For the past month pairs of 160-foot-long concrete bridge beams have been transported to a construction site on the Northeast Extension of the Pennsylvania Turnpike without a hitch. Wednesday morning that all changed. Traffic became a nightmare at the intersection of Routes 309 and 895 in West Penn Township after the front tractor trailer experienced a breakdown. The rear turning mechanism which is required to make all the turns, apparently broke just before the intersection. As employees worked on fixing the problem state troopers and West Penn fire police worked to maintain traffic control at the scene of the busy intersection.