In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant. An interlocking is designed so that it is impossible to display a signal to proceed unless the route to be used is proven safe. In North America, the official railroad definition of interlocking is: "An arrangement of signals and signal appliances so interconnected that their movements must succeed each other in proper sequence". A minimal interlocking consists of signals, but includes additional appliances such as points and Facing Point locks and derails, may include crossings at grade and movable bridges; some of the fundamental principles of interlocking include: Signals may not be operated to permit conflicting train movements to take place at the same time on set route. Switches and other appliances in the route must be properly'set' before a signal may allow train movements to enter that route.
Once a route is set and a train is given a signal to proceed over that route, all switches and other movable appliances in the route are locked in position until either the train passes out of the portion of the route affected, or the signal to proceed is withdrawn and sufficient time has passed to ensure that a train approaching that route has had opportunity to come to a stop before passing the signal. Railway interlocking is of British origin. In June 1856, John Saxby received the first patent for interlocking signals. In 1868, Saxby was awarded a patent for what is known today in North America as “preliminary latch locking”. Preliminary latch locking became so successful that by 1873, 13,000 mechanical locking levers were employed on the London and North Western Railway alone; the first experiment with mechanical interlocking in the United States took place in 1875 by J. M. Toucey and William Buchanan at Spuyten Duyvil Junction in New York on the New York Central and Hudson River Railroad.
At the time, Toucey was General Superintendent and Buchanan was Superintendent of Machinery on the NYC&HRR. Toucey and Buchanan formed the Toucey and Buchanan Interlocking Switch and Signal Company in Harrisburg, Pennsylvania in 1878; the first important installations of their mechanism were on the switches and signals of the Manhattan Elevated Railroad Company and the New York Elevated Railroad Company in 1877-78. Compared to Saxby's design and Buchanans' interlocking mechanism was more cumbersome and less sophisticated, so was not implemented widely. Union Switch & Signal bought their company in 1882; as technology advanced that served to augment the muscle strength of human beings the railway signaling industry looked to incorporate these new technologies into interlockings to increase the speed of route setting, the number of appliances controlled from a single point and to expand the distance that those same appliances could be operated from the point of control. The challenge facing the signal industry was achieving the same level of safety and reliability, inherent to purely mechanical systems.
An experimental hydro-pneumatic interlocking was installed at the Bound Brook, New Jersey junction of the Philadelphia and Reading Railroad and the Lehigh Valley Railroad in 1884. By 1891, there were 18 hydro-pneumatic plants, on six railroads, operating a total of 482 levers; the installations worked, but there were serious defects in the design, little saving of labour was achieved. The inventors of the hydro-pneumatic system moved forward to an electro-pneumatic system in 1891 and this system, best identified with the Union Switch & Signal Company, was first installed on the Chicago and Northern Pacific Railroad at its drawbridge across the Chicago River. By 1900, 54 electro-pneumatic interlocking plants, controlling a total of 1,864 interlocking levers, were in use on 13 North American railroads; this type of system would remain one of two viable competing systems into the future, although it did have the disadvantage of needing extra single-use equipment and requiring high maintenance.
Interlockings using electric motors for moving switches and signals became viable in 1894, when Siemens in Austria installed the first such interlocking at Přerov. Another interlocking of this type was installed in Westend near Berlin in 1896. In North America, the first installation of an interlocking plant using electric switch machines was at Eau Claire, Wisconsin on the Chicago, St. Paul and Omaha Railway in 1901, by General Railway Signal Company. By 1913, this type system had been installed on 83 railroads in 35 US States and Canadian Provinces, in 440 interlocking plants using 21,370 levers. Interlockings can be categorized as electrical, or electronic/computer-based. In mechanical interlocking plants, a locking bed is constructed, consisting of steel bars forming a grid; the levers that operate switches, signals or other appliances are connected to the bars running in one direction. The bars are constructed so that if the function controlled by a given lever conflicts with that controlled by another lever, mechanical interference is set up in the cross locking between the two bars, in turn preventing the conflicting lever movement from being made.
In purely mechanical plants, the levers operate the field devices, such as signals, directly via a mechanical rodding or wire connection. The levers are about shoulder height. Cross locking of levers was effected su
Shrewsbury is the county town of Shropshire, England. The town is on the River Severn and the 2011 census recorded a town population of 71,715. Shrewsbury is a market town whose centre has a unspoilt medieval street plan and over 660 listed buildings, including several examples of timber framing from the 15th and 16th centuries. Shrewsbury Castle, a red sandstone fortification, Shrewsbury Abbey, a former Benedictine monastery, were founded in 1074 and 1083 by the Norman Earl of Shrewsbury, Roger de Montgomery; the town is where he spent 27 years of his life. Located 9 miles east of the Welsh border, Shrewsbury serves as the commercial centre for Shropshire and mid-Wales, with a retail output of over £299 million per year and light industry and distribution centres, such as Battlefield Enterprise Park, on the outskirts; the A5 and A49 trunk roads come together as the town's by-pass, five railway lines meet at Shrewsbury railway station. The town is located 150 miles north-west of London; the town was the early capital of the Kingdom of Powys, known to the ancient Britons as Pengwern, signifying "the alder hill".
This name evolved in three directions, into Sciropscire, which became Shropshire. Its Welsh name Amwythig means "fortified place". Over the ages, the geographically important town has been the site of many conflicts between the English and Welsh; the Angles, under King Offa of Mercia, took possession in 778. Nearby is the village of 5 miles to the south-east; this was once the site of the fourth largest cantonal capital in Roman Britain. As Caer Guricon it is a possible alternative for the Dark Age seat of the Kingdom of Powys; the importance of the Shrewsbury area in the Roman era was underlined with the discovery of the Shrewsbury Hoard in 2009. Shrewsbury's known history commences in the Early Middle Ages, having been founded c. 800 AD. It is believed that Anglo-Saxon Shrewsbury was most a settlement fortified through the use of earthworks comprising a ditch and rampart, which were shored up with a wooden stockade. There is evidence to show; the Welsh were repelled by William the Conqueror. Roger de Montgomery was given the town as a gift from William, built Shrewsbury Castle in 1074, taking the title of Earl.
He founded Shrewsbury Abbey as a Benedictine monastery in 1083. The 3rd Earl, Robert of Bellême, was deposed in 1102 and the title forfeited, in consequence of rebelling against Henry I and joining the Duke of Normandy's invasion of England in 1101. In 1138, King Stephen besieged the castle held by William FitzAlan for the Empress Maud during the period known as the Anarchy, it was in the late Middle Ages. This success was due to wool production, a major industry at the time, the wool trade with the rest of Britain and Europe, with the River Severn and Watling Street acting as trading routes; the Shrewsbury Drapers Company dominated the trade in Welsh wool for many years. Despite its commercial success, Shrewbury was not immune from the effects of the Black Death. Records suggest the plague arrived in the spring of 1349, was devastating. Examining the number of local church benefices falling vacant due to death, 1349 alone saw twice the vacancies as the previous ten years combined, suggesting a high death toll in Shrewsbury.
In 1403 the Battle of Shrewsbury was fought a few miles north at Battlefield. Shrewsbury's monastic gathering was disbanded with the Dissolution of the Monasteries and as such the Abbey was closed in 1540. However, it is believed that Henry VIII thereafter intended to make Shrewsbury a cathedral city after the formation of the Church of England, but the citizens of the town declined the offer. Despite this, Shrewsbury thrived throughout the 17th centuries; as a result, a number of grand edifices, including the Ireland's Mansion and Draper's Hall, were constructed. It was in this period that Edward VI gave permission for the foundation of a free school, to become Shrewsbury School. During the English Civil War, the town was a Royalist stronghold and only fell to Parliament forces after they were let in by a parliamentarian sympathiser at the St Mary's Water Gate. After Thomas Mytton captured Shrewsbury in February 1645; this prompted Prince Rupert to respond by executing Parliamentarian prisoners in Oswestry.
Shrewsbury Unitarian Church was founded in 1662. By the 18th century Shrewsbury had become an important market town and stop off for stagecoaches travelling between London and Holyhead on their way to Ireland. Local soldier and statesman Robert Clive was Shrewsbury's MP from 1762 until his death in 1774. Clive served once as the town's mayor in 176
Westinghouse Air Brake Company
The Westinghouse Air Brake Company was founded on September 28, 1869 by George Westinghouse in Pittsburgh, Pennsylvania. Earlier in the year he had invented the railway air brake in New York state. After having manufactured equipment in Pittsburgh for a number of years, he began to construct facilities and plants East of the city where homes for his employees were built. In 1889, the air brake manufacturing facility was moved to Wilmerding and the company's general office building was built there in 1890. WABCO's direct successor companies include WABCO Vehicle Control Systems, a commercial vehicle air brake manufacturer; the Westinghouse Air Brake Company was established by George Westinghouse in 1869. The Air Brake plant was moved to Wilmerding, Pennsylvania in 1889. Wilmerding is a small town about 14 miles outside of Pittsburgh which, at the time, was only inhabited by about 5,000 people. Socialism was strong in Wilmerding and it was a peaceful non-violent farming borough, it was thought to be “The Ideal Town” for the company because of its location right along the Pennsylvania Railroad and its blue collar inhabitants.
The Air Brake Company employed 3,000 citizens from the surrounding Pittsburgh area, but its work force was composed entirely of individuals from Wilmerding. This stretch of populated farmland known as Wilmerding developed around this new and industrially important company and was put on the map. A little under one third of its population was somehow related and more than not one would end up raising their children in the same home that they were raised in. After the company's development business thrived. Many of the passengers that were departing or coming into Wilmerding stopped to shop at these stores along the narrow sidewalk before heading home. One could get anything from hair cuts to groceries to lumber. Working conditions at the Westinghouse Air Brake Company were more than adequate and the company had many new developments in effect for its employees. In 1869 it was one of the first companies to institute a 55-hour work week. WA&B got the reputation for being the first industry in America to adopt half holidays on Saturday afternoons.
A series of welfare options were instituted to better the working and living conditions of its employees. The Air Brake plant was very prosperous and was nothing far from a gift for this small town. By 1905 over 2,000,000 freight, mail and express cars and 89,000 locomotives were equipped with the Westinghouse Air Brakes, but just as in all big businesses, it had its downs. There was one general complaint among the Wilmerding business men, it was. This made sense since these men and women depended on the company; when the economy struggled and profits in the company declined, workers had to alter their standard of living. Wilmerding’s prosperity and misfortune all depended on the success of the Air Brake Company and when the company was failing the citizens just had to try and adjust to its losses. During this time, in the early 1900s, the Westinghouse Company built houses on a tract of land that it had purchased, in turn, it sold those homes to its workers cheaply; the company offered educational and cultural activities run through the local Y.
M. C. A, to obtain better workers. WA&B catered to those who were not fit in its working conditions. To insure a certain income to employees who might have been unfit for work because of illness or injury, an ordered sum would be paid to the beneficiary. Any employee under 50 was eligible for membership after a physical examination; the members contributed according to the class which they belonged, with their class being determined by the amount of money they made per month. Their contribution ranged from fifty cents to $1.50, which in turn in case of disability would receive benefits for thirty-nine consecutive weeks. According to Wilmerding News during this time, about 76% of WA&B’s employees held a membership with the company; the Westinghouse Air Brake company was still producing products up until around the year 2000, under several different managers over the years. The company had become less important with the shedding of Pittsburgh’s industrial past, but continued manufacturing its products.
The company has two 21st century successors. One, which continues to design and manufacture railway air brakes in Wilmerding, merged with locomotive manufacturer MotivePower Industries, to form Wabtec; the other, now known as WABCO Holdings, Inc. designs and manufactures control systems for commercial road vehicles, including air brakes, is headquartered in Brussels, Belgium. WABCO Holdings, Inc. was floated in a 2007 initial public offering by American Standard, WABCO's owners for 30 years. On 28th March 2019 it was publicly announced that the company will be bought by ZF Friedrichshafen for a price of ~7 billion $ with $136.50 per share in an all-cash transaction. The merger will be completed by the beginning of year 2020; the first form of the air brake consisted of an air pump, a main reservoir, an engineer's valve on the locomotive, of a train pipe and brake cylinder on each car. One problem with this first form of the air brake
Lüdinghausen railway station
The Lüdinghausen railway station is a station of the Dortmund-Enschede railway located at the Westphalian city of Lüdinghausen. It was opened in Summer 1875. Trains of the line RB51 call at Lüdinghausen. In December 2011, the Deutsche Bahn AG stopped selling tickets in Lüdinghausen; the railway station consists of two signal boxes with mechanic operation, two level crossings, two platform tracks with a centre platform, two dead-end sidings with buffer stops, six sets of points, out of which four are remote-controlled, one is operated by waggon shunters with a nearby lever, one is out of order. A local distillery is connected to the station
John Saxby was an English engineer from Brighton, noted for his work in railway signalling and the invention of the interlocking system of points and signals. He was a partner in the firm Saxby and Farmer. Saxby was born at Brighton on 17 August 1821 and in 1834 was apprenticed at the age of thirteen to a carpenter and joiner. In 1840 he was employed as a carpenter at the Brighton railway works of the London and Brighton Railway to make oak mile-posts, where he designed a tool to automate their production, he became the foreman of the carpenters and joiners, pattern makers, gas-fitters, labourers at the works. Two accidents took place on the London Brighton and South Coast Railway during the early 1850s due to signalling failures. Saxby became interested in railway safety and invented an improved signalling lamp, giving considerable benefits and savings on the lamps in use, he invented a device for interlocking points and signals. In 1856 he was awarded a patent for this invention, designed to act at once upon all the points and signals at a railway junction.
Not only were the points and signals activated, but all the other signals in the system were locked against improper use. The first interlocked signalling system was installed at the Bricklayers Arms junction, near the Old Kent Road in South London, it consisted of eight semaphore signals and six pairs of points controlling the routes in and out of London bridge Station and neighbouring goods yards, with linkages to a signal box. In 1861 Saxby left the railway employment and started his own business at Haywards Heath to manufacture signalling apparatus; the following year he was joined in partnership by John Stinson Farmer, an assistant to the manager of the LBSCR. Saxby and Farmer became the leading manufacturers of railway signalling equipment and established a works at Kilburn where they employed 3,000 workers; the firm established works at Brussels. In 1868 the company constructed the world's first traffic signal for road traffic in London's George Street, working to the designs of the South-Eastern Railway engineer John Peake Knight.
In 1875 firm brought out its first mechanical brake, which gave more powerful braking by connecting each vehicle's brakes together. Saxby's son James established a signal works at Creil near Paris in 1878. From the 1860s to the 1880s Saxby and Farmer were the dominant force in railway signalling equipment manufacture. Much of the equipment they provided survived in use for the greater part of the twentieth century. Saxby and Farmer became the major contractor responsible for building signal boxes on behalf of railways; the Type 5 design was one of the most successful and long-lived of all contractors’ signal box designs, between 1876 and 1898 with eleven examples still in use on Network Rail and a further ten on heritage railways or otherwise preserved. The partnership with Farmer ended in 1888 and the French works became part of John Saxby Ltd in 1889. In 1901 the British company that Saxby founded merged with several rivals to create the Westinghouse Brake and Signal Company Ltd; the French company is now part of United Technologies Corporation.
John Saxby died at Hassocks, Sussex on 22 April 1913. He is commemorated with a modern plaque in Brighton Station. Engineer list on steamindex.com The Disastrous Debut of the World’s First Traffic Lights, The Victorianist British industrial history, Graces Guide Memorial plaque, Brighton, at openplaques.org On the fixed signals of railways, Minutes of the Proceedings, 1 January 1874, Institution of Civil Engineers
Severn Bridge Junction
Severn Bridge Junction is the area of railway lines just south of Shrewsbury railway station, in Shropshire, England. It is controlled by a mechanical interlocked signal box of the same name, now the largest operational mechanical signal box in the world; the Network Rail signalling area code is'SBJ.' The complexity of the railway system in the area is brought about by the convergence of five major lines at Shrewsbury, built in the Victoria era by two competing and yet co-operating railway companies, the Great Western Railway and the London and North Western Railway. They were competing to connect the coal and raw material supplies of South Wales with the industrialised Midlands and Northwest. After the GWR amalgamated with the Cambrian Railways in 1921, it was a major point of accessing GWR services into Mid and West Wales: Cambrian Line Shrewsbury to Chester Line Wolverhampton to Shrewsbury Line Welsh Marches Line: North to Crewe via Crewe and Shrewsbury Railway South to Newport via Shrewsbury and Hereford Railway Lines converging in the area include the regionally important Severn Valley Railway, the Stafford to Shrewsbury Line.
The railway junction lies directly south of the railway station. It was constructed jointly by the GWR/LNWR after the completion of improvements to their jointly owned Shrewsbury and Hereford Railway, which at this location junctioned with the Wolverhampton to Shrewsbury Line. To allow freight trains to move to/from South Wales direct to the Midlands and hence avoid the passenger railway station, the junction was constructed in a tight triangular form south of the River Severn. Jointly constructed from 1902 to an enlarged standard LNWR design of 1876, the three storey structure is built of two storeys of red brick and cement, with a third floor of wooden weather board pin-panel containing the glass windows, all topped by a Welsh slate pitched roof. Access is via a door on the rear, with the lower two floors housing interlocking signalling equipment accessed via two internal wooden staircases; the main operational floor houses a 180 lever interlocked frame, divided into two sections: Abbey Foregate to Sutton Bridge.
The frame scale makes it the largest remaining mechanical signal box on the British network, from 2011 it became the largest mechanical signalbox in the world, following the closure of the 191 lever box at Spencer Street in Melbourne, Australia. Today only half of the levers are in operational use, although it still takes two signallers to operate the complete system on a 24/7 basis, allowing 300 train movements per day. Although there have been line closures in the Shrewsbury area, the closure of the joint Motive Power Depot at the end of the steam era in the 1960s, there is still a complex residual converging rail system in the area. Within 1 mile of the junction, there are another five interlocked mechanical signal boxes: Abbey Foregate Junction: located on the Wolverhampton line to allow access to the adjacent Abbey Foregate yard. Crewe Bank: closed 8 December 2012. Crewe Junction English Bridge: controlled the southside of the triangular junction through Coleham to Sutton Bridge Junction.
Closed in 1953, its controls were transferred to Severn Bridge. Harlescott Crossing: closed 8 December 2012. Network Rail believes that to simplify this system to allow it to be remotely controlled through coloured-light signals would not be economical. Hence the current mechanical signalling system in the area is presently envisaged to remain in operation until at least 2030, as long as 2050 on current plans. Shrewsbury Traction Maintenance Depot#Abbey Foregate – the adjacent Abbey Foregate Yard Sutton Bridge Junction Railways of Shropshire Allen, David. "Britain's longest'box". RAIL. No. 319. EMAP Apex Publications. Pp. 56–60. ISSN 0953-4563. OCLC 49953699
A switchman or pointsman is a rail transport worker whose original job was to operate various railway switches or points on a railroad. It refers to a person who assists in moving cars in a railway yard or terminal. Working in railway yards or along sidings, during the pioneering years of rail transport switchmen as a group suffered large numbers of grievous bodily injuries, including in particular crushing injuries and amputations, owing to their work in close proximity to moving trains. An early issue of Switchmen's Magazine recounted the work process for a general audience: "The vocation is the most dangerous of any of the different branches of railroading, that live for years is only due to their extreme carefulness; the least misstep will result in crippling a man for life. Their hours of work are long, the labour hard, rain or shine they have to be at their posts. There is no protection for them from the rains of summer, nor the freezing winds and snows of winter. On their efficient work, the great commercial interests of the country depend, only a little carelessness on their part may result in immense damage to the goods in transit, an error in delivery sometimes causes the loss of an entire consignment of freight, if it happens to be perishable."
Today's switchman works as part of 3 member switching crew consisting of a Locomotive Engineer and Switchman. The Foreman, in charge of the loading of rail cars, is responsible for giving direction to the switchman in order to ensure cars are lined into the correct track and blocked with like cars scheduled to a similar destination, with the engineer in charge of moving the locomotive. Switchmen's Mutual Aid Association Switchmen's Union of North America United Transportation Union