# Outer Ring Road System

The Outer Ring Road System, or more commonly known as ORRS, is a network of major arterial roads in Singapore that forms a ring road through the towns along the city fringe. The ORRS is a semi-expressway, just like the West Coast Highway. Since 1994, roads along the ORRS have been upgraded in stages to provide a smoother route to travel across the island. Roads and interchanges along the ORRS are constantly being upgraded to cater to the ever increasing traffic demand. It starts as Portsdown Avenue in Queenstown and ends as Tampines Avenue 10 in Tampines. The series of roads passes through the areas of Queenstown, Bukit Timah, Central Catchment Nature Reserve, Bishan, Toa Payoh, Geylang and Tampines.

## Route

The route of the ORRS forms a semi-circle shape, connecting several expressways and major arterial roads. Travelling from west to east in a clockwise direction, the route begins at Queenstown with a connection to the Ayer Rajah Expressway. The route continues northward through the residential areas of Bukit Timah via Farrer Road and Adam Road, with the first connection to the Pan Island Expressway. The route continues east through Bukit Brown, Toa Payoh, Bishan and Bartley, via the MacRitchie Viaduct and Lornie Viaduct and a connection to the Central Expressway. From here, the route travels eastwards to Kaki Bukit and Tampines through a series of viaducts.

## Benefit

With the ORRS, traffic volume on city-bound roads will be reduced. It also provides an alternative route east-west travel for motorists without going through the city. Since ORRS is extensively linked to expressways and other arterial roads, such as Bukit Timah Road, motorists can get from one traffic route to another easily.

## Upgrading projects

The first upgrading project started in 1994, with two intersections along Farrer Road being the first to be upgraded. The upgrading projects had to be carried out in stages to minimise disruption to traffic. The completion of the Portsdown Flyover, Queensway Flyover and Queensway Underpass marks another milestone in the realisation of the ORRS. The Farrer Road section of the upgrading project completed in 2009.

## Interchange along ORRS

| Road name | Interchange with | Type | Remarks | Name of interchange |
| Portsdown Avenue | Ayer Rajah Expressway | Diamond | Start of ORRS going eastbound; end of ORRS going westbound. | Portsdown Flyover |
| Portsdown Avenue | Queensway | 3-way | From Portsdown Avenue, it goes straight towards Queensway northbound and the ORRS continues from there. | Queensway Flyover |
| Queensway | Commonwealth Dr | 3-way | - | - |
| Queensway | Commonwealth Avenue | SPUI | Queensway Underpass offers a non-stop drive through this interchange. | Queensway Underpass |
| Queensway | Commonwealth Dr | LILO | - | - |
| Farrer Road | Holland Road | Three-level diamond | To go from Queensway to Farrer Road, one can drive through the Farrer Underpass. | Farrer Underpass, Holland Flyover |
| Farrer Road | Leedon Heights | 3-way | - | - |
| Farrer Road | Empress Road | 3-way | - | - |
| Farrer Road | Bukit Timah Road | Three-level diamond | Bukit Timah Road travels westward only, access the Farrer Flyover to stay on the ORRS. | Farrer Flyover, Bukit Timah Underpass |
| Adam Road | Dunearn Road | Three-level diamond | Dunearn Road travels east bound only, access the Farrer Flyover to stay on the ORRS. | Farrer Flyover, Dunearn Underpass |
| Adam Road | Pan Island Expressway | Parclo | – | Adam Flyover |
| Lornie Highway | Lornie Road | Slip lane | To go from Adam Road to Lornie Highway, one can drive on Adam Flyover. An alternative road is Lornie Road, which is parallel to Lornie Highway, although Lornie Road has a longer distance than Lornie Highway. | Adam Flyover |
| Thomson Road | Thomson Road | Thomson Road | To go from Lornie Highway to Braddell Road, one can drive on MacRitchie Viaduct. | Marymount Flyover, MacRitchie Viaduct, Lornie Viaduct |
| Braddell Road | Bishan Road | Seagull | Bishan Flyover offers a non-stop drive through this interchange. | Bishan Flyover |
| Braddell Road | Lorong 6 Toa Payoh | Trumpet | – | Toa Payoh North Flyover |
| Braddell Road | Bishan Street 11 | LILO | Can only be accessed by traffic travelling eastbound. | – |
| Braddell Road | Lorong 8 Toa Payoh | Slip lane | Lorong 8 Toa Payoh only allows traffic to travel westbound only. Vehicles are not permitted to leave the ORRS here. | – |
| Braddell Road | Central Expressway, Lorong Chuan | 3-level SPUI | Braddell Underpass offers a non-stop drive through this interchange. | Braddell Underpass, Braddell Flyover |
| Braddell Road | Upper Serangoon Road | Three-level diamond | To go from Braddell Road to Bartley Road, one can drive through Bartley Underpass. This interchange is Singapore's first four-tier interchange, with, from highest to lowest, Upper Serangoon Viaduct, Upper Serangoon Road, Bartley Underpass and North East line tunnel. | Woodleigh Underpass, Upper Serangoon Viaduct |
| Bartley Road | Serangoon Avenue 1 | 3-way | – | – |
| Bartley Road | Upper Paya Lebar Road | 3-level SPUI | Only motorists travelling eastbound can only enter and exit to Upper Paya Lebar Road. | |
| Bartley Road East | Hougang Avenue 3 | SPUI | | Bartley Viaduct |
| Bartley Road East | Airport Road | SPUI | Only motorists travelling westbound can only enter and exit to Airport Road. | Bartley Viaduct |
| Bartley Road East | KPE | SPUI | Only motorists travelling westbound can only enter and exit to Airport Road. | Bartley Viaduct |
| Bartley Road East | Kaki Bukit Ave 4 | LILO | - | - |
| Bartley Road East | Bedok North Road | Seagull | To go from Bartley Road East to Tampines Avenue 10, one can drive on Kaki Bukit Viaduct. | Kaki Bukit Viaduct |
| Tampines Avenue 10 | Tampines Avenue 1 | Box, Seagull | Start of ORRS leading westbound; end of ORRS leading eastbound. | – |
^Note 1 : Only expressways, arterial roads and major roads will be mentioned. Minor roads will not be mentioned.