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30 seconds before it reaches the crossing. This initial I/O event, known as the strike- in time, immediately triggers the warning lights and bells at the crossing to start flash- ing and ringing. In addition, motion sen- sors may be deployed at the track circuit to detect the speed of the moving train.
Approximately 5-10 seconds following these initial I/O events, the boom gates come down to bar vehicles and pedestrians from the tracks. Since the RTU adds a millisecond- timestamp to each I/O event that is triggered, you will still be able to clearly identify the se- quence in which the events occurred, even if 10 separate I/O events are triggered and re- corded by different interface modules within a 10-millisecond time interval.
2. 5 kHz-Analog Input Sampling Rate for Precise Data Acquisition. Second, the RTU supports a high frequency sampling rate of 5 kHz per analog input channel, giving railway operators the precision they need to accurately monitor the status of various active warning devices. For instance, trans- mitting analog input from the crossing bar- rier’s motor current and voltage supply at a much higher frequency provides more ac- curate and real-time information about the barrier’s condition and operation.
3. Prerecording Analog Input Prevents Missing Data. Finally, the prerecording function allows the RTU controller to con- tinuously record analog input data before an event trigger point. For railroad cross- ings, waiting until after the track circuit has been triggered to begin motor current log- ging for the boom gate may lead to the loss of critical data due to the latency between the strike-in time and when the data log- ging actually begins.
Smarter Surveillance
Besides taking advantage of RTU control- lers, the smart crossing uses industrial- grade IP cameras to capture and encode real-time video of the clearance zone, which is then streamed to a network video recorder (NVR) inside the wayside cabinet. Although the principal image processing technology that makes the above solution so “smart” is software, the cameras and net- work video recorders deployed also need to be ruggedly designed with industry certi- fied reliability. Because the cameras and network video recorders are mounted out- side, they must be tough enough to with- stand extreme environments and harsh
weather conditions. They need a wide op- erating temperature range (i.e., -40 to 75°C) without the need for a heater or a cooling fan. In addition, look for an IP66-rated camera that possesses high EMI/EMC pro- tection for consistent performance in rainy, dusty, or high EMI environments. Impor- tant certifications are EN 50121, EN 55022, UL/cUL Class 1 Division 2, ATEX Zone 2, and NEMA TS2 for electrical equipment used in railway applications, which ensure reliable performance when exposed to ex- treme shock/vibration, surge/EMI, and ex- plosive environments.
Last, the key feature of today’s smart surveillance solutions is IVA (intelligent video analysis), an application that can in- crease the efficiency and protection cover- age of the system by using triggered alarms, such as the following:
■ Camera Tamper: Triggered when the camera lens is blocked, redirected, de- focused, or painted.
■ Virtual Fence: A virtual “tripwire” in the camera frame will trigger an alarm whenever motion across the line is detected.
■ Alert Zone: Any motion detected in- side the detection zone will trigger an alarm. ■ Removed Object: The camera de- tects whenever an object is removed from the frame and will trigger an alarm after a
certain user-defined time threshold.
■ Unattended Objects: Tracks moving objects in the camera frame and detects ab-
normal loitering.
Although the following IVA screenshots
are taken from a railway station monitoring application, the same triggers can also be used to automatically detect the following crossing scenarios:
■ People entering the crossing.
■ Any moving object other than trains identified on the track.
■ Objects abandoned at trackside.
■ Large metallic or organic objects on the tracks, such as logs, shopping carts, or a motorcycle.
■ People crossing the railroad tracks.
Conclusion
Although active warning systems featuring barrier gates, flashing lights, and warning bells are a fairly common site at high-traffic railroad crossings, these intersections con- tinue to present real dangers to both rail and road traffic. At the same time, it may not always be practical or necessary to re- move a railroad crossing through costly separation in order to improve safety for rail and road travelers. As illustrated in the smart crossing example discussed, the latest advancements in data acquisition and IP video surveillance can equip active warning systems with both real-time and historical information to make railroad crossings smarter and safer.
In other words, smarter data acquisi- tion and IP video surveillance technologies are keys to building an effective intelligent crossing. By providing railway operators, automobile drivers, and pedestrians with the right information at the right time, needless train-and-car collisions can be avoided.
Charles Z.K. Chen and Harry Hsiao are assistant managers with Moxa, Inc. Moxa Americas is based in Brea, Calif. The com- pany provides a full spectrum of quality products for industrial networking, comput- ing, and automation and maintains a dis- tribution and service network that reaches customers in more than 70 countries.
REFERENCES
1. S.C. Mok & I. Savage, “Why Has Safety Im- proved at Rail-Highway Grade Crossings?” Risk Analysis, vol. 25, iss. 4, 867-881, Aug. 2005.
2. G. Cirovic & D. Pamucar, “Decision support model for prioritizing railway railroad crossings for safety improvements: Application of the adaptive neuro-fuzzy system,” Expert Systems with Applications, Oct. 2012.
3. “Fast Track Integration for Wayside Condition Monitoring and Preventive Maintenance,” June 2013. http://www.moxa.com/doc/white_pa- pers/MOXA_White_Paper---Fast_Track_Integra- tion_for_Wayside_Condition_Monitoring_and_ Preventive_Maintenan ce.pdf
4. B.K. Cho & J.I. Jung, “A Study on Intelligent Rail- way Crossing System for Accident Prevention,” B.K. Cho & J.I. Jung, International Journal of Railway [sic], vol. 3, no. 3, pp. 106-112, Sept. 2010.
5. Réseau Ferré de France, “Railroad crossings,” 2009. http://www.rff.fr/spip. php?page=gtext&id_article=1127&lang=en
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