From Damn Interesting:
Damn Interesting » Building the BAM: The tunnels were particularly troublesome. The unswerving straight-line commitment of the original Soviet planners meant that in a number of cases, tunnels were built unnecessarily: later geological reviews suggested that acceptable diversions through easier terrain were possible at greatly reduced cost and with minimal increase in the distance of the track. Yet with commendable enthusiasm the Soviets dug onwards. The Dusse-Alin Tunnel was successfully built in the Stalin era without any survey work whatsoever; incredibly, when the two tunnelling teams of BAMlag workers met in the middle, they were out of alignment by only 20cm. But while the passage lay abandoned for twenty years, water seeped in through the bedrock and froze solid. The dismayed railway engineers of 1974 were left with the problem of dealing with 32,000 tonnes of ice blocking the shaft--and also of disposing of the frozen bodies of the gulag workers they frequently stumbled on while reconditioning the tunnel. When all else failed, the Soviets resorted to raw power. The workers jury-rigged an aircraft jet engine at one end of the tunnel, and hit the ignition. Its stream of superheated exhaust rapidly blasted a path through the wall of ice, clearing the tunnel for further work.