Misplaced Pages

#357642

67-573: The TPG operates trams , trolleybuses and buses for the canton of Geneva and also serves some regions in neighbouring France . Local rail services are provided by the CFF (Swiss Federal Railways) and the SNCF , and passenger ferries across the lake by the Mouettes Genevoises Navigation . The TPG shares a common fare system ( Unireso ) with these services and some in neighbouring France so that

134-403: A combination of friction and weight to start a train. The heaviest trains require the highest friction and the heaviest locomotive. The friction can vary a great deal, but it was known on early railways that sand helped, and it is still used today, even on locomotives with modern traction controls. To start the heaviest trains, the locomotive must be as heavy as can be tolerated by the bridges along

201-404: A heavy train slowly. Slip is the additional speed that the wheel has and creep is the slip level divided by the locomotive speed. These parameters are those that are measured and which go into the creep controller. On an adhesion railway, most locomotives will have a sand containment vessel. Properly dried sand can be dropped onto the rail to improve traction under slippery conditions. The sand

268-400: A modern, exceptionally high-speed train at 80 m/s (290 km/h; 180 mph), the minimum radius would be about 2.5 km (1.6 mi). In practice, the minimum radius of turn is much greater than this, as contact between the wheel flanges and rail at high speed could cause significant damage to both. For very high speeds, the minimum adhesion limit again appears appropriate, implying

335-404: A radius of turn of about 13 km (8.1 mi). In practice, curved tracks used for high speed travel are superelevated or canted , so that the minimum radius of curvature is closer to 7 km (4.3 mi). During the 19th century, it was widely believed that coupling the drive wheels would compromise performance, and this was avoided on engines intended for express passenger service. With

402-482: A single drive wheelset, the Hertzian contact stress between the wheel and rail necessitated the largest-diameter wheels that could be accommodated. The weight of locomotives was restricted by the stress on the rail, and sandboxes were required, even under reasonable adhesion conditions. It may be thought that the wheels are kept on the tracks by the flanges. However, close examination of a typical railway wheel reveals that

469-744: A single ticket can be used for any public transport within its zones and times of validity. The TPG is the successor organization to the Compagnie Genevoise des Tramways Électriques (Geneva Electric Tramway Company), or CGTE, which operated trams throughout the canton and parts of neighbouring France from 1900 until 1 January 1977. In December 2003, the TPG began road-testing a 24-metre (78.7 ft), double-articulated , mega-trolleybus manufactured by Hess and Vossloh Kiepe . The bus can carry 150 passengers. It entered passenger service in January 2004 on line 10 to

536-408: A train can proceed around a turn is limited by the radius of turn, the position of the centre of mass of the units, the wheel gauge and whether the track is superelevated , or canted . Toppling will occur when the overturning moment due to the side force ( centrifugal acceleration) is sufficient to cause the inner wheel to begin to lift off the rail. This may result in loss of adhesion – causing

603-669: Is a network of tramways forming the core element of the public transport system in Geneva, Switzerland . It is operated by Transports Publics Genevois (TPG), and is supplemented by the Geneva trolleybus system and the Geneva bus system . Opened in 1862, the network had grown sufficiently by 1920 to serve large parts of the surrounding countryside. However, by 1960 it had contracted to just one line. Since 1995, it has been greatly expanded. It presently has five tram lines, and further expansions are planned. The network extends into France, with line 17 going to Annemasse , making Geneva one of

670-404: Is between 0.35 and 0.5, whilst under extreme conditions it can fall to as low as 0.05. Thus a 100-tonne locomotive could have a tractive effort of 350 kilonewtons, under the ideal conditions (assuming sufficient force can be produced by the engine), falling to 50 kilonewtons under the worst conditions. Steam locomotives suffer particularly badly from adhesion issues because the traction force at

737-399: Is caused by friction , with maximum tangential force produced by a driving wheel before slipping given by: F m a x = μ W , {\displaystyle F_{\mathrm {max} }=\mu W,} where μ {\displaystyle \mu } is the coefficient of friction and W {\displaystyle W} is the weight on

SECTION 10

#1732851071358

804-495: Is compressed to a film on the track where the wheels make contact. Together with some moisture on the track, which acts as a light adhesive and keeps the applied sand on the track, the wheels "bake" the crushed sand into a more solid layer of sand. Because the sand is applied to the first wheels on the locomotive, the following wheels may run, at least partially and for a limited time, on a layer of sand (sandfilm). While traveling this means that electric locomotives may lose contact with

871-451: Is known as hunting oscillation . Hunting oscillation was known by the end of the 19th century, although the cause was not fully understood until the 1920s, and measures to eliminate it were not taken until the late 1960s. The maximum speed was limited not by raw power but by a possible instability in the motion. The kinematic description of the motion of tapered treads on the two rails is insufficient to describe hunting well enough to predict

938-416: Is lowered with contamination, the maximum obtainable under those conditions occurs at greater values of creep. The controllers must respond to different friction conditions along the track. Some of the starting requirements were a challenge for steam locomotive designers – "sanding systems that did not work, controls that were inconvenient to operate, lubrication that spewed oil everywhere, drains that wetted

1005-421: Is most often applied using compressed air via tower, crane, silo or train. When an engine slips, particularly when starting a heavy train, sand applied at the front of the driving wheels greatly aids in tractive effort causing the train to "lift", or to commence the motion intended by the engine driver. Sanding however also has some negative effects. It can cause a "sandfilm", which consists of crushed sand, that

1072-452: Is needed. The driving wheels must turn faster than the locomotive is moving (known as creep control) to generate the maximum coefficient of friction, and the axles must be driven independently with their own controller because different axles will see different conditions. The maximum available friction occurs when the wheels are slipping/creeping. If contamination is unavoidable the wheels must be driven with more creep because, although friction

1139-399: Is slightly tapered. When the train is in the centre of the track, the region of the wheels in contact with the rail traces out a circle which has the same diameter for both wheels. The velocities of the two wheels are equal, so the train moves in a straight line. If, however, the wheelset is displaced to one side, the diameters of the regions of contact, and hence the tangential velocities of

1206-456: Is the assumption that wheels are round. A glance at the tyres of a parked car will immediately show that this is not true: the region in contact with the road is noticeably flattened, so that the wheel and road conform to each other over a region of contact. If this were not the case, the contact stress of a load being transferred through a line contact would be infinite. Rails and railway wheels are much stiffer than pneumatic tyres and tarmac but

1273-424: Is the taper of the treads. For a given speed, the longer the wavelength and the lower the inertial forces will be, so the more likely it is that the oscillation will be damped out. Since the wavelength increases with reducing taper, increasing the critical speed requires the taper to be reduced, which implies a large minimum radius of turn. A more complete analysis, taking account of the actual forces acting, yields

1340-411: Is used to denote these vehicles, is an acronym for Düwag - Ateliers de Vevey . Following this new procurement, TPG's existing fleet of old trams could be completely withdrawn, as future network expansion, including the introduction of new lines 13 and 16, had already been taken into account when the order for the new trams was placed. In 1988, a referendum on the proposed new network expansion projects

1407-664: The Bachet stop, and line 13 became line 15 at the Palettes stop. In 2009, there was another alteration in the way the lines serviced the ring link: line 12 began switching to line 15 at the Palettes stop, line 13 started to reverse at the Palettes loop and line 17 was redirected to turn around at the Lancy-Pont-Rouge loop. The next network expansion phases included the Tram Cornavin–Meyrin–CERN (TCMC) project,

SECTION 20

#1732851071358

1474-528: The Compagnie Genevoise des Tramways Électriques (CGTE), predecessor of the TPG, was inaugurated. The CGTE set itself the goal of unifying the various systems. All lines were electrified and converted to a uniform metre gauge . For nearly three months in 1904, the CGTE also operated the steepest adhesion railway in Switzerland. The incline reached 11.8%, but the dangers posed by such steep inclines brought about

1541-579: The SR V Schools class , operated with a factor of adhesion below 4 because the traction force at the wheel rim does not fluctuate as much. Other factors affecting the likelihood of wheelslip include wheel size, the sensitivity of the regulator and the skill of the driver. The term all-weather adhesion is usually used in North America , and refers to the adhesion available during traction mode with 99% reliability in all weather conditions. The maximum speed at which

1608-445: The airport . This vehicle was created by adding a middle section to a trolleybus that was originally a single-articulated, 18-metre (59.1 ft) vehicle. In 2005–06, TPG purchased ten all-new double-articulated trolleybuses from Hess , length 24.7 m (81.0 ft), and they are numbered 781-790. As of late 2006, TPG's fleet included 92 trolleybuses, all articulated (of which eleven were double-articulated). As of 27 April 2008,

1675-404: The "vehicle velocity". When a wheel rolls freely along the rail the contact patch is in what is known as a "stick" condition. If the wheel is driven or braked the proportion of the contact patch with the "stick" condition gets smaller and a gradually increasing proportion is in what is known as a "slip condition". This diminishing "stick" area and increasing "slip" area supports a gradual increase in

1742-1036: The TPG network includes 6 tramway routes, 38 cantonal bus routes, 15 intercantonal ( Canton of Vaud ) and international (France) bus routes and 12 nighttime bus routes. In December 2010, Line 18 opened, from Avanchet to Coutance; it was extended as far as CERN in May 2011, closed in December 2011 and replaced by Line 14. In December 2012, the tramway was again split into line 14 (Meyrin-Gravière – P+R Bernex) and line 18 (CERN – Carouge). Construction started in November 2008 and finished in December 2011. Line 14 originally ran from P+R Bernex to Meyrin-Gravière or CERN, but has since then been split into Line 14 (P+R Bernex – Meyrin-Gravière) and Line 18 (Carouge – CERN) in December 2012. Trams in Geneva The Geneva tramway network ( French : Réseau tramway de Genève )

1809-419: The TPG, an autonomous government agency of the canton of Geneva. In 1978, the tracks of the last remaining tramway were renewed under the auspices of the "new" TPG. Planning of the proposed new lines was addressed. However, it was only on 12 June 1988, with the adoption of a new cantonal law about public transport, that the first concrete building proposals were presented. From 1995, these proposals then became

1876-619: The associated tram and trackwork construction workshop was commissioned. Finally, in 1992, the new administration building was opened. Since then, it has been the headquarters of the TPG. In 1987–1989, the TPG procured a total of 45 new, partly low floor , articulated trams , based on the prototype Be 4/6 tram no. 741, which had joined the TPG fleet in 1984. The new trams were supplied by Ateliers de Constructions Mécaniques de Vevey (ACMV) in Villeneuve, Vaud , in collaboration with Düwag and BBC / ABB . The colloquial expression "DAV", which

1943-616: The basis of larger network extensions. By that time, the most pressing modernisation of existing operations had already occurred. In 1984, in Bachet-de-Pesay in the municipality of Lancy , construction work had begun on the new Bachet tram depot. To connect the new facility with the existing network, the route of line 12 was extended on 27 September 1987 by one kilometre (0.6 mi) from Carouge to Bachet . The sidings and maintenance facility in Bachet were opened in 1988, and in 1990

2010-412: The cars or by a pinion meshing with a rack . The friction between the wheels and rails occurs in the wheel–rail interface or contact patch. The traction force, the braking forces and the centering forces all contribute to stable running. However, running friction increases costs, due to higher fuel consumption and increased maintenance needed to address fatigue damage and wear on rail heads and on

2077-406: The construction of the new Route des Nations, a project the commencement of which is still uncertain. [REDACTED] [REDACTED] Media related to Trams in the canton of Geneva at Wikimedia Commons 46°12′37″N 6°8′36″E  /  46.21028°N 6.14333°E  / 46.21028; 6.14333 Rail adhesion An adhesion railway relies on adhesion traction to move

Geneva Public Transport - Misplaced Pages Continue

2144-593: The construction of which began in early 2006, and the Tram Cornavin–Onex–Bernex (TCOB), for which the Swiss Federal Council awarded the concession in January 2007. The first section of the TCMC, between Cornavin and Avanchet , was opened on 8 December 2007. Initially, it formed part of the extended line 16 ( Moillesulaz–Avanchet ) and the new line 14 ( Bachet–Avanchet ). On same date, line 17

2211-486: The critical speed further. However, in order to achieve the highest speeds without encountering instability, a significant reduction in wheel taper is necessary. For example, taper on Shinkansen wheel treads was reduced to 1:40 (when the Shinkansen first ran) for both stability at high speeds and performance on curves. That said, from the 1980s onwards, the Shinkansen engineers developed an effective taper of 1:16 by tapering

2278-413: The critical speed. It is necessary to deal with the forces involved. There are two features which must be taken into account: The kinematic approximation corresponds to the case which is dominated by contact forces. An analysis of the kinematics of the coning action yields an estimate of the wavelength of the lateral oscillation: where d is the wheel gauge, r is the nominal wheel radius and k

2345-425: The dynamics of wheelsets and complete rail vehicles, the contact forces can be treated as linearly dependent on the creep ( Joost Jacques Kalker 's linear theory, valid for small creepage) or more advanced theories can be used from frictional contact mechanics . The forces which result in directional stability, propulsion and braking may all be traced to creep. It is present in a single wheelset and will accommodate

2412-501: The entry into service of a new section between Palettes and Lancy-Pont-Rouge , the ring link was completed, and with it the first phase of the network's expansion. The new ring link section facilitated the extension of line 15 and line 17 to Palettes and Bachet , respectively. From the day the ring link was completed, the four tram lines operating on it, lines 12, 13, 15 and 17 , no longer terminated there, but changed their numbers at designated stops : line 12 became line 17 at

2479-416: The following result for the critical speed of a wheelset: where W is the axle load for the wheelset, a is a shape factor related to the amount of wear on the wheel and rail, C is the moment of inertia of the wheelset perpendicular to the axle, m is the wheelset mass. The result is consistent with the kinematic result in that the critical speed depends inversely on the taper. It also implies that

2546-585: The inclusion on this section of several stations with island platforms , made necessary the exclusive use of bidirectional vehicles to run services on the section. As the numbers of the Flexity Outlook trams in the fleet were then rather limited, the TPG exercised its existing option for 17 more vehicles, while in the meantime the previous through-connection of line 12 with line 16 at the Moillesulaz terminus had to be suspended. According to various sources,

2613-457: The lines were partly replaced by trolleybuses . By 1969, the network had shrunk to just one 8 km (5.0 mi) long tramway, which was served by line 12 ( Moillesulaz–Carouge ). The good technical condition of the tramcars and the fact that they had not yet been written off, led to the provisional retention of the last tramway. In the 1970s, concepts were developed to connect the relatively large suburban communities of Meyrin and Onex to

2680-539: The lines, are located at the following stops: Two cross-border extensions are planned, one towards Saint-Julien-en-Genevois via Plan-les-Ouates , and the other an extension of line 17 towards Lycée des Glières in Annemasse . An extension of line 15 is proposed between Place des Nations and Le Grand-Saconnex , with a possible extension to Ferney-Voltaire in France. However, the realisation of this project would depend upon

2747-464: The only cities in the world with a tram system that crosses an international border (the only others being Strasbourg , between France and Germany , and Basel , between France, Germany and Switzerland). Geneva's and Switzerland's first trams ran on 19 June 1862, with the opening of a horsecar tramway between Place Neuve and Carouge . In 1889, a steam tramway was opened, and in 1894 Geneva's first electric tram entered service. Finally, in 1899,

Geneva Public Transport - Misplaced Pages Continue

2814-565: The opening of the second stage of the TCMC ( Avanchet–Meyrin ) took place on 12 December 2009, with the entry into service of the section to Meyrin ( Gravière ). On 30 April 2011, operations commenced on the section to CERN . The TCOB route to Bernex P+R , which includes, amongst other things, a second crossing of the Rhône, went into service at the end of 2011. The first – very short – section of this route, between Coutance and Genève-Cornavin station, had already commenced operations at

2881-485: The previous lines 13 , 16 and 17 were discontinued, and only one line now operates on most section of track. Although these changes simplify tram operations, they also mean that points on the inner city sections, and in particular Genève-Cornavin station, can no longer be reached from all parts of the network (e.g. Genève-Cornavin is no longer directly served by line 12 ) without the need to change trams en route. Interchange stations , which enable transfers between

2948-429: The rails, and so on.." Others had to wait for modern electric transmissions on diesel and electric locomotives. The frictional force on the rails and the amount of wheel slip drops steadily as the train picks up speed. A driven wheel does not roll freely but turns faster than the corresponding locomotive velocity. The difference between the two is known as the "slip velocity". "Slip" is the "slip velocity" compared to

3015-441: The region where they first come into contact, followed by a region of slippage. The net result is that, during traction, the wheel does not advance as far as would be expected from rolling contact but, during braking, it advances further. This mix of elastic distortion and local slipping is known as "creep" (not to be confused with the creep of materials under constant load). The definition of creep in this context is: In analysing

3082-403: The remaining tramway once again, with an appropriately modern light railway . However, all of these ideas, and also the investments necessary for the maintenance of the remaining infrastructure in the medium term, exceeded the abilities of the privately owned CGTE. A popular initiative demanding the nationalization of the CGTE was then adopted, and on 1 January 1977 the CGTE was transformed into

3149-458: The route and the track itself. The weight of the locomotive must be shared equally by the wheels that are driven, with no weight transfer as the starting force builds. The wheels must turn with a steady driving force on the very small contact area of about 1 cm between each wheel and the top of the rail. The top of the rail must be dry, with no man-made or weather-related contamination, such as oil or rain. Friction-enhancing sand or an equivalent

3216-467: The same distortion takes place at the region of contact. Typically, the area of contact is elliptical, of the order of 15 mm across. The distortion in the wheel and rail is small and localised but the forces which arise from it are large. In addition to the distortion due to the weight, both wheel and rail distort when braking and accelerating forces are applied and when the vehicle is subjected to side forces. These tangential forces cause distortion in

3283-434: The slight kinematic incompatibility introduced by coupling wheelsets together, without causing gross slippage, as was once feared. Provided the radius of turn is sufficiently great (as should be expected for express passenger services), two or three linked wheelsets should not present a problem. However, 10 drive wheels (5 main wheelsets) are usually associated with heavy freight locomotives. The adhesion railway relies on

3350-410: The swift demise of this line. In the 1920s, the city and the canton had a large network of urban and suburban tramways. As of 1923, a total of 120 km (75 mi) of tramways had been built. The network extended into the countryside, and even across the border into France. In 1925, the CGTE began to convert its interurban lines to bus operation. This process continued in the city centre, where

3417-648: The timetable change in December 2010. A new line 18 ran on the route, and was extended to CERN in May 2011. For the inauguration of the TCOB route, the TPG ordered 32 Tango trams, made by the Swiss company Stadler Rail . Like the Cityrunners, the Tango trams are bidirectional. After the new route to Bernex P+R was commissioned, the network was simplified. There are now only four tram lines, nos. 12 , 14 , 15 and 18 . The use of

SECTION 50

#1732851071358

3484-420: The traction or braking torque that can be sustained as the force at the wheel rim increases until the whole area is "slip". The "slip" area provides the traction. During the transition from the "all-stick" no-torque to the "all-slip" condition the wheel has had a gradual increase in slip, also known as creep and creepage. High adhesion locomotives control wheel creep to give maximum effort when starting and pulling

3551-428: The train stays on the track, it becomes evident why Victorian locomotive engineers were averse to coupling wheelsets. This simple coning action is possible only with wheelsets where each can have some free motion about its vertical axis. If wheelsets are rigidly coupled together, this motion is restricted, so that coupling the wheels would be expected to introduce sliding, resulting in increased rolling losses. This problem

3618-415: The train to slow, preventing toppling. Alternatively, the inertia may be sufficient to cause the train to continue to move at speed, causing carriages to topple completely. For a wheel gauge of 1.5 m (4.9 ft) with no canting, a centre of gravity height of 3 m (9.8 ft) and a speed of 30 m/s (110 km/h; 67 mph), the minimum radius of curvature is 360 m (1,180 ft). For

3685-412: The train, and is the most widespread and common type of railway in the world. Adhesion traction is the friction between the drive wheels and the steel rail. Since the vast majority of railways are adhesion railways, the term adhesion railway is used only when it is necessary to distinguish adhesion railways from railways moved by other means, such as by a stationary engine pulling on a cable attached to

3752-399: The tread is burnished but the flange is not—the flanges rarely make contact with the rail and, when they do, most of the contact is sliding. The rubbing of a flange on the track dissipates large amounts of energy, mainly as heat but also including noise and, if sustained, would lead to excessive wheel wear. Centering is actually accomplished through shaping of the wheel. The tread of the wheel

3819-464: The weight of the rotating mass should be minimised compared with the weight of the vehicle. The wheel gauge appears in both the numerator and denominator, implying that it has only a second-order effect on the critical speed. The true situation is much more complicated, as the response of the vehicle suspension must be taken into account. Restraining springs, opposing the yaw motion of the wheelset, and similar restraints on bogies , may be used to raise

3886-507: The wheel rim fluctuates (especially in 2- or most 4-cylinder engines) and, on large locomotives, not all wheels are driven. The "factor of adhesion", being the weight on the driven wheels divided by the theoretical starting tractive effort, was generally designed to have a value of 4 or slightly higher, reflecting a typical wheel–rail friction coefficient of 0.25. A locomotive with a factor of adhesion much lower than 4 would be highly prone to wheelslip, although some 3-cylinder locomotives, such as

3953-556: The wheel rims and rail movement from traction and braking forces. Traction or friction is reduced when the top of the rail is wet or frosty or contaminated with grease, oil or decomposing leaves which compact into a hard slippery lignin coating. Leaf contamination can be removed by applying " Sandite " (a gel–sand mix) from maintenance trains, using scrubbers and water jets, and can be reduced with long-term management of railside vegetation. Locomotives and trams use sand to improve traction when driving wheels start to slip. Adhesion

4020-431: The wheel with multiple arcs, so that the wheel could work effectively both at high speed as well as at sharper curves. The behaviour of vehicles moving on adhesion railways is determined by the forces arising between two surfaces in contact. This may appear trivially simple from a superficial glance but it becomes extremely complex when studied to the depth necessary to predict useful results. The first error to address

4087-406: The wheel. Usually the force needed to start sliding is greater than that needed to continue sliding. The former is concerned with static friction (also known as " stiction " ) or "limiting friction", whilst the latter is dynamic friction, also called "sliding friction". For steel on steel, the coefficient of friction can be as high as 0.78, under laboratory conditions, but typically on railways it

SECTION 60

#1732851071358

4154-470: The wheels at the running surfaces, are different and the wheelset tends to steer back towards the centre. Also, when the train encounters an unbanked turn , the wheelset displaces laterally slightly, so that the outer wheel tread speeds up linearly, and the inner wheel tread slows down, causing the train to turn the corner. Some railway systems employ a flat wheel and track profile, relying on cant alone to reduce or eliminate flange contact. Understanding how

4221-419: Was alleviated to a great extent by ensuring that the diameters of all coupled wheels were very closely matched. With perfect rolling contact between the wheel and rail, this coning behaviour manifests itself as a swaying of the train from side to side. In practice, the swaying is damped out below a critical speed, but is amplified by the forward motion of the train above the critical speed. This lateral swaying

4288-439: Was also served by line 17 , which ran from Plainpalais to Eaux-Vives station . Due to the increased need for rolling stock resulting from the network expansions after 2000, more trams were procured. Initially, the TPG ordered 21 Flexity Outlook Cityrunners from Bombardier Transportation for delivery in 2004-2005, with an option on another 17 vehicles; the option was exercised at the end of 2007. On 13 May 2006, upon

4355-425: Was extended, from Eaux-Vives station to the disused Chêne-Bourg station , and thus revived scheduled services on the short local branch line, including its terminal loop, after a long absence. The first TCMC section was built in a double track configuration. However, the absence of any balloon loop at the provisional terminus at Avanchet , or at the permanent termini at Meyrin–Gravière and CERN , as well as

4422-552: Was opened, and trams returned to the other side of the Rhône. On 28 June 1997, line 13 was extended from Bachet to Palettes and on 28 March 1998, line 16 ( Moillesulaz–Cornavin ) was put into operation. On 14 December 2003, line 13 was extended from Cornavin to Nations . The following year, on 11 December 2004, line 15 entered service; it ran on a new route from Lancy-Pont-Rouge via Acacias to Plainpalais , and continued from there via Cornavin station to Nations . From 10 December 2005, this new section

4489-549: Was unsuccessful. The first phase of development of the network therefore became the construction of a central Plainpalais –Carouge–Bachet–Palettes– Acacias –Plainpalais ring link, and the crossing of the Rhône to the Genève-Cornavin railway station , with a continuation to the Place des Nations and United Nations Office at Geneva . On 28 May 1995, line 13 ( Cornavin–Bachet )

#357642