Traffic signal battery backup systems: Use of event-based traffic controller logs in performance-based investment programming

A stable supply of power is a critical element in reliable traffic signal operation. Battery backup systems (BBSs) are often used to prevent traffic signals from experiencing power disruption. BBSs are designed through the use of engineering judgment because of a lack of operational requirements and well-defined performance measures. New high-resolution traffic controllers have the ability to record event-based data for power failures and traffic counts at a resolution of 0.1 s. With these high-resolution data, this paper proposes performance-based investment programming that uses the average annual signal downtime (AASD) over the analysis period as a performance measure. The AASD is stochastically estimated through the use of hazard-based duration models developed with power failure data. A volume and functional class-weighted stochastic optimization scheme is then presented for a BBS planning project, in which battery capacity is sized to minimize the AASD for a network under given budget constraints.