Federal transportation officials are requiring railroads to establish regional response teams along oil train routes following a series of fiery derailments. The new rule announced Thursday is aimed at having crews and equipment ready in the event of an accident. It applies to oil trains in continuous blocks of 20 or more loaded tank cars and those having 35 loaded tank cars. The U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration issued the rule in coordination with the Federal Railroad Administration. The pipeline safety agency said a review identified challenges that occurred during previous responses to derailments. "This final rule is necessary due to expansion in U.S. energy production having led to significant challenges for the country's transportation system," the agency said. In 2014, the agency issued a report detailing the concerns of fire chiefs and emergency management officials in oil train accidents, including that emergency responders were not fully aware of resources available from railroads and other organizations that would be helpful in preparing for such disasters.