Yellowstone National Park rangers and state and federal transportation officials will conduct safety evaluations of commercial vehicles and operators traveling in the park again this summer.

Park spokesman Al Nash says the inspections are designed to ensure the safe operation and mechanical soundness of commercial buses and trucks on Yellowstone’s roadways. Both the vehicle and the driver are evaluated in order to ensure full compliance with federal regulations that govern commercial vehicle operation.

This is the 15th year of the interagency inspection program. It has resulted in a significant decrease in the most serious "out-of-service" violations, which require that either a commercial vehicle or a commercial driver be taken off the road due to serious mechanical or driver-specific violations.