The Ayer Rajah Expressway (AYE) and the West Coast area are now better protected against floods following the completion of improvement works costing $74 million.
The capacity of the 3km-long Sungei Pandan Kechil canal has been doubled.
It has been widened by 4m in two stretches on the AYE to West Coast Road and on West Coast Road to the sea, as well as made deeper in some parts by up to 1.9m.
The maximum depth along the canal now ranges from 3.3m to 5m deep.
A 6.5m-wide tunnel was also built under the AYE to drain water quickly from the upstream catchment areas to reduce the risk of flooding.
More recreational space has also been built around the canal.
Minister for Communications and Information S. Iswaran, who is an MP for West Coast GRC, announced the completion of the upgrading works at a National Day celebration in the area yesterday.
The canal came under public spotlight in September 2013 after the AYE was closed temporarily as a flash flood brought traffic to a standstill. Intense rainfall, coupled with rising tide, caused water from the canal to overflow onto the expressway, creating a 0.5m-deep pool.
The city-bound stretch of the expressway was shut down for 40 minutes during morning rush hour as a result.
Yesterday, Mr Iswaran said national water agency PUB had initially wanted to just deepen the canal after the flood.
"But after discussions, we decided to make it into an Active, Beautiful and Clean (ABC) Waters project. So now we have a lot of facilities here. It is a very beautiful environment," he said.
Upgrading works started in March 2015, and were initially scheduled to be completed around the end of last year.
But challenges such as the need to divert traffic on the AYE to facilitate the works and the influence of tide levels meant that the completion date had to be pushed back.
Traffic had to be diverted due to the construction of the 6.5m-wide supplementary box culvert under the AYE.
A culvert is a structure that allows water to flow under a road, railroad, trail or similar obstruction from one side to the other.
PUB said the previous culvert under the AYE, which was 2.4m wide, could not cater for intense storm events.
West Coast resident Azlina Buang, 46, who has lived in the area for 30 years, said: "Once, during heavy rain, the canal overflowed and some water actually got into the void deck, so this improvement is very, very important."
The upgrading of the canal is part of Singapore's efforts to boost flood resilience.
Around $1.8 billion has been spent on drainage improvement works to boost flood resilience since 2011.
Another $400 million will be spent over the next two years to upgrade and maintain drains.
Meanwhile, the surroundings of Sungei Pandan Kechil were also improved under the ABC Waters Programme.
The programme is a PUB initiative that aims to provide new recreational spaces, improve the aesthetics of the urban environment and improve water quality through the use of natural cleansing features.
It was implemented at the canal through various measures.
For example, a 2m-wide bridge that linked residential estates to West Coast Plaza has been widened to 10m so that activities can be held there.
Creeper plants were planted along the stretch of the open waterway to give the canal a softer look.
In addition, three rain gardens, which are specially designed plots with plants, were introduced along the canal.
PUB said these gardens are designed to slow down and treat surface run-off of water from the drains of HDB blocks before its discharge into the canals.
An additional walkway was also built alongside the canal.
Resident Joker Tan, 60, a retiree, said: "I told my neighbours that our area looks like a condominium now.
"We can take slow walks, look at fish in the canal and just chit-chat with people there."
Another resident, Dr Muthusamy Karthikeyan, 45, said: "The wait for the construction to be over was worth it. We are now enjoying the new facilities after four years of construction... It is peaceful and beautiful now."
