|
|
|
|
|
|
|
| A cynic knows the price of everything, and the value of nothing. (Oscar Wilde) |
 |
In the downtown areas of most Western cities, where there is difficult to press in more traffic, and where real estate-prices are at a premium, the city planners have resorted to digging tunnels for the traffic. This solution applies both to the road traffic and to the railbound traffic. Tramways are turned into subways for this reason. Subways could be regarded as specially adapted trains. Adapted insofar as suspended power lines are inpractical i tunnels. Instead, power conduits are placed on the ground, usually beside the track. Tunnels are built at great expense to accomodate road traffic and trains when bridges become too huge and cumbersome to fit into the city. |
The FlyWay kind of automatic transport do not need tunnels for that reason. The slender beams fit in almost anywhere. Nevertheless, the beamcars can travel in tunnels, too, and this page will describe how that could be done.
 The headings on this page: |
 |
|---|
oad tunnels underneath cities are, when they are built, designed to swallow as much cars as possible. This is both to justify the huge investments and to remove as much of the traffic as possible from the streets, as this traffic is such a huge inconvenience. At peak traffic hours one vehicle every other second on the average passes past a given point of a 3-lane road tunnel in each direction. This comes to
Thus, road tunnels have considerably lower usage level than subway tunnels. Yet, road tunnels are larger and more expensive. New six-lane road tunnels cost about |
Yet, this is not a proper comparison, since the cost of the vehicles are not included in the price above, whereas the trains are included in the price tag above. The road tunnels are also dangerous to human health because of the exhaust fumes from the cars. If the tunnels are longer than about 500 meters, they have to be equipped with fans and vents. The longer the tunnels, the higher the vents, the stronger the fans. The awkwardness with these arrangements is demonstrated by the fact that 2 of the world´s longest tunnels, the 34-mile-long Seikan-tunnel in Japan and the Channel tunnel between Great Britan and France, only permit non-polluting electrical trains; no motorcars. And not only that: long roadtunnels are potential death-traps! The accident in the Saint Gotthards-tunnel in the Alps in 1999, where a truck caught fire, claimed 39 lives! Motorists caught in the smoke could not get out except by running, and that is not quick enough if one has to escape smoke that can only move along the tunnel. Fireman could not even reach the site of the accident during the first 3 days. |
Illustration shows a vent (the one near center) proposed
The big advantage of road tunnels is of course their flexibility. The cars can be driven wherever the drivers want, whenever they want. |
 |
|
All these attributes apply to tunnels carrying beam traffic! |
 |
 |
 |
|---|
| The first type of tunnel is dug directly under the surface along the streets. A trench is made, in which caissons are then placed at a suitable depth, and successively joined one to the other. | This kind of tunnel would have close contact with nearby houses. It could do double duty by providing electricity, water, etc. It must be sturdy enough to withstand the weight of heavy vehicles on the street above. |
| The second type of tunnel is drilled through the ground at a greater depth, corresponding to the level where subway trains usually go. The drilling would be done by rotating drums, equipped with diamond drillbits (shown on the four crossbars in the illustration), using a drill with the same diameter as the tunnel-to-be. This technique was used under the English Channel, and more recently at the extension of the Jubilee Line of the London underground. |  Rotating drill. Arrows indicate rotational direction. |
|---|
| A third, quite exciting option, is to use floating tunnels. They are lighter than the surrounding water, as they are filled with air. But they are kept suspended beneath the surface by wires, that anchor the tunnel elements firmly to the bottom. This technique is better than floating bridges, since, if they are anchored deeep enough beneath the water surface, the tunnels are invulnerable to waves and ice. |
 The floating tunnel uses technique developed during construction of oil drilling platforms for the North Sea. |
|---|
 Figure 4:2
s stated, SwedeTrack System proposes to use 3 beam sizes in its system.
If we were to assume that the costs were proportional to the cross-sectional area of the tunnels, then the beam-traffic tunnels would cost about 3, 4 and 9 million US $ per kilometer respectively to drill, as compared to prisetags of 66 and 340 million US $ per kilometer respectively, for subway- and roadtunnels. If we instead were to compare maximum capacities for the tunnels (at a very high degree of safety for the beam traffic system, applying rules for so-called brickwall stop, we would get the following result: For tunnels dug underneath the streets, in the speed interval of 20 - 60 km/h (we cannot go faster if we want to be able to brake comfortably in order to turn at right angles into crossing streets and stopping at stations):
For deep, drilled tunnels, having a maximum speed of 135 km/h:
Thus, the beam tunnel, providing higher speed for its vehicles, can attain a higher throughput capacity than a subway train carrying Vehicles that are not used could well be parked on sidings in the tunnels until they are needed. In deep-drilled tunnels it would generally be easier to arrange for intersections and roundabouts for two-way traffic routes, considering their relatively small size. Thus, traffic arrangements of this kind could be moved undeground, if there is not space enough on the surface. As opposed to subways (but like the road tunnels) the beam tunnels could also very well handle freight and carry motorcars, of varying dimensions depending on the diameter of the tunnel. Here and there in the downtown area, such as in parks and along avenues, the beam vehicles could come up above the surface. Steep slopes on the beams could be negotiated with the aid of surfaces with high friction and mobile cables that the vehicles could get a grip on. This technique is nothing new. |
The dug tunnels close to street levels lend themselves easily to integrated solutions, providing such facilities as reclamation of sorted solid refuse, electricity and water supply for heating ducts to houses and to put telecommunication cables.
 Figure 4:4
 Figure 4:5 Figure 4:6 |
aturally, when tunnels are not much bigger than the vehicles going through them, the question as to where the air will go is relevant. It is a considerable waste of energy for the vehicles to have to push air ahead of them, and also to create a drag behind them. The obvious solution to this is shown in figure 4:1 above. The air can escape sideways, into the the smaller tunnel in-between the main ones. If we do not have this tunnel, the air can still escape into the tunnel for traffic headed into the opposite direction.There will, of course, still be some cushion effect left for the vehicles to battle against. So, there might be a case for making the tunnels slightly larger than indicated in figure 4:1. On the other hand, high-speed vehicles close behind each other can each use the drag effect from the vehicle ahead to its own advantage. |
A disadvantage with sideways connection of tunnels is the turbulence that will ensue. This turbulence might increase the air resistance, and also tend to make the cabins unstable. This could be counteracted with the use os small rubber wheels on the cabins, running in rails along the tunnel. Then, there is the danger of fire breaking out in the tunnel. in such a circumstance, a vehicle in a narrow, unconnected tunnel could help suck the smoke out, making it possible for travellers to escape by way of hatches in the meantime. This effect was considered during the design of the automatic subway in Copenhagen, Denmark. |
A look att figure 5:1 above illustrate these arguments. In view A the vehicles are pushing an air cushion "A" in front of them, as well as a drag behinf them "D", because the air has no way to escape. Providing such air escapes (view B) into neighboring tunnels creates circular currents, which, however, could be considerably alleviated and even used to advantage by connecting the tunnels only at certain intervals and at certain lengths, as shown in view C. View D, finally, shows the situation where vehicles are so closely spaced that they take advantage of each other´s drag. |
 SL (the Metropolitan Public Transport Co.) in Stockholm has started traffic with the first trains in an order for up to 200 railway cars from ADtranz. These cars are meant to gradually replace the present underground railway cars. Each car is as long as 3 of the old cars, and one train consists of 3 cars. The 200 cars will altogether cost 4.5 billion swedish crowns (almost $ US 700 million). They are easier to keep clean, more difficult to deface, and more silent than the older cars. Walls, roofs and floors are soundproofed, and the doors maneuvered with electricity instead of pressurized air. |
 But it´s apparently not so easy to take everything into consideration when designing new subway cars. The doors have squeezed some people and dragged them along the platform. And the cars became so hot during the summer of 1999 that they had to be taken out of traffic. These matters have not been any problem with the old cars, which have been running for more than 40 years! |
 |
|
|
|---|
| Copyright © 2004, SwedeTrack System. | Last Updated: 2007-01-17 |
Webmaster |
This site is maintained by Johnson Consulting |
|---|
