Typical back-up battery systems provide battery power in case of an outage to a signal for:

Typical back-up battery systems are designed to ensure that traffic signals maintain functionality during power outages, which is crucial for safety and traffic management. The correct answer, representing a back-up duration of 2 to 6 hours, reflects the average timeframe that these systems are expected to provide reliable power.

This duration allows for a reasonable response time for utility companies to restore power or for maintenance teams to either repair the affected systems or implement temporary alternative measures. While some systems may provide shorter or longer durations based on specific equipment and installation practices, 2 to 6 hours is a common allowance that balances efficiency and operational requirements. This period enables enough time for normalcy to be restored while minimizing risk to drivers and pedestrians in the event of an outage.