In 2008, there were 2,395 incidents at highway-rail intersections (level crossings) in the United States, resulting in 939 injuries and 287 fatalities. Crossing elimination, grade separation, and the implementation of traditional warning devices are not always economically feasible. The development of new intelligent transportation systems and the advancement of such technologies could potentially provide a solution to enhance safety at these intersections. The concept of in-vehicle warning systems for level crossings is not new. Multiple systems have been developed and tested using proprietary equipment and technology in the 1990s as evidenced by the former Federal Highway Administration Joint Program Office (JPO). The Réseau Ferré de France (French Rail Network) and the Valtion Teknillinen Tutkimuskeskus (VTT Technical Research Centre of Finland) have independently initiated in-vehicle level crossing warning system development programs. The system architectures vary from previously U.S.-developed systems and use advanced and cost-effective technologies. At varying stages of development, the two in-vehicle warning system designs address many of the shortcomings of previous generation systems and show great promise at meeting the design goals of being a cost-effective, reliable warning system. They also have the potential for additional capabilities and easy integration into other roadway vehicle intelligent transportation safety systems being developed in both the United States and internationally. The advancement of commercially available technology and equipment create the environment for the development and deployment of a viable global-positioning system-based in-vehicle warning system for highway-rail intersections.