Completion of Moffat Tunnel of Colorado: Fid-Bau Portal

Completion of Moffat Tunnel of Colorado

Betts, Clifford Allen

The 6.2-mile Moffat Tunnel through the Rocky Mountain Continental Divide, 50 miles west of Denver, Colo., was officially opened to railroad traffic on February 26, 1928. The story of its conception many years ago and of the struggles since 1902 leading to its ultimate accomplishment has attracted widespread attention and has given the undertaking an unusually dramatic background. Difficulties encountered during construction due to caving ground and inflows of water led to the development of new tunneling methods which, combined with the unique Improvement District method of financing, added to the interest. Furthermore, the fact that this combination railroad and water tunnel embodied, at the time of its construction, the longest railroad tunnel in the Americas, in addition to a conduit of equal length, permitted the use of new and modern machinery and led to numerous refinements in standard equipment. The history of the early stages of the work up to August, 1925, together with a discussion of the contract, has been published by the Society. Inasmuch as that paper made no reference to the survey methods used in carrying alignment and grades over the range that rises to 12000 ft. above sea level and 2800 ft. above the tunnel, nor to the camps, these are described herein in some detail, together with other phases of the work which have developed subsequent to 1925.