagons stay within the height/shape limits of the line's bridges and tunnels, and prevent out-of-gauge rolling stock entering a stretch of line with a smaller loading gauge. Compliance with a loading gauge can be checked using a clearance car. In the past, they were simple wooden frames or physical feelers mounted on rolling stock. More recently, laser beams have been used. The loading gauge is the maximum size of rolling stock. It is distinct from the minimum structure gauge, which sets limits to the size of bridges and tunnels on a rail line, allowing for engineering tolerances and the motion of rail vehicles. The difference between the two is called the clearance. The terms "dynamic envelope" or "kinematic envelope", which include factors such as suspension travel, overhang on curves (at both ends and middle) and lateral motion on the track, are sometimes used in place of loading gauge. Railway platform height is also a consideration for the loading gauge of passenger trains. Where the two are not directly compatible, stairs may be required, which will increase loading times. Where long carriages are used at a curved platform, there will be gaps between the platform and the carriage door, causing risk. Problems increase where trains of several different loading gauges and vehicle floor heights use (or even must pass through) the same platform. The size of load that can be carried on a railway of a particular gauge is also influenced by the design of the rolling stock. Low-deck rolling stock can sometimes be used to carry taller shipping containers on lower gauge lines although their low-deck rolling stock cannot then carry as many containers. Rapid transit (metro) railways generally have a smaller loading gauge, which reduces the cost of tunnel construction. Those systems have to use their own specialised rolling stock. Out of gauge Larger out-of-gauge loads can also sometimes be conveyed by taking one or more of the following measures: • Operate at low speed, especially in places with limited clearance, such as platforms. • Cross over from a track with inadequate clearance to another track with greater clearance, even if there is no signalling to allow this. • Prevent operation of other trains on adjacent tracks. • Use refuge loops to allow trains to operate on other tracks. • Use of Schnabel cars (special rolling stock) that manipulate the load up and down or left and right to clear obstacles. • Remove (and later replace) obstacles. • Use gauntlet track to shift the train to side or center. • For locomotives that are too heavy, ensure that fuel tanks are nearly empty. • Turn off power in overhead wiring or in the third rail (use diesel locomotive) • Permanently adapt a certain route to larger gauge if there is repeated need for such trains. ==History==

The loading gauge on the main lines of Great Britain, most of which were built before 1900, is generally smaller than in other countries. In mainland Europe, the slightly larger Berne gauge (Gabarit passe-partout international, PPI) was agreed to in 1913 and came into force in 1914. As a result, British trains have noticeably and considerably smaller loading gauges and, for passenger trains, smaller interiors, despite the track being standard gauge, which is in line with much of the world. This often results in increased costs for purchasing new trainsets or locomotives as they must be specifically designed for the existing British network, rather than being purchased "off-the-shelf". For example, the new trains for HS2 have a 50% premium applied to the "classic compatible" sets that will be "compatible" with the current (or "classic") rail network loading gauge as well as the HS2 line. The "classic compatible" trainsets will cost £40million per trainset whereas the HS2-only stock (built to European loading gauge and only suitable to operate on HS2 lines) will cost £27M per trainset despite the HS2-only stock being physically larger. It was recognized even during the nineteenth century that this would pose problems and countries whose railroads had been built or upgraded to a more generous loading gauge pressed for neighboring countries to upgrade their own standards. This was particularly true in continental Europe where the Nordic countries and Germany with their relatively generous loading gauge wanted their cars and locomotives to be able to run throughout the standard gauge network without being limited to a small size. France, which at the time had the most restrictive loading gauge ultimately compromised giving rise to Berne gauge which came into effect just before World War I. Military railways were often built to particularly high standards, especially after the American Civil War and the Franco-Prussian War showed the importance of railroads in military deployment as well as mobilization. The German Empire was particularly active in the construction of military railways which were often built with great expense to be as flat, straight and permissive in loading gauge as possible while bypassing major urban areas, making those lines of little use to civilian traffic, particularly civilian passenger traffic. However, all those aforementioned factors have in some cases led to the subsequent abandoning of those railroads. The loading gauge affected tank design, with the 1945 British Centurion tank the first British tank allowed to exceed the restricted British loading gauge. The 1944 German Tiger II tank had to be changed to narrower transport tracks instead of battle tracks for transport by rail. ==Standard loading gauges for standard track gauge lines==

International Union of Railways (UIC) Gauge The International Union of Railways (UIC) has developed a standard series of loading gauges named A, B, B+ and C. • PPI – the predecessor of the UIC gauges had the maximum dimensions with an almost round roof top. • UIC A: The smallest (slightly larger than PPI gauge). Maximum dimensions . • UIC B+: New structures in France are being built to UIC B+.--> Europe European standards In the European Union, the UIC directives were supplanted by ERA Technical Specifications for Interoperability (TSI) of European Union in 2002, which has defined a number of recommendations to harmonize the train systems. The TSI Rolling Stock (2002/735/EC) has taken over the UIC Gauges definitions defining Kinematic Gauges with a reference profile such that Gauges GA and GB have a height of (they differ in shape) with Gauge GC rising to allowing for a width of of the flat roof. All cars must fall within an envelope of wide on a radius curve. The TGVs, which are wide, fall within this limit. The designation of a GB+ loading gauge refers to the plan to create a pan-European freight network for ISO containers and trailers with loaded ISO containers. These container trains (piggy-back trains) fit into the B envelope with a flat top so that only minor changes are required for the widespread structures built to loading gauge B on continental Europe. A few structures on the British Isles were extended to fit with GB+ as well, where the first lines to be rebuilt start at the Channel Tunnel. Owing to their historical legacies, many member states' railways do not conform to the TSI specification. For example, Britain's role at the forefront of railway development in the 19th century has condemned it to the small infrastructure dimensions of that era. Conversely, the s of countries that were satellites of the former Soviet Union are much larger than the TSI specification. Other than for GB+, they are not likely to be retrofitted, given the enormous cost and disruption that would be entailed. Double-decker carriages double-decker Intercity train railways A specific example of the value of these loading gauges is that they permit double decker passenger carriages. Although mainly used for suburban commuter lines, France is notable for using them on its high speed TGV services: the SNCF TGV Duplex carriages are high, the Netherlands, Belgium and Switzerland feature large numbers of double decker intercity trains as well. In Germany the Bombardier Twindexx was introduced in InterCity service in December 2015. Great Britain Great Britain has (in general) the most restrictive loading gauge (relative to track gauge) in the world. That is a legacy of the British railway network being the world's oldest, and of having been built by a large number of different private companies, each with different standards for the width and height of trains. After nationalisation, a standard static gauge W5 was defined in 1951 that would virtually fit everywhere in the network. The W6 gauge is a refinement of W5, and the W6a changed the lower body to accommodate third-rail electrification. While the upper body is rounded for W6a with a static curve, there is an additional small rectangular notch for W7 to accommodate the transport of ISO containers, and the W8 loading gauge has an even larger notch spanning outside of the curve to accommodate the transport of ISO containers. While W5 to W9 are based on a rounded roof structure, those for W10 to W12 define a flat line at the top and, instead of a strict static gauge for the wagons, their sizes are derived from dynamic gauge computations for rectangular freight containers. Network Rail uses a W loading gauge classification system of freight transport ranging from W6A (smallest) through W7, W8, W9, W9Plus, W10, W11 to W12 (largest). The definitions assume a common "lower sector structure gauge" with a common freight platform at above rail. In addition, gauge C1 provides a specification for standard coach stock, gauge C3 for longer Mark 3 coaching stock, gauge C4 for Pendolino stock and gauge UK1 for high-speed rail. There is also a gauge for locomotives. The size of container that can be conveyed depends both upon the size of the load that can be conveyed and the design of the rolling stock. • W6A: Available over the majority of the British rail network. • W8: Allows standard high shipping containers to be carried on standard wagons. • W9: Allows high Hi-Cube shipping containers to be carried on "Megafret" wagons that have lower deck height with reduced capacity. which are designed to carry Euro-pallets efficiently • W10: Allows high Hi-Cube shipping containers to be carried on standard wagons Recommended clearance for new structures, such as bridges and tunnels. • UIC GC: Channel Tunnel and Channel Tunnel Rail Link to London; with proposals to upgrade the Midland Main Line northwards from London to GB+ standards. A strategy was adopted in 2004 to guide enhancements of loading gauges and in 2007 the freight route utilisation strategy was published. That identified a number of key routes where the loading gauge should be cleared to W10 standard and, where structures are being renewed, that W12 is the preferred standard. • Piccadilly line with tunnels of • Victoria line with tunnels of ; enlarged to reduce air friction. • Glasgow Subway with tunnels of and a unique track gauge of only . • Tyne and Wear Metro with tunnels of ; built to mainline rail network standards. Sweden The Swedish Transport Administration (Trafikverket) has largely replaced static reference profiles with kinematic reference profiles. The two main standards are SE-A and SE-C. The SE-B profile has been withdrawn, as all track has been upgraded to at least SE-A. SE-C is required for all new construction and, when economically viable, during upgrades. Some SE-A track has been partially upgraded to SE-C and accommodates profiles such as P/C 450 (P/C 447) and GC or loads such as SECU containers. Both SE-A and SE-C are defined for straight track, with the corresponding structure gauge. On curved track, the structure gauge is widened to allow the 24-metre reference vehicle to pass. By European standards, SE-C is unusually large, permitting vehicles up to 24 metres long and almost 4 metres wide. However, vehicles with softer suspension that allows greater lateral movement must be narrower to remain within the kinematic reference profile. Netherlands In the Netherlands, a similar shape to the UIC C is used that rises to in height. The trains are wider allowing for width similar to Sweden. About one third of the Dutch passenger trains use bilevel rail cars. However, Dutch platforms are much higher than Swedish ones. Betuweroute • Betuweroute: to allow double stacked container trains in the future. The present overhead line does not allow this height, as it has to follow standards. Channel Tunnel • Channel Tunnel: North America Freight The American loading gauge for freight cars on the North American rail network is generally based on standards set by the Association of American Railroads (AAR) Mechanical Division. The most widespread standards are AAR Plate B and AAR Plate C, but higher loading gauges have been introduced on major routes outside urban centers to accommodate rolling stock that makes better economic use of the network, such as auto carriers, hi-cube boxcars, and double-stack container loads. The maximum width of on (AAR Plate B), (AAR Plate C) and all other truck centers (of all other AAR Plates) are on a radius or 13° curve. Gallery File:Boeing 737 fuselage train hull 3473.jpg|Boeing 737 Next Generation fuselage being transported by rail on a flatcar File:DTTX 724681 20050529 IL Rochelle.jpg|Double-stack container service requires the highest loading gauge in common use in North America. File:ETTX 905721 20050529 IL Rochelle.jpg|A Norfolk Southern autorack on a TTX flatcar also requires the highest loading gauge in common use in North America. File:Santa_Fe_TOFC_(Trailer_on_Flat_Car)_(10589289363).jpg|A Santa Fe semi-trailer carried on a flatcar as part of a TOFC train. Passenger service The old standard North American passenger railcar is wide by high and measures over coupler pulling faces with truck centers, or over coupler pulling faces with truck centers. In the 1940s and 1950s, the American passenger car loading gauge was increased to a height throughout most of the country outside the Northeast, to accommodate dome cars and later Superliners and other bilevel commuter trains. Bilevel and Hi-level passenger cars have been in use since the 1950s, and new passenger equipment with a height of has been built for use in Alaska and the Canadian Rockies. The structure gauge of the Mount Royal Tunnel used to limit the height of bilevel cars to before it was permanently closed to interchange rail traffic prior to its conversion for the REM rapid transit system. New York City Subway The New York City Subway is an amalgamation of three former constituent companies, and while all are standard gauge, inconsistencies in loading gauge prevent cars from the former BMT and IND systems (B Division) from running on the lines of the former IRT system (A Division), and vice versa. This is mainly because IRT tunnels and stations are approximately narrower than the others, meaning that IRT cars running on the BMT or IND lines would have platform gaps of over between the train and some platforms, whereas BMT and IND cars would not even fit into an IRT station without hitting the platform edge. Taking this into account, all maintenance vehicles are built to IRT loading gauge so that they can be operated over the entire network, and employees are responsible for minding the gap. Another inconsistency is the maximum permissible railcar length. Cars in the former IRT system are . Railcars in the former BMT and IND can be longer: on the former Eastern Division, the cars are limited to , while on the rest of the BMT and IND lines plus the Staten Island Railway (which uses modified IND stock) the cars may be as long as . Boston (MBTA) The Massachusetts Bay Transportation Authority's (MBTA) rapid transit system is composed of four unique subway lines; while all lines are standard gauge, inconsistencies in loading gauge, electrification, and platform height prevent trains on one line from being used on another. The first segment of the Green Line (known as the Tremont Street subway) was constructed in 1897 to take the streetcars off Boston's busy downtown streets. When the Blue Line opened in 1904, it only ran streetcar services; the line was converted to rapid transit in 1924 due to high passenger loads, but the tight clearances in the tunnel under the Boston Harbor required narrower and shorter rapid transit cars. The Orange Line was originally built in 1901 to accommodate heavy rail transit cars of higher capacity than streetcars. The Red Line was opened in 1912, designed to handle what were for a time the largest underground transit cars in the world. Los Angeles (LACMTA) The Los Angeles Metro Rail system is an amalgamation of two former constituent companies, the Los Angeles County Transportation Commission and the Southern California Rapid Transit District; both of those companies were responsible for planning the initial system. It is composed of two heavy rail subway lines and several light rail lines with subway sections; while all lines are standard gauge, inconsistencies in electrification and loading gauge prohibit the light rail trains from operating on the heavy rail lines, and vice versa. The LACTC-planned Blue Line was opened in 1990 and partially operates on the route of the Pacific Electric interurban railroad line between downtown Los Angeles and Long Beach, which used overhead electrification and street-running streetcar vehicles. The SCRTD-planned Red Line (later split into the Red and Purple lines) was opened in 1993 and was designed to handle high-capacity heavy rail transit cars that would operate underground. Shortly after the Red Line began operations, the LACTC and the SCRTD merged to form the LACMTA, which became responsible for planning and construction of the Green, Gold, Expo, and K lines, as well as the D Line Extension and the Regional Connector. Asia Major trunk raillines in East Asian countries, including China, North Korea, South Korea, as well as the Shinkansen of Japan, have all adopted a loading gauge of maximum width and can accept the maximum height of . China The maximum height, width, and length of general Chinese rolling stock are , and respectively, with an extra out-of-gauge load allowance of height and width with some special shape limitation, corresponding to a structure gauge of . China is building numerous new railways in sub-Saharan Africa and Southeast Asia (such as in Kenya and Laos), and these are being built to "Chinese Standards". This presumably means track gauge, loading gauge, structure gauge, couplings, brakes, electrification, etc. An exception may be double stacking, which has a height limit of . Metre gauge in China has a gauge of . Japan, standard gauge Translation of legend: • Blue: Rural railway vehicle gauge (Rural Railway Construction Rules 1919) • Grey: Conventional Cape gauge (3 ft 6 in track gauge) railway vehicle limits (Ordinary Railway Structure Rules 1987) • Figures in () are previous Cape gauge rolling stock limits (Railway Construction Rules 1900) • Green: Shinkansen vehicle limits Trains on the Shinkansen network operate on track and have a loading gauge of maximum width and maximum height. This allows the operation of double-deck high-speed trains. Mini Shinkansen (former conventional narrow gauge lines that have been regauged into ) and some private railways in Japan (including some lines of the Tokyo subway and all of the Osaka Metro) also use standard gauge; however, their loading gauges are different. The rest of Japan's system is discussed under narrow gauge, below. Hong Kong South Korea The body frame may have a maximum height of and a maximum width of with additional installations allowed up to . That width of 3,400 mm is only allowed above as the common passenger platforms are built to former standard trains of in width. Philippines There is currently no uniform standard for loading gauges in the country and both loading gauges and platform heights vary by rail line. The North–South Commuter Railway allows passenger trains with a carbody width of and a height of . Additional installations shall also be allowed up to at a platform height of where it is limited by half-height platform screen doors. Above the platform gate height of above the platforms, out-of-gauge installations can be further maximized to the Asian standard at . Meanwhile, the PNR South Long Haul will follow the Chinese gauge and therefore use a larger carbody width of from the specifications of passenger rolling stock, and a height of per P70-type boxcar specifications. which was completed in 2020. The Kwinana, Eastern and Eastern Goldfields lines in Western Australia were built with a loading gauge of wide and tall to allow for trailer on flatcar (TOFC) traffic when converted to dual gauge in the 1960s. ==Broad gauge==

Indian Gauge • The smallest loading gauge for a gauge railway is the Delhi Metro, which is wide and tall. • Indian Railways has a maximum passenger loading gauge of and a freight loading gauge of 3,250 mm, with development allowing a width of . • Sri Lanka Railways has a loading gauge of between and . 5 ft and Russian gauge In Finland, rail cars can be up to wide with a permitted height from on the sides to in the centre. The track gauge is , differing from the Russian track gauge. The Russian loading gauges are defined in standard GOST 9238 (ГОСТ 9238–83, ГОСТ 9238–2013) with the current 2013 standard named "Габариты железнодорожного подвижного состава и приближения строений" (construction of rolling stock clearance diagrams [official English title]). It was accepted by the Interstate Council for Standardization, Metrology and Certification to be valid in Russia, Belarus, Moldova, Ukraine, Uzbekistan and Armenia. That matches with the Tc, Tpr and the universal 1-T loading gauge. Iberian gauge In Spain, rail cars can be up to 3.44 m (11 ft 3.5 in) wide with a permitted height of 4.33 m (14 ft 2.5 in) and this loading gauge is called Iberian loading gauge. It is the standard loading gauge for conventional (Iberian gauge) railways in Spain. In Portugal, there are three railway loading gauge standards for conventional (Iberian gauge) railways: Gabarito PT b, Gabarito PT b+ and Gabarito PT c. Gabarito PT b (also called CPb) and Gabarito PT b+ (also called CPb+) allow rail cars to be 3.44 m (11 ft 3.5 in) wide with a permitted height of 4.5 m (14 ft 9 in), although CPb+ has a slightly larger profile area. Gabarito PT c allows rail cars to be 3.44 m (11 ft 3.5 in) wide with a permitted height of 4.7 m (15 ft 5 in). Gabarito PT b and PT b+ are both used, being PT b+ more common overall. Gabarito PT c is currently not used. In Lisbon, there is a suburban railway line, the Cascais Line, that follows a fourth non-standard loading gauge. Irish Gauge Ireland and Northern Ireland Australia Brazil == Narrow gauge ==

Narrow gauge railways generally have a smaller loading gauge than standard gauge ones, and this is a major reason for cost savings rather than the railgauge itself. For example, the Lyn locomotive of the Lynton and Barnstaple Railway is wide. By comparison, several standard gauge 73 class locomotives of the NSWR, which are wide, have been converted for use on cane tramways, where there are no narrow bridges, tunnels or track centres to cause trouble. The 6E1 locomotive of the South African Railways are wide. A large number of railways using the gauge used the same rolling stock plans, which were wide. Great Britain Ffestiniog Railway • gauge = • width (brakevan mirrors) = • width (brakevan body) = • height = • length = (carriage) Lynton and Barnstaple Railway of Lyn • gauge = • Lyn (locomotive) over headstocks • length = • width = • height = • Passenger • length = • width = wide, • width over steps = • height = Japan, narrow gauge Translation of legend: • Blue: Rural railway vehicle gauge (Rural Railway Construction Rules 1919) • Grey: Conventional Cape gauge (3ft 6in track gauge) railway vehicle limits (Ordinary Railway Structure Rules 1987) • Figures in () are previous Cape gauge rolling stock limits (Railway Construction Rules 1900) • Green: Shinkansen vehicle limits The Japanese national network operated by Japan Railways Group employs narrow gauge . The maximum allowed width of the rolling stock is and maximum height is ; however, a number JR lines were constructed as private railways prior to nationalisation in the early 20th century, and feature loading gauges smaller than the standard. These include the Chūō Main Line west of Takao, the Minobu Line, and the Yosan Main Line west of Kan'onji ( height). Nevertheless, advances in pantograph technology have largely eliminated the need for separate rolling stock in these areas. There are many private railway companies in Japan and the loading gauge is different for each company. South Africa The South African national network employs gauge. The maximum width of the rolling stock is and maximum height is , Other gauge for the United Kingdom and Sierra Leone: • Minimum radius: • Width: (see Everard Calthrop) • Wagon length (freight): over headstocks • Wagon length (passenger): over headstocks • Tank engine length: over headstocks == Structure gauge ==

being upgraded in 2014. The structure gauge, which refers to the dimensions of the lowest and narrowest bridges or tunnels of the track, complements the loading gauge, which specifies the tallest and widest allowable vehicle dimensions. There is a gap between the structure gauge and loading gauge, and some allowance needs to be made for the dynamic movement of vehicles (sway) to avoid mechanical interference causing equipment and structural damage. == Out of gauge ==

While it may be true that trains of a particular loading gauge can travel freely over tracks of a matching structure gauge, in practice, problems can still occur. In an accident at Moston station, an old platform not normally used by freight trains was hit by a train that wasn't within its intended W6a gauge because two container fastenings were hanging over the side. Analysis showed that the properly configured train would have passed safely even though the platform couldn't handle the maximum design sway of W6a. Accepting reduced margins for old construction is normal practice if there have been no incidents but if the platform had met modern standards with greater safety margin the out of gauge train would have passed without incident. Trains larger than the loading gauge, but not too large, can operate if the structure gauge is carefully measured, and the trip is subject to various special regulations. == Gallery ==

File:BS Ladelehre Westbahnhof.JPG|German equipment outline gauge File:Lademass.jpg|Template to check if the load is exactly within the loading gauge File:Loading gauge at Moccone.jpg|Equipment outline gauge at Moccone File:Loading Gauge Eritrea.jpg|Eritrean loading gauge ==See also==