A 1958 automobile design by Ford would have reduced traffic congestion. As Wikipedia describes it:
The Ford Nucleon was a nuclear-powered concept car developed by Ford Motor Company in 1958. No operational models were built. The design did not include an internal-combustion engine, rather, a vehicle was to be powered by a small nuclear reactor in the rear of the vehicle. The vehicle featured a power capsule suspended between twin booms at the rear. The capsule, which would contain radioactive core for motive power, was designed to be easily interchangeable, according to performance needs and the distances to be traveled.
After a crash, people would have avoided the neighborhood of the collision for decades.
(Thanks to investigator Ron Josephson for bringing this to our attention.)