Towards autonomously driving trains on tracks with open access

Compared to automobiles on roads, trains have less degrees of freedom as they are bound to railroads. Thus, it should be more straight-forward to let them drive autonomously compared to automobiles. Several autonomous trains and subways already exist; however they operate on closed tracks. Typical examples are airport trains, also known as people movers. This paper sketches the conceptual, technical and legal challenges towards autonomously driving trains on existing railroads that are freely accessible and thus require reliable obstacle recognition. We try to generalize the experiences made so far in several large-scale research projects that aim at automating small, secondary railways. We summarize the results of a prototypical autonomous train system that we called autoBAHN.