4.3　Field Work

4.3.1　Natural geographic situations along the lines shall be understood，such as terrain and landform，traffic，water system，vegetation，as well as the distribution of cities and towns.

4.3.2　Field reconnaissance shall be carried out for important sections which may affect the routing scheme，including planning areas，areas on which relevant agreements are reached，crowded areas，forests，quarries，ammunition depots，oil depots，microwave towers，and communication facilities.For lines with important crossing-over or parallel adjacent to communication lines，field annotation shall be conducted and instruments shall be used for field survey if necessary.

4.3.3　Where any surface features or landform which may affect the route are found inconsistent with the available data，annotation and supplementary survey shall be carried out.

4.3.4　For any substation and power plant involved in the lines，the survey personnel shall cooperate with the design personnel to collect the plans of ingoing and outgoing lines.