The days of scrambling to place an extra coupon on your car to avoid the "summons auntie" could soon be numbered. The Urban Redevelopment Authority and the Housing Board - together with the Government Technology Agency of Singapore - announced yesterday that they are developing a parking app to act as "a transition step and provide important learning points" before the move to the next-generation Electronic Road Pricing (ERP) system.

The new satellite-based ERP system - expected to be introduced in 2020 - will help facilitate street-side parking charges in addition to road charges.

The new app will calculate how much motorists have to pay based on the carpark selected and their estimated parking duration, on a per minute basis.

Motorists who end their parking session earlier will be refunded. Parking attendants will be able to use the vehicle's number plate to check whether a motorist has paid and if the parking session is still valid.

"The mobile app will provide more convenience for motorists as they need not return to their vehicles to add more coupons to extend their parking session," the three government bodies said.

A trial to test the "robustness" of the app will be conducted involving public-sector officers at 84 selected public carparks in the city, in areas such as Fort Canning and Tanjong Pagar, between this month and next month.

The trial is expected to be extended to members of the public later this year.

A similar app called ParkMobile is in use in the United States in more than 200 cities.

Teacher Syahidah Rahmat, 30, said of the Singapore app: "I always forget to buy parking coupons, so I think this is a good move."

First introduced in 1980, parking coupons are still in use at 1,150 carparks here. In February, Second Minister for National Development Desmond Lee said in Parliament that coupon parking would be phased out "eventually".