RWE, when it comes time to do a project, local surveyors and civil engineers will be hired to do precise topological surveys, grading plans, etc. When I an designing a project at a high level, I will do it precisely enough to be within 1/2% on my estimates to the companies which will be paying the bills. Then I hire and work with the architects and engineers to develop the detailed engineering plans.
I don't do detailed roadway and bridge design. Same for railways. I just lay them out where they need to go on my projects, connect them up to existing streets, roads, and interstates, in order to develop a master plan, estimates and schedules. I will do other detailed designs. But who knows - I may have to do a detailed design of a short highway bridge again someday.
