The Highway Patrol Division (HPD) is the largest division in the agency and it is comprised of troopers assigned throughout the state who fulfill the department's mission of protecting human life and property by enforcing state laws on Arizona's highways. The division combines enforcement, training and public outreach to improve highway safety while attempting to reduce collisions and increase the efficiency of the highway transportation system. The division also enforces commercial motor vehicle laws and certifies school bus drivers and tow trucks. HPD deters criminal activity by patrolling more than 6,800 miles of state and federal highways; serving as the front line in detecting criminal activity on Arizona's roads and highways. HPD also also provides vital support to the state of Arizona and its citizens by patrolling the Capitol district, staffing the Arizona Department of Transportation's Traffic Operations Center and providing assistance to other local, county, state and federal agencies.