5.1　General Principles

5.1.1　Line routing scheme selections shall be made upon comparison of various schemes，based on the engineering design mandate and overall planning of communications networks.Engineering designs shall ensure quality of communications，safety and reliability，as well as cost-effectiveness of the networks whilst facilitating construction and maintenance.

5.1.2　Per the existing terrain，buildings，facilities and established construction planning，the selection of line routing shall give full consideration to various initiatives being planned by other departments including city，industrial and mining constructions，railways，highways，shipping，water conservancy，long-distance pipes，and land use etc.

5.1.3　In compliance with the main routing direction，lines shall be selected along the roads or streets to keep as straight as possible whilst avoiding roadside facilities，sections under renovation and areas with possible chemical corrosions and mechanical damages.

5.1.4　The routing lines shall be chosen in appropriate sections that are geologically stable and relatively flat with limited earthwork，in order to avoid potential damages from landslide，collapse，debris flow，goaf and Karst surface collapse，ground subsidence，ground fissure，seismic liquefaction，sand burial，wind erosion，saline soil，collapsible loess and bank collapse caused by natural catastrophes or human behaviors.In addition，the routing shall also avoid lakes，swamps，and draining flood zones，ponds and ditches as much as possible.In areas with many obstacles，obstacles shall be bypassed reasonably and should not importune long straight line.

5.1.5　Lines shall not be laid on dams or under dam foundations.

5.1.6　Lines should not be built through large factories and large industrial sites such as mining areas.When necessary，lines shall take effective protection measures considering the impact on line safety.

5.1.7　Duct methods shall be used as much as possible for urban areas.When laying in the field，lines should not go through villages or go near towns and development zones.When there is need to do so，the impacts on local construction planning shall be considered.

5.1.8　Lines should avoid forests，orchards and other economy forests or shelter belts.

5.1.9　The selection of line routing shall consider the protection of cultural relics and the environment in general within the construction regions，in order to minimize disturbance and damages of the existing water systems，land surface and the original landscape.

5.1.10　Considering the influence of high voltage，line routing should not choose areas that are vulnerable to lightning and thundering due to the strong electromagnetic field.

5.1.11　The extension of optical（copper）cable networks shall consider the integrity of the network system and give priority to add new routings on different roads in order to enhance network security.