The decision took Autostrade and Abertis by surprise: over the past weeks the firms felt confident that their plan to create the largest toll-road company in the world was on track.

Called "the Wattway," the roads will be built through joint efforts with the French road-building company Colas and the National Institute of Solar Energy.

Last week, one operated by the taxi company Uber struck and killed a woman pushing her bicycle across a wide road in Arizona.