This report in the Transit Strategies Series explores commuter rail. Commuter rail is passenger rail service that is designed to transport large volumes of passengers over long distances in a fast and comfortable manner. One of the challenges to the development of new commuter rail lines in Middle Tennessee is that the most desirable rail corridors are CSX lines that have very heavy freight traffic. Except for the Nashville and Eastern line that is used for Music City Star service, and with the possible exception of a Clarksville line, other potential commuter rail lines would be CSX lines that are heavily used for freight traffic. It will be extremely difficult to significantly expand commuter rail in Middle Tennessee in the foreseeable future. Longer term, this situation may change.