Rail trails are former railroad right-of-ways that have been converted into a multi-use trail. Many trails are built because of federal legislation that provides for rail-banking - a way to temporarily convert the land into a trail with the possibility that it could be converted back into a railroad should the need arise. This preserves the right-of-way for railroading purposes, however, there are few examples of trails being converted back into a railroad. Railroad right-of-ways are desirable for trails because they are generally very straight with broad sweeping curves, gentle grades up or down, and go from one location to another.
Please enjoy this program talking about rail trails from PBS.
Below are a list of rail trails in Indiana.