The Ayer Rajah Expressway (AYE) between Yuan Ching Road and Jurong Town Hall Road may be shifted to free up more land south of Jurong Lake for housing.
The Urban Redevelopment Authority (URA), elaborating on what Prime Minister Lee Hsien Loong said during his National Day Rally speech on Sunday about shifting the AYE, said the highway currently "truncates the Pandan Reservoir area from the Jurong Lake District". This means developments in the south will be separated from new amenities being developed around the lake and the Jurong East MRT station.
A realigned AYE would "integrate the Pandan Reservoir area with Jurong Lake District to form a larger and more cohesive development area".
The URA did not comment when asked by The Straits Times why its Concept and Master plans did not factor in such future land needs, which would have determined the original alignment of the AYE.
Transport economist Michael Li from Nanyang Business School said "that's a good question, but it's also a very tough question to answer".
"The truth is no one can predict what a country needs in 30, 40 years... it boils down to the evolving role of Jurong," he said.
Dr Li added that such a project need not be disruptive to traffic, as the new portion will be completed before the existing stretch is removed.
National University of Singapore transport researcher Lee Der Horng echoed a similar point on why this project was not in earlier plans: "From a planning point of view, Concept Plans and Master Plans provide the blueprints for development needs. However, such plans must also remain flexible to address emerging needs in a timely manner so adjustments can be made as and when necessary."
Retired traffic engineer Joseph Yee, however, questioned the benefit of moving such a short stretch of the AYE. "When the western part of the PIE (Pan-Island Expressway) was moved, it was quite a long stretch, about 7km. And it made good sense because when Jurong West was developing, it brought an expressway out of a town," he said.
But in the case of the proposed realignment of the AYE, he said: "It's only about 2.5km and the land space freed up will not be as much."
And if a longer stretch were to be realigned, he said it would affect flyovers on either end of the highway and that would be very disruptive and costly.
Prof Lee said the new plans are likely to be necessary to accommodate the tracks and station of the proposed high-speed rail link between Singapore and Malaysia. Malaysia is keen to have the Singapore station in the central business district, but Singapore seems to favour Jurong East as a site.
Observers estimate such a realignment project would cost $50 million to $100 million today.
Dr Li emphasised that it is important to get the cost-and-benefit analysis right.
"If there is a need, we should do it (shift the AYE) sooner rather than later, because it will be much more costly later," he said.
The URA said that this was still a conceptual plan and its "feasibility will have to be studied in greater detail".