Well, people were expected to and are now riding subway cars (BART) from San Francisco to San Jose, a distance of 40 odd miles which incidentally is about the same distance as Boston to Nashua.
Not sure why they ever even think of building this, especially when there is already a Commuter Rail link between the two cities, sounds pretty ridiculous to me.
Aren't all "diesel locomotives" actually electric traction at the wheels and with a few add ons, could run off catenary?
Technically, yes, but you would likely need a lot more than "a few add-ons" to transform them into pure Catenary-Electric Locomotives, and all that comes at a price that would probably be so high that it would just do better to buy brand new catenary-electrics off the market
Photo by Alan Thomas: NYNH&H I-4 Pacific #1372 proudly thunders through Forest Hills as it makes its way to Providence R.I.