Six years of discussions between the authorities and the nature community shaped where and how the Cross Island MRT Line would be built, and how best to reduce damage to the fragile ecosystems within Singapore's largest green lung if works were to tunnel under it.
Now that the Transport Ministry has decided to run the 50km public transport line beneath the country's most important nature reserve instead of around it - as conservationists had hoped - both parties want the conversation to continue.
The Government wants continued input from the nature community, who range from biologists to green groups; and members of the nature community are keen for their voices to be heard as the mega construction project unfolds.
Senior Minister of State for Transport Lam Pin Min said on Wednesday, when the decision was announced, that the Government wants to keep working with nature groups as construction plans progress, to harness their expertise and experience. "I hope this will not be the end of the journey working together, in fact it is only the beginning," he said.
Where the new MRT line would run was critical, because the direct alignment would involve construction under an area protected by law.
The extensive discussions, with more than 40 meetings between the Government and about 10 members of the nature community since 2013, was not an all-out war. Both sides were consulted, and listened.
The level of consultation was much appreciated, said the green groups and biologists involved. While the decision did not go their way, the discussions helped reduce the impact of the works on the reserve, they pointed out.
Spider researcher Joseph Koh, for one, admitted he would have been "very upset" with the decision to route the line under the reserve had it been made six years ago.
But now, it is clear that the Government took on board suggestions from the community, he noted.
For example, the tunnel for the Cross Island Line will go 70m under the reserve - much deeper than ordinary tunnels, which typically go 20m to 30m underground. Other concessions include reducing the number of boreholes drilled in the reserve in preliminary soil tests.
"We want to work closely with the Land Transport Authority (LTA) to have a say in how the advanced engineering phase is built up," Mr Koh said. "Only through working together in the spirit of consultation and mutual respect can we achieve a win-win situation to protect nature, and not impede what is required for Singapore."
Other nature groups and experts consulted told The Straits Times that continuing the dialogue could facilitate discussions in other areas, and for future projects.
Nature enthusiast Zac Lim said this could include the possibility of "compensatory planting" elsewhere, to make up for the trees that will have to be cut down.
Even though the tunnel will be 70m underground, two forest patches outside the reserve have to be cleared for ventilation structures.
One of these forest patches on the eastern end of the reserve is a stronghold for the critically endangered Raffles' banded langur, a species of monkey which has a population size of 61.
Dr Vilma D'Rozario, co-founder of the Singapore Wildcat Action Group, said continued engagement will help ensure the impact of the Cross Island Line is reduced as much as possible.
Critically endangered leopard cats, for example, could lose their rainforest homes with more development in the vicinity of the nature reserves. She said: "But I can't say what's the next step for me. I'm terribly disappointed with the decision."
Land-scarce Singapore will constantly have to strike a balance between development and conservation, she noted.
In the nation's fractured forest landscape, all remaining plots of rare, mature forest are important. Yet, many are already under threat as they are on state land earmarked for development - such as the Mandai nature precinct or the Tengah residential estate.
"The Cross Island Line had an added significance as it involved development in a protected area," said Dr D'Rozario. "Development under the nature reserve will set a precedent for more development in our nature reserves in the future, and we should not take the risk."
National University of Singapore biologist N. Sivasothi, who was among those consulted, said the engagement process with LTA had been detailed, transparent and fruitful, something he hopes will extend to future developments, and with other agencies. He said: "This needs to be the norm, as envisaged by Singapore's fourth-generation leaders, with all other agencies and development projects."