Abstract :
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.
THE DECLINE
OF RAIL AS A FORM OF PASSENGER TRANSPORT
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.
HIGH SPEED LINES
To have a
high speed rail system, making the high speed trains is really the tip of an
iceberg. What really makes systems a success or failure is the railway that
they run at. Railways like roads have speed restrictions, and like on roads,
often the speed restrictions are below the top speed of the train. Building a
fast train is easy, but its building tracks good enough to allow trains to
safely and smoothly travel at 160-200 mph or 250-320 km/h, which are also long
enough to allow the trains to accelerate up to these speeds (often many miles)
and decelerate, is quite difficult
FEATURES OF
A HIGH SPEED RAILWAY
No level
crossings (grade crossings)
Fenced off
Concrete
foundations
Wide
spacing between lines
Curves of
radius less than 5 km are avoided and are tilted
Gradients
more than on conventional railway line
Through
stations are constructed with 4 tracks
Tunnels
avoided
Level
crossings are the most common reason for accidents on railways, where road
vehicles break down or get stuck on the railway and the train
crashes through them All high speed lines are fenced off. Indeed in the UK all railway
lines are fenced off anyway, however on continental Europe many railway lines
are easy to get onto. High speed lines are fenced off for obvious reasons, to
eliminate the risk of any animal or people wandering onto the railway line.
Foundations
for high speed lines are much deeper than conventional railways. Usually a
layer of concrete and tarmac is put down (like a road) and then the ballast is
put on top. This is to try and stop movements in the ground from affecting the
alignment of the railway.
The wide
spacing between the lines is important because when two trains pass each other
the speed difference can be as much as 600km/h or 370mph. If the two trains are
too close together this causes at first a burst of air pressure when they first
pass and then a drop in pressure during the coaches. Although this isn't enough
to push the trains off the track, repeated stress on the windows may cause
fatigue and they may break eventually. So for safety reasons two tracks in each
direction are placed further apart than on normal lines.
Gentle
curves are key in what high speed lines are about. Tight curves on TGV lines
have a radius of about 3 miles or 5 km. Curves are also banked up a lot more
than on conventional lines. This is because slow trains will not run on them
and it is extremely rare for a TGV to come to a stop because of a signal. The
degree of banking is calculated to exactly balance centrifugal forces at
running speed.
Download :
Download :