Innovative Concepts and Technology for Railroad-Highway Grade Crossing Motorist Warning Systems : Volume 1. Overview and Concept Generation and Analysis

Raab, F. H.; Brooker, M. C.; Ryan, T. E.; Waechter, J. R. · 1977 · ROSA P / United States. Federal Railroad Administration

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Summary

This 1977 report, sponsored by the Federal Railroad Administration and conducted by the Transportation Systems Center, addresses the need for innovative concepts and technologies to improve railroad-highway grade crossing motorist warning systems. The research was motivated by the high costs, limited functional capabilities, and rigid reliability constraints of existing train-activated protection equipment. Because the railroad industry is conservative and liability-driven, it rarely invests in speculative, high-risk research. Consequently, the Federal Railroad Administration initiated this program to explore novel approaches that could reduce life-cycle costs, increase functional capability (such as constant warning time), and remove non-technical constraints like dependence on railroad-owned track circuits. The study involved two parallel contracts awarded to Cincinnati Electronics Corp. and Tracor-Jitco, Inc., each tasked with generating and analyzing innovative system concepts. The report reviews various ideas, including communication-link systems, radar train detection, locomotive-mounted transmitters, and new motorist warning signals. Cincinnati Electronics focused on a communication-link concept where a train is detected by a sensor at the end of the approach, and the data is transmitted to the crossing control via VHF radio or carrier systems. They recommended Hall-effect magnetic sensors for detection and microprocessor-based control to ensure constant warning times. Tracor-Jitco proposed a "track radar" system using audio-frequency signal reflections along the track to determine train location, velocity, and direction, potentially allowing for constant warning times and broken-rail detection. Both firms also evaluated alternative motorist warnings, such as strobe lights and advance warning signals. The findings indicate that while several concepts are technically intriguing, they face significant hurdles regarding reliability, fail-safe operation, and environmental tolerance. Cincinnati Electronics concluded that their communication-link system could allow public authorities to assume responsibility for warning systems, potentially reducing costs, though sensor development remains challenging. Tracor-Jitco’s track radar concept offered potential cost reductions and improved performance but required extensive further analysis to verify practicality. Locomotive-mounted transmitters were deemed problematic due to fail-safe concerns and the need to equip entire fleets. Regarding motorist warnings, the report suggests that improvements should remain within the framework of conventional signals (e.g., flashing lights) to maintain driver familiarity, though innovative methods like strobe lights for train presence and amber lights for malfunctions were recommended. The significance of this report lies in its comprehensive survey of speculative technologies that could fundamentally alter grade crossing safety infrastructure. It highlights that while current evolutionary advances are limited, innovative concepts like communication links and advanced track circuits offer potential for greater safety and cost-effectiveness. However, the authors conclude that these concepts are years away from practical application and require rigorous further research, failure-mode analysis, and testing to determine their true viability. The study underscores the importance of balancing innovation with the strict safety and reliability standards inherent to railroad operations.

Key finding

Innovative concepts such as Hall effect sensor-based communication links and reflection-based track circuits show potential for improved functionality but require extensive further development to meet the rigorous reliability and fail-safe standards of grade crossing safety.

Methodology

review

Provenance

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• rail grade crossings