Most realistic post-apocalyptic scenarios?

[Borgholio]

They have electrified trains using elevated wires or electrified tracks. Anybody know what the maximum practical distance is for those sorts of things?

[madd0ct0r]

using AC transmission to local booster stations? as far as you're willing to build new power stations for. Much like the coal and water depots for the old steam trains.

Also good potential for semaphore towers for long distance communication ala Pterry.

[Borgholio]

Why use semaphore? With electricity you could use radio. The wireless telegraph existed as early as the late 19th century. Morse code worked quite well for decades.