A fan made expansion, like Japan, available from the base Age of Steam page. A bit more bare-bones in its presentation, but also fairly expansive, and helps fill the high scale niche. The only special rule involves building a tunnel between two cities, which requires not only a large cash expenditure (8$), but the engineer role as well. The files are available here: https://boardgamegeek.com/filepage/7196/cheshire-based-board-age-steampdf and here: https://boardgamegeek.com/filepage/7197/mersey-tunnel-ruletxt