Pressurized camera enclosures should be used and sun covers provided where appropriate. The primary objective of detection in actuated signals is to allocate green time according to traffic demand. This greatly reduces delays and improves system effectiveness. Through relatively low error rates in vehicle presence detection VIPS can accommodate this primary objective. A small problem can arise in low volume situations when a vehicle is not detected.
Similar problems arise with other detection technologies.
This undesirable combination needs to be investigated on a case by case basis and if detection is still uncertain, fixed cycles be established for low volume situations. Similarly, in cases where the VIPS data reliability is low due to poor picture or other factors, the controller should default to a fixed cycle. In principle, VIPS need to be initialized just once after the initial installation. Detection zones are located and all default values downloaded for uninterrupted operation. Tripwire systems have been quite reliable to recover from power failures and other operational disruptions.