In the early 80's I was riding the R5 out from Phila to Fort Washington, and I was sitting across from one of the old timer Septa guys. We hit the zone just out of the city and the train sped up, so I had to ask - why? what is special about this spot and why can't the train just go fast the whole way? He told me that there was a city ordinance that kept the trains speed limited to keep down the noise. It sounded plausible, but since then a lot has changed, New trains, new rails, but apparently the same speed limit. Is there really a city speed limit?