Availability 1 : General. A measure of the probability in signal maintenance that the equipment will be available for use, determined as MTBF/(MTBF + MTTR) where MTBF = mean time between failures and MTTR = mean time to repair
Peter Milne and Kieran Sharp, ARRB Group, and Bob Ungers, consultant, Austroads Glossary of Terms (4th Ed.), Austroads Ltd., Sydney, NSW, Australia 2010. http://www.bicyclensw.org.au/files/u1/Austroads_Gl ossary_of_Terms_4th_edition.pdf (Road Trfc and Transp Sfty - Brit) {529}