SMALL-AREA DETECTION AT INTERSECTION APPROACHES

This technical report is concerned with small-area detectors, those that detect vehicles at a spot location upstream of the stop bar, at intersection approaches. The principle criteria for detector location must include; sufficient set back to minimize delay to approaching vehicles and at the same time, avoid long minimum greens, avoid short greens and locate detectors accordingly, use a set-back equal in passage time to the allowable gap, at least one and one half seconds of passage time and enough to ensure motion detection. More advanced actuated control have a variable initial interval and thus can count beyond the first waiting vehicle. The advanced design control can be set back further from the stop line than their more basic counterparts. Green extension systems can be used with semiactuated, basic full-actuated or even pretimed controllers.