Recently, the authors proposed a distributed dynamic route guidance system called UTOSPF (Urban Traffic Open Shortest Path First) based on Wireless Sensor Networks (WSNs) and Open Shortest Path First (OSPF) protocol. In UTOSPF, the routes will be found only based on Estimated StreetTravel Times (ESTTs) which will be needed to pass the streets and regardless of Waiting Times for Green Light (WTGLs) which drivers spend behind the red lights. In this paper, a simple method will be proposed to involve the WTGLs in calculation of optimal routes and its simulation results will be presented. Simulation results show that this method can improve the average speed of vehicles up to 66% as compared to random routes and up to 27% as compared to original UTOSPF, in the simulated scenarios.