Public Transport

Here is Berlins (pop. 3.7 mil.) metro and rapid transit train network:
Remarkably similar design, a ring route with routes coming out in all directions. In Berlin the rapid transit trains are more focused in the middle and only really diverge at the ring with metros covering most of the space. While in Chengdu the trains don't share a rail, (except for the airport service) and have longer branch lines. The regional trains (thin red lines on the map) in Berlin go through the center similar to the rapid transit and make a few stops along some of the branch lines and the high speed rail only stops at the main station and one major station in each cardinal direction (marked with the train in a yellow circle).

Also here is the tram network, it's mostly east Berlin (guess when the other half was demolished), but slowly branching out into the west: