What is the most common type of vehicle detection method used at signalized intersections?

Inductive loop detection is the most common type of vehicle detection method used at signalized intersections due to its reliability and effectiveness at accurately sensing the presence and passage of vehicles. This method involves the installation of loops of wire within the pavement surface at strategic locations, typically at stop lines or detection zones. When a vehicle passes over the loop, it causes changes in the inductance of the loop, which can be detected and processed to trigger traffic signals accordingly.

Inductive loops are favored for several reasons: they are not affected by adverse weather conditions or ambient light, can provide real-time data on traffic flow, and require relatively low maintenance after installation. They have been widely implemented for decades and are well-understood by traffic engineers, making them a default choice in many locations.

While other methods, such as video detection, infrared sensors, and radio frequency detection, offer various benefits, they may not match the widespread utility and proven track record of inductive loop systems. Video detection, for example, can be affected by environmental conditions and may require more complex processing and technology to optimize its effectiveness. Thus, inductive loop detection remains the prevalent method for vehicle detection at signalized intersections.