ALTERNATIVE PROPOSAL TO SATISFY REQUIREMENTS OF FRA RS&I -- RULE GROUNDS AUTHORS

Transcription

1 ALTERNATIVE PROPOSAL TO SATISFY REQUIREMENTS OF FRA RS&I -- RULE GROUNDS AUTHORS TIMOTHY C. HEYWOOD SENIOR DESIGN ENGINEER WAYSIDE PRODUCTS ALSTOM SIGNALING, INC. JAMES B. BALLIET VICE PRESIDENT PRODUCT OPERATIONS ALSTOM SIGNALING, INC. P.O. BOX ROCHESTER, NY TELEPHONE: (585) (Tim Heywood) (585) (Jim Balliet) FAX: (585) September 12, 2003

2 ABSTRACT The use of using solid state devices, including microprocessors, in vital signaling applications has reached a first generation level of maturity. It is now clear that governing rules issued by the Department of Transportation, relevant primarily to the use of electromechanical devices to implement vital signaling functions, may now need review and amendment. A potential alternative is possible in lieu of, or in advance of, rule amendment. The ALSTOM position is to highlight how, with the use of new technologies, railroad practices meant to satisfy the governing rules, standards and regulations [FRA RS&I) can be changed and remain practical from a safety and business case perspective. The intent of this position paper is to specifically identify opportunities for new practices involving FRA RS&I Rule {Grounds} testing where state of the art electronic control systems (and software) are now used employing ground detection capability. Scope of the paper includes: Definition of governing rule regarding mandatory tests required to show absence of grounds within signaling system Critical considerations for providing an alternative to the mandatory personnel supported field test Proposal for implementation using system components for interlocking and track circuits available from ALSTOM Safety and business related impact Proposal for new railroad practices relating to Rule The goal is to provide North American rail customers familiarity with new and existing technology and its utilization in lowering after sale customer costs while at the same time maintaining or improving on the accepted safety practices employed. INTRODUCTION Signaling control systems provided by railroad suppliers must be designed to operate functionally and safely regardless of the technology used. Over the past 10 years much emphasis has been placed on the formulation of new rules in correlation to the advent of microprocessors and associated software used to implement vital signaling functions. This is just the beginning as RSAC and other government sponsored committees address the future (reference the NPRM establishing a safety performance goals for PTC systems.) As technology evolves, the methods used to implement signaling functions and provide safety assurance evolve in turn. Safety critical hazards normally associated with the rail environment will either be reduced through improved mitigation strategies the new technology affords, create new hazards to be introduced requiring new safety strategies or no effect may be seen This is highly dependent on the function being performed, the type of technology employed

3 and/or the safety methodology employed. A KEY COST DRIVER FOR RAILROADS One of the major cost factors of rail operations is in the maintenance of the signaling control system. Reliable equipment or not, performing mandated testing to insure the safety integrity of the rail environment places a huge demand on time and resources. Labor costs and equipment obsolescence (electromechanical, mostly) are escalating in the face of diminishing maintenance workforces. The message to rail equipment suppliers has become radical, regarding an evolution from commodity, acquisition oriented purchases to the purchasing of products that address the full life cycle of application. In addition, suppliers are asked to design-in capability to detect and resolve maintenance situations, normally considered outside the bounds of pure signaling control. One such example, is the holy grail of train detection; the self adjusting track circuit. As ballast becomes contaminated with age and use, it may be possible to postpone ballast replacement as the track circuit accommodates a degraded impedance characteristic. While there are still a few pieces of the puzzle to fill in before such a capability is a reality, more and more emphasis is being placed on expanded maintenance saving functionality integrated within interlocking and track circuit equipment. In summary, the intent is clear and critical to railroad signaling departments; to reduce to a great degree, the number of maintenance calls that are made per year. Specifically, that the Signals Dept. needs to focus maintenance on trouble calls where the most critical actions are required. A call is also being made to equipment suppliers to have the new intelligent control systems take a bigger role in detecting, reporting and adapting to degradation in the signaling infrastructure so as to allow smoother planning as to when maintenance actions can take place. Hazard Mitigation The Rules, Standards and Instructions established by the Federal Railroad Administration have defined the means to insure safe rail system operation primarily implemented with mechanical and electromechanical devices for train detection, interlocking and peripheral subsystems. Many hazards, identified with specific implementations of such devices as relays, switch machines, signals, etc., form the basis of the rules. One such class of hazards is associated with the breakdown of the insulation boundary between floating devices or circuits and earth ground. Up to this time, mitigation of these hazards has been accomplished through mandated maintenance actions with reports issued to the FRA. With the onset of solid state detection circuits and communications, the once manual test may now be performed by a check function integrated within the electronic control equipment. It is with this new capability that this proposal is concerned. ABOUT GROUNDS Stated in the FRA RS&I for Rule 236.2:

4 Vital circuits shall be kept free of grounds equal to or in excess of 75% of the release value of relay or electromagnetic device in circuits. This rule s requirements apply to vital signal circuits such as highway crossings, dragging equipment protection, interlocking controllers, etc. where the circuits are selected or fed by relays (relay contacts) energized by the power supply used for the application. Potential hazards may result from undetected grounds which could provide a path around a relay contact or maintain a relay in an energized position when the conditions for being energized (per signaling design) have been removed. These hazards may arise either through long term degradation of the signaling equipment due to natural conditions of age, weather, etc. or through unintended actions occurring during maintenance activities, rodent infestations, vandalism or other situations. Because of this, Railroads perform the grounds test of the power source used for the signaling circuits (along with many other mandated tests) every three months, minimum. In some cases, these tests are performed more even more frequently. This varies with each railroad. THE FINANCIAL LOOK AT GROUNDS TESTING Currently, some railroads make maintenance calls to equipment locations each month with an intent of proving isolation of the signaling power source from earth ground. This can be viewed as a cost and risk avoidance process and not directly related to emergency or higher priority realtime issue resolution. Still individual railroads spend hundreds of thousands of dollars each year for prevention. It is also conceivable that safety critical failures may occur between the planned periodic tests, resulting in derailments, delays, or accidents. This would translate in a multimillion dollar exposure to the railroad. The questions are: Can infrastructure testing be done more consistently and at a lower cost than the current practice? Can it be verified that a newer reliable approach also reduces overall risk of system failure? CONSIDERATIONS FOR ALTERNATIVE STRATEGY With the introduction of processor based signaling equipment, an alternative method for fulfilling requirements of FRA mandated ground test can now be considered. Required is a means to provide active reporting periodically that indicates all signaling locations in a given territory are free of ground faults to the signaling battery. Ideally, this is to be accomplished without utilizing maintenance personnel. The considerations used, when incorporating automated test functionality into a dc coded track circuit control device, are shown below. Specifically, requirements applied to a sample intermediate block signal location are: Perform a periodic test for ground to each side of the signal battery B12 and N12 energy feed.

5 Set ground current threshold detection below that relevant to the release value of signaling circuits (equivalent to 75% of relay release per RS&I) Provide positive indications for absence and presence of detected grounds in either energy leg Communicate from the signal location instantly upon the detection of a ground Communicate periodically a no ground present message revealing the integrity of the ground isolation and the health of the detection circuit from the signal location. Provide a means to provide an instant and self revealing alarm condition to dispatch or maintenance staff when an improper ground is detected New Product Capabilities Address the Issue ALSTOM s DC Coded Track Circuit [GENRAKODE II] has recently introduced two new features that work together to provide automated ground testing at any or all locations employing signaling functions. (Detailed explanations of GENRAKODE II operation and related features are available upon request). The first of the new features is a ground fault monitor [GFM] integrated with the unit s power regulator circuit. The second is a new code format [CODE T] that communicates alarm information in the form of a coded message transmission multiplexed with the vital codes used for intermediate signal control and train detection. Chief among the CODE T features is the ability to identify alarm type and location. When applying these two features together, the absence or presence of an unwanted ground on the location signal battery is revealed nearly continuously by the GFM at each location. Application logic is used to initiate a ground detected alarm or supply free of grounds message transmission using CODE T on the rails and in the direction of a more rigorous communication drop. The local application logic can also be used to downgrade signals appropriate to the type of failure. That is, detection of a ground could lead to the issuance of a tumbledown signal request within a dc coded track block, if so desired. Ground Fault Monitor (GFM) Operation The GFM receives isolated B12/N12 and earth ground feeds via the track circuit chassis connectors. The presence or lack of a ground fault (measured as a detected current between B12 and/or N12 and earth ground) is assessed continuously. The detection circuitry is factory preset to a conservative value (0.6 ma) and can be easily adjusted by Railroad personnel upon installation or when a different detection threshold is desired. In addition, the integrity of the circuitry that performs the test is self-checked every 10 minutes for 45 seconds to confirm proper functionality. This is done by disconnecting the ground connection internal to the GFM and injecting faults simulating a detected ground and observing monitor output for corresponding indications. The switches used for this self-checking are in turn cycle-checked to ensure their controllability. Furthermore, the detection circuitry is designed so that a circuit failure could not result in an injected ground fault of even 20% of the typical ground threshold. Railroad personnel can also easily perform manual tests of the

6 integrity of the detection circuitry. While providing GFM functions, the same circuit provides chassis power, low battery indications and has multiple, ground detection threshold, adjustment levels. This is critical to providing a threshold detection point just below the 75% level mandated by the FRA. In this way, maintenance actions can be performed prior to the situation where a violation has occurred and an FRA inspection is required. CODE T CODE T [Trouble Code] is achieved by varying widths of coded pulses sent down the rails by the GENRAKODE II track circuit, similar to CODE 5. Up to 8 alarm or trouble situations can be identified within the application logic at any of 27 track circuit locations (location IDs repeated on consecutive signaling blocks typically). These could be Power Out, Intrusion, Crossing alarm, and now ground faults, etc. The CODE T information is logged at each location as well as transmitted to adjacent track circuit locations. A maintenance worker can go to any location if desired to view trouble anywhere within a signaling block. CODE T transmissions are overlaid on the vital message transmissions with a final destination being the next control point location (interlocking). The cycle of CODE T transmissions related to no grounds detected can be set per customer request. Currently, this is being communicated toward each control point once every 24 hours. Detection of an earth ground at a location within a block (e.g. intermediate signal location), initiates CODE T transmissions in both directions nearly immediately with knowledge of alarm situation available at control points within minutes. Handling of Ground Fault and Trouble Code at Control Point The current method for analyzing ground detected alarms could be via the track circuit, interlocking controller or in the railroads central office. Data related to trouble codes that occur within the signaled block is received by the Control Point GENRAKODE II and passed to ALSTOM s VPI or Control Point In A Box Interlocking configurations. Detailed trouble code information can be easily observed through serial ports on either VPI or GENRAKODE II products anywhere in the equipped territory. Depending on the interlocking application and communications bandwidth, trouble codes can be assigned as indication bits for sending to the dispatcher (current practice on one Class I Railroad) or through various other supplemental radio methods. Final structure for providing alarm information is primarily customer dependent. BUSINESS CASE AND SAFETY IMPACT The business case supporting this technical alternative is very clear. The actual quantitative assessment is unique for each railroad, difficult to formulate, and is not considered here. The analysis, though, would include actual costs of performing mandated tests (minimum) to the quantified risk associated with a train accident (cost avoidance). From a general (or qualitative) perspective, large benefits can be easily shown:

7 Proactive knowledge of degraded conditions prevents the potential for an accident due to an erroneously permissive movement authority Advance knowledge of field failures reduces train delays Integration of the reporting mechanism into the signaling equipment reduces or eliminates the need to have maintenance personnel visit each equipment location four or more times a year. Large benefit in labor cost associated with travel and test time and test reporting, Ability to focus on highest priority issues eases maintenance planning Personnel safety risk reduced JUSTIFICATION FOR ALTERNATIVE APPROACH TO RULE Code T has been in use for over two years on several railroads and will continue to be the backbone for providing the means to reducing track maintenance costs. The creation of a GFM capability can now be added as a reliable means to change the way railroads perform FRA mandated tests today. It is felt that these new capabilities can be utilized to satisfy the requirements of the FRA, which require periodic proof that floating signal circuits remain as such: SUMMARY A ground fault monitor continuously evaluates the integrity of the signal battery supply leads and alarms any instance of detectable current flow at or above a set threshold established by the railroad in line with the characteristics of the specific signaling circuit. An active circuit is used to indicate both absence or presence of grounds on both supply terminals A self checking feature is incorporated to insure that monitoring circuitry is free from error Transmissions of successful ground checks are provided once a day; considered sufficient with respect to current 3 month test cycle Immediate transmission of indication of detected ground or other trouble condition. Again, well in advance of existing detection method Alarm can be set to reveal potential ground in advance of serious condition permitting maintenance action prior to a required FRA inspection. Multiple alternatives to provide alarm indication via CTC or directly to maintenance personnel. ALSTOM believes that the use of the latest capabilities embedded within the GENRAKODE II and VPI product lines not only provides an alternative to railroad current test methods and procedures but also provides a more rigorous solution that significantly reduces risk of accidents due to a degraded signaling environment. Most importantly to railroads, it reduces the overall cost impact and risk associated with prevention of field failures, train delays and accidents.

8 Therefore, when installed as indicated in this proposal, it is considered a viable replacement for current methods and should be found acceptable as meeting the intent of FRA Rule This paper illustrates the concept as it has been applied to one Class I railroad property. Adaptations to other railroad properties are considered straightforward. Full technical details are available upon request.

9 ACKNOWLEDGEMENTS The author would like to express his appreciation to Jim Balliet, Rob Hochman, and Henry McCauley of the ALSTOM Product Development Group for their background information on this topic. REFERENCES [1] DEPARTMENT OF TRANSPORTATION FEDERAL RAILROAD ADMINISTRATION - OFFICE OF SAFETY, RULES AND REGULATIONS GOVERNING RAILROAD SIGNAL AND TRAIN CONTROL SYSTEMS, Part 236 Rules Standards and Instructions Governing the Installation, Inspection, Maintenance and Repair of Signal and Train Control Systems Inspection and Test section of the Rules and Regulations Governing Railroad Signal and Train Control Systems, Revisions to May 1, 1998 REVISION LOG Revision Date Description By Checked Approved Jan-2003 Initial draft for limited distribution JBB - -