Nicoll Drive, which hugs the eastern shoreline next to Changi Beach, is being raised in anticipation of rising sea levels triggered by global warming.
The road-raising project - which elevates the 1km, two-lane dual carriage by up to 0.8m - is the first Singapore is undertaking to brace itself for the effects of climate change.
The Land Transport Authority (LTA) said: "As this stretch of road is located near the coastline, the works are being carried out to minimise the risk of seawater inundation as part of the Government's overall coastal protection measures for climate change adaptation."
The authority said the project is expected to be completed by the middle of this year, and added that it had no immediate plans to raise other roads near the coast.
Experts have warned that rising sea levels will have a devastating impact on Singapore.
In a recent report, research group Climate Central said that even if the world could limit temperature rise to 2 deg C, 130 million people living in coastal areas would be affected by higher sea levels caused by melting polar ice.
An interactive Climate Central map shows parts of Changi Airport, Jurong Island and parts of the west coast under water if global temperatures were to rise by 2 deg C.
Previous studies by retired Professor Wong Poh Poh of the department of geography at the National University of Singapore (NUS) indicated that coastal reservoirs such as Kranji, Sarimbun and Seletar could also be under threat.
Sea water would enter these catchment areas, making the water undrinkable. Prof Wong could not be reached for comment, but assistant professor Daniel Friess of the NUS' Department of Geography said Singapore needs to future- proof its critical infrastructure in the face of climate change.
He said: "Planning for coastal flooding and sea level rise is a challenge in Singapore, as we are projected to experience high rates of sea level rise in this region over the next 100 years.
"We have relatively little space to relocate critical infrastructure... So we will have to come up with integrated and innovative solutions that involve retrofitting infrastructure - such as raising roads - and strengthening coastal defences."
The Building and Construction Authority (BCA) has an entire division devoted to coastal protection.
A BCA spokesman said Phase 1 of the Second National Climate Change Study, completed last year, projects the mean sea level to rise by up to 0.76m by the end of the century. She added that an ongoing "coastal adaptation study", which is expected to be completed by next year, would spell out what needs to be done to prepare for that predicted rise in sea level.
Meanwhile, she said, Singapore is adequately protected from coastal floods for the immediate future.
"About 70-80 per cent of our coastal areas already have hard walls or stone embankments, which help protect against coastal erosion," she said, adding that if necessary, these will be reinforced.
She reiterated that the minimum land reclamation height was raised from 3m to 4m above the mean sea level in 2011.
As for Nicoll Drive, the road-raising project is expected to help motorists stay dry during unusually high tides. This happened at least twice - in 1974 and 1999.
In the 1974 incident, which happened on Feb 9, several parts of the city were also submerged - without a single drop of rain.