Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Rolling with the changes

West Rail Operation and maintenance

West Rail is a hybrid of mass transit and high speed commuter railways.

Innovations to signalling and rolling stock have been needed to fit the bill.

Originally the Kowloon-Canton Railway was designed as a suburban railway connecting the inner city with the new towns. But over the last 20 years the New Territories have grown into heavily populated areas - many of the villages are turning into new towns in their own right, ' says KCRC general manager for railway systems Leo Mak.

The result, he explains, is that lines are under pressure to deliver a service more like that offered by the MTR: Trains are required to travel at high speeds but between relatively closely spaced stations, and to provide high capacity, with many peak hour passengers standing. Trains also need to be able to accelerate and brake fast at 1m/sec2 and 1.1m/sec2 respectively.

'To achieve this we're operating at 25kV AC, which is standard for suburban and intercity services but uncommon for urban mass transit type services, ' says Mak. '25kV offers efficiencies when transmitting power over large distances. It is ideal for the 30.5km long West Rail.' So the high voltage power can be used by the trains' motors, which require lower voltage to achieve rapid acceleration and deceleration, it is stepped down to 600V by on-board transformers.

There will initially be 20 seven-car trains per hour running on West Rail in each direction. As passenger numbers grow, trains will be extended to nine cars, running at a frequency of 33 per hour.

'This requires very advanced signalling, ' says Mak. 'We're using a moving block Seltrac system, which allows the distance between trains to be varied according to how fast they are running, making better use of line capacity.' Supplied by Alcatel, it is a newer and more refined generation of the signalling used on London's Docklands Light Railway, on the Ankara Metro and the Vancouver Skytrain.

'Our system is like a person running: the faster a train goes the further ahead it looks, so it can anticipate when it will have to slow down or stop. We can get down to 50m separation between trains, ' Mak adds.

He says the Seltrac system will also ensure that the regularity of trains is maintained after incidents or 'system perturbation', where conventional signalling systems would struggle to cope with a logjam of backed-up trains. For good measure the system provides basic automatic train protection, or ATP, a safety feature which ensures minimum braking distances are observed.

Train operation is automated.

Carriage doors have to match up with sliding screen doors separating station platforms from the track to within 300mm.

'Our stopping accuracy is 99.5%, ' Mak boasts. However, he says fine tuning the system has been tricky, as trains have to stop to plus or minus 300mm over more than 30km of track.

West Rail is at the leading edge of railway technology in other ways too. Its 154 cars use regenerative as well as conventional braking: Power is put back into the overhead transmission lines as trains slow down, offering the system an overall energy saving of 10%-20%. Motors are 90% efficient compared to those on existing East Rail and MTR trains which are around 80% efficient, says general manager for rolling stock William Leung.

Rolling stock is fitted with computerised monitors that track faults so that they can be remedied before they become real problems.

Keeping it going

As soon as design of West Rail got under way KCRC's general manager for infrastructure and buildings Maurice O'Brien started thinking about maintenance. 'We hold regular group meetings to probe engineering issues - how to handle track slab maintenance, for example. To date we've produced more than 500 papers, covering each aspect of the scheme, ' he says. The process is similar to that involved under the UK's Construction (Design & Management) Regulations.

The brainstorming sessions have steered decisions to eliminate construction and expansion joints from the rails, so reducing the maintenance workload. There are no bearings between the viaduct piers and deck to wear out.

And they have also resulted in emergency exits from tunnel and viaduct doubling as contractors' access points.

'But our biggest challenge will be minimising corrective maintenance, ' O'Brien adds.

On West Rail all assets will be closely watched to see at which stage individual components start wearing out and needing repair or replacement. O'Brien's team will then carry out pre-emptive work.

'Light bulbs might seem a fairly trivial thing to be focusing on, but going in to replace individual bulbs costs far more than replacing them before they blow on a wide scale basis. You can apply the same approach to any part of the system: You're carrying out an operation just once, albeit maybe on a large scale, rather than mobilising each time something goes wrong.

'There is a set of standard questions: what happened, what caused it, has it happened anywhere before, what do we do to fix it, what can we do to prevent it happening again?'

O'Brien is constantly seeking ways to enhance the efficiency of maintenance operations and KCRC has ISO1400 certification for continuous improvement. 'It motivates people to come up with good ideas from the shop floor.'

All buildings, viaducts and tunnels have a 120 year design life, says O'Brien. Mechanical and electrical plant such as escalators, lifts, platform screen doors and air conditioning plant has a 20year life span. But the signalling system will be obsolete within 15 years, he predicts. This is because the computer processing units used will be overtaken by a new generation. Rather than sort out all of the compatibility problems that will be associated with upgrading the existing system, it will be easier and cheaper to replace the entire system as new technology becomes the industry standard.

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.