Visitors to the zoo may have noticed an "overhead bridge" in Mandai Lake Road, but it is not to be used by humans.
When operational next month, the Mandai Wildlife Bridge will help animals cross the road safely to get to the slivers of forest on either side.
Work started in June 2017, and the bridge was officially unveiled by developer Mandai Park Holdings (MPH) yesterday.
It declined to disclose the cost of the bridge, but said it was a key investment for improving animal connectivity in the area.
Animals faced risks crossing the road, even during the construction of the bridge.
The Straits Times had earlier reported that animals, including a critically endangered pangolin and a leopard cat, had been killed by vehicles in the vicinity of the project site.
The 140m-long bridge is the latest in a slew of measures that MPH has put in place to reduce roadkill while works for a hub of five wildlife parks are under way.
Rope bridges have also been installed to help tree-dwelling species cross the road, and visual aids to urge motorists to slow down can be found in the area.
By 2023, a new Rainforest Park and relocated Bird Park will join the existing trio of attractions there - the Singapore Zoo, Night Safari and River Safari.
The land on which the two new parks will be built is state-owned, but secondary forests have regenerated there. The area also sits immediately outside the Central Catchment Nature Reserve, forming a rich landscape of wildlife.
Native plants of different heights will be used to help create a forest-like environment on the bridge, which is connected to vegetated areas within the development sites.
The ends of the bridge have been made slightly wider so that animals will be funnelled towards them. Fences have been installed along both sides of Mandai Lake Road to prevent animals from getting to the road.
On why the bridge took three years after works started to begin operating, Dr Lee Hui Mien, vice-president for sustainable solutions at Mandai Park Development - MPH's development arm - said the bridge is the first feature to be completed as part of the rejuvenation of the area.
Since works for the nature precinct began in early 2017, MPH has come under fire from the nature community, including the late wildlife consultant Subaraj Rajathurai, over the roadkill in Mandai Lake Road.
The Straits Times understands that five colugos - native nocturnal mammals found only in good forests - have also been found dead on the road since works started.
The Mandai Wildlife Bridge is not the first such in Singapore.
An existing National Parks Board's eco-link bridge spans the Bukit Timah Expressway.
Professor Peter Ng, head of the National University of Singapore's Lee Kong Chian Natural History Museum, said the wildlife bridge had long been part of the developer's plans for the area, after consultations with the nature community and government agencies since 2012.
But construction could begin only after development plans for the area were more concrete, said Prof Ng, who is also chair of Mandai Park Holdings' Environmental Advisory Panel.
"The roadkill incidents were unfortunate. Could some animals have been saved if the bridge had been built earlier? Perhaps the leopard cat, but not the others like the colugo," he said.
But the bridge was a long-term investment, he added.
"Once the vegetation matures and animals start getting used to it, the bridge would surely help more animals cross the road unimpeded," he said.