Much public debate was stirred before the launch of the North East MRT line back in 2003.

Commuters taking Singapore's first fully underground, automatic train system had to pay fares of up to 25 cents more, compared with using the older North-South and East-West lines, which are primarily above ground.

The justification was that a fully underground line would cost more to operate - station platforms are air-conditioned, for example. But commuters also argued that a driverless system would allow operator SBS Transit to save on manpower costs.

Still, this practice of charging a fare premium became the norm for subsequent underground MRT lines launched, such as the Circle and Downtown lines, which started running in 2009 and 2013, respectively.

But this will be scrapped from Dec 30, the Public Transport Council (PTC) announced two days ago, in a radical move to simplify the rail fare structure. This equitable treatment of rail fares is a welcome move to commuters for several reasons.

Two upcoming MRT lines- the third stage of the Downtown Line (DTL3), which is targeted to open next year, and the Thomson-East Coast Line, which will launch progressively from 2019 - will also be fully underground.

Removing any fare disparities will allow commuters to travel freely across the MRT network without having to bear an extra cost of using fully underground lines.

This is complemented by another change in the way train fares are calculated. From Dec 30, train fares will be derived based on the shortest path between the commuter's start and end points. This ensures commuters will always pay the lowest fares.

Commuters who happen to live in a part of the island which is served by a fully underground MRT line should not be made to pay more to use it.

The rationale that fares should be charged to help operators cover costs is becoming less relevant, given the huge reforms in the public transportation sector, with the Government investing in bus contracting and taking over rail assets.