SINGAPORE - The current option to overhaul the problematic Bukit Panjang LRT is the only viable one, said Transport Minister Khaw Boon Wan.

Alternatives such as tearing it down and building a totally new system or having buses replace the line were not feasible because the roads in the Bukit Panjang area would not be able to cope, he told the House on Friday (May 18).

Responding to questions from MPs, Mr Khaw said it would take 40 double-deck or 80 single-deck buses running at a frequency of as high as three minutes to cater to the BPLRT's passenger load.

And even if bus priority measures were in place, a bus ride from Choa Chu Kang to Bukit Panjang would take half an hour, according to the minister.

He added that if all cars were banned in the area, an all-bus system might work, but "even then it's barely".

Mr Khaw said the overhaul by Bombardier - which supplied the original system - will take up to 2024.

The overhaul, he said, will address three root causes of the 20-year-old line's seemingly endless problems - its signalling system, traction power system and train propulsion system.

Mr Ang Wei Neng (Jurong GRC), who is also chief executive of ComfortDelGro Taxi, asked if a bus rapid transit system was an alternative.

"Have you considered running buses on the track?" he asked.

Mr Khaw replied that "you cannot just simply take the existing viaducts and then you run buses on it".

"You actually got to do extensive civil engineering work on the viaducts," he said. "You actually got to pull it down, rebuild and reconfigure."

And that, he said, would mean no LRT service for years.

"Long term, is it possible? I hope so because if our car-lite Singapore arrives, not immediately, in 20 years' time... we can tear down the viaducts, redo it... or have cyclists on the viaducts, which is a favourite idea of Minister Vivian Balakrishnan.

"He always envisage a day when you can just cycle on the LRT tracks. Or there may be other ideas, maybe theme parks ought to adopt it to do something else."