Vehicle Detection Sensor for car counting

In traffic industry, a lot of ground loops are used to measure traffic of vehicles on street and freeway.
Also similar things are done at parking facility, but it has to be installed into ground.

OPTEX vehicle sensor which uses Microwave sensing technology could work similar to ground loop.
It can be installed on a post or wall, so no hassle to dig driveway.
Also it could ignore most of people traffic and detect vehicle reliably.