Proxy Solutions works with a receiver and tags. If the tag approaches the receiver, this causes one or more actions. 

You can choose to place the receiver on the vehicle or somewhere in the warehouse.

A first possibility is to place the tags somewhere in the warehouse (like for example on a busy cross road). When the receiver/the vehicle comes close to the cross road/tag, an action is caused on the vehicle (like for example a horn sound). Now other vehicles/employers know a vehicle is approaching.

A second possibility is to mount the receiver somewhere in the warehouse and to place the tags on the vehicles or on the employers. Now they know when a vehicle is approaching via a visual warning like a lamp or via a sound signal.