An electric road, eroad, or electric road system (ERS) is a road which supplies electric power to vehicles travelling on it. Common implementations are overhead power lines above the road and ground-level power supply through conductive rails or inductive coils embedded in the road. Overhead power lines are limited to commercial vehicles while ground-level power can be used by any vehicle, which allows for public charging through power metering and billing systems. Of the three systems, ground-level conductive rails are estimated to be the most cost-effective. Korea was the first to implement a public electric road with a commercial bus line in 2013 after testing an experimental shuttle service in 2009. Sweden has been performing assessments of various electric road technologies since 2013