Property egress bridge/structure

Have property in Acadiana area that is locked by other land owners on 3 sides. The remaining side is bordered by a state Highway. Access to the property for many years was over a wooden bridge with pipe base over a large drainage ditch (gulley, coulee etc) about 15–20’ deep and across. The old pipes that formed the base across are all that is left after the parish dug out the gulley. Anyway contacted the police jury and they will build a structure to allow us to have egress onto the property but we provide the materials at our cost. My question is where is the best place/person/business that can look at the situation and provide the best option (s) and needed plan/materials list for me to provide to the PJ? TIA