The design and implementation of an automated bus in revenue service on a bus rapid transit line

This paper describes the development of an automated steering control system that has been implemented and deployed on a 60-ft articulated bus in Eugene, Oregon for revenue service. With operators controlling the speed, the automated steering system needs to conduct S-curve precision docking and lane keeping maneuvers in a challenging real-world environment consisting of a three-mile-long narrow urban segment with sharp curves, six stations, and dedicated and mixed traffic lanes. Because the automated steering bus was intended to carry passengers for an extended period of time, in addition to the normal performance and robustness considerations, the system design needed to incorporate the redundancy, fault detection, and fault management into the controller structure. This paper introduces the safety-centered system architecture and discusses the methodologies adopted to meet the elevated safety and performance requirements. With the experience of not only designing but also deploying this safety-critical vehicle control system, this paper may provide new insights into addressing safety as an integral element of the automated vehicle system design. The resulting system also offers an example of using duplex redundancy in automated vehicle control systems.