For the short term, 20 of the busiest airports in the United States were scheduled for Runway Safety Action Team (RSAT) visits based on a combination of a history of runway incursions, incidents of aircraft turning onto the wrong runway and the risk of wrong-runway incidents. These teams identified more than 100 short-term fixes that including new or improved signage, improved markings, driver training and other actions. A second tier of 22 airports has been identified for evaluation. Federal Aviation Administration (FAA) Advisory Circular AC 150/5340-1L Standards for Airport Marking incorporates the results of the study. Note the AC linked here does not include the appendices. To view the full AC, visit the FAA's Airports website.