For two years he carried out a variety of engineering tasks, including surveying and building railroads, and at the same time gained experience and an understanding of the subject.

During his time at the Great Northern, Stevens built over a thousand miles of railroad, including the original Cascade Tunnel.

Then, in 1905, at Hill's recommendation, he was hired by United States President Theodore Roosevelt as chief engineer of the Panama Canal.

Reflecting his background, he saw the early stage of the canal project itself as primarily a problem in railroad engineering, which included rebuilding the Panama Railway and devising a rail-based system for disposing of the soil from the excavations.

Stevens would also have been aware that the original Cascade Tunnel, for which he was responsible, had been built too close to the ruling grade (maximum gradient for a single locomotive) and was perhaps turning from a credit to a debit.

Following the collapse of Imperial Russia in 1917, leaders of the provisional government appealed to President Wilson for help with their transportation systems and overall ability to stay in the war.

Stevens was selected to chair a board of prominent U.S. railroad experts sent to Russia to rationalize and manage a system that was in disarray; among his work was updating the Trans-Siberian Railway.

[7] The board traveled across Russia on the Trans-Siberian railway and noticed significant amount of inefficency and made a comprehensive list of suggestions.

Russian officials were initially reluctant to implement them, but with Premier Kerensky interventions in September, progress started to happen, but it ended abruptly with the overthrow of the provisional government in the October Revolution.

Stevens remained in Allied-occupied Manchuria and in 1919 headed the Inter-Allied Technical Board charged with the administration and operation of the Chinese Eastern and Siberian railways.