I was about to make a comment about the poor rollout of signal upgrades in San Francisco but I checked wiki page about the Metropolitan Line first. Welp. Put

I was about to make a comment about the poor rollout of signal upgrades in San Francisco but I checked wiki page about the Metropolitan Line first. Welp. Put succinctly the problem is Thales (nee Alcatel). Curiously DLR (and Jubilee and Northern lines) use the same system.