Electronic Road Pricing was not introduced to generate revenue, Transport Minister Raymond Lim said yesterday.

It actually rakes in less than the Area Licensing Scheme (ALS), the previous plan to manage peak-hour traffic.

He was responding to opposition MP Low Thia Khiang (Hougang), who said motorists feel they are being ?squeezed? by having to pay to use expressways and yet still face jams.

Mr Lim did not cite figures, but said revenue collected from ERP, which was introduced in 1998, is about 20 per cent less than under the ALS, when motorists bought and displayed tickets to enter the Central Business District during peak hours.

Mr Low spoke on the issue after Non-Constituency MP Sylvia Lim, also from the Workers? Party, asked about the effectiveness of ERP in easing congestion on the Central Expressway (CTE). Both said their comments reflect feedback from motorists.

Ms Lim said ERP rates do little to deter motorists from using expressways, even when rates are hiked.

Passenger cars now pay between 50 cents and $4 since the latest increase last week . She was concerned about the CTE, which is now the costliest road to use.

Mr Lim explained that ERP is not the only way to manage traffic flow, but the most ?direct? way of doing it.

?There?s no silver bullet to it,? he said of dealing with traffic congestion.

?We have all these measures and we have to keep on adjusting, all the time.? As for the CTE, ERP keeps average speeds there within an ?optimal? range of 45 to 65kmh during morning and evening peak periods.

If the ERP had not been put in place in the evening, he said, average speeds would have slowed to well below 25kmh, leading to a possible gridlock.

Other measures are being taken to ease CTE congestion, he said, referring to work to widen a 2km section between Ang Mo Kio avenues 1 and 3.

Ms Lim said motorists who pay to use the northbound CTE in the evening are ?cheesed off? as they still encounter jams.

This is because drivers who use alternative routes rejoin the expressway from Ang Mo Kio avenues 1 and 3.

MPs laughed when Minister Lim asked if Ms Lim was asking for more gantries. He said the situation will be monitored and major access points taken into account.