5　Survey at Preliminary Design Stage

5.1　General Provisions

5.1.1　The survey at preliminary design stage shall include data collection，field reconnaissance，participation in route selection，surveying of important crossing-over，crowded areas and relative location of danger effect on telecommunication lines，aerial photographing，control survey on photographs，photograph annotation，aerial triangulation，surveying of skeletonized plans and sections，route optimization with threedimensional digital model，and so forth.