The UK government has committed 500 million pounds (roughly $780 million US) to the project over the next five years, and the off-road trials follow a substantial feasibility study conducted by Highways England. It looked into everything from how the infrastructure could be installed under the UK's major roads, how existing EVs and hybrids could be retrofitted to take advantage of it, and what specific type of "dynamic wireless power transfer" could be used. Though the trials are said to be the first of their kind, in that the end goal is to install it along major roads, Highways England has a lot of prior art to take inspiration from. Qualcomm's Halo wireless charging tech was once earmarked for Formula E racetracks, for example, and South Korea already has electric buses running on special wireless charging routes.
This article by Jamie Rigg originally ran on Engadget, the definitive guide to this connected life.