Vehicle Revenue Hours (VRH) : The hours traveled when the vehicle is in revenue service (i.e., the time when a vehicle is available to the general public and there is an expectation of carrying passengers)
Ilan Kelman (ed.), Vulnerability and Resilience Definitions and References, Version 2, 2007. http://www.islandvulnerability.org/docs/vulnres.pd f, (Vulnr and Resilience - Brit) {524}