A full scale traffic experiment investigating saturation flows at traffic signal junctions has been conducted on the Test Track at Crowthorne. Conventional and new junction layouts were tried. At conventional junctions the effects of stopline and lane widths, radius and angle of turn for turning vehicles, geometric stagger and exit constriction, and the flow opposing a saturated stream of right-turners were investigated. The new designs incorporated flared entries, substantial deflection for straight-ahead vehicles, and provision for deep non-hooking right-turn movements. They showed potential for high saturation flows both for the straight-ahead and the right-turn movements. The designs were also used in a roundabout mode, with the signals switched off, and had adequate capacity for use in off-peak periods, even though the roundabout design was non-optimal. (A)

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