Colo. Rev. Stat. § 40-24-105
Whenever it becomes necessary to build or construct any new bridges or culverts on any county road over or along which any person, company, corporation, or association is operating and maintaining an electric railroad, said person, company, corporation, or association shall pay to the party constructing or erecting the same one-half of the expense for the erection and construction of the bridges or culverts which are used jointly by the public and said railroad and shall thereafter pay one-half of the necessary expense of keeping said bridges or culverts used jointly by the public and said railroad in good repair; and the county in which said county road is situated shall contribute and pay out of the county road fund the other one-half of the expense for the construction and maintenance thereafter of any such culverts or bridges. Said bridges or culverts shall be constructed under the joint supervision of the owner or operator of said electric railroad and the board of county commissioners of such county.
C.R.S. § 40-24-105