To reduce the risk of lorry cranes colliding into overhead road structures, these vehicles will have to be fitted with an audio warning system from next year.
The system will detect if the lorries' cranes have been stowed, and alert the drivers through an audio buzzer in their cabins if not.
Since 2013, there have been 20 cases of overhead road structures, such as walkway shelters and overhead bridges, being hit by vehicles which are over the general height limit of 4.5m.
In June this year, a lorry crane crashed into a walkway shelter at an open-air carpark in Bukit Batok, causing the structure to topple and crush a car.
"Many of these incidents could have been prevented if the drivers had stowed the cranes before setting off," the Land Transport Authority (LTA) said in a press release yesterday.
Under the new regulations, all lorries mounted with cranes after Jan 1 are required to have the audio warning system. All existing lorries with cranes have until Sept 30 next year to comply with this requirement, the LTA added.
For cranes which can be fully stowed, a limit switch is to be installed at the base of the crane and linked to an audio buzzer in the driver's cabin.
When the crane boom is fully stowed, it will rest on a mechanical lever of the limit switch. When it is not, the lever is lifted and this triggers an audio warning to the driver.
For crane booms which cannot be fully stowed, an angle sensor can be installed on the inner boom. This sensor will alert drivers when the crane is not fully stowed and is above its maximum stowed height.
The LTA said road humps will be built at six locations with high covered linkways by February. It added: "The road humps will help reduce the speed of over-height vehicles approaching high covered linkways and lessen the impact if an over-height vehicle were to hit the high covered linkway."
The locations include Jalan Membina near Zhangde Primary School; Tampines Central 4 near Tampines MRT station; and Bukit Batok Central Link near West Mall.
Drivers who are found guilty of damaging road structures and buildings can be fined up to $5,000, or jailed up to two years, or both. Repeat offenders face a fine of up to $10,000, a jail term of up to five years, or both.
Singapore Transport Association chairman Dave Ng said that while installing the audio warning system will be an added cost of about $150 to $450 to transport firms, it will greatly improve the safety of lorry crane operators and other road users.