The proposed high-speed rail line linking Singapore and Kuala Lumpur should not be seen as a project benefiting only the present generation but many generations to come, says a leading rail infrastructure expert.
Mr Colin Stewart, global rail leader at international engineering consultancy Arup, said: "You are building something that is a legacy for the future. It would be here for at least 100 years.
"We tend to think in terms of very short payback periods. There are many other things we do as countries and cities that are not so easily quantifiable in terms of payback. For instance, we build roads, even to remote parts, without thinking much about payback. Or street lighting."
Earlier this year in February, Singapore and Malaysia announced plans for the rail link, which is expected to offer a 90-minute commute between the Republic and Kuala Lumpur by 2020.
Mr Stewart, who specialises in high-speed rail systems, said project costs vary from £15 million (S$29 million) to £40 million per kilometre, depending on the complexity of construction.
That translates to as much as $30 billion for the Kuala Lumpur-Singapore high-speed link. Such projects would be like other public services, he added, and require government subsidies.
"The reality is that high-speed rail can be transformational," he said in an exclusive interview with The Straits Times. "They're more than just trains going faster. They have an ability to change and enhance economies within a region."
As for the relatively small number of people travelling between Kuala Lumpur and Singapore today - about 5.2 million a year by air - Mr Stewart said a proper demand study should be carried out.
"I've not seen any numbers yet. But it is clear that when there is a high-speed rail line, travel demand will rise," he said, adding that passenger numbers could vary from 4,000 to 15,000 an hour.
The line can be operated with a small number of trains initially, with more added as demand grows.
But detractors have warned of the prolonged fiscal burden that such a project might pose, especially if growth turns out to be slower than projected. Also, there are already air, road and rail links between Kuala Lumpur and Singapore and some question whether a high-speed rail link is necessary.
"You could say the same for London and Paris," Mr Stewart said. "But today, the majority of travel between the two cities is done by high-speed rail, particularly between the centres of London and Paris. It has become the preferred choice."
For high-speed rail lines to be feasible, he said five things have to be in place.
First, stops must be at least 100km apart, otherwise journey times will be too long, and energy expended on accelerating and braking will be high. This would dilute the superior energy-efficiency of such a mode of travel. Hence, there could only be a maximum of three stops in Malaysia.
Second, the line should stop where there are speedy and convenient ways for passengers to transfer. Each train would carry around 1,300 people. Mr Stewart suggested one stop at Changi Airport, and another at a city MRT interchange.
Third, an efficient Customs and immigration clearance system has to be in place. Mr Stewart noted that it would be the world's only cross-border high-speed line other than London-Paris.
A proper risk analysis also needs to be done to determine the level of security required. Breaches or intrusions can have dire safety consequences for trains travelling at 350kmh.
Finally, the line has to be built to cater to changes in technology. Trains could be travelling at 400kmh or faster in the future.
Mr Stewart said a Kuala Lumpur-Singapore line is "highly feasible" if "done properly", and that such a project had to be viewed in the long term. "In the UK, rail lines built in the Victorian era still form the backbone of the medium-speed system in the country. It's providing very high capacity, compared with what the system was first intended for."
Malaysia is slated to present Singapore with a detailed technical and engineering assessment report by the end of this month.
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