If there are a lot of vehicles using a gate it must be set to close automatically, you cannot rely on users closing the gate once they're in. If a gate closes automatically after a time delay, there's the risk of it closing on a vehicle. The most effective way to prevent this is to install Photocells, which have a beam of infrared light that crosses the driveway and when broken by a vehicle, prevent the gate from closing. Photocells can also be used to close the gate automatically when a vehicle is safely through.
Swing Gates require 2 sets of photocells whereas sliding gates require only 1.
If a gate is used by cars as well as trucks then two sets of photocells at different heights may be required to cover them.
If a vehicle with a trailer stops in the gateway the photocell may not detect it, they also may not detect pedestrians, so a Gate Operator should have a feature where it will reverse if the gate is obstructed to allow for this. 12V and 24VDC operators have the most effective sensitivity to the gate being obstructed so should always be used with housing estates.