Ray-tracing propagation models for urban microcellular environments become time consuming as the validation of higher order of ray interactions presents a significant computational overhead. This letter presents a time efficient ray validation algorithm for ray-tracing models. The model presented in this letter uses a pre-computed database of building faces that are completely or partially visible to each face and vertical edge of all the buildings in the radio environment. This database is used to readily validate the ray-segments between the transmitter and receiver. The validation results show considerable time saving over previous models.