The law around gate safety can be quite confusing but is rightly very serious. Following deaths and injuries from automated systems the Health and Safety executive and DHF (Door Hardware Federation) have published guidelines to raise the safety standards for automated gates.
In cases of accidents or injuries the system manager can be prosecuted if their system is found to be unsafe or poorly maintained.
If you employ staff at your site such as a gardener, cleaner or childminder, the level of compliance rises. At this point you will automatically take on liabilities under the Health & Safety at Work Act.