Auxiliary operation
An auxiliary service is carried out at the railway in special operational situations or in the event of malfunctions.
In contrast to the regular operations such as switch switching , route setting or signal setting , the permissibility of which is checked at any time by the security system and, if necessary, prevented, with the auxiliary operation - mostly as a result of technical malfunctions - the operator takes over the security responsibility instead of the failed technology by bypassing the security level of the interlocking .
Auxiliary operations are operator actions that require a protocol, including the auxiliary route resolution, the connection of the route key lock or the back block unlocking device, the auxiliary switch changeover, the auxiliary clearance message and the connection of the additional signals Zs 1 , Zs 7 and Zs 8 . Depending on the type of interlocking, auxiliary operating devices are sealed or equipped with a counter. With a sealed key, only the use can be determined, but not the frequency. Sealed keys are used when proof of each individual use is not necessary or not practical. One example of this is the turnout unlock button, with which turnouts can be changed despite a faulty track vacancy detection. Route auxiliary resolutions are sealed in mechanical interlockings, but counted in the presence of auxiliary resolution buttons and in all subsequent interlocking designs.