A 5KM partly undersea 10-lane road linking the Kallang-Paya Lebar Expressway (KPE), Ayer Rajah Expressway (AYE) and East Coast Parkway (ECP) will open on Dec29, freeing up land that will form a new Central Business District (CBD).
Costing $4.3 billion and taking four years to build, the subterranean Marina Coastal Expressway (MCE) is touted as Singapore's 10th expressway, although it is more like an extension of the KPE.
The Land Transport Authority (LTA) said the MCE will provide direct access to the Marina downtown, as well as offer speedy east-west commutes - taking over a role of the ECP.
The southern part of the ECP will be downgraded to an arterial road serving the Marina area.
A 1km section leading from Marina Boulevard to Prince Edward Road will be removed to free up a 70ha land parcel.
LTA deputy chief executive Chua Chong Kheng said: "Without an expressway going through the area, we get a neat and size-able plot for development.
"Today, the ECP cuts the area into two."
Without the ECP dividing it, the new CBD also joins the old business district seamlessly.
The new downtown will boast a densely built-up precinct that is well connected by the MRT.
It is also envisioned to be a pedestrian and cyclist-friendly area, flanked by Gardens by the Bay, Marina Barrage and an international cruise centre.
"It will be a quality live-work- play precinct," Mr Chua said.
A number of road changes will be made to serve this area.
The downgraded section of the ECP - west of Sheares Bridge - will be renamed Sheares Avenue.
By the third quarter next year, Marina Boulevard and Central Boulevard, the two main roads in Marina South, will be straightened and expanded to form high- capacity roads leading to and from Shenton Way.
There will also be direct access to Maxwell Road from the area.
Motorists on the fringe will face changes too. The Fort Road connection to the ECP will be removed because there will be insufficient distance for motorists to filter into the highway when the MCE opens.
Those who use this access to go to the city will have to find other routes, such as via Nicoll Highway, or travel on the East Coast Park Service Road to make a U-turn to join the ECP farther east.
Electronic Road Pricing (ERP) gantries will also be re-positioned, to reflect the status of the expanded business district. But the LTA said most motorists will not pass more gantries than they do today.
But this does not apply to those driving from areas such as Bukit Timah and Serangoon, who rely on the Ophir Road connection to get to the west via the ECP. They will have to pass two gantries instead of one today.
National University of Singapore transport researcher Lee Der Horng said the changes will improve safety. Like other observers, he noted that the ECP stretch in the Marina area "is actually quite dangerous".
A number of serious accidents have occurred in recent months at the section before the Marina Bay Sands, including a fatal one involving a 30-year-old businessman driving a Lotus sports car.
Professor Lee added that removing a section of the ECP goes towards creating "a neater urban landscape, and orderly traffic flow".