Electric power consumption has been increasing rapidly across the globe; this increase specially ac-

celerated in the last decade. Consequently, existing transmission lines are becoming overloaded beyond

their power transfer capability. The inadequacy of the transmission lines has contributed to power inter-

ruptions and instability of the power system. Construction of new transmission lines can be a solution

to mitigate these problems. However, to build the whole structure of a new transmission line, a huge

investment is required. Besides this, environmental concerns would create further barriers that delay the

accomplishment of the project. In this paper, different types of transmission lines (HVAC-HVDC) were

examined technically and economically in our study. In addition, the cost analysis of underground and

overhead lines was examined by considering current economic conditions. In this context, the constru-

ction phases of the underground and overhead lines and the financial criteria affecting the construction

process were discussed in detail. In addition, in this review, pure ac power transmission and simultane-

ous ac-dc power transmission capability in transmission systems are examined from a technical point of

view, and the extent of losses due to corona in transmission systems is discussed with various examples.