In Colorado, BLM owns approximately 310 buildings located on 44 administrative sites and 110 recreation sites. BLM is also responsible for maintaining a transportation system consisting of about 4,000 miles of roads, 1,215 miles of trails, and 20 bridges. BLM engineers work closely with resource specialists, local governments, and volunteers to construct and maintain roads, buildings, recreation sites, dams, trails, and water developments.