The highways will be double-decked

Gregory Benford : science fiction author and astrophysicist
The best way of visualizing the new world of A.D. 2000 is to introduce you to the Dobsons, who live in Tottenville, a hypothetical metropolitan suburb of 100,000. The highways that radiate from Tottenville are much like those of today, except that they are broader with hardly any curves. In some of the older cities, where it was difficult to alter the streets because of the immense investment in real estate and buildings, the highways are double-decked. The upper deck is for fast nonstop traffic; the lower deck is much like our avenues, with brightly illuminated shops. Beneath the lower deck is the level reserved entirely for business vehicles.
In the homes, electricity is used to warm walls and to cook. Factories all burn gas, which originates in sealed mines. The tars are removed and sold to the chemical industry for their values, and the gas thus laundered is piped to a thousand communities. But that’s not the only source of energy in Tottenville. Theoretically, 5000 horsepower in terms of solar heat fall on an acre of the earth's surface every day. Many farmhouses in the future will be heated by solar rays and some cooking will be done by solar heat

GREGORY BENFORD, Popular Mechanics, (2012), "The Future That Never Was: Pictures from the Past', [online], Available: