The idea that using borrowed money to buy assets is the smart road to riches might lose currency, changing attitudes to home ownership as well as to parts of the finance sector such as private equity.

Kevin Balke, a research engineer at the Texas A&M University Transportation Institute, says that while smart lights can be particularly beneficial for some cities, others are so jammed that only a sharp reduction in the number of cars on the road will make a meaningful difference.

Smart transit systems could manage traffic far more efficiently than the massive road and parking-lot systems required by vehicles in the U.S., for example.