Philly banned 3Ms

[traffic light guy]

Out of the entire city, there's only one intersection that has 3Ms, but I wouldn't count it since it borders Glenside: https://www.google.com/maps/@40.0859597,-75.2118487,3a,75y,152.5h,94.39t/data=!3m6!1e1!3m4!1sTZ1QWwxw2OvzV49n9Iqfrw!2e0!7i16384!8i8192. I've been looking at old trolley and septa photos and it appears to be that 3M Signals were extremely common in the city during the 70's. I heard that Philly banned them all in the Late-90s/Early 00's, when they converted all the red signals to LEDs. Before fully converging to LED signals in 2010.

[NE2]

I don't think you know what 'banned' means.