The IMR is a Soviet armoured engineer vehicle based on a T-55 tank with the turret replaced by a crane and an armoured cupola. A pincer was added for removing trees, and a front-mounted dozer blade fitted. The IMR is manned by a crew of two and has a top speed of 48 kmh and a range of 400 km. Found on http://www.probertencyclopaedia.com/browse/FAFVI.HTM
Interlocking Machine Room, where local signalling control and interlocking equipment is located. The modern equivalent is the SER or Signalling Equipment Room. Found on http://www.trainweb.org/tubeprune/dictionary.htm