It's actually called Historic Highway Bridges in Pennsylvania (bet you thought I was making it up, heh). Yes, it is good, but you have to be of a particular mindset to consider it a scintillating read. It is very comprehensive, lists everything, gives good, clear diagrams of different bridge types, lots of historical background, and excellent b&w photos. It's published jointly by the Commonwealth of Pennsylvania the Pennsylvania Historical and Museum Commission, and the Pennsylvania Dept. of Transportation.