Workers spent parts of three summers drilling, blasting, and clearing rubble to cut through gneiss and shist layers and create Rock Cut along Trail Ridge Road. Constructed from 1929 to 1933, Trail Ridge Road opened the alpine tundra to motorists, and public support for it far outweighed controversy over preserving the high country. Construction crews took special care to protect the terrain at Rock Cut by covering nearby rock outcrops to avoid scarring and by collecting rubble after each dynamite blast, turning many rocks lichen-side up. In 1933, the first year the road fully opened, about 290,000 people and 83,000 automobiles entered Rocky Mountain National Park.