Increasing interests in Vehicular Ad hoc networks over the last decade have led to huge investments. VANET (Vehicular Ad-hoc Network) is a new field of technology which has been widely used in autonomous systems. Due to rapid topology changing and frequent disconnection makes it difficult to design an efficient routing protocol. Various routing protocols for VANETs have been recently proposed. Most approaches ignored parameters which effect performance of real VANET applications like environmental changes. Environmental changes can affect both performance and throughput in VANET. In this paper, we proposed a routing algorithm based on ant colony optimization and DYMO (Dynamic MANET On-demand) protocol which copes with changes in environment. Ant colony optimization algorithm is a probabilistic technique which has been widely used in finding routes through graphs. Two parameters were considered to evaluate discovered paths in this paper: (i) delay time, (ii) path reliability. Ns-2 was used to implement the proposed algorithm and monitor its performance through different amount of modifications in environment. Results proved that the proposed ant colony routing algorithm can achieve better performance in compare of other well-known methods like Ad Hoc on Demand Distance Vector (AODV)
