The German Aerospace Center (DLR) is developing a Railway Collision Avoidance System (RCAS), a 'safety overlay' system which can be deployed on top of any existing safety infrastructure in train networks. The core idea of RCAS is to broadcast the position and intended track of trains as well as additional data like vehicle dimensions to all other trains in the area using ad-hoc train-to-train communications. This enables train drivers to have an up-to-date accurate knowledge of the traffic situation in the vicinity, and act in consequence. Computer analysis of the received information, the own position and movement vector and an electronic track map detects possible collisions, displaying an alert signal, and advising the driver of the most convenient strategy to follow in order to avoid the danger. The system is adaptive to a variety of situations like advancing trains or road vehicles or obstacles.



The RCAS project is a DLR internal project in DLR's transportation research programme, with participation of three different of its research institutes. In the first three years of the project, the responsibility of the scientists of the Institute of Communications and Navigation (project lead) included the development of the robust train-to-train communications technology for railway specific conditions. The engineers of the Institute of Transportation Systems took particularly care of the operational aspects of RCAS. Researchers of the Institute of Robotics and Mechatronics complemented the RCAS approach by optical subsystems.

Main aspects of the recently started phase II of the project include multisensor-navigation and -integrity, improved and new algorithms for data fusion and situation analysis, optical 3D subsystems as well as a comprehensive safety review.