Drawing on the method associated with Technology Readiness Levels (TRLs) and previous efforts, this article provides a maturity assessment of several electric road system (ERS) technologies with focus on the power transfer technology subsystem, and the transition context is also discussed. ERS involves electric power transfer from the road to the vehicle while the vehicle is in motion and could be achieved through different technologies such as rail, overhead line, and wireless solutions. ERS is a technology area with immense potential to reduce fossil fuel dependency, reduce greenhouse gas emissions, reduce air pollution as well as reduce noise in urban environments, while increasing energy efficiency in the transport sector. There are numerous promising ERS development and demonstration projects globally since several years. However, the investment cost for large-scale deployment of ERS is considerable and decision makers will require knowledge about how mature different solutions are compared to other transportation solutions.