How long should traffic signals run on battery during a mains outage?

Four hours at full load is the effective Australian benchmark, and it is well sourced. Queensland TMR’s MRTS213 requires 4 hours at a 1400 W full test load. Australian traffic controller products in the SCATS ecosystem are built to roughly the same figure, around 4 hours at maximum load for both integrated and external UPS controller families. NZTA’s ITS UPS specification allows 1 to 8 hours determined per site as part of the installation design, based on criticality and fault response capability. Note this differs from the North American pattern, which typically splits full-operation hours from extended flash-mode hours.