Three-quarters complete and pressing westward, November 1925 forced crews to contend with the softest and most unpredictable ground encountered to date.
Moffat Tunnel Construction Happenings from 100 Years Ago
By November 1925, the Moffat Tunnel stood roughly three-quarters complete, with the main headings of both bores driven more than 23,000 feet beneath the Continental Divide. By late November, more than fourteen thousand feet of the railroad bore had been opened to its full 16-by-24-foot dimensions, representing roughly forty-six percent of the total length. On paper, progress looked steady; underground, the mountain had changed temperament. Ten thousand three hundred feet from the West Portal, crews struck the softest ground yet—a gray, water-laden material that behaved like newly mixed cement. Ordinary timbering bowed and splintered under the pressure, and progress slowed “almost to a crawl,” one engineer admitted, as workers resorted to dense breast-boarding and double sets of timber to hold back the mountain. Tunneling crews of the era often used food metaphors for soft, running ground; in 1925, the material under West Portal behaved with a heaviness and flow that a modern reader might picture as a kind of gravy.
At East Portal, 13,500 feet in, they faced a different obstacle: a heavy flow of sixty to eighty gallons a minute from fissures in a hard-rock seam, delaying progress by several feet a day. As the grade crested at the apex and began sloping down toward the western crews, gravity drainage would cease, and pumps might soon be needed to lift water back toward the apex so it could escape out the east side. For a time that November, the two ends of the tunnel labored under opposing forms of resistance—one collapsing, one flooding.
Even so, the pace of excavation impressed outside observers. The Moffat Tunnel Commission, led by W. P. Robinson, reported that 14,680 feet of the full-size railroad bore were complete—10,672 feet on the east, 4,213 on the west—and that crosscuts between the twin bores were seventy-seven percent finished. In the smaller water tunnel, engineers ambitiously expected the two headings to meet by January 1, 1926, with the main railroad headings connecting by July 1, 1926—six months ahead of schedule. If that held, trains might pass under the Divide before the contractual deadline of July 19, 1927. Still, the Commission cautioned newspapers against premature optimism. “Progress on the Moffat Tunnel is very satisfactory,” the official statement read, “but some papers have been led into an error as to the probable time of completion.” The reminder was deliberate: “All this is predicated upon fairly good ground at the west portal, but this remains bad.”
The local press captured both the strain and the spirit of the work. The Rocky Mountain News reported that west-side crews had struck ‘rock disintegrated by water and pressure… of the same consistency as newly mixed concrete,’ with forces ‘exceeding the heavy rock pressures already passed in the bore’ and ‘sufficient to crush ordinary timbers to bits.’ Other reports the same week described the pressure as strong enough to ‘break ordinary timbering like match sticks,’ underscoring the severity of the ground conditions at West Portal. Engineers added that progress had slowed “almost to a crawl,” as pressures in this zone surpassed those encountered “from the portal to the breasts of the bore,” requiring extra timbering beyond what ordinarily held the ground. In contrast, the Steamboat Sentinel and Herald Democrat focused on the eastern crews who had passed the tunnel’s high point and begun working downgrade toward the west—an engineering milestone that meant every new foot brought the two sides measurably closer. For the first time, both portal crews were advancing on the same side of the Continental Divide: the Divide had been crossed underground.
Thanksgiving brought a different kind of relief. At West Portal, two hundred fifty men and visitors crowded into the camp hall for an “athletic smoker”—a boxing event that pitted the tunnel’s two sides against each other in sport rather than in production. West Portal won two decisions, two draws, and a knockout; East Portal earned two draws of its own. The following week, newspaper columns filled with small human notes: R. J. (or Guy J.) Tanner, a veteran drill operator described as “one of the best,” returned to Boulder to spend the holiday with his parents. Roy Gordon traveled from the tunnel to Greeley to be with family. In Denver, a short notice recorded that Frank Beck appeared before the State Industrial Commission to seek compensation for the loss of his foot in a cave-in the previous December at West Portal. There were also marriages—Clarence Quick of East Portal to Ethel Knowles of Hutchinson, Kansas, and Arthur Brown of East Portal to Mildred Smith of Denver. In these glimpses from scattered papers, one sees the rhythm of a community living within an industrial epic: weddings, injuries, homecomings, and prizefights conducted under a mountain that still threatened to collapse.
Late in the month, the Commission turned from ground pressure to paperwork. On November 26, filings were made with the U.S. General Land Office for the formal railroad rights-of-way at both portals—1.77 miles at the west and 0.21 mile at the east. The request required the approval of Secretary of the Interior Hubert Work. Attorney Erskine Myer explained that the filings merely extended existing rights-of-way across federal land in the Arapaho and Colorado National Forests and did not affect private property already deeded to the Commission. The U.S. Forest Service had granted permission to clear timber along the corridors. Such quiet administrative steps rarely made headlines, yet they would determine how trains would legally reach both portals when the bore was finished.
By the close of November 1925, the figures told a story of both triumph and tension: 23,500 feet driven in the main headings, 14,000 feet enlarged to full size, and the Divide’s internal high point crossed from east to west. The crews were entering their third winter under the mountain, now armed with experience as well as ambition. The public saw a clean statistic—seventy-five percent complete—but the men underground saw something different: timbers bending, drills stalling, the hiss of water in darkness, and the small warmth of Thanksgiving light at the portal.
If October had been a month of acceleration, November was one of reckoning. The mountain had revealed its softest core just as the tunnel neared its hardest test. Each foot gained that month demanded new invention, new caution, and new faith that the opposite heading was still on line. The work continued, measured not only in feet of progress but in proof that endurance, not optimism, would carry Colorado through the last quarter of the Divide.
Image Caption #1: With the surrounding ground exerting pressure “sufficient to break ordinary timbering like match sticks,” workers in the pioneer bore labored under conditions that could change without warning.
Image Caption #2: Requiring extra timbering beyond what ordinarily held the ground, this section shows how progress slowed to a crawl.
B. Travis Wright, MPS | Preserve Rollins Pass | November 25, 2025
Want to uncover more incredible Moffat Tunnel stories? Our blog is filled with deeper dives into its history, untold tales, and connections to Rollins Pass. Explore more and journey through time with us!
The primary purpose of our work is to inform the public.
