Unitsky String Technologies
27 September 2019
Battle of technologies: SkyWay vs monorail
We are starting a series of publications in which we will compare SkyWay technology with existing modes of transport, analyze their features and find out how exactly SkyWay transport complexes favorably differ from the well-known and familiar ways of servicing passengers and goods, as well as what a beneficial alternative they can be.
The first article will focus on the nearest “neighbor” of SkyWay on the second level monorail transport.
A bit of history
This type of transport appeared for the first time in Russia in 1820: a resident of the village Myachkovo near Moscow Ivan Elmanov has built a “road on pillars” trolleys pulled by horses rolled on an upper longitudinal beam.
Just a year later, a monorail road was patented in England by engineer Henry Palmer, who has built its first section in 1825. Since no one in Europe knew about the project of the Russian inventor, this year became the official starting point in the history of monorail transport.
In the nearly two hundred years since Elmanov’s and Palmer’s roads were built, the world has seen dozens of monorail projects that differed in varying degrees of design and technical performance, up to the use of gyroscopes, jet engines and a magnetic cushion.
“Wuppertaler Schwebebahn” deserves a special mentioning. It is a monorail suspension road in the German city of Wuppertal that came down in history as the first monorail put into operation. It remains in operation even today servicing about 85,000 passengers per day. The line has survived two World wars and continues to make a profit, remaining a good example of a safe way to transport passengers. Perhaps the secret of Wuppertal road’s success was that it was difficult to lay a land or underground railway line in the valley of Wuppertal river in the early twentieth century, and they managed to build the monorail directly over the river.
However, Wuppertal’s experience is rather an exception to the general rule: today monorail is among the outsiders in the transport market. It would seem that an adequate idea to isolate highways by placing them above the ground, should provide a high level of safety and speed of transporting passengers and goods. But in practice, even modern types of monorails cannot boast of outstanding performance or low capital costs for construction. It often turns out expensive and inefficient.
Even high-speed Maglev, which can travel at speeds up to 600 km/h, has turned out economically unprofitable because of the high costs of construction and maintenance. Another confirmation of this is the experience of operating the Moscow monorail, which the city administration transferred to the excursion mode of operation in 2017, and then finally raised the question of the reasonability of its use due to low profitability.
Monorail and SkyWay
The visual similarity of monorails with string transport complexes is the basis for some “experts” to estimate the market prospects of SkyWay technology. The logic of Yunitskiy’s opponents is simple: the transport is externally similar, so if the monorail became unclaimed, SkyWay will repeat its fate, too. However, there is only one similar feature in these transport systems: in both cases transport is moving on a special overpass. But there are much more design differences. Anyway, let’s proceed in the right order.
A reinforced concrete or metal trestle is almost always used in monorail roads. The cost of its erection varies from 17 to 100 and more million USD per kilometer.
In string transport complexes, the overpass can withstand high loads with low material consumption due to the use of pre-stressed steel structures. This not only significantly reduces the cost of building SkyWay lines, but also provides benefits to SkyWay transport in aesthetic terms: instead of massive monorail overpasses, it is possible to build lightweight, slender and at the same time durable structures that will not look monstrous against the background of the city panorama and beyond.
Most monorail systems (except Maglev trains) use rolling stock with a running gear fitted with pneumatic tires. This solution has a number of benefits and substantial disadvantages.
The use of pneumatic tires leads to significant energy costs for motion. For example, in comparison with railway transport, energy losses can differ by 57 times, since pneumatic wheels have greater rolling resistance and rotation inertia in contrast to “steel wheel rail” systems.
Theoretically, trains with pneumatic tires can overcome steeper slopes (over 15%) in contrast to rail systems. However, in practice, this advantage is insignificant, since it requires a more efficient power plant and additional energy costs that will ultimately lead to a decrease in the level of comfort for passengers.
In addition, pneumatic tires are more vulnerable to weather conditions, in particular, to the icing of track structure in winter. This requires additional cleaning of the overpass from snow and ice, or placing the running gear in an isolated box protected from rain (Safege system), which complicates its maintenance.
The design of the chassis of the SkyWay rolling stock includes a scheme in which a steel wheel rests on the rail surface. In contrast to the pneumatic tire, SkyWay wheel has low rolling resistance due to the narrow contact spot (in the rolling direction), which ensures low energy consumption by the rolling stock.
In addition, the use of the “steel wheel rail” layout solves the problem of icing, since such a system does not need additional cleaning of the track structure. Running tests of SkyWay rolling stock at EcoTechnoPark proved it in practice.
The most commercially successful of all the traditional monorail systems are monorails produced by the Japanese company Hitachi and Canadian Bombardier. The key to their profitability was the use of ALWEG system in the structure of the running gear: two carrying wheels are on top of the rail + four supporting ones at the sides. This scheme allows to eliminate the disadvantage of low speed in a conventional monorail and helps to cope with large passenger traffic up to 137 thousand passengers per day.
For comparison, the motion speed in urban Skyway complexes can reach 150 km/h, and, due to the use of intelligent rolling stock control systems, the theoretical peak capacity of such a system at 20-hour operation is 360 thousand people per day in one direction (taking into account a two-second allowed interval, as well as the 10-passenger base capacity of a single module). In addition, the performance of SkyWay transport complexes can be further raised by increasing the capacity of modules and combining them into trains.
We can go on comparing the two transport systems quite a long time, however, even the above points make it clear: elevated overpass transport can be different, but the structural differences between seemingly similar complexes can be very significant. So essential that one system can remain an expensive toy with very vague market prospects for as long as you want, while the other can effectively solve any existing transport problems.
© 19772019 Anatoly Yunitskiy. All Rights Reserved.