What has Singapore done

Certificate of Entitlement (COE): The Singapore Land Transport Authority fixes the quota of vehicles each year for bidding. The bidder has to pay for a 10-year COE, which is expensive

Taxes: Imported motor vehicles pay customs duty of 41 per cent. Registration fee is US $1,000 for private vehicles and US $5,000 for company vehicles. Road taxes are renewed periodically to encourage low-emissions vehicles. Taxes on cars increase 10th year onwards, 110 per cent in the 11th year to a maximum of 150 per cent of the market value of cars

Road pricing: Singapore operated a manually controlled road pricing scheme from 1975-98. Motorists paid for entry into a central restricted zone

Electronic road pricing: Introduced in 1998. Overhead gantries deduct the charges from a smart card onboard. Enforcement cameras assess fines in case of violation. Motorcycles, heavy vehicles added. Operating costs are 10 per cent or less of the revenue collected through the system