Automatic Switching of Electric Locomotives in Neutral Sections

A neutral section is a phase break that is used on the Transnet freight rail system to separate the single-phase supply from the 25kV three-phase overhead traction supply. The 25kV is a stepped-down voltage from an 88kV three-phase supply coming from the national grid. Electric locomotives operate only on a single-phase supply and require a separation of supplies as the trains traverse from one phase to the other; consequently, electric locomotives are required to switch off at the neutral sections. The most common automated schemes that have been implemented in switching electric locomotives are ground, on-board, and pole switching systems; one downside to these types of schemes is their relatively large investment and infrastructure costs. This paper proposes a new automated scheme that employs the use of computer vision and image processing methods. The system uses two unique markers that are externally situated along the railway tracks and used to trigger either the opening or closing of the electric locomotive vacuum circuit breakers as the trains traverse through the neutral sections. The two markers were designed in accordance with Transnet guidelines and the system employs shape detection algorithms, including a circular Hough transform (CHT), to locate the markers, and histogram of oriented gradient (HOG) for feature extraction and training of the classifier. The model has an accuracy of approximately 72%.