Track Monitoring in Canada
Ontario, Canada: Until 1998, CN Railways maintained a full-time, manned watch for track settlements at a section of track near the city of Hamilton. Ground water drains through the foundation material of the track here, opening voids that result in settlements over a 35-meter long section.
The settlement problem persisted despite ground improvements, so CN housed an inspector at the site. The inspector walked the track before and after the passage of every train, checking for settlements. He then contacted the local signals office if the track bed required maintenance.
Now, the manned-watch has been replaced by Slope Indicator's automated track monitoring system. The system provides the same critical information, frees track inspectors for other areas, and saves the company the significant expense of supporting a manned watch.
For the first three months of automatic monitoring, a man was kept on site, but now CN relies entirely on the automated system. Confidence in automated monitoring was bolstered by CN's expertise in communications and by their specifications for the system, which were the following:
Continuous Monitoring: The system must provide non-stop monitoring, store data for remote access, and trigger alarms at remote signals office. The system must halt monitoring during passage of train to prevent false triggering of alarms.
Two Settlement Alarms: The system must check sensor readings and trigger alarms if (1) settlement exceeds 16 mm per 3 meters or if (2) settlement exceeds 25 mm per 3 meters. The first level allows trains to be slowed. The second level allows trains to be halted.
Two System Alarms: The system must warn the signals office if the data logger fails or if there is a power failure. The system is powered by batteries and continues to operate without mains power, which is used only for charging the batteries.
Graphical Software: The software must display retrieved data graphically so that problems areas can be identified quickly.
The initial system, installed in 1998, consisted of a CR10X data logger , EL beam sensors , and GraphX software . This was essentially the same system used for track monitoring in UK . Alarms were sent by spread-spectrum radio and a telephone modem allowed remote access to the logger.
In 2000, the system was upgraded with new sensors that are designed specifically for track monitoring. The new sensors feature articulated linkages that accommodate reballasting operations that involve lifting of the track. The sensors also have a wider range so that re-zeroing is not regularly required.
In 2006, the monitoring system was upgraded once again. This time it incorporates the Atlas web-based monitoring system. Readings from the logger are still collected by a telephone modem but are now forwarded to the Atlas data center. Atlas provides near-real time processing and presentation of the data, which is available to engineers through their web browsers.
In the screen shot at right, you can see a photograph of the site appearing the a web browser. The small green boxes that represent sensors. If you pass the mouse pointer over a box, the actual data value appears. The green would change to red if an alarm condition occurred. Clicking on a box pops up a five day trend plot. Atlas also automatically generates daily reports and emails them to selected users.