Pennsylvania State Troopers are investigating a grisly fatality on the northbound side of the Route 1 Morrisville Toll Bridge heading into New Jersey. The accident occurred Thursday morning on the northbound side of the bridge after a tractor trailer struck a woman walking along the center median, police said. The bridge runs between Trenton and Bucks County. The woman killed in the accident has yet to be identified and troopers are searching for two other motorists who struck the woman and left the scene after she was initially hit by a tractor-trailer. Police said the two other motorists may…