Drainage canal in flood-prone Bukit Timah fully upgraded

SINGAPORE – The flood-prone Bukit Timah area will likely experience some relief during the year-end rainy season, now that canal upgrading works there are completed.

National water agency PUB on Oct 23 announced that the last 900m stretch of a 2.3km canal there has been enlarged.

The upgraded canal can hold 30% more floodwater than before, which could help limit flash floods like those that had recurred in the area over the past 15 years.

Work to upgrade this stretch started in 2019 and was initially expected to be completed by the first quarter of 2024. The delays were due to the Covid-19 pandemic, changes in construction schedule to minimise peak traffic congestion, among other issues.

But because of Bukit Timah’s low-lying, valley-like terrain, and due to increasingly erratic rainfall patterns caused by climate change, drainage infrastructure alone may not be able to prevent flash floods completely, PUB cautioned.

There are also limitations to installing more drains in land-scarce Singapore, the agency noted, pointing to how the whole Bukit Timah area is already served by three drainage canals spanning 10km in all.

To address this, PUB said it will at the end of 2026 call for a study to identify longer-term solutions to strengthen flood resilience across Bukit Timah.

The study will assess a range of anti-flood solutions, including underground structures to hold floodwaters. It will also explore solutions that can integrate with existing infrastructure and future developments, added PUB.

Acknowledging that the Bukit Timah area is one of Singapore’s “most challenging catchments”, PUB’s deputy chief executive of flood resilience Angela Koh said very intense storms can still overwhelm drainage infrastructure.

“We will continue to improve drainage and raise roads where feasible, while taking a holistic review of the catchment to identify more integrated solutions for the longer term,” she added.

The 2.3km Upper Bukit Timah Canal is the main anti-flood measure for a 1,000ha area. The canal runs from Beauty World to Maple Avenue.

The rainfall catchment area it supports includes homes, as well as other malls and public facilities like Beauty World Plaza, Bukit Timah Shopping Centre and Dunearn Village, as well as Beauty World and King Albert Park MRT stations.

On Oct 23, PUB announced that the final 900m stretch of the canal running from Rifle Range Road to Jalan Kampong Chantek has been widened and deepened.

Works on the final stretch, which cost about $60 million, began in October 2019. Once angular in shape, the canal has been converted into a U-shaped drain and box culvert, allowing it to convey 30% more stormwater, said PUB.

The Bukit Timah area has historically been prone to flooding because its valley-like terrain forms a basin that channels stormwater quickly into the low-lying canal. Urban development over the decades has also contributed to an increase in runoff.

The last major flooding event in the Upper Bukit Timah area was in April 20, 2025, when downpours led to flash floods in four areas including a stretch between Clementi Road and Blackmore Drive.

The flash floods subsided after about an hour, and the amount of rainfall over Singapore that evening amounted to nearly half of Singapore’s average monthly rainfall in April.

Dunearn Road near Sime Darby Centre experienced flash floods a couple of times in 2021. In August that year, a flood between Sime Darby Centre and Binjai Park affected bus operations along Dunearn Road for about an hour.

However, the seven–year upgrading period for the 900m stretch of the canal had also resulted in traffic congestion for commuters and residents in the area.

With several schools located in the area, traffic was also an issue for students and parents during drop-off and school dismissal times.

In 2023, Holland- Bukit Timah GRC MP Christopher de Souza had asked Parliament if the works along the 900m stretch could be expedited.

Minister for Sustainability and the Environment Grace Fu then said the works will be delayed from 2024 to 2026 to align with the development of a green corridor in the same area.

This is because the future Bukit Timah-Rochor Green Corridor will have an elevated sky park for pedestrians over the Upper Bukit Timah Canal, and PUB helped build the foundations for the sky park on top of the canal.

This elevated connection from the Rail Corridor to Jalan Kampong Chantek is estimated to be completed by 2027.

The Covid-19 pandemic had also pushed back the canal’s completion by a year, PUB said.

The construction area was also constrained and narrow since it is flanked by two major roads – Bukit Timah Road and Dunearn Road. This restricted the extent of works that could be carried out at any one time.

The working hours were also shortened to between 9.30am and 4.30pm to minimise traffic disruptions during peak hours, said PUB.

“To carry out the works safely while minimising disruption along Bukit Timah Road and Dunearn Road, traffic was progressively diverted, and replacement lanes were provided to create the temporary workspace required for construction,” added the agency.

The Upper Bukit Timah Canal is one of three drainage canals which serve the entire Bukit Timah area from Beauty World to Serangoon Road. Together, these drains span nearly 10km.