A car drove under a tractor-trailer this morning on Western Avenue in Chartiers Township, but firefighters said there were no major injuries. The crash occurred shortly before 9:30 a.m. near the Markwest gas processsing plant outside Houston. Two adults and a child were in the car, firefighters said, which appeared to be traveling south when it and the tractor-trailer collided. The car went under the trailer of the truck. Chartiers police and firefighters are at the scene.