  Millimeter wave (MmWave) systems are vulnerable to blockages, which cause
signal drop and link outage. One solution is to deploy reconfigurable
intelligent surfaces (RISs) to add a strong non-line-of-sight path from the
transmitter to receiver. To achieve the best performance, the location of the
deployed RIS should be optimized for a given site, considering the distribution
of potential users and possible blockers. In this paper, we find the optimal
location, height and downtilt of RIS working in a realistic vehicular scenario.
Because of the proximity between the RIS and the vehicles, and the large
electrical size of the RIS, we consider a 3D geometry including the elevation
angle and near-field beamforming. We provide results on RIS configuration in
terms of both coverage ratio and area-averaged rate. We find that the optimized
RIS improves the average averaged rate fifty percent over the case without a
RIS, as well as further improvements in the coverage ratio.
