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.

This data exchange in the military field is based upon encrypted signals which cannot be analyzed or jammed by hostile forces.

Otherss were concerned that the floating library would just end up in recycling bins, as the books can be hard to spot in jammed subway cars.