A second tractor trailer in as many days was involved in a wreck in Grand Teton National Park Thursday night. The Thursday wreck involved a truck that was northbound on US Highway 89/287 about 11:00 pm and plowed into the new roundabout at Gros Ventre Junction. Park officials say there were no injuries, but the roundabout suffered substantial damage, not to mention the truck that rammed into it. The incident is under investigation. The first accident took place north of Moose when the rig slid off the road under icy conditions. Park officials urge motorists to slow down when highway conditions have deteriorated.