These devices are often referred to as pads in the road, but nothing could be further from the truth. They are in fact made up of a roughly rectangular shaped wire loop, laid repeatedly around the rectangle to create a coil.
A miniature magnetic induction field is then created above, so that when a metallic vehicle passes over this magnetic induction field, its presence is detected and throws a pulse switch to open the entrance. They are typically used on busy, accessible gateways to allow freedom of vehicle movement; sometimes for exit only, but sometimes loops are laid inside and outside to allow free entrance and exit.
They are often overridden by a timeswitch so that access can be restricted to certain hours and out of hours only. Authorised users with other forms of switching (e.g. remote controls) can pass through. The road loops are laid into special positions in the roadway, often being disc-cut into tarmac or concrete and linked back to the control panel by twisted wires. Once installed, the sensitivity of the induction loops can be set to sense the types of anticipated vehicular traffic from a vehicle as small as a metal wheelbarrow up to an excavator. Induction roadloops can sometimes be used in a vehicle still present mode to act as a safety device, as opposed to a switching device. Induction roadloops are often fitted in conjunction with other forms of switching.
Keyswitch
Traditionally, the key has been the method of opening a secure entrance and the keyswitch provides exactly the method by which an authorised key holder can switch the gates to open electrically. The keys are an orthordox type of cylinder key and extra keys can be cut locally at a qualified locksmith. The keyswitch has a metallic finish, giving a stylish, but strong appearance. A keyswitch is often combined with other forms of switching at the gateway.
Pushbutton + Timer
The simplest and often the most effective form switching at the gateway is by means of a weatherproof push button. Two of these are generally installed, one on the outside for entry and one on the inside for exit. They can be positioned anywhere to suit your individual installation and are normally put on the right hand side of the entrance when coming in and on a button post on the driveway, so as to be reached from the vehicle driver’s window, on exit. These weatherproof push buttons are often used in conjunction with a timeswitch.
The times at which the gateway can be opened by these buttons may be restricted to accommodate regular deliveries and garbage collection and in this way, once the timeswitch has cut off the pushbuttons, only the people who have the authority to enter will be able to pass through the entrance, with remote controls or other forms of switching. The timeswitch has a 72 hour battery back-up in case of a power cut. This simple, but effective method of switching, always ensures that a pair of closed gates will be presented to passers-by, but at the same time allows limited access to “bonafide” visitors and for deliveries.
Proximity card readers
A ‘card reader access control’ system is a very efficient way for a large number of users to be accommodated and monitored as they pass through an electric gateway. This slotless, stainless steel touchplate is not affected by the weather and the card is "read" instantly and effortlessly. It is often used in combination with other methods of switching.