Traffic lights across the U.S. are dangerously easy to hack, according to a University of Michigan study.
Under the supervision of local transportation officials, computer researchers were able to change traffic lights in a Michigan city in May by just using a laptop in their truck.
CNN Money reports the lights and controllers in the study are made by Econolite, one of the largest makers of signals, cameras, and traffic management systems in North America.
Its lights are used in 100,000 U.S. and Canadian intersections.
It's unclear if all of those systems are susceptible to hacking.