TEXT 6. POST OFFICE RAILWAY
An interesting example of a fully-automated railway is a two-foot gauge Post Office Railway which runs under the centre of London connecting major sorting offices with the railway termini,. Opened in 1927, it has carried mails day and night through its deep tube tunnels. Mails are carried at a speed of 35 mph in trains which have no one on board to drive or supervise.
Fifty electric units are in use on the Post Office Railway, sixteen dating back to 1930 and the remaining 34 built in 1979. These trains take the place of about 2,000 post office cars which would otherwise run on the congested London streets.
To avoid accidents the cars automatically cut off current from the section immediately behind them. Special tracksicie devices stop the trains just before they arrive at stations and bring them in at a low speed.
The original signalling system is soon to be replaced with solid state interlocking. There are 10 spare electric units being held in store ready for refurnishment should traffic levels require more stock.
TEXT 7. STEP TOWARDS UNMANNED RAILWAY
Advanced electronic equipment designed for the Bedford— St. Pancras commuter line north of London could make this line Britain's first completely automatic railway.
The equipment enables one computerized signal box to control the entire 50-mile line, including driverless trains, unmanned stations, and announcements to passengers on trains and at stations.
Station announcements are made by computers imitating the actual human voice. The system is much cheaper and more flexible than using human announcers or tape-recorders.
Train control is achieved through lineside cables linking the signal box with its video (TV) and computer and the radio transmitters located at intervals of 5 to 15 km along the track. The transmitter, in turn, sends messages to passing trains.
For the present, the system is limited to two-way communications between the driver and the dispatcher controlling the train. It is a significant achievement which means that in an emergency a driver needs no longer stop the train and walk along the line to a telephone: he can talk directly to the dispatcher.
In the future, however, not a single line, but the entire network, with hundreds of commuters travelling up and down the line or waiting at dozens of stations, could be controlled with this system from a single box.
Do'stlaringiz bilan baham: |