We herein consider directional transmission based on adaptive beamforming in which multiple vehicles are served at the same time usingmultiple directional beams; this represents one promising technology that could improve the capacity of vehicle-to-infrastructure (V2I) communication. We propose an iterative resource-allocation method to maximize the capacity of V2I communication by taking into proper account the interference between directional beams, which reduces capacity. We also consider a heuristic resource allocation scheme, which has significantly less computational complexity than the iterative scheme and negligible performance degradation. We make use of computer simulations to show that the capacity of V2I communication can be improved using our proposed schemes