In April 1925, as collapsing ground tested progress, the Moffat Tunnel neared midpoint—driven by George Lewis’ invention below James Peak.
Moffat Tunnel Construction Happenings from 100 Years Ago
In early 1925, with the dream of traversing under James Peak only half fulfilled, George Lewis—assistant to the president of the Moffat Tunnel Commission—was appointed general manager of the project. A seasoned mine manager with long experience in Colorado’s Cripple Creek district, Lewis brought an inventive mind and steady leadership to a project facing mounting uncertainty. Tunnel workers had long struggled against unpredictable rock stresses—pressures too complex for the mathematical knowledge of the day. At the same time, the tunnel’s purpose—to replace the treacherous, weather-prone crossing over Rollins Pass with a safe, year-round rail connection between Denver and the Western Slope—was too important to abandon. Faced with overwhelming challenges at the West Portal, Lewis didn’t merely manage the crisis; he transformed it. His invention—the Lewis Traveling Cantilever Girder—would become one of the most significant breakthroughs of the entire tunnel enterprise.
Innovative ideas, particularly in engineering, often meet resistance—especially when they challenge methods long accepted as standard. When Lewis presented his design to the Commission, doubts quickly surfaced. The machine would be costly, and all previous attempts at holding wall-plates in unstable ground had fallen short. Experienced engineers could offer no solution better than the traditional methods already in place. Yet in choosing Lewis as their general manager, the Commission had selected a man who was no stranger to adversity—and who did not believe in the impossible.
The idea struck Lewis late one night after a discouraging engineering meeting at West Portal. Restless and unable to sleep, a vivid memory surfaced: months earlier, he had seen a house being moved through Denver’s Civic Center, supported on dollies and jacks. If something so seemingly slight could bear so much weight, he reasoned, perhaps a similar approach could temporarily support the tunnel arches until permanent structures could be installed. Springing from bed, Lewis immediately roused the engineering force and explained his idea. All through the night, they debated and sketched out the concept, testing its possibilities against the stubborn realities of the mountain.
Hardly had daylight come when Lewis, plan in pocket, sped toward Denver in a “fast motor car.” Arriving at the Commission’s offices, he invited the critical review of Clifford A. Betts, the Commission’s office engineer. Together they analyzed the plan point by point, made suggestions for improvement, and prepared a finished drawing. Lewis then built a small working model and presented it to the board of directors. Skepticism remained. The cost was substantial, and success was not guaranteed.
Calmly, Lewis addressed the Commission. “Gentlemen, let me build this machine. I believe in it. If it does what is expected, the Tunnel District will pay for it gladly. If it fails, the Commission can take a proportion of my salary each month until the cost has been met.” That quiet confidence broke through where argument could not, and permission was granted.
Construction of the full-scale girder began immediately.
C.A. Betts, Office Engineer of the Commission, has given the following description of the machine:
“The new needle bar consists of two 65-foot steel girders, 3½ feet in depth, tied together by rigid struts and braces and carried on dollies running along steel channels placed on 12-inch by 12-inch stringers resting on the bench, but it is designed to cantilever to the rear beyond the end of the bench a maximum distance of 20 feet, where it serves as a support for the arch timbers while the shovel removes the bench and the posts are being set. The roof load is transferred to the girders by means of cross-arms, suspended from these girders by stirrup hangers which extend beneath the wall-plates. The slack is taken up by 15-ton screw jacks. When excavation has proceeded to the maximum 20-foot overhang of the needle bar, it is moved ahead to a new position. This new needle bar carries an endless belt conveyor between the girders so that muck from the 18-foot by 10-foot widened heading into which the machine must move for the enlarging operation, can be carried out beyond the bench and dumped thru a chute into waiting cars in the completed tunnel. This feature has made the Lewis needle bar adaptable to the heading and bench method of tunneling, as well as to the service tunnel and cross-cut method where excavation from the heading was completed thru the cross-cut ahead of the bench. Such attachments to the girder as electric hoists for raising posts, light wiring and piping, add to its convenience and indicate its wide range of use.”
Installed in March 1925 and placed into operation in April, the Lewis Girder was set into the top heading of the tunnel, sustaining sixty feet of roof while excavation occurred beneath it. Unlike earlier cantilever devices, which had to be dismantled and rebuilt at each advance, Lewis’s girder traveled forward on its own track. It could overhang fourteen to twenty feet of freshly excavated tunnel without showing distress; when a heavy collapse occurred during timbering, one of the girder’s massive forty-two-inch steel beams bent but prevented a cave-in. When the load was removed, the beam sprang back to shape.
Lewis notably refused to patent it at the time, placing the success of the project over personal gain.
By April’s end, labor costs at West Portal had fallen from $3.61 to $2.24 per cubic yard. The cost of setting plumb posts dropped nearly 20%, and the time required for a full cycle of tunnel enlargement operations plummeted from twenty-three hours to just thirteen. The Lewis Girder didn’t merely save money; it stabilized a dangerously unpredictable tunnel and gave the project the momentum it desperately needed. Nicknamed “Big Bertha” by the workers at West Portal, the Lewis Girder was now an assured success.
The Lewis Girder was a triumph of American engineering improvisation—and one that grew directly from the working spirit of the tunnel’s crews.
By mid-April 1925, the broader tunnel project was reaching historic milestones. On April 15, the water bore crossed the halfway mark, with 16,223 feet completed out of the 32,426 feet needed to pierce through James Peak. This achievement came just one year and seven months after the contract was signed on September 12, 1923, despite full mechanical operations not beginning immediately. Early progress had been slowed by surveying challenges, installation of heavy equipment, and severe winter conditions, but once underway, the crews pushed forward with remarkable determination.
The railroad tunnel headings had advanced to approximately 48% completion, with full-size enlargement completed for about 22% of the total length across both sides. Cross cuts were 55% complete. Around 400 men worked at West Portal, and 275 at East Portal, each side battling very different conditions: collapsing ground in the west and shattering hard rock in the east. Both environments posed daily dangers to the crews, who advanced with little more than grit and perseverance.
In late April, workers at the East Portal of the Moffat Tunnel established a new world record for tunnel driving, when they bored a total distance of sixty-five feet in the main heading of the railroad tunnel in a total of twenty-four hours working time. Despite the world record, contemporary reports noted that “work on the Moffat Tunnel slacked up somewhat during the past month due to extra hard rock at East Portal and soft rock at West Portal. At East Portal a big seam of rock was encountered, some days 150 pieces of steel being broken. The rock is again approaching normal.” It was a striking irony of the project that the same mountain offered such different challenges—one side dangerously soft and unstable, the other side hard enough to shatter steel. The record reflected not just technical achievement but the relentless endurance of the tunnel crews.
Still, optimism ran high. The Commission expressed confidence that the tunnel “will be completed and trains running under the mountain before the winter of 1926.”
Recognition soon followed. In April, state examiners reviewed the Commission’s financial records, writing, “The bonds required of the treasurer and members of the commission are all on file and the unexpended balance is properly accounted for, as shown.” They further praised the tunnel’s progress, stating, “Taking into consideration the adverse conditions which have been met, particularly at the West Portal, the progress made has been remarkable. This may be accounted for in the morale of the employees and the new machinery invented or made over by them, as the various uncertainties arise with which to accomplish their motto, ‘Speed of Construction.’” That motto had become not just a slogan but a shared mission, uniting every worker inside the mountain.
At the same time, preparations were underway to bring the story of the tunnel to a national audience. From late March to early April, thousands of feet of film were shot at the tunnel’s western portal for The White Desert, a movie adaptation of Courtney Ryley Cooper’s novel. A newspaper article mentioned, “I was… privileged to see a private showing of the first two reels of film of Courtney Ryley Cooper’s novel. The reels are composed principally of ‘long shots’ of railroad operation at Corona and of activities at the western portal of the tunnel. Blasé dramatic critics and moving picture men who attended the preview were astounded at the marvelous photography and the scenic effects on ‘the Hill [over Rollins Pass].'” When completed and released, The White Desert was expected to introduce more than a million and a half people to the drama and ambition of the Moffat Tunnel project.
Meanwhile, life at West Portal was not solely defined by work and hardship. On April 23, 1925, the newly formed West Portal baseball team held its first practice at the Fraser Grounds. By mid-May, they hoped to be ready for their first competitive games—bringing camaraderie and a sense of community to one of Colorado’s most grueling construction efforts.
Though optimism filled the spring air, the mountain would continue to test those building the tunnel in ways they could scarcely imagine. Yet it was Lewis’s sleepless idea—and the unwavering resolve of hundreds—that pushed the Moffat Tunnel closer to the day when steel rails would finally run beneath the Continental Divide. The Lewis Traveling Cantilever Girder, born from desperation and daring, would stand as the defining construction innovation of the project—etched into the story of ingenuity, endurance, and a relentless belief that even the greatest barriers could be overcome.
Caption: The Lewis Traveling Cantilever Girder inside the Moffat Tunnel. While multiple transverse cross braces stabilized the structure, a single X-shaped brace is visible in this view, holding the two I-beam girders in rigid spaced relation. Below the girder, the unexcavated “bench” of rock is seen—the next section of tunnel slated for excavation. Looking closely, the untimbered side of the excavation can also be observed, particularly along the left side of the image.
B. Travis Wright, MPS | Preserve Rollins Pass | April 30, 2025
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