A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat ) which is then dissipated. Most shock absorbers are a form of dashpot (a damper which resists motion via viscous friction).
100-724: The Colne Valley Viaduct is a bridge, under construction as of 2024, which will carry the High Speed 2 railway over the Colne Valley Regional Park and the Grand Union Canal , in Hillingdon , west London. When completed, its length of 3.4 kilometres (2.1 mi) and a weight of 116,000 tonnes will make it the largest railway bridge in the UK. It is one of the largest single civil engineering works of HS2 Phase 1. A contract for
200-422: A "two-tube" shock absorber, this device consists of two nested cylindrical tubes, an inner tube that is called the "working tube" or the "pressure tube", and an outer tube called the "reserve tube". At the bottom of the device on the inside is a compression valve or base valve. When the piston is forced up or down by bumps in the road, hydraulic fluid moves between different chambers via small holes or "orifices" in
300-552: A 9.8-mile (15.8 km) tunnel under the Chiltern Hills , to emerge near South Heath , northwest of Amersham . The route will roughly parallel the A413 road and the London to Aylesbury Line , to the west of Wendover . This is a green cut-and-cover tunnel under farmland, with soil spread over the final construction in order to reduce visual impact and noise, and allow use of the land above
400-456: A PSD shock absorber, which still consists of two nested tubes and still contains nitrogen gas, a set of grooves has been added to the pressure tube. These grooves allow the piston to move relatively freely in the middle range of travel (i.e., the most common street or highway use, called by engineers the "comfort zone") and to move with significantly less freedom in response to shifts to more irregular surfaces when upward and downward movement of
500-519: A branch to the Midland Main Line north of Derby for trains to continue to Sheffield. The original scheme also included a through station at Toton , between Nottingham and Derby. The HS2 eastern section was largely eliminated, leaving a branch from Coleshill near Birmingham to East Midlands Parkway station, just south of Nottingham and Derby, where the HS2 track would end, with trains continuing north onto
600-551: A complete disappearance of the "comfort vs. control" tradeoff, it also reduced pitch during vehicle braking and roll during turns. However, ASD shocks are usually only available as aftermarket changes to a vehicle and are only available from a limited number of manufacturers. Coilover shock absorbers are usually a kind of twin-tube gas charged shock absorber inside the helical road spring. They are common on motorcycles and scooter rear suspensions, and widely used on front and rear suspensions in cars. The principal design alternative to
700-502: A compression valve, whose role has been taken up by the dividing piston, and although it contains nitrogen gas, the gas in a mono-tube shock is under high pressure (260-360 p.s.i. or so) which can actually help it to support some of the vehicle's weight, something which no other shock absorber is designed to do. Mercedes became the first auto manufacturer to install mono-tube shocks as standard equipment on some of their cars starting in 1958. They were manufactured by Bilstein , patented
800-444: A correspondingly effective shock. The next phase in shock absorber evolution was the development of a shock absorber that could sense and respond to not just situational changes from "bumpy" to "smooth" but to individual bumps in the road in a near instantaneous reaction. This was achieved through a change in the design of the compression valve, and has been termed "acceleration sensitive damping" or "ASD". Not only does this result in
900-517: A farmhouse was compulsory purchased while a watersports centre was required to relocate. Both properties are to be demolished. Various preparatory works were also undertaken during the 2010s, including the diversion of water mains, the realignment of 275 kVa overhead power line, and a reinforcement of a gas mains, along with other measures. Towards the northern end of the viaduct, a temporary construction compound has been assembled, which accommodates offices, plant, employee welfare facilities, and
1000-467: A great future for racing due to its light weight and easy fitment. One of the earliest hydraulic dampers to go into production was the Telesco Shock Absorber, exhibited at the 1912 Olympia Motor Show and marketed by Polyrhoe Carburettors Ltd. This contained a spring inside the telescopic unit like the pure spring type 'shock absorbers' mentioned above, but also oil and an internal valve so that
1100-484: A junction connects to the north-south West Coast Main Line . There will be new stations at Old Oak Common in northwest London; Birmingham Interchange , near Solihull ; and Birmingham city centre . The trains will reach a maximum speed of 360 km/h (225 mph) when operating on HS2 track, dropping to 201 km/h (125 mph) on conventional track. The length of the new line has been reduced substantially since it
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#17328550416661200-402: A more attractive visual and tactile design. However, the viaduct has been subject to criticism from Stop HS2 for ignoring the needs of local residents. Rail industry periodical Rail Engineer notes that the site of the viaduct features multiple factors of sensitivity, pertaining to both environmental and public interests, as well as access issues during the construction phase. The main deck of
1300-455: A new high-speed railway will be more cost-effective and less disruptive than upgrading the existing conventional rail network. The DfT has forecast that improved connectivity will have a positive economic impact, and that favourable journey times and ample capacity will generate a modal shift from air and road to rail. On 21 August 2019, the DfT ordered an independent review of the project. The review
1400-650: A new museum quarter, with the original station building becoming a new museum of photography, fronting onto a new Curzon Square, which will also be home to Ikon 2 , a museum of contemporary art. Clearing the site for construction commenced in December 2018. Grimshaw Architects received planning permission for three applications in April 2020. The new station is expected to have a zero-carbon rating and over 2,800 square metres (30,000 sq ft) of solar panels. The plan makes provision for HS2 service passenger interchanges to
1500-545: A report released in February 2015 due to the increased costs and construction time that would be involved. During 2017, Contract C1 (Central 1), which covers the 21.6 km section of the line that the viaduct falls within, was awarded to the Align JV joint venture , comprising Bouygues Travaux Publics , Sir Robert McAlpine and VolkerFitzpatrick . RC Works were carried out by Kilnbridge Construction Services. On 19 January 2018,
1600-609: A review by the Conservative–Liberal Democrat coalition , a route was proposed, subject to public consultation, based on a Y-shaped route from London to Birmingham with branches to Leeds and Manchester , as originally put forward by the previous Labour government, with alterations designed to minimise the visual, noise, and other environmental impacts of the line. In January 2012, the Secretary of State for Transport announced that HS2 would go ahead in two phases and
1700-564: A tunnel bored under Long Itchington Wood, the route will pass through rural areas between Kenilworth and Coventry , crossing the A46 to enter the West Midlands. Birmingham Interchange Station will be on the outskirts of Solihull , close to the strategic road network, including the M42 , M6 , M6 toll , and A45 . These roads will be crossed on viaducts. The station is adjacent to Birmingham Airport and
1800-404: Is a dramatic reduction in "foaming" or "aeration", the undesirable outcome of a twin-tube overheating and failing which presents as foaming hydraulic fluid dripping out of the assembly. Twin-tube gas charged shock absorbers represent the vast majority of original modern vehicle suspension installations. Often abbreviated simply as "PSD", this design is another evolution of the twin-tube shock. In
1900-419: Is a hydraulic shock absorber, which usually includes a piston, a cylinder, and an oil-filled chamber. The piston is connected to the piston rod, which extends into the cylinder and divides the cylinder into two parts. One chamber is filled with hydraulic oil, while the other chamber contains compressed oil or air. When there is an accident or vibration in the vehicle, the piston moves into the cylinder, forcing
2000-508: Is compatible with electronic control. Primary among benefits cited in Multimatic ’s 2010 patent filing is the elimination of performance ambiguity associated with flexible shims, resulting in mathematically predictable, repeatable, and robust pressure-flow characteristics. An extra tube or container of oil connected to the oil compartment of the (main) shock via a flexible pipe (remote reservoir) or inflexible pipe (piggy-back shock). Increases
2100-400: Is constantly evolving due to the continuous improvement of vehicle dynamics and passenger comfort. In common with carriages and railway locomotives, most early motor vehicles used leaf springs . One of the features of these springs was that the friction between the leaves offered a degree of damping, and in a 1912 review of vehicle suspension, the lack of this characteristic in helical springs
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#17328550416662200-406: Is converted to heat inside the viscous fluid. In hydraulic cylinders , the hydraulic fluid heats up, while in air cylinders , the hot air is usually exhausted to the atmosphere. In other types of shock absorbers, such as electromagnetic types, the dissipated energy can be stored and used later. In general terms, shock absorbers help cushion vehicles on uneven roads and keep wheels in contact with
2300-493: Is expected to be fully complete in May 2025. Shock absorber Pneumatic and hydraulic shock absorbers are used in conjunction with cushions and springs. An automobile shock absorber contains spring-loaded check valves and orifices to control the flow of oil through an internal piston (see below). One design consideration, when designing or choosing a shock absorber, is where that energy will go. In most shock absorbers, energy
2400-512: Is immediately adjacent to Moor Street station , and approximately 400 metres (0.25 mi) northeast of New Street station , which is separated from Curzon and Moor streets by the Bull Ring . Passenger interchange with Moor Street would be at street level, across Moor Street Queensway; interchange with New Street would be via a pedestrian walkway between Moor Street and New Street (opened in 2013). In September 2018, one of Birmingham's oldest pubs,
2500-405: Is intended to be a major civil engineering work of High Speed 2, being amongst the largest and perhaps the most prominent single feature to be constructed during Phase 1. In terms of its basic configuration, it is a gently curved structure along a horizontal radius of 5,280 metres (17,320 ft), supported by 57 spans and weighing roughly 116,000 tonnes in total. The viaduct crosses over both
2600-563: Is the shortest on the route and will take passengers underneath an ancient woodland. The Bromford tunnel will take trains into Birmingham city centre . In April 2023, HS2 announced that work on the Euston tunnels linking Old Oak Common to Euston was being deferred and that tunnel-boring had been rescheduled to start in summer 2025. In October 2023, the Government announced that any Euston terminus would not be government-funded. However, in May 2024,
2700-472: The Channel Tunnel . London and Birmingham will be served directly by new high speed track, and services to Glasgow , Liverpool and Manchester will use a mix of new high speed track and the existing West Coast Main Line . The majority of the project is planned to be completed by 2033. The new track will be built between London Euston and Handsacre, near Lichfield in southern Staffordshire, where
2800-604: The Elizabeth Line and Great Western Line . The plan makes provision for HS2 service passenger interchanges on foot to the West Coast main Line and London Underground ("Tube") services via the adjacent Euston tube station and Euston square tube station . The West Midlands Metro , a tram service, is to serve Curzon Street, providing access to onward services from Birmingham Snow Hill , Birmingham New Street and Wolverhampton . There are five twin-bore tunnel sections on
2900-570: The Fox and Grapes , was demolished to make way for the new developments. The West Midlands Metro will be extended to serve the station. Development planning for the Fazeley Street quarter of Birmingham has changed as a result of HS2. Prior to the announcement of the HS2 station, Birmingham City University had planned to build a new campus in Eastside . The proposed Eastside development will now include
3000-623: The North London line and Hythe Road on the West London line . Birmingham Interchange will be a through station situated in suburban Solihull, within a triangle of land enclosed by the M42 , A45 , and A452 highways. A people mover with a capacity of over 2,100 passengers per hour in each direction will connect the station to the National Exhibition Centre , Birmingham Airport , and
3100-479: The River Colne and the Grand Union Canal , at which points its spans are spaced at intervals of 80 metres (260 ft); the majority of over-land spans cover shorter lengths of either 45 or 60 metres (148 or 197 ft). Considerable attention has been directed to the viaduct's aesthetic design and to avoid unnecessarily impacting the surrounding landscape and local community. To reduce its impact upon wildlife and
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3200-540: The South East , as HS2 will reduce travel times from London to Birmingham Airport to under 40 minutes. Birmingham Curzon Street will be the terminal station at the end of a branch that connects to the HS2 spine via a junction at Coleshill . A station of the same name existed on the Curzon Street site between 1838 and 1966; the surviving Grade I listed station building will be retained and renovated. The site
3300-552: The Water Orton rail corridor, the Birmingham to Derby line through Castle Bromwich , and through a tunnel past Bromford . A key feature of the HS2 proposals is that the new high-speed track will be connected to the existing West Coast Main Line track at Handsacre, north of Birmingham, taking trains north on the existing track. This is the only connection between the new and existing track. This connection allows HS2 services to serve
3400-546: The taxi rank at Euston was moved to a temporary site at the front of the station so that demolition of the One Euston Square and Grant Thornton House tower blocks could commence. The demolition period was scheduled to last ten months. In June 2020, workers finished the demolition of the western ramp and canopy of the station. This part of the station had housed the parcels depot, which fell into disuse after parcel traffic shifted to being serviced by road. In March 2023,
3500-532: The Colne Valley to voice their objections to the project. In April 2019, 12 Extinction Rebellion protesters began treesitting in order to prevent HS2 Limited chopping down trees as part of preparatory works at Harvil Road, near to the proposed site of the viaduct. There had been a protest camp next to the road since October 2017, which HS2 began evicting in January 2020. In order to clear the viaduct's intended path,
3600-469: The Conservative Party conference that Phase 2 would be abandoned. The cancellation left a new high-speed track from London to Handsacre , northeast of Birmingham, with a branch to central Birmingham. The construction of Euston station would depend on private sector funding: if funding were to be secured for the station access tunnel, construction would be the responsibility of HS2 Ltd. Euston station
3700-539: The Gabriel Snubber started being fitted in the late 1900s (also the similar Stromberg Anti-Shox). These used a belt coiled inside a device such that it freely wound in under the action of a coiled spring but met friction when drawn out. Gabriel Snubbers were fitted to an 11.9HP Arrol-Johnston car which broke the 6 hour Class B record at Brooklands in late 1912, and the Automator journal noted that this snubber might have
3800-407: The Government was reportedly prepared to pay the upfront tunnelling cost of around £1bn to avoid further costly delays to the project. It would then recoup costs from the wider development of the Euston station site. The Northolt tunnels are being constructed with four TBMs; two tunnelling West to East and two tunnelling East to West, with the plan to meet in the middle. TBM Sushila and Caroline ,
3900-711: The HS2 eastern leg. The London to Sheffield service will remain on the Midland Main Line, equalling the proposed original HS2 journey times. The integrated Rail Plan proposed a study to determine the best method for HS2 trains to reach Leeds. In June 2022, the Golborne spur was removed from the Crewe-to-Manchester Parliamentary Bill. Without this link, trains to Scotland would join the existing West Coast Main Line further south at Crewe, instead of south of Wigan . The Department of Transport stated that
4000-526: The Midland Main Line to serve the existing stations at Nottingham, Derby, Chesterfield, and Sheffield. HS2 trains would serve the centres of Nottingham and Derby, unlike in the previous proposal. Upgrades to the East Coast Main Line were proposed to offer time improvements on the London to Leeds and Newcastle routes. Services from Birmingham to Leeds and Newcastle were planned to use the remaining section of
4100-588: The National Exhibition Centre. North of the station west of Coleshill there will be a complex triangular branch junction, with six tracks at one section, will link the HS2 Birmingham city centre spur with the main spine. The spine continues north from the branch to the northerly limit of the high speed track which is a connection onto the WCML at Handsacre. The Birmingham city centre spur will be routed along
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4200-464: The Oakervee Review had been completed and disagreed with HS2 Limited over mitigation works. During March 2021, Hillingdon Council and HS2 Limited came to an agreement in which, in light of written assurances from the latter, the former shall not pursue a judicial review into the scheme. Shortly following this decision, full planning permission for the viaduct was secured. The Colne Valley Viaduct
4300-702: The Phase 2b route, was introduced in July 2017. Phase 2a received royal assent in February 2021. The High Speed Rail (Crewe - Manchester) Bill for Phase 2b was paused under the Sunak ministry . One of the stated aims of the project is to increase the capacity of the railway network. It is envisaged that the introduction of HS2 will free up space on existing railway lines by removing a number of express services, thus allowing additional local train services to accommodate increased passenger numbers. Network Rail considers that constructing
4400-591: The United Kingdom with the opening of the first part of High Speed 1 (HS1), then known as the 67-mile-long (108 km) Channel Tunnel Rail Link between London and the Channel Tunnel . In 2009, the Department for Transport (DfT) under the Labour government proposed to assess the case for a second high-speed line, which was to be developed by a new company, High Speed Two Limited (HS2 Ltd). In December 2010, following
4500-510: The WCML outside the village of Handsacre north of Lichfield in Staffordshire . There will be a branch to a new station at Birmingham Curzon Street . There will also be new stations at Old Oak Common , in northwest London, and Birmingham Interchange , near Solihull . The section between Old Oak Common and the West Midlands is scheduled to open around 2030, with the link to Euston following between 2031 and 2035. The high speed track, including
4600-675: The West Coast Main Line. The route to the north begins at Euston station in London, entering a twin-bore tunnel near the Mornington Street Bridge at the station's throat. After continuing through to the Old Oak Common station, trains proceed through a second, 8-mile (13 km) tunnel, emerging at its northwestern portal. The line crosses the Colne Valley Regional Park on the Colne Valley Viaduct and then enters
4700-536: The West Midlands , held talks to "revive the high speed rail project with private investment" after meeting private investors, Mark Harper ( Secretary of State for Transport ), and Huw Merriman ( Minister of State for Rail and HS2 ). Harper said that he was considering the plans with an "open mind". Burnham told the Transport Select Committee of the House of Commons that the gist of the plans were to revive
4800-437: The action of the auxiliary spring in the unit itself. The first production hydraulic dampers to act on the main leaf spring movement were probably those based on an original concept by Maurice Houdaille patented in 1908 and 1909. These used a lever arm which moved hydraulically damped vanes inside the unit. The main advantage over the friction disk dampers was that it would resist sudden movement but allow slow movement, whereas
4900-451: The adjacent Euston Square tube station , which serves the Circle , Hammersmith & City , and Metropolitan lines. The government announced that this aspect of the project would only commence if the private sector were to agree funding. Old Oak Common station, between Paddington and Acton Main Line station, is under construction and scheduled to be completed before Euston. It will be
5000-585: The branch to Birmingham, is 225 kilometres (140 mi) long. It is flanked by the WCML and the Chiltern Line . Upon opening, HS2 and West Coast Main Line compatible trains will operate from London, reaching Birmingham in 49 minutes and Birmingham Interchange in 38 minutes. Trains will journey to other destinations on a mix of HS2 and conventional track. Journeys to Liverpool will take 1 hour 50 minutes, to Glasgow 4 hours, and to Manchester 1 hour 40 minutes. Trains will progress on HS2 track to Handsacre, then use
5100-460: The bridge building machine was launched. By December 2022, 125 of the 1,000 bridge segments had been placed in their final position. Construction reached the half-way point (1.7km) in November 2023. In February 2024, construction was halted for "urgent remedial works" in the week before the launching girder was due to begin crossing the Grand Union Canal . This involved repeating cable tensioning in
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#17328550416665200-519: The cities of Liverpool, Manchester and Glasgow on a mix of new high-speed track and the existing West Coast Main Line. Purpose-built trains will be capable of operating on new and existing tracks. High Speed 2 is to share a southern terminus with the West Coast Main Line at London Euston. Euston is to be remodelled to integrate the new HS2 platforms and concourse with the current conventional rail station. There will be an improved connection to
5300-406: The construction of Phase 1 is worth roughly £6.6 billion, with preparation including over 8,000 boreholes for ground investigation. In October 2018, demolition began on the former carriage sheds at Euston station . This will allow the start of construction at the throat of the station at Mornington Street Bridge, and twin-bore 8-mile (13 km) tunnels to West Ruislip . In January 2019,
5400-516: The country, under the title Network North . The locations of these projects would range from southern Scotland to Plymouth . Money would be distributed in the North, Midlands and South of England according to where the reduction of costs (not benefits) will lie. Around 30 per cent of the cost savings would be spent on railway projects. After it was found that the list of projects included schemes that had already been built or were swiftly deleted, Sunak said
5500-414: The design and first appeared in 1954s. Because the design was patented, no other manufacturer could use it until 1971 when the patent expired. Spool valve dampers are characterized by the use of hollow cylindrical sleeves with machined-in oil passages as opposed to traditional conventional flexible discs or shims. Spool valving can be applied with monotube, twin-tube, or position-sensitive packaging, and
5600-629: The design concept for the Colne Valley Viaduct, which was created by Knight Architects and Atkins , was unveiled by the British Government. This concept was produced in consultation with the Colne Valley Regional Park Panel. Additional work on the viaduct's design has also been undertaken by Grimshaw Architects . In April 2019, Buckinghamshire County Council requested that the government pause all preparatory work until
5700-517: The existing Birmingham International railway station . The AirRail Link people-mover already operates between Birmingham International station and the airport. In addition, there is a proposal to extend the West Midlands Metro to serve the station. In 2010, Birmingham Airport's chief executive, Paul Kehoe, stated that HS2 is a key element in increasing the number of flights using the airport, with added patronage by inhabitants of London and
5800-535: The first two of the four TBMs to be used, were launched from the West Ruislip portal in October 2022. The third launched in February 2024 and the fourth followed in April 2024, with the all the tunnels planned to be finished in 2025. The 10-mile (16 km) Chiltern tunnels was scheduled to take three years to dig, using two 2,000-tonne (2,000-long-ton; 2,200-short-ton) tunnel boring machines (TBM). In July 2020, work
5900-408: The general public alike, four-metre (13 ft) high translucent acoustic barriers are to be installed along the entire length of the viaduct; these will reduce noise emissions while only incurring a minimal impact upon the view of onboard passengers. The design of the overhead electrification equipment was also bespoke to reduce its visual impact. The exterior concrete surfaces are faceted to provide
6000-482: The government postponed works on Euston station, saying that this was necessary to "manage inflationary pressures and work on an affordable design for the station". Delivery of services between Birmingham and Old Oak Common would instead be prioritised, with the Elizabeth line providing passenger transfer between Old Oak Common and central London until at least 2035, the earliest time at which Euston would be available under
6100-505: The government was considering the recommendations of the Union Connectivity Review, which gave alternatives such as a more northerly HS2 connection to the West Coast Main Line than Golborne and upgrades to the West Coast Main Line from Crewe to Preston . The Department of Transport will publish its response subject to the funding allocated in the integrated Rail Plan. In October 2023, Prime Minister Rishi Sunak announced at
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#17328550416666200-410: The ground. In a vehicle, shock absorbers reduce the effect of traveling over rough ground, leading to improved ride quality and vehicle handling . While shock absorbers serve the purpose of limiting excessive suspension movement, their intended main purpose is to damp spring oscillations. Shock absorbers use valving of oil and gasses to absorb excess energy from the springs. Spring rates are chosen by
6300-524: The hydraulic fluid through small holes, creating resistance and dissipating energy in the form of heat. This dampens oscillations, reducing further bouncing or wobble of the car. Shock construction requires a balance of features such as piston design, fluid viscosity, and overall size of the unit to ensure performance. As technology developed, other types of shock absorbers emerged, including gas and electric shock absorbers, that provided improved control and flexibility. The design and manufacture of shock absorbers
6400-430: The hydraulic piston that absorbs and dissipates vibration. Now, composite suspension systems are used mainly in 2 wheelers and also leaf springs are made up of composite material in 4 wheelers. Shock absorbers are an important part of car suspension designed to increase comfort, stability and overall safety. The shock absorber, produced with precision and engineering skills, has many important features. The most common type
6500-403: The legislative process would be achieved through two hybrid bills . The High Speed Rail (London - West Midlands) Act 2017 , authorising the construction of Phase 1, passed both Houses of Parliament and received Royal Assent in February 2017. A Phase 2a High Speed Rail (West Midlands - Crewe) Bill , seeking the power to construct Phase 2 as far as Crewe and to make decisions on the remainder of
6600-416: The list was intended to provide illustrative examples. In January 2024, opposition leader Keir Starmer said it would not be possible for any future Labour government to reinstate Phase 2, since contracts would have been cancelled. This was confirmed in April 2024 by Louise Haigh , the shadow transport minister. In January 2024, Andy Burnham , Mayor of Greater Manchester , and Andy Street , Mayor of
6700-766: The manufacturer based on the weight of the vehicle, loaded and unloaded. Some people use shocks to modify spring rates but this is not the correct use. Along with hysteresis in the tire itself, they damp the energy stored in the motion of the unsprung weight up and down. Effective wheel bounce damping may require tuning shocks to an optimal resistance. Spring -based shock absorbers commonly use coil springs or leaf springs , though torsion bars are used in torsional shocks as well. Ideal springs alone, however, are not shock absorbers, as springs only store and do not dissipate or absorb energy. Vehicles typically employ both hydraulic shock absorbers and springs or torsion bars. In this combination, "shock absorber" refers specifically to
6800-457: The mayors concluded in March 2024 that the best option would be a new line between Handsacre and Manchester Airport , to meet Northern Powerhouse Rail. The cost could be covered by a combination of government funding and private finance. HS2 parallels the West Coast Main Line (WCML), merging with the WCML at Handsacre. The line will be between Euston railway station in London and a junction with
6900-512: The more complex pier head units will each require three days to complete. To appropriately handle rail braking loads,of up to 9,000 tonnes a total of four shock absorber units are to be integrated into the deck structure of the viaduct. The structure will also feature four expansion joints. The foundations will consist of driven piles upon which the faceted framework is installed; water-based piers are considerably more complex in shape and design. As early as 2018, protestors had taken up positions in
7000-536: The most recently completed span, which includes drilling out the concrete join. The final pre-cast deck segment was installed on 5 September 2024. High Speed 2 High Speed 2 ( HS2 ) is a high-speed railway which is under construction in England. The line will run between Handsacre , in southern Staffordshire , and London, with a spur to Birmingham . HS2 is to be Britain's second purpose-built high-speed railway after High Speed 1 , which connects London to
7100-510: The new plans. The Colne Valley Viaduct is a 2.1-mile (3.4 km)-long bridge to carry the line over the Colne Valley Regional Park in Hillingdon , West London. The viaduct is situated between the Northolt and Chiltern tunnels. The bridge-building machine was launched in May 2022, signalling the start of construction. The final deck segment was put into place in September 2024. The viaduct
7200-419: The oil damped in the rebound direction. The Telesco unit was fitted at the rear end of the leaf spring, in place of the rear spring to chassis mount, so that it formed part of the springing system, albeit a hydraulically damped part. This layout was presumably selected as it was easy to apply to existing vehicles, but it meant the hydraulic damping was not applied to the action of the main leaf spring, but only to
7300-537: The part of Phase 2 between Handsacre and High Legh in Cheshire; trains would then proceed on Northern Powerhouse Rail to Manchester Piccadilly . Burnham said the cost could be "considerably less" than earlier plans if the maximum speed of trains was reduced. The Phase 2b Bill remains in the House of Commons but the Committee paused its work after the October 2023 announcement. A provisional report commissioned by
7400-414: The piston and via the valve, converting the "shock" energy into heat which must then be dissipated. Variously known as a "gas cell two-tube" or similarly named design, this variation represented a significant advancement over the basic twin-tube form. Its overall structure is very similar to the twin-tube, but a low-pressure charge of nitrogen gas is added to the reserve tube. The result of this alteration
7500-465: The piston starts to occur with greater intensity (i.e., on bumpy sections of roads— the stiffening gives the driver greater control of movement over the vehicle so its range on either side of the comfort zone is called the "control zone"). This advance allowed car designers to make a shock absorber tailored to specific makes and models of vehicles and to take into account a given vehicle's size and weight, its maneuverability, its horsepower, etc. in creating
7600-487: The pre-cast factories for the project. Sufficient space for the storage and treatment of up to 3,000,000 cubic metres (110,000,000 cubic feet) of chalk slurry has also been provisioned for the construction of the Chiltern tunnel to the north of the viaduct. During March 2021, construction of the viaduct's foundations commenced, although test piling had occurred before this. Between spring and summer 2021, an internal access road
7700-455: The pressure tube in response to changes in road smoothness. The two pistons also completely separate the shock's fluid and gas components. The mono-tube shock absorber is consistently a much longer overall design than the twin-tubes, making it difficult to mount in passenger cars designed for twin-tube shocks. However, unlike the twin-tubes, the mono-tube shock can be mounted either way— it does not have any directionality. It also does not have
7800-602: The programme to be". This report was clarified to mean following the cancellation of Phase 2. On 18 November 2021, the government's delayed Integrated Rail Plan was published. The plan significantly affected parts of the HS2 programme, including curtailing much of the eastern leg. Under the original proposal for the eastern leg, the high-speed line would have been built with a link to the East Coast Main Line south of York for trains to continue to Newcastle. A branch would take trains into Leeds. There would also have been
7900-471: The project was progressively cut until only the London to Handsacre and Birmingham section remained. The project has both supporters and opponents . Supporters of HS2 believe that the additional capacity provided will accommodate passenger numbers rising to pre- COVID-19 levels while driving a further modal shift to rail. Opponents believe that the project is neither environmentally nor financially sustainable. In 2003, modern high-speed rail arrived in
8000-593: The rail network—was still valid, and that no "shovel-ready" interventions existed that could be deployed within the timeframe of the project. As a consequence, Oakervee recommended that the project go ahead as planned, subject to a series of further recommendations. After concluding that the project should proceed, the review recommended a further review of HS2 that would be undertaken by the Infrastructure and Projects Authority and would concentrate on reducing costs and over-specification. On 15 April 2020, formal approval
8100-529: The rotary friction dampers tended to stick and then offer the same resistance regardless of speed of movement. There appears to have been little progress on commercialising the lever arm shock absorbers until after World War I , after which they came into widespread use, for example as standard equipment on the 1927 Ford Model A and manufactured by Houde Engineering Corporation of Buffalo, NY. Most vehicular shock absorbers are either twin-tube or mono-tube types with some variations on these themes. Also known as
8200-408: The route from London to Birmingham. The Euston tunnel will take passengers from Euston station to Old Oak Common station . The Northolt tunnel will cover the area between Old Oak Common and the Colne Valley Viaduct in West Ruislip. The Chiltern tunnel will be the longest tunnel on the route and will travel 10 miles (16 km) underneath the Chiltern Hills . The Long Itchington Wood tunnel
8300-621: The second bore in November 2022, and finished it in March 2023. The Bromford tunnels from Water Orton in North Warwickshire to Birmingham are being bored by TBMs Mary Ann and Elizabeth. Mary Ann started tunnelling in June 2023 and will finish in 2024, while Elizabeth started in March 2024 and will finish in Autumn 2025. The main stages of construction officially began on 4 September 2020, following previous delays. The civil engineering aspect of
8400-493: The section of the railway pertaining to the viaduct was awarded during 2017 and the design concept was released to the public on 19 January 2018. Preparatory work commenced shortly thereafter, including a compulsory land purchase and the establishment of temporary facilities, including a factory, onsite. Construction of the viaduct commenced during March 2021 with the main deck completed in September 2024 with full completion expected for May 2025. Protestors have occasionally occupied
8500-404: The site, and allegations over the viaduct's aesthetic and environmental impact upon the area have been made. Various means for High Speed 2 to traverse the valley of the River Colne were considered. One option which was studied as an alternative to using a viaduct was the extension of the nearby Northolt tunnel , which was also being built for the new line, however this option was dismissed in
8600-468: The speed of trains and their frequency, and general cost-cutting predominately affecting Phase 2b, would be assessed. The House of Commons Public Accounts Committee , in a January 2024 report, in relation to the revised planned route, stated that: "HS2 now offers very poor value for money to the taxpayer, and the Department [for Transport] and HS2 Ltd do not yet know what it expects the final benefits of
8700-526: The spring and vehicle combination bounced with a characteristic frequency, these auxiliary springs were designed with a different period, but were not a solution to the problem that the spring rebound after striking a bump could throw you out of your seat. What was called for was damping that operated on the rebound. Although C.L. Horock came up with a design in 1901 that had hydraulic damping, it worked in one direction only. It does not seem to have gone into production right away, whereas mechanical dampers such as
8800-467: The temporary London terminus of HS2 until Euston is completed. There will be connections with the Elizabeth Line , Heathrow Express to Heathrow Airport , and the Great Western Main Line to Reading , South West England , and South Wales . Old Oak Common railway station will also be connected, via out of station interchanges , with London Overground stations at Old Oak Common Lane on
8900-503: The tunnels for agriculture. After passing west of Aylesbury , the route will pass through the corridor of the former Great Central Main Line , joining the alignment north of Quainton Road to travel through rural Buckinghamshire and Oxfordshire up to Mixbury , south of Brackley , from where it will cross the A43 and open countryside through South Northamptonshire and Warwickshire, passing immediately south of Southam . After progressing through
9000-452: The twin-tube form has been the mono-tube shock absorber which was considered a revolutionary advancement when it appeared in the 1950s. As its name implies, the mono-tube shock, which is also a gas-pressurized shock and also comes in a coilover format, consists of only one tube, the pressure tube, though it has two pistons. These pistons are called the working piston and the dividing or floating piston, and they move in relative synchrony inside
9100-526: The viaduct is to be manufactured at a nearby temporary factory, the assembly of which is to commence from the northern end. In total, 908 deck units and 92 pier head units will be produced; weighing between 60 and 140 tonnes, each one unique to its intended place in the overall structure. Assembly will use a match-casting technique with relatively tight tolerance, supported by an adjustable steel formwork and prefabricated steel reinforcement where relevant. While two deck units are to be typically cast each day,
9200-443: Was also fitted to many cars. One of the problems with motor cars was the large variation in sprung weight between lightly loaded and fully loaded, especially for the rear springs. When heavily loaded the springs could bottom out, and apart from fitting rubber 'bump stops', there were attempts to use heavy main springs with auxiliary springs to smooth the ride when lightly loaded, which were often called 'shock absorbers'. Realizing that
9300-406: Was built, while the onsite factory building the viaduct segments were commissioned during the autumn. During May 2022, deck construction commenced from the northern embankment. In December 2021, the first six-metre-tall (20 ft) pier for the viaduct was cast. Construction of four jetties across the lake was also completed to support work on the piers that will be built in the water. In June 2022,
9400-466: Was chaired by Douglas Oakervee , a British civil engineer , who had been HS2's non-executive chairman for nearly two years. The review was published by the DfT on 11 February 2020, alongside a statement from the Prime Minister confirming that HS2 would go ahead in full, with reservations. Oakervee's conclusions were that the original rationale for High Speed 2—to provide capacity and reliability on
9500-400: Was completed on a 17-metre (56 ft)-high headwall at the southern portal of the twin-bore tunnel. The tunnels are lined with concrete that is cast in sections at a purpose-built facility at the southern portal; the first sections were cast in March 2021. Tunnelling began in May 2021, with TBM Florence , moving at a speed of up to 15 m (49 ft) per day. The second TBM, Cecilia ,
9600-546: Was first announced in 2013. It was originally to split into eastern and western branches north of Birmingham Interchange; the eastern branch would have connected to the Midland Main Line and East Coast Main Line , with a branch to a terminus in Leeds , and the western branch would have had connections to the West Coast Main Line at Crewe and south of Wigan, and a branch to a terminus in Manchester . Between November 2021 and October 2023
9700-594: Was given to construction companies to start work on the project. In July 2023 the Infrastructure Projects Authority annual report gave Phases 1 and 2A project a "red" rating , meaning "Successful delivery of the project appears to be unachievable. There are major issues with project definition, schedule, budget, quality and/or benefits delivery, which at this stage do not appear to be manageable or resolvable. The project may need re-scoping and/or its overall viability reassessed." Measures such as reducing
9800-410: Was initially proposed to have 11 platforms to accommodate HS2 trains. There is a reduction to six platforms, as a proposal from October 2023 will cap the throughput to 9–11 trains per hour, rather than the 18 of which the HS2 track would otherwise be capable. Sunak said the £36 billion saved by not building the northern leg of HS2 would instead be spent on roads, buses, and railways in every region of
9900-419: Was launched in July 2021. Florence, the first of two TBMs, completed tunnelling and broke through in late February 2024, and in March 2024, the second TBM, Cecilia, completed tunnelling. In December 2021, TBM Dorothy was launched, tunnelling under Long Itchington Wood. It completed the first bore in July 2022, and was returned to its initial position to complete the second, parallel bore. Dorothy started
10000-533: Was the reason it was "impossible" to use them as main springs. However the amount of damping provided by leaf spring friction was limited and variable according to the conditions of the springs, and whether wet or dry. It also operated in both directions. Motorcycle front suspension adopted coil sprung Druid forks from about 1906, and similar designs later added Friction disk shock absorber rotary friction dampers, which damped both ways - but they were adjustable (e.g. 1924 Webb forks). These friction disk shock absorber s
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