24-569: The Kalamunda Zig Zag was a zig zag rail line that was part of the Upper Darling Range railway line in Western Australia , opening in July 1891 and closing in July 1949. Most of it was converted to a public road in 1952, part of which is now a tourist drive called Zig Zag Scenic Drive that offers views of Perth from the hills . The Kalamunda Zig Zag was completed in July 1891, as part of
48-487: A zig zag was built between Ridge Hill and Gooseberry Hill stations, being cheaper to build than a continuous gradient line. The Kalamunda Zig Zag closed on 22 July 1949 along with the rest of the line. In 1952 the track was removed and most of the Kalamunda Zig Zag converted into a narrow bitumen road. Part of this road is now a tourist drive called Zig Zag Scenic Drive, with the zig zag section that descends down
72-612: A centre buffer and chain coupler. On sharp reverse curves , the buffers can become locked by slipping over, and on to, the back of each other. Although careful track design makes this a rare occurrence, a series of derailments at Stuttgart Central Station in 2012 were caused by buffer-locked wagons. Buffer-lock could occur on very sharp switches on rolling stock with the older, rounded buffers. Newer buffers are rectangular and are wider than they are tall. Buffers and chain couplers allow curves to have around 150 m (492 ft) radius, but sharp S-curves are not allowed. If it were not for
96-403: A hill the rear of the train would catch up with the wagons held back by the locomotive, but the guard could minimise that. That method of train working was why the guard, just like the driver, was required to prove his route knowledge before being given charge of a heavy train. Loose-coupled trains travelled at low speeds and were phased out in the 1970s. An improvement on the loose-coupled train
120-409: A light vehicle located between heavier ones (particularly with buffer couplings ), the move on the middle road of a zig zag can cause derailment of the light wagon. Buffers and chain coupler Buffers and chain couplers (or couplings ) – also known as "buffers and screw", "screw", and "screwlink" – are the de facto International Union of Railways (UIC) standard railway coupling used in
144-416: A simplified version of the loose-coupler is used, consisting of a single central buffer with a chain underneath. Sometimes there are two chains, one on each side of the coupler. The chain usually contains a screw-adjustable link to allow close coupling. These variants are also used elsewhere. On sharp curves, a single centre buffer is less likely to be subject to buffer-locking. The Eritrean Railway also uses
168-450: A train is required to switch its direction of travel in order to continue its journey. While this may be required purely from an operations standpoint, it is also ideal for climbing steep gradients with minimal need for tunnels and heavy earthworks. For a short distance (corresponding to the middle leg of the letter "Z"), the direction of travel is reversed, before the original direction is resumed. Some switchbacks do not come in pairs, and
192-514: Is as steep as 1 in 27 with an average of 1 in 38. Every year the City of Kalamunda holds a "Zig Zag Walk" event, in which the zig zag section is closed to all but pedestrians, providing people with the opportunity to admire the views and see the area's wildflowers; Zig Zag Scenic Drive is a part of the Darling Range Regional Park . The Zig Zag Walk occurs around early October every year. On
216-499: Is the "Instanter" coupling, in which the middle link of a three-link chain is specially triangular shaped, so that when lying "prone" it provides enough slack to make coupling possible, but when the middle link is rotated 90 degrees, the length of the chain is effectively shortened, reducing the amount of slack without the need to wind a screw. The closeness of the coupling allows the use of inter-vehicle pipes for train brakes. Three-link and Instanter couplings can be operated entirely from
240-569: The Darling Scarp being one-way in the direction of descent with a speed limit of 40 kilometres per hour (25 mph) and, as of May 2022, closed to motor vehicles between the hours of 8:30 pm and 11 am. This section of road was closed to motor vehicles completely by the City of Kalamunda in May 2020 due to reports of anti-social behaviour at night including hooning , drug use and cruelty to wildlife. After more than 12 months of closure,
264-520: The EU and UK, and on some railways in other parts of the world, such as in South America and India, on older rolling stock. Buffers and chain couplers are an assembly of several devices: buffers, hooks and links, or turnbuckle screws. On the modern version of the couplers, rail vehicles are mated by manually connecting the end link of one chain which incorporates a turnbuckle screw into the towing hook of
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#1732901476035288-779: The Upper Darling Range railway line in Western Australia, which was built by the Canning Jarrah Timber Company from a junction with the Midland line at Midland Junction to Canning Mills to transport railway sleepers to Perth 's growing railway system. On 1 July 1903, the line was taken over by the Western Australian Government Railways . To overcome a steep gradient up the Darling Scarp ,
312-414: The couplers, much sharper curves could be allowed, provided the train is not too long. The width between the buffers tends to increase as the track gauge increases and decrease as the track gauge decreases, which means that if wagons are changed from one gauge to another, the buffers might no longer match. That is because the buffers are originally extensions of the frames, which are spaced according to
336-647: The frame, but they were improved with the use of rubber pads behind the buffer face and later by enclosed mechanical, then hydraulic, springs to damp possible jarring. Each chain incorporates both a hook and a turnbuckle. A peculiarly British practice was the "loose-coupled" freight train, operated by the locomotive crew and a "guard" at the rear of the train, the successor to the brakesman of earlier times. That train type used three-link chain couplings for traction and side buffers to accept pushing forces but, since such trains were not fitted with an automatic through-train braking system, there were no pipes to connect between
360-527: The gauge of the track. As well, the height of the buffers is usually lower on narrow gauge railways , corresponding to the generally lower height of the rolling stock. Therefore, narrow gauge railways often use centre couplers without buffers. However, in the case of Iberian broad gauge railways, the height and spacing of the buffers are the same as for standard gauge railways in Europe including Great Britain , in order to allow through-running of rolling stock by
384-405: The grades required are discontinuous. Civil engineers can generally find a series of shorter segments going back and forth up the side of a hill more easily and with less grading than they can a continuous grade, which must contend with the larger scale geography of the hills to be surmounted. Zig zags suffer from a number of limitations: If the wagons in a freight train are marshaled poorly, with
408-521: The last Sunday of October each year, there is a community arts festival called the "Zig Zag Festival" held in Stirk Park, Kalamunda . The zig zag is also used as a stage in the Targa West Rally. The road is closed to all traffic and the stage is run in reverse road direction, from the bottom to the top. Zig zag (railway) A railway zig zag or switchback is a railway operation in which
432-412: The other wagon, drawing together and slightly compressing the buffer pairs, one left and one right on each headstock. That limits slack, and lessens shunting shocks in moving trains. By contrast, vehicles fitted with the semi-automatic Janney Type E coupler can experience significant jarring during mating and shunting. Very early rolling stock had "dummy buffers", which were simple rigid extensions of
456-411: The road reopened in July 2021 on a 12 month trial basis, with motor vehicle access limited to between 11 am and 8:30 pm. In May 2022, City of Kalamunda councillors voted to keep the road open permanently with the night and early morning motor vehicle curfew to continue, despite concerns about the ongoing cost to do so. The sections of the railway that made up the zig zag were: The gradient
480-559: The side of the wagons, using a shunter's pole, which has a hook on the end, and is safer when shunting is being done. Similarly, the screw-adjustable coupler can be connected by a shunter's pole once it has been unscrewed. Ordinary three-link couplings have been superseded by instanter, screw or buck-eye couplers in UK freight trains today. On some narrow-gauge lines in Europe , and on the Paris Metro ,
504-552: The train may then need to travel backwards for a considerable distance. A location on railways constructed by using a zig-zag alignment at which trains must reverse direction to continue is a reversing station . One of the best examples is the Darjeeling Himalayan Railway , a UNESCO World Heritage Site railway in India, which has six full zig zags and three spirals . Zig zags tend to be cheaper to construct because
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#1732901476035528-449: The vehicles. The last vehicle of the train was a heavily ballasted guard's van with its brakes controllable by a handwheel operated by the guard. The slack between vehicles coupled in this way was very convenient when starting heavy trains with a relatively low-powered locomotive on the level or on a rising gradient. On the driver's command the guard would apply his brake as hard as possible. The driver would then gently reverse to close up
552-454: The wagons on to their buffers. Then the locomotive would be driven ahead, picking up the load wagon by wagon, thus giving an easy start up the gradient. Wagons of that era did not have roller bearings and the grease-lubricated plain bearings exerted considerable resistance to motion, especially on a cold day, so starting wagon-by-wagon in this way allowed the locomotive to move off with low initial resistance. The disadvantage of that convenience
576-430: Was that the guard could be badly thrown about as the train changed speed due to the inter-wagon gaps opening or closing. In the worst case, the jerks could break a coupling or cause a derailment. A skilled guard would observe or listen to his train and apply or release his brake to keep the last few couplings reasonably taut, acting as a shock-absorber. The same effect occurred when the route changed gradient. When going over
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