I read recently in Transport Topics magazine, ( largely trucking - oriented ), that Pennsylvania did indeed post quite a few highway bridges with lower weight limits. This is causing delays and re - routing around said bridges, sometimes 50 miles or more in length.
From my travel experiences to my father's hometown of Scranton, I can attest to the truth in the saying : " In Pennsylvania there are 2 Seasons -- Winter and Road Construction." The harsh winters require the use of road salt, which of course eats metal bridges and the footings for concrete spans as well. I'm sure SEPTA has similar issues with decaying bridges, even without the use of salt in the same quantities as highways. As noted in the article, most of their infrastructure, inherited from the Pennsy and Reading RR's, is quite old.
The issue of urban areas within a state contributing more in highway and transit taxes than they get back, is true in most states that have a rural / urban mix. That's life in the Big City !!!
As well, the Federal Highway Trust Fund fuel tax on gasoline has not been raised since 1994. In that same time frame, miles driven on Interstates has gone up dramatically, as has the fuel economy of the vehicles we drive. So basically, we pay less per mile to drive further. Unless we here in the West want to pay tolls on Interstates, the Federal Gas Tax will have to increase. And this is NOT a Republican or a Democrat thing, it is a close - approaching reality.