This e-supplement is a companion to our report entitled "Public Transit Security Information Sharing: DHS Could Improve Information Sharing Through Streamlining and Increased Outreach," GAO-10-895 Section 1410 of the Implementing Recommendations of the 9/11 Commission Act of 2007 directed GAO to assess the role of the PT-ISAC and other related federal mechanisms for sharing security-related information with the public transit industry. The purpose of the survey was to assess the satisfaction of public transit agencies with federal efforts to share security-related information, and the extent to which these efforts can be improved.