A Massive-Open-Online-Carpooling system that can significantly reduce Cairo's traffic congestion by engaging all commuters in a game-like system where they can contribute and get recognized for their contribution by the minute!
Commuters smartphones simply use Bluetooth to identify carpoolers within the same car and GPS to track the distances travelled while carpooling. Smartphones then report this data to a Server that calculates "carpooled miles" per commuter and rewards them using a gamified scheme offering points, badges and ranks (global and amongst friends).
I think this will be effective because:
1- It doesn't require any purchase/action on the citizen side other than downloading a mobile app. 2- Because it translates the carpooling action into numbers that can be translated into pollution or energy savings.
Please leave your comments if you have any. It's unlikely this will make it to the book. I am planning to pursue this so feedback will be appreciated.