I’m needing a good rough estimate of the cost per mile to build a 50 mile 138KV, 1272 ACSR transmission line in the central US excluding land acquisition cost? Route is straight, land is flat, mostly open range and sparsely populated. Considering wooden H-frame or concrete structures. Sorry, I know there are lots of variables.
I think that 250,000 to 350,000 $/km can be considered as a (very) preliminary cost estimate. In addition to land costs and authorization issues, some design criteria (e.g. number of suspension towers versus number of anchoring towers, wind and snow loads, etc…) can have a substantial impact on the cost and therefore these issues shall be decided in order to have a realistic cost estimate.
Below you can find a document with cost comparisons between different ENTSO-E countries; for example a 150 kV line (lattice steel towers, single 31.5 mm ACSR curlew-like conductor) in a flat rural area would cost about 270 k€/km, i.e. about 600k$ per mile:
It is a 20+ page document and worth a thorough review. Here is the cover page, and one interesting chart…
Above is a snippet.