Novel roadway animal detection system to help improve wildlife connectivity on Old Upper Thomson Road

Thomson Nature Park, Singapore's seventh nature park, opens on Oct 11. It boasts rich biodiversity and is a key conservation site for a rare primate called the Raffles' banded langur.
Thomson Nature Park, Singapore's seventh nature park, opens on Oct 11. It boasts rich biodiversity and is a key conservation site for a rare primate called the Raffles' banded langur.ST PHOTO: LIM YAOHUI
A rope-ladder crossing along Old Upper Thomson Road will help canopy-dwelling animals cross overhead.
A rope-ladder crossing along Old Upper Thomson Road will help canopy-dwelling animals cross overhead.ST PHOTO: LIM YAOHUI
Long-tailed macaques in Old Upper Thomson Road.
Long-tailed macaques in Old Upper Thomson Road.ST PHOTO: LIM YAOHUI

SINGAPORE - One by one they crossed the tarmac, their tails trailing behind them as they left the safety of one forest to reach the other patch of green at the other side of Old Upper Thomson Road.

A camera was watching their every move. As it detected the animals' presence, lights flashed under a sign that read "Animals Ahead".

And as a car neared the flashing sign, its red brake lights came on. The car slowed, and the troop of long-tailed macaques raced into the safety of the forest.

For the first time, the authorities are leveraging technology to better protect Singapore's native wildlife as they make their way from forest to forest to find food or mates.

This novel roadway animal detection system was unveiled by the National Parks Board (NParks) on Friday (Oct 11), during the opening of the new Thomson Nature Park, a 50ha green space buffering the rich forests of the neighbouring Central Catchment Nature Reserve.

The $400,000 system, which includes a computer algorithm that determines if an animal or human is crossing the road, was co-funded by NParks and the Land Transport Authority (LTA), and is part of a year-long pilot that aims to reduce wildlife-vehicle collisions along Old Upper Thomson Road.

Biodiversity surveys and "clues" such as track marks, droppings and claw marks on trees had shown that native animals, including critically endangered ones such as the Raffles' banded langur, a species of monkey, and the Sunda pangolin often cross this road to get from forest to forest.

The 3km-long Old Upper Thomson Road separates the new Thomson Nature Park from the eastern end of the Central Catchment Nature Reserve.

Animals do not recognise geographical boundaries, said NParks director for conservation Sharon Chan, and often move out of the reserve into other forests to find food or mates.

Indeed, animals such as the Malayan porcupine, Sunda pangolin, lesser mousedeer and the straw-headed bulbul have been spotted within the new nature park. Even the Raffles' banded langur - a critically endangered monkey found only in Singapore and southern Peninsular Malaysia - has been sighted there.

The authorities have implemented a raft of measures to help animals move safely between the nature reserve and the nature park.

Other than the roadway animal detection system, they have also built five underground culverts and two overhead rope bridges - a ladder-rope bridge and a single-rope bridge - along Old Upper Thomson Road to help ground-dwelling and arboreal or tree-dwelling animals get across the road safely.

NParks had also collaborated with the LTA to convert the dual-lane road into a single one-way lane with a park connector since June 2018.

There are also plans to close the road to vehicular traffic between 7.30pm and 6am daily, although more details on this will be provided later, said NParks.

LTA chief executive Ngien Hoon Ping said the agency has always been working closely with NParks to safeguard the environment and to mitigate environmental impact when embarking on infrastructural developments.

He said: “Joint efforts, such as the one on the roadway animal detection system, help us understand how technology could be deployed to achieve our aims.”


Dr Andie Ang, a primate scientist and chair of the Raffles’ Banded Langur Working Group, welcomed the installation of the rope ladder, saying it was placed in a location where it was needed, as the langurs have been spotted in the area. 

On the other hand, it would take time for animals like the langurs to get used to artificial structures, and so long-term monitoring is necessary, she added.

But she lauded the initiatives to reduce vehicular traffic on Old Upper Thomson Road. "Cars will have to slow down, making it safer for the animals to cross, and also for the people using the park connector," said Dr Ang.

An LTA spokesman said that in deciding whether to proceed with road changes for Old Upper Thomson Road, “LTA reviewed prevailing traffic conditions and ascertained that there would be limited impact on motorists and there is an alternative route for motorists to get to their destination.” 

Where nature and history meet

At the other end of the Thomson Nature Park is the Rambutan Trail, one of five new trails at the new park.

At one point in the trail, the busy Upper Thomson Road is barely 100m away. But it may seem a world away to visitors walking amid the lush vegetation under the Malayan wild vines, where remnants of the old Hainan Village still exists.

The 100 households which used to live there had many rambutan trees, said former villager Ho Gui Mei, 65. The rambutans were not the usual type, but juicy, succulent ones that were famed all across the island.

"Whenever the rambutan trees started flowering, traders across Singapore will come to our village and offer us a sum of $50 to $100 to harvest all the rambutans," said Madam Ho, a retired marketing director. "We had to be disciplined. Once they 'reserved' a tree, we couldn't pluck the fruit from it."

The famed rambutans were the efforts of another former villager, Mr Han Wai Toon, who experimented to create the perfect rambutan, reminiscent of the lychees he used to eat in his home town in Hainan.

He pioneered a growing technique called inarching, which involved grafting six additional stems from adjacent saplings onto one quality rambutan tree, according to a signboard on the Rambutan Trail.


"This technique provided the equivalent of extra roots and vastly increased the amount of nutrients and water absorbed by the trees," said the signboard. "Unlike growing (a plant) from a seed, grafting retains the good qualities of favoured rambutan varieties."

The village is now gone, but traces of it, from old wells to village steps, can still be seen at the new nature park. Visitors can also get a glimpse of rambutans when the trees fruit, but they have to keep their hands off, NParks warned, as the fruit is for the denizens of the forest.

The Raffles' banded langur, for one, has been spotted feasting on these tantalising treats, said NParks' Ms Chan.

Mr Desmond Lee, Minister for Social and Family Development and Second Minister for National Development, officially opened the Thomson Nature Park on Friday.

As a buffer park ringing the Central Catchment Nature Reserve, the Thomson Nature Park was an important part of Singapore's efforts to conserve its natural heritage and native biodiversity, he said.

There are altogether seven nature parks buffering the Central Catchment and Bukit Timah Nature Reserves, with one more - the Rifle Range Nature Park - expected to be completed in 2020.

"The buffer parks... not only protect our nature reserves, but they also provide Singaporeans with more green spaces," said Mr Lee. But the Thomson Nature Park is special for another reason, he said, as it offers a layer of history of early Singapore.

"I hope that more Singaporeans will have a greater appreciation for our biodiversity and green spaces," he added. "Such collective efforts help ensure that our natural heritage is protected for future generations to enjoy."