ERTMS/ETCS RAMS Requirements Specification Chapter 2 - RAM

EEIG ERTMS Users GroupThe relevant mission is then defined as the ERTMS/ETCS operation in absenceof Immobilising Failures and, for that mission, the following reliability requirementsare defined:® The Mean Time Between Immobilising hardware Failures MTBF-I ONB , definedfor Onboard equipment, shall be not less than 2.7 . 10 6 hours.® The Mean Time Between Immobilising hardware Failures MTBF-I TRK , definedfor Trackside Centralised equipment, shall be not less than 3.5 . 10 8 hours.® The Mean Time Between Immobilising hardware Failures MTBF-I LNS , definedfor Lineside Distributed equipment, shall be not less than 1.2 . 10 5 hours.2.2.2.2.3 Service FailuresService Failures are defined, for the ERTMS/ETCS context, in the Glossarycontained in Chapter 0.The purpose of this paragraph is to identify the ERTMS/ETCS system levelfailures which can result in one of the above conditions and to define, for thesefailures, appropriate reliability targets.In the ERTMS/ETCS context, Service Failures may beidentified as all theERTMS/ETCS failures which cause the nominal performance of one or moretrains to be reduced and/or at most one train to be switched in on sight mode (see[2.2]).The relevant mission is then defined as the ERTMS/ETCS operation in absenceof Service Failures and, for that mission, the following reliability requirements aredefined:® The Mean Time Between Service hardware Failures MTBF-S ONB , defined forOnboard equipment, shall be not less than 3.0 . 10 5 hours.® The Mean Time Between Service hardware Failures MTBF-S TRK , defined forTrackside Centralised equipment, shall be not less than 4.0 . 10 7 hours.® The Mean Time Between Service hardware Failures MTBF-S LNS , defined forLineside Distributed equipment, shall be not less than 1.4 . 10 4 hours.2.2.2.2.4 Minor FailuresMinor Failures are defined, for the ERTMS/ETCS context, in the Glossarycontained in Chapter 0.Doc. Ref.: 02s1266- page 25/83