In last night's Roadmap stream Matt mentioned about turning the whole train around in Boston at the top end of the NEC, I think I've found the turn loop where this happens....
A loop like that is pretty interesting for Amtrak to have! Usually, Amtrak trains turn around using a wye junction, which requires a lot less trackage. But with the loop, we’ll be driving a whole service in reverse, so that’s neat.
Ah, silly me, I assumed that Amtrak was around since the beginning of time, transporting friendly reptile creatures around. I guess some of the older railroad companies didn't think of making wyes in the 1800s.
That is for the MBTA, who uses a push pull configuration, Amtrak does not. On a side note for balloon loops, they aren't just used for passenger service. Southern Pacific had 2 built on Donner Pass, one near Blue Canyon and the other at Truckee, as it was easier to turn snow removal equipment this way for a return trip over Donner Summit during snow fighting season.
There are a couple in London on the Tube. Kennington has one for turning back trains on the Charing Cross route, there is one at Heathrow via T4. The Central can use the Hainault Loop, but don't normally do a full loop and return. Other ones I know are at the Eurotunnel Shuttle Terminals where arriving shuttles are turned in the loop to be pointing in the correct direction for loading
Ooo, this reminds me. There's also a long defunct loop under the River Thames in London, right next to the Hungerford bridge, built before the Charing Cross branch of the Northern line was extended from Embankment to Kennington. It was sealed up when the line was extended south, but became the star of a war time drama when a German bomb fractured the roof of the abandoned loop and water from the Thames threatened to break the seal and flood the Northern line. Full story here.
Hunter Valley region of NSW/Australia, coal central (Newcastle is the world's largest coal export port). The Bowen Basin coalfields (and the ports) up in QLD also have lots of balloon loops.
Amtrak was established in 1971 to operate on rail lines that were no longer used by other rail compaines