Vehicle sensors

Vehicle sensor options

Inductive technologies are primarily sensors for metalic objects such as vehicles. They do not detect people or animals, so may not be considered as safety devices.

Inductive Loop Vehicle Sensors       

Traditional road loops are multiple loops of wire laid in the wearing surface of the road. A detector module is connected to the loop. Vehicles entering the sensing area trigger the detector circuit. Detectors that remain activated while the vehicle remains may be considered for presence duty.

Single Point Vehicle Sensors

New devices now involve a single sensor set in the road wearing surface. The area of detection is defined by the sensitivity it is set to. Single point sensors are much quicker to install. Used mainly for activation, not presence.

Optical Roadside Vehicle Sensors 

Simple photobeams are easy to instal, but are not recommended because they leave the site insecure. Exit sensors need to be more selective. A photobeam will not discriminate between a vehicle and an animal. 

Infra red ToF sensors (time of flight) however measure distance, and some texture. A shiny hard surface has a different profile to a soft moving surface. 

Doppler Roadside Vehicle Sensors

Microwave Doppler devices measure the speed of approach. The target must be moving. They are easy to mount at the roadside, and while more responsive to vehicles, they still respond in part to people and animals. Doppler sensors can be combined with other inductive technologies for an effective roadside vehicle sensor.

Inductive Loop Vehicle Sensors

Loops can be cut into solid road surfaces. Any breakup of the surface will tear the loop so be sure the surface is sound. The filler material should suit the road material. Loops can be pre-made in poly' pipe for burying in gravel drives.

Single point exit sensors

Single point exit sensors, sometimes described as mini-loops, are much easier to instal than full size inductive loops. Only one short lead is required to the sensor in the middle of the road. They are much less prone to cable damage if the road surface breaks up, and hidden below ground makes them vandal resistant. These exit sensors are intrinsically more reliable.

Single point exit sensors only detect metallic objects. They are normally placed in the driveway, but long range can still be effective at the side of the road. 

Single point safety sensors

Magna sensors are magnetic field sensors that respond to metallic objects; vehicles but not persons or animals. Like the single point exit sensor mini-loops, they are positioned in the driveway centre. Unlike mini-loops, they can be set in any orientation, which means these devices can be installed horizontally in a plastic duct.

Some sensors are programmed for presence detection, others for exit purposes. Both will maintain a signal as long as the vehicle is present. All single point sensors are more resistant to road damage and vandal damage.