TABLE OF CONTENTS Before any design or planning work on an overhead line is contemplated the national and regional authorities must first be consulted in order to ensure no statutory regulations are being contravened with regard to:
safety factors on supporting structures and conductors
maximum conductor working temperatures
clearances between accessible ground and conductors
minimum separation between the overhead line and railways, telegraph lines and pipelines
planning permissions.
The logical sequence for the design and planning of the routing of an over-head line is shown in Fig. 16.1. It is assumed in this example that the client, or his consultant, carries out the preliminary routing and includes this information in a tender specification such that competitive tenders may be received from a variety of design and construct contracting organizations. The contractor will then carry out the detailed line routing and profile work. By careful preliminary routing the effect on the environment may be minimized. In addition, the client is in a position to narrow the choice of the tower and span design to the most economic. At the same time the client is able to take into account a strategy for minimum maintenance costs.
The preliminary routing work determines the physical constraints involved and allows the establishment of the least-cost solution for the overhead line. Estimated quantities for the towers, foundations and conductors may then be included in tender documentation...
