The Milwaukee Road built temporary wood trestles at all but Kelly Creek and Clear Creek, but fire danger led the railroad to begin replacing the wooden structures immediately with earth-filled embankments or by building steel bridges inside and over them. The Milwaukee adopted a relatively new steel design, deck girder bridges with solid concrete floors, in which large I beams on top of steel towers supported U-shaped concrete tubs that held a layer of rock ballast for the ties and rails. Although the initial cost was greater, maintenance was much less because local section gangs could regularly attend the track on the trestles instead of relying on special bridge gangs. The ballasted floors practically eliminated impact stress and vibration from trains crossing the trestles, making the steel bridges safer, smoother riding, and more permanent. On the Route of the Hiawatha Trestles, Small Creek trestle number 216 was 515 feet long and 120 feet high, Barnes Creek trestle number 218 was 507 feet long and 117 feet high, Kelly Creek trestle number 220 was 850 feet long and 230 feet high, Turkey Creek trestle number 224 was 494 feet long and 146 feet high, Russell, No Name, trestle number 226 was 281 feet long and 90 feet high, and Bear Creek trestle number 228 was 570 feet long and 155 feet high.