Commuters riding the rails Tuesday morning might have noticed federal agents on board. But there was no security threat. The Transportation Security Administration was conducting one of its random rides on FrontRunner and TRAX trains -- part of its routine training exercises. TSA spokesman Dwayne Baird said officers randomly ride rails around the nation to provide a visual presence along with UTA police and local law enforcement agencies. Baird said he could not disclose how many officers rode FrontRunner and TRAX Tuesday. While some agents at rail stops were in uniform, Baird said many riding in trains were plainclothes, and passengers likely never knew they were sitting next to a federal officer.