U.S. Department of Transportation
Federal Highway Administration
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Washington, DC 20590
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This chapter offers technical information needed to address the design, installation, operation, maintenance, and inspection of event recording devices at locations with interconnected highway-rail grade crossing signal systems.
This section describes the functional requirements for event recording devices to be installed at highway-rail grade crossing locations with highway traffic signal preemption. The intent of these devices is to provide operating and maintaining agencies with a tool to assist them in ensuring that interconnected signal systems are working as designed. These devices can be installed as standalone units or integrated with other devices installed in a highway traffic signal controller cabinet or railroad grade crossing equipment bungalow. The functional requirements of three different potential interconnected system configurations are discussed in this section, and are classified as "new", "hybrid", and "legacy" systems. The new configuration refers to new or future systems with interfacing capabilities between highway and railroad signal controllers using IEEE Standard 1570 (8). A hybrid configuration refers to existing systems having some level of event recording and/or processing capabilities. The legacy configuration refers to existing systems having no event recording or processing capabilities. For the highway components of these systems, the minimum requirements should be supported by all types of highway traffic signal control architectures and assembly types.
Minimum required events and alarms are proposed for each system configuration. For each proposed event and alarm, there is a description of the event or alarm and an explanation of how it can be monitored and recorded. For new and hybrid system configurations utilizing IEEE Standard 1570, these explanations include how the events and alarms can be generated from the information included in the defined IEEE Standard 1570 messages. For the hybrid and legacy systems that will not be utilizing the IEEE Standard 1570, the explanations include how the events and alarms can be generated from the various equipment and circuits input to the event recorder.
"New" systems have the capability to interface between the highway traffic signal controller and railroad grade crossing controller using IEEE Standard 1570. IEEE Standard 1570 uses a serial communication interface between the highway and railroad systems to communicate vital safety-critical system information such as preemption requests and health status, as well as additional information and data used to monitor each system. IEEE Standard 1570 is explained in further detail in a subsequent section (see "IEEE Standard 1570").
There are currently only a few existing highway traffic signal controllers that provide even a limited amount of support for IEEE Standard 1570. These controllers use IEEE Standard 1570 as another means of providing the preemption input and only support the two safety-critical IEEE Standard 1570 messages, which are subsequently described in detail. At present, there are no highway traffic signal controllers capable of using the additional IEEE Standard 1570 railroad messages (other than preemption information) to modify the preemption sequence in the traffic controller. Highway agencies and/or traffic signal equipment manufacturers will need to develop this functionality in the future. The additional information provided via the IEEE Standard 1570 messages will still be a useful maintenance tool for highway agencies and railroads through monitoring and event recording.
The supervisory component of the interconnected interface should be performed using the defined IEEE Standard 1570 messages over the serial communication interface. This system should meet the Federal requirements for processor-based signal and train control systems defined in 49 CFR 236 Subpart H (see "49 CFR 236 Subpart H Requirements").
Figure 3 shows a functional block diagram of a typical new system configuration.
This section provides an explanation of the IEEE Standard 1570, the IEEE standard for the interface between the rail subsystem and the highway subsystem at a Highway Railroad Intersection (HRI). The following summarizes the content of the IEEE Standard 1570, including the necessary components and the messages the standard defines in detail.
The IEEE 1570 standard defines the Advanced Transportation Controller (ATC) as the platform that provides the digital data communication link at the highway traffic signal control cabinet. The term "ATC" refers to a specific controller standard that is a product of a national standards development effort comprised of the Institute of Transportation Engineers (ITE), American Association of State Highway and Transportation Officials (AASHTO), and the National Electrical Manufacturers Association (NEMA). This standard is still being developed with the latest version 06.05, which is pending approval as of this writing. There are several other enhanced controller platforms currently available on the market that are in use by agencies and could support the IEEE 1570 standard. For this reason, the generic term "traffic controller" is being used in this report so as to not preclude the use of alternative traffic signal controller platforms that an agency may want to use to support the IEEE 1570 communications standard in a future deployment.
The primary purpose of an interconnection interface between the highway and railroad controllers at a HRI is to preempt highway traffic signal operation in order to clear traffic from the crossing as a train approaches. Existing standards define analog interfaces, generally using an electrical cable to convey voltage between the two subsystems, where the absence of voltage on the wires results in the highway traffic signal entering preemption operation. As required by Federal regulations, this existing interface is designed to meet both fail-safe and closed loop principles.
IEEE Standard 1570 specifies a digital communications interface between the highway and railroad subsystems that provides equivalent functions and maintains the safety requirements of existing systems. In addition to providing the preemption functions currently carried out by an interconnection circuit, this interface specifies digital data communications to provide for the sharing of additional information between the highway and railroad subsystems. This standard also supports future upgrades in equipment functionality on both sides of the system, but it does not mandate that functionality.
Figure 3: New System Configuration Functional Block Diagram
The IEEE Standard 1570 interface uses a digital serial connection between the highway advanced transportation controller (ATC) and the railroad wayside equipment terminator. Both the ATC and the wayside equipment terminator handle numerous control functions, which typically reside in separate physical devices and communicate via an internal communications network. IEEE Standard 1570 does not make assumptions about the technology used to implement those control functions. The standard only specifies the interface between highway and railroad subsystems and not the interfaces internal to the highway or railroad subsystems. In other words, this interface provides a means for control functions in the ATC and the wayside equipment terminator to communicate with one another without specifying the internal communication structure in either system. This allows for flexibility in the actual allocation of components and supports alternative equipment placement should it be necessary in the future.
The HRI interface consists of a virtual or logical component and a physical component. The virtual component is what provides the channel for communication between the ATCs and the wayside equipment terminator. It consists of the message formats and information content that flow between the two systems. The physical component of the interface is the physical connection that facilitates the transfer of data between the highway and railroad internal data networks, acting as a bridge between the two independent components.
The HRI interface architecture is made up of four functional components: ATC functions, ATC gateway, wayside functions, and wayside gateway. Figure 4 shows the HRI interface and the functional components of the HRI interface architecture, which are described following the figure.
The ATC functions are those functions internal to the ATC that obtain or generate the information to be transmitted to the railroad system across the HRI interface. They also process data received from the railroad system.
The ATC gateway acts as the internal router and interface bridge controller for the ATC. It is responsible for interfacing with the internal ATC functions and routing incoming or outgoing messages across the HRI interface to the wayside gateway or to the appropriate ATC function.
The wayside functions are those functions internal to the wayside equipment terminator that obtain or generate the information to be transmitted to the highway system across the HRI interface. They also process data received from the highway system.
The wayside gateway acts as the internal router and interface bridge controller; for the wayside equipment terminator. It is responsible for interfacing with the internal wayside functions and routing incoming or outgoing messages across the HRI interface to the ATC gateway or to the appropriate wayside function.
More than one type of protocol is specified for the HRI interface. This gives equipment manufacturers flexibility to implement the HRI interface to fit an installation's specific circumstances. The data link and physical layer protocols provide the physical infrastructure for the HRI physical interface. The protocols specified for these layers include Ethernet, RS232, RS422, and RS485. These protocols should support the transfer of individual message packets of up to 128 bytes in length at a minimum of 19.2 kilobytes per second, meaning the protocols should be capable of transferring a 128 byte message packet across the HRI interface in less than 250 milliseconds.
Figure 4: HRI Interface
HRI Messages
IEEE Standard 1570 defines a total of 12 messages for exchange over the HRI interfaces, which are listed in Table 6.
This section, which addresses the required minimum amount of information to be shared between the highway and railroad subsystems, describes how four of the eight defined messages should be used to transfer information to the event recorder in system configurations using the IEEE Standard 1570 protocol for communication. A description of each of the four messages recommended for use is provided with an explanation of the standard information included in each message packet.
The same standard data format is used for all defined HRI messages. The information in this standard data format includes the message length, a time stamp (date and time, from the month down to the second), a message sequence number, a message label, and a message version number. Also included is information identifying the message as vital or non-vital and the actual message data.
Table 6: HRI Messages
| MESSAGE ID | MESSAGE NAME | SOURCE | DESTINATION | SAFETY-CRITICAL? |
|---|---|---|---|---|
| 9.4.40 | HRI Rail Crossing Operational State | Railroad | Highway | Yes |
| 9.4.41 | HRI Approaching Train Information | Railroad | Highway | No |
| 9.1.41 | HRI Approaching Train Information Request | Railroad | Highway | No |
| 9.4.42* | HRI Wayside Equipment Status | Railroad | Highway | No |
| 9.1.42* | HRI Wayside Equipment Status Request | Highway | Railroad | No |
| 9.4.43 | HRI Roadway Obstacle Detection State | Highway | Railroad | Yes |
| 9.4.44* | HRI ATC Equipment Status | Highway | Railroad | No |
| 9.1.44* | HRI ATC Equipment Status Request | Highway | Railroad | No |
| 9.4.45 | HRI User-Specific Wayside Message | Railroad | Highway | No |
| 9.1.45 | HRI User-Specific Wayside Message Request | Highway | Railroad | No |
| 9.4.46 | HRI User-Specific ATC Message | Highway | Railroad | No |
| 9.1.46 | HRI User-Specific ATC Message Request | Railroad | Highway | No |
*Reserved for future use
HRI Rail Crossing Operational State (9.4.40)
This message is transmitted from the railroad system to the highway system and is defined as a safety-critical message. The message is sent at a frequency of once per second, and is called the vital heartbeat message from the wayside system. Byte 0 of the message data includes a field named RHBA, for receiving vital heartbeat (9.4.43) from the ATC system. The status of this field will be either '0' for "Not Receiving Message 9.4.43" or '1' for "Receiving Message 9.4.43". The definition of receiving or not receiving is determined locally and should be defined by the equipment manufacturers or the highway agency and railroad. Receipt of the vital heartbeat message from the ATC system, as well as the highway system's receipt of the wayside vital heartbeat message within the specified allowable time, represents the vitality of the HRI interface.
Also included in byte 0 of the message data is the number of crossings. The standard is defined for 1 to 8 crossings, each of which may contain from 1 to 8 tracks and up to a maximum of 8 trains associated with each crossing. The overall message length is dependent on the number of crossings and the number of trains associated with each of those crossings. Bytes 1 through 7 are repeated for each crossing, and bytes 5 through 7 are repeated for each train associated with each of the crossings. Other fields defined in this message include:
Note that not all of these fields are required for use as outlined in this section.
HRI Roadway Obstacle Detection State (9.4.43)
This message is transmitted from the roadway system to the railroad system and is defined as a safety-critical message. The message is sent at a frequency of once per second, and is called the vital heartbeat message from the ATC system. Byte 0 of the message data includes a field named RHBW, for receiving vital heartbeat (9.4.40) from the wayside system. The status of this field will be either '0' for "Not Receiving Message 9.4.40" or '1' for "Receiving Message 9.4.40". The definition of receiving or not receiving is determined locally and should be defined by the equipment manufacturers or the highway agency and railroad. Receipt of the vital heartbeat message from the wayside system, as well as the railroad system's receipt of the ATC vital heartbeat message within the specified allowable time, represents the vitality of the HRI interface.
This message also provides safety-critical crossing obstacle information to the railroad system. The information fields defined in the message include:
It is noted that the standard is not intended to define the functionality of obstacle detection; it is only intended to provide a framework for transferring such information to the railroad system should any obstacle detection exist. The specific functionality should be agreed upon by the highway agency and railroad. Obstacle detection functionality is not required for event recording as defined in this section.
HRI User-Specific Wayside Message (9.4.45)
This message is transmitted from the railroad system to the highway system and can be defined as either an informational message or as a safety-critical message. The highway agency and railroad should jointly determine the message definition. Transmission of the message can be defined as either on request or on a periodic basis. Therefore, the message frequency should also be determined and agreed upon by the highway agency and railroad. If the message is sent upon request, the defined HRI User-Specific Wayside Message Request (9.1.45) will be used. This is a one byte query message sent from the ATC system to the wayside system to request that the wayside system send the HRI User-Specific Wayside Message (9.4.45).
The data content and format of the user-specific message should be defined by the highway agency and railroad. Additionally, the highway agency and/or railroad should specify data fields in this message to include the following information:
This message data is required in order to monitor and record several of the events described in "Events". The highway and railroad equipment used to communicate these messages, as well as the event recording devices used to monitor these messages, should be programmed to support the user-specific message settings.
HRI User-Specific ATC Message (9.4.46)
This message is transmitted from the highway system to the railroad system and can be defined as either an informational message or as a safety-critical message. The highway agency and railroad should jointly determine the message definition. Transmission of the message can be defined as either on request or on a periodic basis. Therefore, the message frequency should also be determined and agreed upon by the highway agency and railroad. If the message is sent upon request, the defined HRI User-Specific ATC Message Request (9.1.46) will be used. This is a one byte query message sent from the wayside system to the ATC system to request that the ATC system send the HRI User-Specific ATC Message (9.4.46).
The data content and format of the user-specific message should be defined by the highway agency and railroad. Additionally, the highway agency and/or railroad should specify data fields in this message to include the following information:
This message data is required in order to monitor and record several of the events described in "Events". The highway and railroad equipment used to communicate these messages, as well as the event recording devices used to monitor these messages, should be programmed to support the user-specific message settings.
49 CFR 236 Subpart H Requirements
The primary purpose of the safety-critical interconnection interface between the highway and railroad systems of a highway-rail grade crossing is to preempt highway traffic signal operation in order to clear traffic from the crossing as a train approaches. As required by Federal regulations, this existing interface is designed to meet both fail-safe and closed loop principles. Section 8C.09 of the MUTCD specifies, "This preemption feature shall have an electrical circuit of the closed-circuit principle, or a supervised communication circuit between the control circuits of the highway-rail grade crossing warning system and the traffic control signal controller." Part 16.30.10 of the AREMA C&S Manual (9) states that, "The interconnection between the traffic control signal and the railroad warning system shall be a double break relay circuit or serial data circuit in accordance with IEEE Standard 1570-2002." New systems should also provide fail-safe supervision of the vital preemption functions to be carried out using the serial communication interface specified in IEEE Standard 1570. 49 CFR 234.275 states that, "Highway-rail grade crossing warning systems, subsystems, or components that are processor-based and that are first placed into service after June 6, 2005, which contain new or novel technology, or which provide safety-critical data to a railroad signal or train control system that is governed by part 236, subpart H or I, of this chapter, shall also comply with those requirements. New or novel technology refers to a technology not previously recognized for use as of March 7, 2005."
New systems using the IEEE Standard 1570 interconnection interface between the highway and railroad systems are subject to the requirements of 49 CFR 236 Subpart H. 49 CFR 236 Subpart H specifies the minimum performance standards for safety-critical products. This includes the requirements railroads are subject to for development, installation, implementation, inspection, testing, operation, maintenance, repair, and modification of safety-critical products. Additionally, 49 CFR 236 Subpart H contains a detailed explanation of the required filing and approval processes for Railroad Safety Program Plans (RSPPs) and Product Safety Plans (PSPs). It also specifies product implementation procedures, operation requirements, testing and records recording requirements for safety-critical products, and the requirements of training and qualification programs for these products. Supervisory components and acceptable message frequencies of the IEEE Standard 1570 communication interface should be specified in the RSPP and PSP.
Each railroad subject to this subpart must submit a RSPP to the FRA for approval. The RSPP is the principal safety document for all safety-critical products and it must establish the minimum PSP requirements that will govern the development and implementations of the safety-critical products. These plans must include complete descriptions of the preliminary safety analysis, including the methods used to evaluate a system's behavioral characteristics, the risk assessment procedures, the system safety precedence followed, and identification of the safety assessment process. A RSPP also requires identification of verification and validation methods, including the standards to be used in this process. Finally, the RSPP requires a description of the process used to identify human factors issues and development of design requirements to address those issues, as well as to specify requirements for product configuration management. Railroads should consult 49 CFR 236.905 for a complete description of the contents required in a RSPP.
Railroads must also submit a PSP for each new product subject to 49 CFR 236 Subpart H. The PSP must provide complete descriptions of the product and all of its components, the railroad operation(s) it is intended for, the product operational concepts, and safety requirements. The PSP also must include all safety assessment, verification and validation processes and the associated results, a hazard mitigation analysis, a risk assessment, description of the safety assurance concepts, and a human factors analysis. Complete descriptions of the specific training for railroad employees and contractors and of the specific procedures and test equipment needed to ensure safe and proper installation, implementation, operation, maintenance, repair, inspection, testing, and modification are also required to be included in a PSP. Among several other requirements, a PSP must also include, for each of the requirements of 49 CFR 234, an explanation of how the product meets the requirement, why the requirement is not applicable to the product design, or how the new product satisfies the requirement using alternative methods. Railroads should consult 49 CFR 236.907 for a complete description of the contents required in a PSP.
As stated in 49 CFR 236.909, the minimum performance standard for products covered by this subpart is that, "The safety analysis included in the railroad's PSP must establish with a high degree of confidence that introduction of the product will not result in risk that exceeds the previous condition. The railroad shall determine, prior to filing its petition for approval or informational filing, that this standard has been met and shall make available the necessary analyses and documentation as provided in this subpart." This section also explains the requirements for full and abbreviated risk assessments that must be completed to support the minimum performance standard.
Full risk assessments are required to address the safety factors associated with the introduction, modification, replacement, or enhancement of safety-critical products. This includes any risks from the previous condition that are no longer present as a result of the new product or change, new risks associated with the changed or new product, and risks that are not affected. 49 CFR 236 Appendix B contains the specific requirements of a full risk assessment. An abbreviated risk assessment may be submitted instead of a full risk assessment if there are no new hazards introduced as result of the change, and there is not an increase in hazard severity or exposure from the previous condition. Railroads should consult 49 CFR 236.909 for specific requirements of an abbreviated risk assessment to support the minimum performance standard.
Event Recording
New system configurations should include an event recording device to monitor the communication between the highway and railroad systems. The recording device(s) should be connected to the communication interface between the ATC gateway in the highway traffic signal controller cabinet and the wayside gateway in the railroad grade crossing equipment bungalow, and should monitor the messages sent between the two systems. Event recorders installed should be able to process the IEEE Standard 1570 messages in order to monitor the status of the various highway traffic signal and railroad grade crossing subsystems and record the required events, as necessary. The proposed minimum required events to record are listed below with a general description and an explanation of the associated IEEE Standard 1570 message and message field that contains the information required for a recorded event.
Highway Events
Railroad Events
Figure 5 illustrates the sequence of railroad events to be recorded for each train movement through the highway-rail grade crossing.
![Figure 5. Image. Railroad Events to be Recorded for Each Train Movement. Sequential illustration of events to record for each train movement: 1. Pre-Emption Circuit Drops [A]; 2. Supervisory Circuit Drops; 3. Approach Circuit Drops [B] ; 4. XR Relay Drops; 5. Gate Up Contact Drops; 6. Gate Down Contact Picks Up; 7. Island Circuit Drops [C] ; 8. Directional Stick Relay Picks Up; 9. Trailing Circuit Drops [D] ; 10. Approach Circuit Picks Up [B] ; 11. Island Circuit Picks Up [C] ; 12. XR Picks Up; 13. Gate Down Contact Drops; 14. Gate Up Contact Picks Up; 15. Trailing Circuit Picks Up [D] ; 16. Directional Stick Relay Drops. The sequence runs top to bottom (A to E) along the left side of the image, with events labeled at 1, 3, 7, 9, and 15.](images/fig5.gif "Figure 5. Image. Railroad Events to be Recorded for Each Train Movement. Sequential illustration of events to record for each train movement: 1. Pre-Emption Circuit Drops [A]; 2. Supervisory Circuit Drops; 3. Approach Circuit Drops [B] ; 4. XR Relay Drops; 5. Gate Up Contact Drops; 6. Gate Down Contact Picks Up; 7. Island Circuit Drops [C] ; 8. Directional Stick Relay Picks Up; 9. Trailing Circuit Drops [D] ; 10. Approach Circuit Picks Up [B] ; 11. Island Circuit Picks Up [C] ; 12. XR Picks Up; 13. Gate Down Contact Drops; 14. Gate Up Contact Picks Up; 15. Trailing Circuit Picks Up [D] ; 16. Directional Stick Relay Drops. The sequence runs top to bottom (A to E) along the left side of the image, with events labeled at 1, 3, 7, 9, and 15.")
Figure 5: Railroad Events to be Recorded for each Train Movement
Alarm Reporting
In addition to monitoring the IEEE Standard 1570 messages and recording the required events, the device should be able to process this information in order to flag recorded events and/or report alarms. Event recorders should use user-specific logical expressions to relate fields of various IEEE Standard 1570 messages to determine that the highway and railroad systems are working as designed. As defined by the highway agency and/or railroad, any recorded event or logical combination of events should be flagged as an alarm. A list of situations that should result in the reporting of an alarm along with explanations of how they can be determined is provided below. At a minimum, flagging event records will allow highway agency and/or railroad personnel to determine if a problem exists at a crossing during regular maintenance or inspections.
The following is a list of proposed situations for which an alarm should be reported. These alarms should be determined by monitoring the recorded events or IEEE Standard 1570 messages previously described. Event recorders should be capable of processing and relating the fields of each recorded event or IEEE Standard 1570 message described in order to trigger the alarm(s).
"Hybrid" systems are existing systems having some level of event recording and/or processing capabilities. This includes a wide variety of existing system configurations of varying age and technology capabilities of technology in both the highway and railroad systems.
Highway agencies and railroads should jointly determine if they will upgrade their respective systems to support the IEEE Standard 1570 serial communication interface. The upgrade would require updating various existing equipment executive software and programs to generate and process the defined ATC and wayside messages. In some instances, upgrades may require completely new installations. In either case, the requirements of 49 CFR 236 Subpart H will need to be met.
Existing event recording devices may also require updates to their executive software or programs to support IEEE Standard 1570. The event recording devices should be able to monitor the status of message fields being sent across the serial communication interface between the highway and railroad gateway devices. This allows events to be recorded and alarms to be reported. If necessary, the communications capabilities of the event recording devices may need upgrading to support the transfer of events associated with alarms to a central office database.
If highway agencies and railroads do not jointly upgrade their respective equipment to support IEEE Standard 1570, then their systems should support a minimum level of monitoring, event recording, and alarm reporting required of legacy systems (see "Legacy Systems"). Highway agencies and railroads may consider future upgrades to support communication capabilities using IEEE Standard 1570.
Figure 6 shows a functional block diagram of a typical hybrid system configuration.
Figure 6: Hybrid System Configuration Functional Block Diagram
"Legacy" systems are existing systems having no event recording and/or processing capabilities. These systems will need to be modified to include new event recording equipment capable of future communication via IEEE Standard 1570.
Figure 7 shows a functional block diagram of a typical legacy system configuration.
Figure 7: Legacy System Configuration Functional Block Diagram
Event Recording
Legacy system configurations should be equipped with an event recording device to monitor the highway and railroad systems. The recording device(s) should be capable of supporting IEEE Standard 1570 serial communication should the location receive future upgrades utilizing this interface. The recording device(s) should support the number of digital and analog inputs required to monitor the highway and railroad. Event recorders should be able to process the various digital and analog inputs to monitor the status of the highway traffic signal and railroad grade crossing equipment and record the required events as necessary. The minimum events to record, along with explanations, is provided below. These events/circuits are intended for those existing systems that are currently incapable of and/or not utilizing the IEEE Standard 1570 communication protocol.
Highway Events
Railroad Events
Alarm Reporting
In addition to monitoring the status of various highway and railroad equipment and recording the required events, the device should be able to process this information in order to flag recorded events and/or report alarms. Event recorders should use user-specific logical expressions to relate the status of equipment to determine that the highway and railroad systems are working as designed. As defined by the highway agency and/or railroad, any recorded event or logical combination of events should be flagged as an alarm. A list of situations that should result in the reporting of an alarm along with explanations of how they can be determined is provided below. At a minimum, flagging event records will allow highway and railroad maintenance personnel to determine if a problem exists at a highway-rail grade crossing during regular maintenance or inspections. The following is a list of proposed situations for which an alarm should be reported. These alarms should be determined by monitoring the circuits and recorded events previously described. Event recorders should be capable of processing and relating the recorded events described in order to trigger the alarm(s).
This section describes the general functional requirements for event recording devices to be installed at highway-rail grade crossing locations with highway traffic signal preemption. These requirements are for event recording devices in any of the three system configurations (new, hybrid, and legacy).
The event recorder can be installed in the highway traffic signal controller cabinet, railroad grade crossing equipment bungalow, or in both. Highway agencies and railroads should jointly determine the location of the event recording device(s). The recording device should support time and date stamping of events and have sufficient capacity to record the required events from the highway and railroad for a period of one month prior to overwriting itself. The event recorder should have an internal battery backup to store data in the event of a power loss. For the required highway traffic signal events, the event recorder should dynamically record all required events for a time period of at least 60 seconds, but not less than highway the traffic signal cycle length, prior to a rail preemption call and for an equal time period after the call for rail preemption is terminated.
The event recording device should support two types of user interfaces. A visual display interface should dynamically indicate the status of each input, providing a valuable troubleshooting maintenance tool as well as supporting scheduled maintenance and inspection tasks. This requirement can be satisfied by a series of LED front panel indicators or an LCD alpha-numeric screen. A laptop computer or other portable device interface should provide for initial unit programming at the specific installation location as well as the ability to retrieve and display recorded event logs. If integrated as part of the highway traffic signal controller and/or railroad grade crossing controller, the controller should also support the computer/portable device requirement.
It is recommended that the event recording device support communications with an internet database or back office location to report alarms to the maintaining authorities as they occur. If an event recorder determines that alarm conditions have been met and flags an event record or several event records used to determine such conditions, it should report the alarm and send the associated event records to an internet database or back office system. This allows the highway agency and railroad to act as quickly as possible to investigate the problem. To support these features, the event recording devices should support an Ethernet-based connection to the back office system. This can be achieved by connecting through a high-speed communications link supplied to the equipment cabinet, or through wireless methods such as a cell modem connected to the event recorder. At remote locations, this communications link may not be achievable. The Ethernet connection should be shared by the maintaining agencies through a closed communications network. For new systems using IEEE Standard 1570 communication, the internet database or back office system receiving the reported alarms should support IEEE Standard 1570 so that it can process the alarms and recorded event messages sent to the database. This helps to initiate the required action from the highway agency and/or railroad maintenance personnel, if necessary.
Time Reference Requirements
The event recording device should maintain an accurate time reference. Traditionally, time referencing for highway traffic signal control devices had been based on the 60 Hz AC frequency of the utility generated service. However, it should be noted that on June 14, 2011, the Federal Energy Regulatory Commission stated that it is proposing an experiment that would allow more frequency variation in the nation's power grid. This may adversely impact time referencing systems that rely on electrical frequency for accuracy. Highway traffic signal controllers connected as part of a larger control system architecture may rely on a central device (system field master or remote computer station) to receive a time reference. In the event of power failure to the highway traffic signal controller, an internal crystal-based oscillator backed up by an internal battery should serve to keep time. The accuracy of this backup system would vary based on controller type and manufacturer.
In recent years, a GPS-based time reference system has begun to be used to maintain accurate time in a highway traffic signal controller. Typical installations consist of a small, round antenna installed on top of the highway traffic signal controller cabinet. There are two methods of transmitting the GPS information into the controller. The first method uses a contact closure as a single function input into the controller. (For example, this is typically a manufacturer-defined pin on the "D" connector for a NEMA TS-1 cabinet assembly.) The second method is for a serial connection into an unused communication port (RS232) on the controller.
For the event recorder, a GPS-based time reference should be used to maintain accurate time for both the highway traffic signal and railroad grade crossing recording systems. This should include the existing highway traffic signal controller and conflict monitor/malfunction management unit installed in the cabinet. All devices installed in the highway traffic signal controller cabinet and railroad grade crossing equipment bungalow should have the same time reference for event logging.
Electrical Requirements
The event recording device should be adaptable to accommodate variations in electrical data transmission based on signal cabinet/bungalow architecture. Each highway traffic signal controller and railroad grade crossing architecture utilizes different electrical levels and protocols for in-cabinet communications. NEMA TS-1, for example, employs a single function to single conductor architecture for device-to-device data transmission. A full eight-phase NEMA TS-1 traffic controller has 171 wires connected to it, allowing for +24 VDC (ground true) input/output to the unit. Type 170 and Type 179 use a similar configuration with a 102 conductor interconnection to the controller. NEMA TS2, type 1 uses serial data transmission (SDLC) to interface with other cabinet devices and terminals. The 2070 and other types of device cabinets have the user option to specify a variety of cabinet interface configurations including single function/single conductor or serial interface. For the event inputs identified, the input electrical levels will vary on cabinet type.
Electrical interfacing should conform to NEMA TS-2 "Traffic Controller Assemblies with NTCIP Requirements - Version 02.06" for NEMA-based cabinet assemblies; Caltrans "Transportation Electrical Equipment Specification" for 170-, 179-, and 2070-based cabinet assemblies; and "Advanced Transportation Controller (ATC) Standard" (latest approved version) for ATC-based cabinet assemblies. It should be noted that ATC Version 06.05 was the latest proposed at the time of this writing.
Environmental Requirements
The event recorder should be manufactured such that it meets the minimum environmental and test requirements as defined in NEMA TS-2 "Traffic Controller Assemblies with NTCIP Requirements - Version 02.06" for NEMA-based cabinet assemblies; Caltrans "Transportation Electrical Equipment Specification" for 170-, 179-, and 2070-based cabinet assemblies; and "Advanced Transportation Controller (ATC) Standard" (latest approved version) for ATC-based cabinet assemblies. The recording device should also meet the environmental requirements recommended in AREMA C&S Manual Part 11.5.1 "Recommended Environmental Requirements for Electrical and Electronic Railroad Signal System Equipment."
Inspection & Testing
Event recording devices should conduct self-diagnostics and testing as recommended in AREMA C&S Manual Part 3.1.29. Upon start-up and after reset, the recorders should perform self-diagnostics and the results of self-diagnostic tests should be recorded with a date and time stamp. The recorders should also verify proper operation and perform self-diagnostics periodically, while continuing to monitor and respond to status changes. If the tests are successful, the recorder should locally indicate being operational and, if possible, report being online and operational. If the tests are not successful, the recorder should create an event record and report an alarm. The recording devices should also verify input states by providing multiple sampling or time integration when evaluating the status of each input. Finally, the recorders should include a timer that requires the continuous servicing by the self-diagnostics in order to keep operating. If the timer expires, the recorder should reset itself and perform self-diagnostics upon resetting. This should also create an event record indicating the system was reset.
The event recording device should be tested to determine that it functions as intended when it is installed or modified and at least once a month, as required of grade crossing warning systems in 49 CFR 234. During regular joint inspections, highway agency and/or railroad inspecting personnel should download the recorded data from the event recording device to compare with known train events, if the data is not already regularly uploaded to and monitored from a back office database.
The cost of event recording devices varies based on the processing and reporting capabilities as well as storage capacity and recording needs of the highway-rail grade crossing. Larger highway-rail grade crossing locations or locations with more equipment that require additional monitoring and recording may require expanding the event recorder's inputs and outputs. Depending on the amount of information being recorded, event recorders may also need expanded memory so that they can store events for the required one month period prior to overwriting the memory. The geographic location of the highway-rail grade crossing and the available communication options will also impact the cost of event recording devices. For example, remote locations may require additional equipment for effective monitoring and alarm reporting.
Current pricing for basic event recording devices, without expanded inputs and outputs or memory, is between $1,500 and $2,500. Additional analog and digital I/O modules can cost from $500 to $2,000 depending on the size, type, and manufacturer. Memory expansion cards or modules can cost up to $1,000. Optional communication modules or cards typically cost up to $1,500. Given that the proposed event recorder will be required to contain more functionality than existing systems, event recording devices could cost up to $10,000 depending on the size of the location and necessary equipment. Back office systems needed for reporting alarms and remotely monitoring and testing highway-rail grade crossing equipment can cost from $10,000 to $150,000 based on the level of monitoring and automatic testing desired.
The prices for event recording devices capable of supporting IEEE Standard 1570 and monitoring the communication messages will most likely be greater than the costs provided here. These recording devices will need new executive software and the necessary communication options and equipment to support IEEE Standard 1570. Manufacturers will incur expenses for product development, which will in turn increase the costs of the new recording systems. Event recorder manufacturers typically provide railroads with discounted prices for buying in bulk, which vary based on the price of the product and quantity purchased.
Railroad maintenance standards and requirements for testing and inspecting highway-rail grade crossing signal systems are mandated by the Code of Federal Regulations Title 49 Part 234 Subpart D and AREMA. However, there is no national traffic signal counterpart to these standards and requirements. Traffic signal system maintenance, testing, and inspection processes are typically developed by State and local highway agencies. The following presents information pertaining to minimum maintenance, testing, and inspection policies and practices to be followed by State and local highway agencies for highway-rail grade crossing locations.
Relevant 49 CFR 234 sections are also presented. The ultimate goal is to encourage a working relationship between highway agencies and railroads through a joint testing and inspection procedure to ensure that highway-rail grade crossing signal systems and interconnected highway traffic signal systems are communicating correctly and working properly. Achieving this goal will satisfy the four actions recommended in the Safety Advisory 2010-02 noted in Chapter 1.
Performing preventive inspections and maintenance activities at highway-rail grade crossing locations is considered proactive risk management by State and local highway agencies. The Traffic Signal Installation and Maintenance Manual (4) recommends that these preventive inspections and maintenance activities be conducted at a 6-month intervals.
Railroads should perform inspections, testing, and maintenance activities at highway-rail grade crossing locations as required by 49 CFR 234.
Safety Advisory 2010-02 set forth requirements for State and local highway agencies to perform joint inspections in coordination with railroads at highway-rail grade crossing locations. The joint inspections should be performed at a maximum interval of twelve months.
It would be desirable for the 6-month preventive inspections and maintenance activities to be scheduled and initiated by the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing. Ensuring that each highway-rail grade crossing with a jurisdiction is inspected and maintained within the specified interval may be the responsibility of the State (district) or local traffic engineer.
The monthly and quarterly inspections, testing, and maintenance activities conducted by the railroad should be scheduled and initiated as currently done in accordance with 49 CFR 234.
It is encouraged that the annual detailed joint inspections be scheduled and initiated by the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing. The State (district) or local traffic engineer would be responsible to coordinate scheduling with the appropriate railroad. The State (district) or local traffic engineer would also ensure that each highway-rail grade crossing location within his/her jurisdiction is jointly inspected within the specified interval.
At least one highway traffic signal technician may conduct each 6-month preventive inspection and maintenance activity, verifying the elements identified under "Procedures". However, if deemed necessary, a traffic engineer may also perform the 6-month preventive inspection and maintenance activity. When two traffic personnel are present, the highway traffic signal technician would be responsible for the functionality of the highway traffic signal system whereas the traffic engineer would be responsible for the signal operations, signs, pavement markings, and other safety concerns.
Each monthly and quarterly inspection, testing, and maintenance activity performed by the railroad should be conducted by at least one railroad inspection/testing personnel. The railroad inspection/testing personnel should be responsible for the functionality of the railroad grade crossing warning system. The railroad inspection/testing personnel should be familiar with the requirements of 49 CFR 234 to ensure that all aspects of the highway-rail grade crossing are reviewed as specified.
Each detailed annual joint inspection may be conducted by at least one highway traffic signal technician, one traffic engineer, and one inspection/testing personnel from the railroad. The highway traffic signal technician would be responsible for the functionality of the highway traffic signal system whereas the traffic engineer would be responsible for the signal operations, signs, pavement markings, and other safety concerns. The railroad inspection/testing personnel should be responsible for the functionality of the railroad grade crossing warning system. Coordination between the highway traffic signal technician, the traffic engineer, and the railroad inspector is important to ensure that all aspects of the interconnected highway-rail grade crossing signal system are properly working.
Identification
Highway-rail grade crossings that have interconnection between the highway traffic signal system and the railroad grade crossing warning system should be identified as such. The warning labels shown in Figure 8 may be affixed inside the main door of the highway traffic signal controller cabinet and the railroad grade crossing equipment bungalow, respectively.
Figure 8: Example Warning Labels
A field example of a warning label is shown in Figure 9. In addition to the warning, the label also includes contact information for the responsible highway agency and railroad.
Figure 9: Field Example of Warning Label
Plans
Signed and sealed plans required for proper testing and maintenance of the highway traffic signal system may be kept at each highway-rail grade crossing location within the highway traffic signal controller cabinet. This may also include signed and sealed plans for signing and pavement markings installed in advance of the highway-rail grade crossing on all roadway approaches. It is an effective practice to maintain legible and current plans that contain an accurate database of all programming resident in each of the various control devices. If modifications are made to the highway traffic signal system or to signing and pavement markings, modifying or replacing the plans within the highway traffic signal controller cabinet would be the duty of the highway agencies.
As required by 49 CFR 234.201, plans required for proper testing and maintenance of the railroad grade crossing warning system should be kept at each highway-rail grade crossing location in the railroad grade crossing equipment bungalow. It is the responsibility of the railroad to keep these plans legible and correct. If any modifications are made to the railroad grade crossing warning system, it is the responsibility of the railroad to modify or replace the plans contained in the railroad grade crossing equipment bungalow. Additionally, it should be the responsibility of the railroad to notify the appropriate highway agency of any changes made to the railroad grade crossing warning system that may have an impact on the operation of nearby highway traffic signal systems.
Six-month Highway Preventive Inspections and Maintenance Activities
The 6-month preventive inspections and maintenance activities are intended to verify that basic highway traffic signalization parameters are functioning properly, that appropriate signing and pavement markings are in place and in good condition, and that no other safety concerns are present. The items to be verified by a highway traffic signal technician (and traffic engineer, if present) may include the following:
The issues identified through the 6-month preventive inspection process need to be brought to the attention of the appropriate responsible parties. Problems to be addressed immediately may include signalization, missing signing, and lighting outages. Additionally, seriously deteriorated pavement conditions should be given immediate attention while less significant deteriorations may be addressed in the short-term. Signing and pavement markings in poor condition may be updated at a regularly scheduled interval. It is important that controller cabinet debris or animal infestations be cleared at the time of the inspection.
Monthly and Quarterly Railroad Inspections and Maintenance Activities
The CFR regulations explain in detail the components of the railroad grade crossing warning system that should be inspected, tested, and maintained on a monthly and quarterly (3 month) basis. The purpose is to ensure that the warning system functions as designed, including being visible and audible to highway users approaching the crossing. At each of the specified intervals, railroad inspection/testing personnel should verify the following:
Monthly
The railroad having jurisdiction over the highway-rail grade crossing should be responsible for inspection, testing, and maintenance up to the point of interconnection with the highway traffic signal control system. The State or local highway agency should be responsible for inspecting, testing, and maintaining all remaining circuitry and highway traffic signal control devices. The test should ensure that an approaching train activates the railroad grade crossing warning system and initiates the highway traffic signal clearance sequence. The railroad should check contacts and devices interconnected with the highway traffic signals and advanced warning signs to ensure they perform as intended as defined in 49 CFR.
Inspection/testing personnel should also verify the proper operation of the interconnect circuit and observe that highway traffic signal preemption is operating as intended. Ideally, preemption should be verified with the actual passing of a train through the highway-rail grade crossing location; however, this is not always feasible. Under these circumstances, inspection/testing personnel may simulate a train movement by de-energizing the interconnection circuit, thereby activating the preemption sequence. If the crossing is equipped with advanced preemption, inspection/testing personnel should observe a train movement to verify proper operation. Inspection/testing personnel should note any repairs or adjustments made. If the interconnection circuit is discovered to be not operational and/or any inconsistency is discovered, inspection/testing personnel should notify the State or local highway agency having jurisdiction over the highway-rail grade crossing as well as report the findings to the appropriate railroad supervisor. If the railroad equipment is found to be operating properly and the highway traffic signal system does not respond, inspection/testing personnel should notify the State or local highway agency having jurisdiction over the highway-rail grade crossing of the problem. The railroad may request the presence of State or local highway agency personnel during the monthly preemption testing.
Quarterly
These tests are used to assure that trains are being properly detected on each of the railroad approaches.
Detailed Annual Joint Inspections
The detailed annual joint inspections are intended to verify that all aspects of the interconnected highway-rail grade crossing signal system are properly working. It is desirable that the detailed annual joint inspections be conducted by highway agency and railroad personnel as described.
A highway traffic signal technician and traffic engineer may verify the following:
Railroad inspection/testing personnel should verify the following:
During the detailed annual joint inspection process, it is desirable to maintain the normal operation of the highway-rail grade crossing. If normal operation is to be suspended, other provisions should be made prior to the inspection to ensure highway-rail grade crossing safety for all transportation modes at the location.
For the 6-month preventive inspections and maintenance activities, a report completed by the highway traffic signal technician (and traffic engineer, if present) may include information such as the highway-rail grade crossing location, the technician's name (and traffic engineer, if present) and employee identification number, the date and time, the tasks performed, and the problems noted. A minimum of two copies of the 6-month report may be required, both signed by the highway traffic signal technician (and traffic engineer, if present). One report may be kept within the highway traffic signal controller cabinet and one may be filed at the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing. Upon the next inspection, the report within the highway traffic signal controller cabinet would be replaced. The report filed at the State (district) or local highway agency office may be discarded after a period of five years. If interim maintenance activities are required to the highway traffic signal system, it is important that signed documentation be attached to the most current report on file.
For the detailed annual joint inspections, a report should be completed by the highway traffic signal technician, traffic engineer, and railroad inspector. The report may include information such as the highway-rail grade crossing location, the participants' names and employee identification numbers, the date and time, the tasks performed, and the problems noted. A minimum of four copies of the joint inspection report may be required, signed by the highway traffic signal technician, traffic engineer, and railroad inspector. One report may be kept within the highway traffic signal controller cabinet, one may be filed at the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing, one should be kept within the railroad grade crossing equipment bungalow, and one should be filed in the office of a railroad supervisory official having jurisdiction, as required by 49 CFR 234.273. The reports within the highway traffic signal controller cabinet and the railroad grade crossing equipment bungalow would be replaced upon the next joint inspection. The report filed at the State (district) or local highway agency office may be discarded after a period of five years. The report filed with the railroad supervisory official should be kept until the next report for that test is filed and at least for one year, also as required by 49 CFR 234.273. If interim adjustments have been made to the highway traffic signal control system or railroad grade crossing warning system, it is important that signed documentation be attached to the most current report on file.
Several example inspection and diagnostic forms are attached in Appendix F. These forms can be modified by highway agencies and railroads for use during the 6-month preventive inspections and maintenance activities and the detailed annual joint inspection of highway-rail grade crossings.
The following reference documents may be consulted when performing inspections and maintenance activities:
