“For 30 years, we’ve built a lot of roads and a lot of highways,” Jean-Louis Borloo, the French environment minister, said at the end of a two-day summit last week. “That’s over. Our road capacity is not going to increase further.” A draft document released by Mr Borloo before the summit expressed the hope that cars and planes would become “solutions of last resort” in coming decades It has been a long time since politicians spoke this way. In general, as western publics move closer to universal car ownership, their appetites for highway construction tend to become insatiable. American congressional elections are often won by the candidate who can credibly promise to pave more farmland and countryside.

Poland’s recent elections fit this pattern handsomely. Jaroslaw Kaczynski, the eccentric incumbent prime minister, provided a fat rhetorical target on many issues, but it was on the respective soundness of the candidates’ road-building plans that the victorious challenger, Donald Tusk, often chose to do battle.