We consider vehicle-to-infrastructure (V2I) type communication over millimeter wave (mmWave) frequencies and evaluate its performance limitations in terms of coverage. Specifically, we analyze the outage probability and average outage duration for a communicating vehicle exchanging data with roadside units (RSUs), where the system performance is limited by the path-loss that the intermediate links experience. The path-loss depends on the length of the link, as well as the number of vehicles blocking the line-of-sight (LOS) path. By using a Markov chain formulation and its steady-state solution, we obtain analytical expressions for the outage probability and average outage duration. After demonstrating that the durations of outage events constitute a greater limitation on the system performance than outage probability, we examine two approaches to mitigate this limitation: increasing the RSU density and increasing the path-loss threshold for munication.