http://www.straitstimes.com/forum/letters-on-the-web/go-high-tech-to-make-expressways-safer
Driverless patrol car will be dangerous, if it mulfunctions while driving on Expressways. Unmanned drones monitoring high speed cars will be safer than driverless patrol cars.
But, the problem is how long the drone can fly in the sky. If it's extremely short, the drone cannot be used in regular operation.
