To me, that sounds like a far better use of fifty billion dollars than high-speed rail, light rail, windmills, solar panels, ethanol, battery cars, recycling centers, kneeling buses, 0bamacare,and the host of other socialist boondoggles that soak up the productive potential of America.
At least people would use the underground utilities, and their asthetic value alone is worth more than all the "green" horseshit we're forced to support.
GO--that's for about a half-million customers. According to the UL link, that comes out to just under $80,000 PER CUSTOMER over the course of the project--money which doesn't come for "da gubmint" but directly from the ratepayers. Of course, that's just principal. To actually fund such a project, rate cases would have to be made with the state, bond issues floated (and a VERY substantial interest rate promised, probably tax-free), which would drive costs well over double the initial estimates.
Then there would be the NIMBY types because even though all those big power lines are underground, right of way still has to be cleared, lines marked, mapped, and registered, and yes, as one previous poster stated, what happens when (NOT IF, WHEN) some dipshit doesn't do the 72-hour call ahead and get the lines marked? Not to mention that they don't call this place "The Granite State" for no reason.
Underground lines are fine in urban settings. Rural or for transmission? Not so much.
If you're going to create new infrastructure, go ahead and put your sub-trans and distribution stuff underground, but it's simply not worth trying to "fix" stuff that's already existing. Money just doesn't exist for it, and when it boils right down, you're not going to find a customer willing to pay for it.