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Exit control and safety devices are a necessary part of any
automated or electric gate system. The most common types of exit
control devices and vehicle safety devices are vehicle loops.
For pedestrian safety, the most common device is the photo-cell
or photo-eye. Vehicle loops are formed from twisted wire that
is either installed under the road surface (pre-formed loops) or
cut into the existing asphalt or concrete roadway (cut-in
loops). These wires form a magnetic field that will sense an
automobile and that will initiate a programmed response to the
gate system. Typically that response is to open, close or
reverse, depending on what type of vehicle loop.
The Photo-Eye is used for pedestrian safety and is a device
that emits a beam of light that is either caught by another
sensor or reflected back to the original sensor using a
reflective plate that is mounted to one of the gate post. This
serves as an important safety device for pedestrians because if
the beam of light is broken or interfered with then the gate
will not close. It is similar to a vehicle safety loop in that
it will prevent the gate from closing but a vehicle loop will
not sense an individual because it detects large quantities of
metal whereas a photo eye will detect anything that interferes
with the beam of light, including a small child. |
