Comment by torton

Several North American older systems go down to 10-11 meters, although perhaps the tightest curves are getting upgraded over time:

LRT systems on which the existing minimum curve radius falls below 15 meters include:

• Boston—10 m (33 ft) and 13 m (43 ft) for the Green and Mattapan lines, respectively;

• Newark—10 m (33 ft);

• San Francisco—13 m (43 ft); and

• Toronto—11 m (36 ft).

https://onlinepubs.trb.org/Onlinepubs/tcrp/tcrp_rpt_02.pdf (1995)