Mean Distance Between Service Interruption (MDBSI)

Wednesday, January 1, 2025


Value	Resiliency: A transportation system prepared for rapid economic, environmental and social change.
Metric	Muni Mechanical Performance Measured by Mean Distance Between Service Interruption
Purpose	The Mean Distance Between Service Interruption (MDBSI) measures the transit fleet’s mechanical reliability and success of preventative maintenance efforts. A higher MDBSI value indicates improving the mechanical performance of our fleet and better service reliability for Muni customers.
Definition	MDBSI is determined by the total vehicle mileage divided by the total reportable road calls, or service disruptions due to mechanical failures, and is reported by mode. Reportable road calls are the total of NTD Major and Other Mechanical failures.
Methodology	sum ([vehicle mileage]) ÷ sum ([reportable road calls])
Target	Achieve 6,000 MDBSI for Motor Coach and Trolley Coach, 5,500 MDBSI for LRV (Breda), 25,000 MDBSI for LRV (Siemens), and 2,900 MDBSI for Historic Streetcar in FY 24-25.
Reporting Frequency	Monthly
Contact	For questions, comments, and accessibility issues, please contact the Performance Team at performance@sfmta.com.
Notes	N/A