I share Editor-at-Large Han Fook Kwang's concerns that the expensive and complex satellite-based Electronic Road Pricing system might not be the most direct or cost-effective policy to address traffic congestion ("Satellite-based ERP: Great technology but what's the policy?"; March 13).

Motorists and urban planners have long challenged the underlying concept of ERP.

Strong anecdotal evidence suggests that the selective introduction of tolls on arterial routes has succeeded in merely transplanting the traffic congestion from one road to another, rather than deterring private vehicle use to begin with.

With specific regard to a satellite-based ERP system, a pricing policy based on overall road use would disproportionately affect long-distance commuters, who might live far away from their workplaces and are thus forced to pay more simply out of circumstance.

If the current pricing model of a "restricted zone" is to remain, the existing gantry-based system would seem perfectly adequate, and far less expensive.

No major metropolis in the world is immune to traffic jams. Rather than eliminating congestion entirely, the realistic question is how best to manage it.

The certificate of entitlement (COE) system is a good starting point. After all, controlling the overall vehicle population tackles the root cause of widespread congestion.

In 2007, Singapore had 851,336 vehicles on 3,297km of roads, making for a vehicle density of 258 vehicles per kilometre. In 2014, 972,037 vehicles plying 3,496km of roads resulted in a density of 278 vehicles per kilometre.

More stringent limits on vehicle population growth are, hence, necessary to prevent unsustainable levels of vehicle density.

This could be enacted by way of tighter COE controls, and a more equitable distribution of the quota that prioritises those who require vehicles the most.

As Mr Han so eloquently put it, solving congestion might entail "no technology, just good old-fashioned policy".

Paul Chan Poh Hoi