Singapore has a road system covering , which includes  of expressways. The Singapore Area Licensing Scheme, implemented in 1975, became the world's first congestion pricing scheme, and included other complementary measures such as stringent car ownership quotas and improvements in mass transit. Upgraded in 1998 and renamed Electronic Road Pricing, the system introduced electronic toll collection, electronic detection, and video surveillance technology. A Global Navigation Satellite System will replace the physical gantries by 2020. As Singapore is a small island with a high population density, the number of private cars on the road is restricted to curb pollution and congestion. Car buyers must pay for duties one-and-a-half times the vehicle's market value, and bid for a Singaporean Certificate of Entitlement (COE), which allows the car to run on the road for a decade. Car prices are generally significantly higher in Singapore than in other English-speaking countries. As with most Commonwealth countries, vehicles on the road and people walking on the streets keep to the left.