SINGAPORE - The Parking.sg app, which lets motorists pay for parking at public carparks through their mobile phones, is already available for download, even before its debut on Sunday (Oct 1).

According to the Apple App Store and Google Play store, the app was updated on both stores on Friday (Sept 29).

As of Saturday 11.40pm, the app was downloaded between 1,000 and 5,000 times on the Google Play store, with 29 reviews. The Apple App Store does not give an indication of the number of times an app has been downloaded.

The Parking.sg app was announced by Prime Minister Lee Hsien Loong at this year's National Day Rally.

It can be used at all 1,100 carparks which still require coupons. Through the app, motorists can use their credit or debit cards to pay parking charges.

The app, however, can be used only for cars and light goods vehicles for now.

The scheme will be extended to motorcycles and heavy vehicles by the end of the year, the Housing Board, the Urban Redevelopment Authority (URA) and the Government Technology Agency of Singapore said on Friday.

The agencies added that even as the new app is rolled out, paper coupons can still be used.

The app will automatically calculate parking fees based on 30-minute blocks, but if motorists move their vehicles out earlier and end the session, they will be charged on a per-minute basis and get a refund.

This will prevent overpaying.

Under the coupon system, motorists pay 60 cents for 30 minutes, even if they leave earlier.

The app, which will be available from the Apple App Store and Google Play Store, will also alert motorists when their parking sessions are about to expire. Instead of running back to their vehicle to display more coupons, they can extend their sessions through the app.

To pay for parking with the app, motorists will have to key in their vehicle number, the parking duration as well as a carpark code.

They will be given a list of carparks nearby which they can select from when they enable the location function in their mobile devices.

The HDB and URA said they have put up additional signs at carparks that will reflect their unique code.

Enforcement checks by parking wardens will continue, added the authorities, reminding motorists to activate their Parking.sg app after they have parked their vehicles.