Why not just ask the local utility?  Are you doing this parkway project for free?  Why expect electrical engineering services at no cost?





 

David Castor
www.cvoes.com

Well the parkway is about 450 miles long so there are numerous providers.  I am not looking for EE services at no cost.  I am sure there are people on here that have done enough of this to give a resonable estimate the same as I can tell someone roughly what it will cost to pave a road, install 36" RCP, etc.   

The first question the companies are going to ask is: What's wrong with the over head lines?

We have a reverse problem. The lines were there before interstate, but now the road salts seem to be collecting on the insulators. And the highway department won't admit they are causing the problem.

And yes we have a boring crew that can burry the lines, but how do you justify the cost.

This is a scenic parkway and not a highway or interstate.  We will be paying the utility provider/contractor to take the lines underground.  We have about 183 utility crossings and all we want to do is place about 20-23 of these underground.  These are the ones that only serve a few houses, etc.   All I am looking for is a rough estimate.  The local providers I have talked to have given me numbers from $15 LF (Which sounds way to low to me) to about $124 LF including removing existing poles.  I just wanted to get a few more numbers.. I am not here to argue points that I am sure are all valid.  Many people look at this as a roadway, we look at it as a park with a roadway running through it.  We have a responsibilty to protect the vistas and we feel it is justified to spend the money to place some of these lines underground.   

The costs are likely to vary widely based on such things as voltage level of facilities, ampacity (how much current required), switching apparatus, number of poles to be eliminated, how many overhead transformers to be replaced with ground level (or underground) units, etc.

The smaller installations won't have many opportunities for economies of scale, either.

I wouldn't expect to be able to do very much for $15 a foot, that seems very low to me, too.

I would suggest running the budgetary numbers at the $124 rate.  If you feel that your project has this amount of resources at your disposal, then I would hire an electrical professional to determine some more accurate numbers.



 

Not to mention what ground you are digging into (sand, clay, shale etc), what re-instatement is required (grass, concrete, tar etc), gathering the new information for their mapping system, if there are any specific site issues (ie works can only be done after hours etc), what country you are in, whether it is an urban or rural area, etc.

ausphil

I was involved in a some underground conversion studies a few years ago that involved cost estimates as you are suggesting. As others have said, we found costs vary widely. Circuits may vary from a small single-phase street lighting to 600 amp 3-phase primary. The cost difference is enormous. Large primary feeders in congested areas can run upwards of $1 million per mile. In any case $15/ft seems too low for much of anything.

If restoration is complex or minimizing disruption is important, directional boring may be preferable to trenching.

Do you have utilities besides power to deal with?

Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.

As others have said, you need to know a lot more to make a reasonable estimate.  Are these 3Ø lines?  What cable size will you use?  What is the voltage?  Will you be able to cut and trench across the parkway or will you have to bore?

Don't forget the costs at each end for cable terminations.