With nine kilometres running underground, the 12km long Kallang-Paya Lebar Expressway (KPE) holds the record as South-east Asia’s longest underground expressway. It opened on Sept 20, although a shorter 3km stretch between the Pan-Island Expressway and the East Coast Parkway has been open since late last year.

It cost $1.7 billion as underground roads are 10 times more expensive to build and 30 times more costly to maintain. It is considered an engineering feat of work as it goes through soft soil and under a canal and a river.

The KPE runs from the East Coast Parkway (ECP) to the Tampines Expressway (TPE) and provides a faster and more direct route to the city for residents in the north-east. The KPE serves estates such as Hougang, Punggol and Sengkang, which previously only had the Central Expressway (CTE) to use to get to the city. It is expected to cut travel time by as much as 25 per cent.

With 16 Electronic Road Pricing gantries, this expressway will become possibly the most expensive road to use, although its gantries will not be turned on until it becomes congested.

An array of safety features have been put in place to deal with accidents and other traffic incidents that may happen in the KPE tunnel. Traffic is constantly monitored at the KPE Operations Control Centre with images fed from 103 surveillance cameras.

Here are some of the things motorists should do and safety features that can be found in the tunnel:

Turn on the radio: Motorists should tune in to their radios in case there is a safety warning. LTA officers can interrupt radio programming to make emergency announcements.

Stay within the speed limit: Because of its long underground portion, the KPE has a 70kmh speed limit. The Traffic Police are very strict about this – they catch an average of 210 speedsters every week via 10 speed cameras along the expressway.

Traffic marshals: If a vehicle breaks down, a traffic marshal on a scooter will be sent to the site to provide assistance. The traffic marshal will also direct motorists out of the tunnel to ground level in the event of an emergency.

Detection cameras: 188 detection cameras operate round the clock to check for the presence of stationary vehicles. Signals are sent back to the control room where staff can then pinpoint the area where an accident or vehicle breakdown has occurred.

Heat detection system: A fibre-optic heat detection system can detect changes in temperature and send the information back to the control centre.

Emergency phones: These red phones along the tunnel have direct lines to the Traffic Police, Singapore Civil Defence Force and Singapore Power.

Crossover doors: Emergency rescue vehicles can use doors separating the two carriageways of the KPE to get from an unaffected carriageway to the affected one in the opposite direction to reach an accident site.