ecosign

More documents

Recommendations

Info

Photo:Archive ISR Why a 3S system? Professor Josef Nejez, ISR, explains the technical reasons for the choice of the 3S system for the Peak to Peak Gondola. In order to understand why the 3S system was found to be the optimum solution for linking two ski areas located on either side of a deep valley, we must first of all consider the basic Prof. Dr. Josef Nejez differences in terms of engineering and operation between the main types of aerial passenger ropeways on the market today. The main differences between modern ropeway systems concern the number of ropes employed and the mode of operation. With regard to the ropes, the basic distinction is between monocable and bicable configurations, and for the mode of operation between reversible (jigback) and continuously circulating systems. The ropes In the case of a monocable system, fixed or detachable grips are used to attach the carriers to a rope that provides support and traction at the same time. The rope employed on a monocable system is called the haul (or hauling) rope. On a bicable system, the carriers are suspended from a carriage that travels along a track rope and is pulled by a separate haul rope. In this case, carrier support and traction are distinct functions performed by two ropes of different construction. The track ropes take the form of full-locked coil ropes, which are highly compact on section and thus ideally suited to absorb shear loads (wheel loads from the carriages). The haul ropes are round strand Lang’s lay ropes, which have two key characteristics that fulllocked coil ropes do not: the flexibility needed to negotiate the rope sheaves and suitability for splicing so as to create an endless loop. The hauling rope on a monocable system must also meet that require- Photos:Whistler Blackcomb Although the haul rope is not yet in place here, the rope configuration for the 3S system is clear. ment and the same rope construction is accordingly used as for the haul rope on a bicable system. There are other significant differences between full-locked coil ropes and round strand ropes which affect their potential uses in the field of ropeway engineering, namely the rope strength design factor, fill factor (share of the metallic section in the geometrical section of the rope) and rope surface. Compared with round strand ropes, the full-locked coil ropes used as track ropes can have a lower rope strength design factor, while the fill factor is higher and the rope surface is much smoother. The lower design factor and higher fill factor provide for longer spans, while the smoother surface provides a better track for the carriage wheels. So far we have only referred to one track rope and to one haul rope or hauling rope, meaning a rope that serves to provide support, traction or both support and traction. But each of these functions can be assigned to more than one rope. On big jigbacks, this is usually the case with regard to the support function; instead of just one track rope such installations are built with two parallel track ropes. Similarly, if the haul rope on a continuous loop system (gondola) is replaced by two parallel synchronized haul ropes with a gage that is wider than the width of the carrier, we have what is No need to be a tightrope walker for a highlevel walk on the 3S system!
known as a Funitel system. Installations with two or more haul ropes are not normally built today, however. Operating mode In the case of a reversible system or jigback, the cars travel to and fro between the terminals. They do not pass through the stations. In the normal case, a reversible operates with two carriers, which have a bigger capacity than the gondolas on a continuous loop system. System capacity on a reversible is determined by carrier capacity and transit time (including dwell time in the terminals). This means that system capacity also depends on line speed and the length of the line. A circulating system, on the other hand, operates with a large number of smaller carriers moving continuously in the same direction on two lines (uphill and downhill) between the terminals, and the carriers pass through the stations. In this case system capacity depends on individual carrier capacity and the time interval between the carriers but not on line length. From these distinctions and other ropeway engineering fundamentals (output of the primary mover, rope tension, etc.), the following basic principles can be defined for the choice of operating mode: Reversibles are the system of choice for short, steep lines with a significant vertical difference between the terminals and also for long unsupported spans. Circulating systems are ideal for long lines with relatively little vertical, with monocables used for short spans and bicable solutions for medium spans. The 3S system In certain respects the 3S combines the respective advantages of reversible and circulating systems. In terms of ropeway engineering, the 3S is a bicable circulating system with twin track ropes. In the case of the Peak 2 Peak, this rope configuration is the key to the record-breaking 3 km unsupported length of the middle span and to a design capacity of 2050 P/h and direction. A comparison between the 3S and reversible systems shows that, for the 4.4 km line linking Whistler and Blackcomb, a reversible would have to operate with 300passenger cabins for the same system capacity. That is 50% more than the biggest reversible cabins built to date. The stop-and- go mode of operation with the relatively long terminal dwell times required for passenger handling with such big cabins would be much less efficient than the comparatively continuous traffic flows available with the 28-passenger gondolas actually chosen. A conventional bicable installation would not have been the solution for the Peak 2 Peak either because of the very long unsupported span across the valley. In the case of a bicable circulating system, the haul rope can be supported by sheave trains on the towers but haul rope support between the towers is only provided by the carrier grips. This means that the weight of the haul rope is transmitted to the track rope via the gondola carriages. This mechanism is especially problematical when the gondolas are fed onto the line at the start of operations in the morning and again when they are taken off the line in the evening; when the first gondola enters a rope span in the morning and the last gondola exits the span in the evening, half the weight of the haul rope in that span is supported by the grip on the gondola and is transmitted to the track rope via the carriage. That involves very considerable additional loads on various components with a number of negative consequences, e.g. on the service life of the track rope. With the 3S system, the problem is solved with the help of slack carriers with an integrated haul rope support sheave attached to the track ropes at relatively short intervals. That ensures even distribution of the weight of the haul rope on the track ropes. It also avoids longitudinal swing in the carriers resulting from the dynamics of acceleration and deceleration (starts and stops) and avoids the danger of haul rope entanglement. This solution has long been em- performance in strong winds. ployed on big reversibles with double track ropes. Another big advantage of the 3S system is also worth mentioning, and that is its outstanding wind stability. The twin track ropes act as dampers on lateral swing in the carriers, and that is the key to the exceptional performance of the 3S in side winds. The Peak 2 Peak Gondola, for example, is designed to operate in 80 km/h winds, which makes it the least susceptible to strong winds of all the Whistler Blackcomb lifts. In summary, one is tempted to say that, had the 3S system not yet existed, it would have been necessary to invent it for the link between Whistler und Blackcomb! Josef Nejez 3S Peak 2 Peak Gondola Altitude Whistler terminal 1834 m Altitude Blackcomb terminal 1870 m Vertical height 36 m Line length 4400 m No. of towers 4 Tower height 35 – 65 m Longest span 3024 m Max. height above ground 436 m Track ropes 2 x 56 mm Haul rope 46 mm Drive terminal Whistler Drive output (continuous) 520 kW Tensioning terminal Blackcomb Haul rope loop 8850 m No. of carriers 28 Carrier capacity 28 pers. Line speed 7.5 m/s Carrier interval 49 s Transit time 11 min System capacity 2050 P/h TECHNICAL DATA The 3S configuration offers excellent 9
Page 1 and 2: www.isr.at DECEMBER 2008 INTERNATIO
Page 3 and 4: transportation and traffic systems
Page 5 and 6: Doug Forseth, Senior VP of Operatio
Page 7: Warren Sparks, Executive Vice-Presi
Page 11 and 12: Max Baumann, Vice President Marketi
Page 13 and 14: ith the haul rope spliced and all
Page 15 and 16: TECHNICAL DATA ● Cabin dimensions
Page 17 and 18: Photos: Neveplast Another INTERNATI
Page 19 and 20: Kamov helicopters were on duty for

ecosign

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?