ABSTRACT

Railways are a vital infrastructure of any country. Passengers and goods have to be transported safely as per schedule to various destinations. To ensure that the whole system runs efficiently it is important that the trains, tracks and schedules are monitored continually and corrected fast if there is any deviation or disruption. If there is an accident, the cause has to be ascertained quickly and remedial action initiated. GeoEvent Recorder is a GPS based data recorder developed by ASL®, which can be used to record event occurrences with location and time stamp. At the control station movement of trains, train parameters and track conditions are continually monitored on a map (GIS) and controlled for efficient performance of the train fleet.

INTRODUCTION

“Indian Railways (IR) is one of the largest and busiest railway networks in the world, transporting just under 5 billion passengers and almost 350 million tons of freight annually. IR is the largest commercial or utility employer with more that 1.6 million employees. The railways traverse through the length and width of the country, the routes cover a total length of 63940 km. In 2005, IR owned a total of 216717 wagons, 39936 coaches and 7339 locomotives and ran a total of 14244 trains, including 8002 passenger trains daily.” [1]

“The main problem plaguing the Railways is the high accident rate which stands at 300 a year. Human error is the primary cause (83%) blamed for mishaps. Contributing to the Railways problems are the old communication, safety and signaling equipment, aging colonial-era bridges and century old tracks which require continual maintenance and upgrade.” [1]

To address the problem it is necessary to get a first hand account of the status of the various components in the Railway Network. The condition of the trains, the tracks, the signaling systems have all to be monitored to ensure that they are all in proper working order. The Research Design and Standardization Organization (RDSO) of the Indian Railways initiated a few projects for this purpose. The projects are as follows [5]:

• Development of Microprocessor based control system with event recorder and vigilance control device for diesel electric locomotion
• Development of event recorder cum vigilance control device for diesel locomotion
• Onboard diagnostic system of diesel locomotives
• Satellite Imaging for Railway Navigation (SIMRAN)
• GPS based railway network mapping and train tracking
• Wireless connectivity

These projects when completed should help in providing accurate data on train performance and result in overall improvement in maintenance and diagnosis of the train. The data derived from the event recorder will also be invaluable in rail accident investigations.

“Black Box”, a mandatory device on all planes, is an event recorder cum voice recorder that is used in accident investigations to determine the cause of accidents (pilot error, equipment error or environmental factors). These event recorders are increasingly being used for monitoring of equipment and system performance.

Accident / Incident recorders do not prevent accidents, however they are used to understand accident causes and event sequences and so prevent future incidents and accidents. Knowing the causes of accidents permits changes to be made to equipment, maintenance procedures, operating procedures and/or training to minimize the chance of future accidents. When the event recorder is used also as a “maintenance and monitoring equipment”, service availability may improve by warning of impending failures (trend analysis) or aiding and locating existing faults. Resulting in maintenance productivity and maintenance cost reduction.

GeoEvent Recorder is a GPS based Event Recorder that has the capability of capturing events with both a time stamp and a location stamp. Since the time and location parameters are extracted from the GPS string the events are accurately logged with both the where and the when information. This information is invaluable as these two parameters allow the events to be correlated with other findings both on the spatial as well as the temporal plane.

RAILWAY EVENT RECORDERS

Locomotive event recorders have been in use for quite some time. Data storage is provided by magnetic tape, battery-backed RAM, nonvolatile EEPROM or “flash” memory. Solid state memory is available from 256K bytes to 2 M Bytes and can be downloaded via a communications unit or a removable memory card. There are two types of event recorders [4]:

1. Non-integrated stand alone recorders where the sensors have to be interfaced to the recorder
2. Integrated digital systems that interface with the locomotive Process Controller (LPC) computer via a serial bus.

Event Recorders are required to monitor the following minimum parameters:

1. Train speed
2. Selected direction of motion
3. Time
4. Distance
5. Throttle position
6. Applications and operations of the train automatic air brake
7. Applications and operations of the independent brake
8. Application and operations of dynamic brake, if so equipped and
9. Cab signal aspect(s), if so equipped and in use

Since the Event Recorders are meant for incident / accident analysis. The Federal Railroad Administration , USA, has sent a directive for locomotives originally manufactured before October 1, 2006, and equipped with an event recorder that uses magnetic tapes as its recording medium to have the recorder removed from service on or before October 1, 2009 and replaced with a certified crashworthy event recorder memory.

The requirements of a crashworthy unit is indicated in the table below.

Table 1: Crashworthy Specifications [2,3]

 GEOEVENT RECORDER

 GeoEvent Recorder is a GPS based data recorder developed by ASL®, which can be used to record event occurrences with location and time stamp. Various parameters are measured via the analog and digital inputs of the recorder. The expected range of safe operation is preprogrammed and whenever the readings exceed the limit the “event” is captured and an alarm activated. The event can also be communicated to the next station or the central control station via a communication channel (GSM, CDMA or Radio). The events with location and date stamp are recorded in a non-volatile compact flash. The complete data can be retrieved through a USB 2.0 port. The retrieved data can be used for analysis of train performance at regular intervals. Through the communication interface real-time location and telemetry can be sent for monitoring and diagnostic purposes. At the control station movement of trains, train parameters and track conditions are continually monitored on a map (GIS) and controlled for efficient performance of the train fleet.

The product is based on system on chip approach.

As shown in the diagram above, the system implemented on the chip has the following components:

1. 32 – bit CPU
2. UART
3. USB 2.0
4. Event Handler
5. Compact Flash interface to USB using FAT File System.

Figure 2: GeoEvent Recorder – Block Diagram

The product is developed to capture events with the time and location stamp. The events captured are stored in the Compact Flash. The Event handler inside the SOC is used to capture the events. The Event Handler gets the inputs from 8 physical inputs, which are used to measure various health parameters of a mobile unit. The handler also gets inputs from the manual switches. Whenever the event occurs, the handler passes the event to the CPU, which in turn gets the GPS data from the onboard GPS receiver in serial format through one of the UARTs implemented on the system.

Once the event occurs on the physical input, i.e. when the physical health measure cross the threshold set by the user, the handler keeps track of the behavior of that parameter for specific amount of time and stores the values with the location and time on the compact flash while on the move.

The product also has optional communication link available in the form of either GSM/GPRS or CDMA or Radio Interface. The communication link can establish the communication with a control station from the mobile unit. The CPU use this link to send some critical events to control station in real time, which can help in averting emergency conditions by sending help to the mobile unit having problems. The GSM or CDMA module is also connected with CPU through the second UART.

The events, which are not reported to control station through communication link, are stored in the on board Compact Flash. The reason behind using the Compact flash is, it is a removable memory solution available in various huge storage capacities, making it possible to support the customers with the large storage capacity required for their application. As the storage capacities are higher, it can store the events from all type of inputs for longer times, which makes it possible to store data for longer journeys.

The data stored in the system is transferred to control station PC for analysis of the health and other parameters of mobile unit through a serial link. And as the data stored are quite big, they are to be retrieved through high speed communication. USB 2.0 has been implemented on the SOC, giving higher data rates of 480 Mbps, in comparison to speeds of around 1 Mbps for UARTs. The Compact Flash is formatted for FAT File system, which is shown as Mass Storage Device through USB on the PC. The data stored in the CF thus can be transferred easily in WINDOWS as it will be shown as a “REMOVABLE DRIVE” ICON.

The SOC has one more UART for connection of serial display as an optional feature. The display used with this initial production is 240 X 64 graphical display. The Display is a separate unit with Keypads, which makes the SOC based system without display as a Black box capturing events. The display unit can be placed at a convenient location accessible by the driver.

The forth UART on the SOC has been provided for debugging of the system through the control station PC if required. This port can be also used transfer data of small size from the scratch pad memories provided onboard.

There are two program memories to run the embedded application and to configure the SOC on startup.

CONTROL STATION APPLICATION

A GSM/GPRS/CDMA or Radio Modem receives the location and time stamped information from the GeoEvent Recorder in the train and tracks the movement of the vehicle at preset intervals. The information is stored in a MySQL database and is available for analysis. It is also possible to download the data from the compact flash in the GeoEvent Recorder by giving a “download” command via the communication link.

The train can be tracked on a map with information of the nearest landmark. Figure 3 show the movement of a train on the Chennai Suburban line.

Figure 3: Train on Chennai Suburban Line

CONCLUSION

 As opposed to existing Railway Event Recorders, GeoEvent Recorder has the added feature of location and time stamping all events. It also has the ability of communicating unusual incidents or events to the control station so that other trains traveling on the same track may be alerted.