Growing traffic volumes in cities demand new ways to manage routes. Current Intelligent Transport Systems (ITS) face safety and privacy issues, high data costs, and security vulnerabilities. We propose a lightweight system using fog computing and homomorphic encryption. Vehicles anonymously share encrypted travel data with a trusted fog node, allowing the Traffic Control Centre to safely manage congestion without compromising individual privacy. Experimental results show our system outperforms existing approaches, offering a secure and efficient solution for future ITS.