Hmm yeah, it looks like the actual electrification was done a while ago. I had been looking at the section http://en.wikipedia.org/wiki/Keystone_Corridor#High-speed_co..., which discussed a 2005-06 project to "replac[e] diesel trains with electric" after upgrading the caternaries.

This non-referenced answer http://answers.yahoo.com/question/index?qid=20081220144240AA... says locomotives weigh roughly 130 tons, and each carriage weighs 65 tons. That's a lot more than a one ton car.

Cities sprinter should be lighter ("just" 100 tons), it's directly derived from the Siemens Eurosprinter line, which are 4-axle locomotives, and in Europe, locomotive heavier than 22.5 or so tons per axle would be almost useless. Even that is very heavy (ES engines weight about 85 tons), and a typical European EMU (locomotives are fading out of the favor in Europe, for anything else than freight, and rightly so) are even lighter (50 to 60 tons per carriage). Anyway, cities sprinter is heavier because of an additional armor required by the US regulations and it needs a lot of power (it has output of 6.4 megawatts, imagine that). Perhaps you could make a battery car to (very slowly and so-so) finish the trip from Harrisburg to Pittsburgh. But you really can't expect that it'd be viable to equip a main line electric locomotive with batteries. And making it even heavier is a bad choice too, as that would (especially at higher speeds, above 160 km/h, and this engine is perfectly capable of 200 km/h trips, common in Europe) put an immense wear on the infrastructure (everywhere the locomotive is used), making it, in the long run, cheaper to just electrify the line (which is what should be done).

I thought the train equipment was a little lighter than that, and automobiles normally weigh somewhat more than 2000 pounds.

In any event, doesn't the train being heavier mean that it can carry a much bigger battery pack than the automobile?

Amtrak's newest diesels produce 4200 horsepower, which is just over 3 megawatts. 40 Roadster battery packs (at 53 kilowatt hours per battery pack, and about a thousand pounds per battery pack) would store roughly 2 megawatt hours (35-40 minutes of the diesel at full throttle), weigh 20 tons, and probably cost something under $2 million at Tesla Model S era pricing. The catenary locomotives Amtrak is buying are over $6.6 million each, so the cost to add batteries sufficient for Richmond or Springfield service might well increase the cost of the locomotive by less than 50%.

Good point. Wikipedia suggests that there are battery powered locomotives - http://en.wikipedia.org/wiki/Electric_locomotive#Electric_lo...

Charging such a massive ammount of batteries quickly could potentially be problematic.

I think the right strategy for charging a locomotive battery pack would be to install a short section of 25kV catenary at the station/layover facility at the end of the route. Amtrak has some HHP-8 locomotives which are 8000 horsepower, about 5 megawatts, which demonstrate that carrying about 5 megawatts through a catenary system to a locomotive is not terribly difficult.

Recharging will take longer than refuelling a diesel, but if the recharging can be done in under an hour, that's probably tolerable.

What's preventing Amtrak from electrifying Richmond-DC and NH-Springfield?

There may be a good reason to avoid using batteries - it takes rather a lot of AAs to move a train