AN ENGINEERING MARVEL
The CPR had a problem. The problem was that the railway had to climb 1,070 feet (330 m) in a very short 10 miles (16 km) to the west from Field at 4,267 feet (1,301 m) climbing to the top of the Continental Divide at 5,340 feet (1,630 m). This is a very difficult climb for trains loaded with cargo. The narrow valleys and high mountains limited the space where the railway could stretch out and decrease the grade. So the decision was made to bore extra mileage into the mountains and lower the grades. The trains would not have to climb as far in such a short distance and would avoid snow and landslides. The Spiral Tunnels were completed in 1909.