Book has a copyright date of 1955. But descriptions talk about cars in the 60s. Also, I don't know how many 6 lane Super Highways there were in '55.
Book is about a multiple car, fatal accident; the people involved and the impact the accident had on the survivors. Main character is a successful architect who is taking a forced vacation. His wife had been killed in another auto accident, and his work is suffering. There is also 2 Bandits fleeing with $40,000 from a bank robbery, and a sole survivor of a family of four, who needs to be rescued from a greedy relative. I'd say this is one of McDonald's Better early works.