The ubiquitous Electronic Road Pricing (ERP) gantry may become a thing of the past several years down the road.
The Government is looking to develop a next-generation ERP system, based on satellite technology, which will not need the large gantries that require space and time to set up.
But some motorists were concerned that, without the gantries, they might unwittingly enter a chargeable zone.
Transport Minister Lui Tuck Yew said yesterday that the new system, tentatively called ERP2, will allow the Land Transport Authority to tackle congestion more effectively and quickly.
The current in-vehicle unit (IU) for ERP gantries will have to be replaced for ERP2.
Undergraduate Beatrice Chua, 21, who drives, was worried that, if the ERP gantries are removed, it might be hard to tell where the priced roads are, even if signs are put up.
Motorcyclist Pang Chew Ting, 24, said alerting people beforehand via the new IU that they are about to reach a chargeable road "would be good".
National University of Singapore transport researcher Lee Der Horng said the new IU could be similar to vehicle-navigation systems available on the market now, and deliver value-added services.
Mr Lui - who was speaking during a site visit to the Marina Coastal Expressway, slated to open by year's end - said other possible uses of ERP2 include finding stolen cars, and doing away with parking coupons by using the new IU for charges.
He added that data collected through ERP2 would be rendered anonymous, with the Government working through privacy policies and safeguards.
When ERP2 is rolled out, "we will start it off only on roads that are already priced under today's ERP system", Mr Lui said, adding that the Government did not intend to charge motorists the minute they left home or started their engines.
"(A motorist) will generally have the same paying experience," he said of ERP2, which will be introduced only where there is congestion.
With ERP2, motorists could also be charged based on the distance travelled, rather than at discrete points only, as is the case with ERP gantries.
Distance-based charging will also be "fairer and more equitable", as motorists will be charged proportionally to how much they contribute to congestion, he noted.
Mr Lui also said the Government is looking to tweak the certificate of entitlement (COE) system.
The conditions determining which vehicles qualify for Category A COEs could be changed, such as by introducing new criteria like engine power.
This will address concerns of how Cat A COEs - for cars up to 1,600cc, which are typically smaller, budget models - are being used to buy higher-end cars.
The Government is also considering a surcharge on the second car and above owned by the same person.
With distance-based charging, COE prices could be brought down by the authorities as "owning a car doesn't do any harm in terms of congestion", said transport expert Alexander Erath.