Thanks to the advances in wireless technologies, mobile vehicular networks are likely to become the most relevant form of mobile ad hoc networks (MANET). Vehicular communication which facilitates the exchange of information between vehicles is the prerequisite not only for extending the access to the Internet while on the road, but also to cater for special applications such as of road traffic and travel management. However despite the increasing number of studies on vehicular routing protocols, the support for applications other than the access to the internet remains limited. In this paper we propose a novel vehicular communication system for road congestion detection and avoidance by disseminating and exploiting road information. The system is an integrated solution for sharing congestion information using a simple geocast protocol and dynamic Dijkstra algorithm for planning and computing least congested travel itineraries. In this paper, we show, through simulation results, that the proposed solution not only allows vehicles to detect road congestion ahead of time, but also contributes to reducing the congestion level on the roads by allowing vehicles to avoid congestion points.