Solar Helping Traffic Control

A Wanco solar full matrix message sign on 8th St. SW, DC
Battery box pictured on bottom

Solar equipment on the roads is everywhere. This ranges from traffic arrows to flood lights to speed limit postings to traffic cameras.

I walked around DC and found many instances of solar message boards. The one I preferred was by Wanco. Wanco's full matrix message sign had one solar panel, one battery box on the trailer, and the light from the sign was clear even in broad daylight. 

According to Wanco, the "panels charge batteries automatically without intervention" and the computer "shuts down solar-panel charging system when batteries are fully charged, preventing damage". You can keep the battery connected to the solar panels or connect it to commercial power.

Sign as viewed from front

The solar-battery combination is ideal for highway safety and traffic control. It's mobile. Most of these solar devices are mounted on a trailer or bed of a construction vehicle. It's self-contained. It doesn't require constant refueling, plugging in, emptying or changing. 

I'd be interested in seeing the applications of solar devices on the roads in rural countries outside of America, especially where roads are not as established.