In January of that year, Nelson Bennett was given a contract to construct a tunnel under Stampede Pass. The contract specified a short amount of time for completion, and a large penalty if the deadline were missed. While crews worked on the tunnel, the railroad built a temporary switchback route across the pass. With numerous timber trestles and grades which approached six percent, the temporary line required two M class 2-10-0s — the two largest locomotives in the world (at that time) — to handle a tiny five-car train. On May 3, 1888, crews holed through the tunnel, and on May 27 the first train passed through directly to Puget Sound.