High Speed Trains
Published on Mar 13, 2020
When English inventor Richard Trevithick introduced the steam locomotive on 21 February 1804 in Wales, it achieved a speed of 8 km/h (5 mph). In 1815, Englishman George Stephenson built the world's first workable steam locomotive.
In 1825, he introduced the first passenger train, which steamed along at 25 km/h (16 mph). Today, trains can fly down the tracks at 500 km/h (311 mph). And fly they do, not touching the tracks.
There is no defined speed at which you can call a train a high speed train but trains running at and above150 km/h are called High Speed Trains.
Since the automobile has become more widespread with the existence of motorways, cars may reach speeds of up to 75 mph (120 km/h) or thereabouts depending on local laws. Standard mainline railway trains running at 100 mph (160 km/h) have found it difficult to compete with the car, as once journey time to and from the station and waiting for the trains had been calculated, rail travel did no longer offer a significant journey time advantage over the car.
In order to attract people to railways ticket prices had to be at the lowest possible, meaning minimal profits. No one would want to build a brand new railway line; the interest payments would crush any company. All this has meant that in the early-mid 20th century new railways were unheard of and some small lines were often closed down because they made a loss.
Problems Running On Existing Railways
The primary problem with existing railways is that they can have tight curves. The centrifugal forces on an object going round a bend are the function of the square of velocity, i.e., double the speed, quadruple the centrifugal forces, triple the speed, centrifugal forces increase by nine-fold. Therefore even what might appear mild curves provide problems at speed.
Other key problems are that running on existing railway; the new fast trains have to be scheduled in around the conventional trains. This can be a tricky thing, especially on a busy network; fast trains can easily become stuck behind slow running ones, resulting in delays.
Safety is also a paramount consideration. Although since initial construction 100 years ago the track will have been replaced many times, the foundations of the railways are the same which means after heavy rains for example the track may sag slightly and lose some alignment, a real problem only at high speed. Level crossings also pose a problem.
Maglev - Magnetically Levitated Trains
The principle of a Magnet train is that it floats on a magnetic field and is propelled by a linear induction motor. They follow guidance tracks with magnets. These trains are often referred to as Magnetically Levitated trains which are abbreviated to Maglev. Although maglev don't use steel wheel on steel rail usually associated with trains, the dictionary definition of a train is a long line of vehicles traveling in the same direction - it is a train.
Advantages Of Maglev
Well it sounds high-tech, a floating train; they do offer certain benefits over conventional steel rail on steel wheel railways. The primary advantage is maintenance. Because the train floats along there is no contact with the ground and therefore no need for any moving parts. As a result there are no components that would wear out. This means in theory trains and track would need no maintanence at all. The second advantage is that because maglev trains float, there is no friction. Note that there will still be air resistance. A third advantage is less noise, because there are no wheels running along there is no wheel noise. However noise due to air disturbance still occurs. The final advantage is speed, as a result of the three previous listed it is more viable for maglev trains to travel extremely fast.
Limitations Of Geography
High speed railway lines need to be as straight and level as possible. Therefore often the railways are carried over dips and hills in the countryside by embankments, viaducts, cuttings and tunnels. (Tunnels are sometimes unsuitable due to wind turbulence problems.) However these greatly increase the cost of the railway and of course, if the landscape is mountainous then it becomes very difficult to build it straight and leveled. Naturally, railways cannot be built over water for long distances.
While the very high speed trains like the TGV could be regarded as the Rolls Royce of trains, tilting trains could be thought of as the cheap and cheerful mini metro. The price differential is fairly similar too; it costs about 20 times more per unit distance to build a dedicated high speed line than it does to upgrade existing lines for tilting trains. This is what makes tilting trains extremely attractive.
However there are disadvantages. 140 mph or 230 km/h is about as fast as trains go when not on dedicated lines. And then they have to be fitted in with slower moving traffic. With rail travel growing all over Europe, the problems of railways reaching saturation point has forced new lines to be build. This is why despite the success of the Italian Pendolini, a new high speed line with 300 km/h trains is being built, because existing lines are at saturation point.
More Seminar Topics:
Electro-Hydraulic Brake (EHB) System,
Electronic Fuel Injection,
Four-Wheel Steering System,
Full Authority Digital Engine Control,
Homogeneous Charge Compression Ignition HCCI,
High Speed Trains,
Hot Runner Technology,
Hybrid solar Desiccant Cooling System,