Broken Rail!

Port Townsend, today. I received this photo from one of my sources, taken at a recent derailment on the BHP Billiton line out to Port Hedland in Australia. Few details are available - it is a private railroad, and it is virtually in the middle, or very close to, the middle of nowhere. And let me be clear, there has not been a determination made as to what caused this derailment last weekend.



Last July, a derailment on Transnet's Sishen - Saldanha Bay Heavy Haul Corridor (HHC,) resulted in more than 100 fully loaded iron ore cars leaving the rails, causing one big headache. And, as I pointed out in "B Whale: The Rail Connection," delivery to the ore terminal is a "just in time" - JIT - schedule, as ships queue for loading.


Derailments can be costly. BHP Billiton's Newman to Port Hedland line is a Heavy Haul Corridor, in the same class as the Estrada de Ferro Carajas (EFC) operated by Vale (pronounced "Valley") in Brazil which I thoroughly documented last year. And Transnet's Sishen - Saldanha Bay HHC in South Africa.

Despite the fact that these lines are well constructed and heavily maintained, structural failure does happen. A sudden wheel failure. Or a section of rail suffering structural failure.

Pennsylvania Railroad Inspection Car, circa 1891

I had a first hand encounter as a young lad, when the Sperry Rail Service inspection car 136 came to Prince Rupert in 1958. A technician spent considerable time giving me the grand tour of the car, and showing me the instrumentation, archaic by today's standards, used to inspect rail using ultra sound technology.

It has long been the dream of track maintenance engineers to find a way to use ultra sound to detect broken rails, remotely, similar to slide detector fences. Slide detector fences active when a rock or slide disrupts an energized fence, activating a stop signal to the block of rail affected.


Many attempts to use ultra sound to monitor long stretches of track have failed. I recently learned that South Africa's Transnet, working with Council for Scientific and Industrial Research and the Institute for Maritime Technology (IMT) in South Africa, are apparently on the verge of applying ultra sound to monitor rails, over long distances, to detect rail structural failure.

A transducer is bolted in place on the rail. When it vibrates, the railway line vibrates at an ultrasonic frequency, in the nanometer range. The sound propagates down the rail for a distance of up to 1,5 km (4,900 feet,) where a pickup sensor "listens" for the arrival of a valid signal.

If valid signal not detected within a set time, an alarm activated, with a stop signal sent to rail traffic in the block. This means that hundreds of kilometers of rail can be monitored continuously and remotely, with Transnet able to pinpoint the section where the rail break has occurred.

The detector system has been tested in Canada, on the New York subway, Hong Kong and is currently undergoing trials in Japan. Some tests have been more successful than others depending on tracks configuration and lengths, and under different ambient temperatures.

The goal is to fine-tune the technology, resulting in a reliable system within the next two to three years.

See Also:
Sperry Rail Services 131
Sperry Rail Services 131 Hit by Derailment!
Sperry Rail Services 136