"This report offers conclusions about the lessons learned in the development, construction, and operation of rails-with-trails so that railroad companies, trail developers, and others can benefit from the history of trails in existence today. 'Rail-with-trail' (RWT) describes any shared use path or trail located on or directly adjacent to an active railroad corridor. About 65 RWTs encompass 385 km (239 mi) in 30 States today. These trails are located adjacent to active rail lines ranging from a few slow-moving short-haul freight trains weekly, to high-frequency Amtrak trains traveling as fast as 225 km/h (140 mi/h). Dozens of RWTs are proposed or planned. While most are located on public lands leased to private railroads, many are on privately owned railroad property. Hundreds of kilometers of RWTs traverse Western Australia, Canada, and Europe."
Federal Transit Administration: http://transit-safety.volpe.dot.gov