 The bore was also improperly <unk> at first . A shaft sunk into the top of the tunnel failed to provide enough fresh air , and the crews of the steam engines would often complain of the intense heat and smoke due to the poor air circulation . <unk> solutions failed to work , and by 1912 the railroad was forced to install a huge fan , powered by a 310 horsepower ( 230 kW ) diesel motor and staffed by operators day and night , to <unk> the tunnel . The <unk> , constructed by 1916 , was abandoned by the CGW with the acquisition of diesel <unk> by 1947 . 
