Rail inspection
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Rail inspection is the practice of examining
rail tracks A railway track (British English and UIC terminology) or railroad track (American English), also known as permanent way or simply track, is the structure on a railway or railroad consisting of the rails, fasteners, railroad ties (sleepers, ...
for flaws that could lead to catastrophic failures. According to the United States
Federal Railroad Administration The Federal Railroad Administration (FRA) is an agency in the United States Department of Transportation (DOT). The agency was created by the Department of Transportation Act of 1966. The purpose of the FRA is to promulgate and enforce rail saf ...
Office of Safety Analysis,Federal Railroad Administration
/ref> track defects are the second leading cause of accidents on railways in the United States. The leading cause of railway accidents is attributed to
human error Human error refers to something having been done that was " not intended by the actor; not desired by a set of rules or an external observer; or that led the task or system outside its acceptable limits".Senders, J.W. and Moray, N.P. (1991) Human ...
. The contribution of poor management decisions to rail accidents caused by infrequent or inadequate rail inspection is significant but not reported by the FRA, only the NTSB. Every year, North American railroads spend millions of dollars to inspect the rails for internal and external flaws.
Nondestructive testing Nondestructive testing (NDT) is any of a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage. The terms nondestructive examination (NDE), n ...
(NDT) methods are used as preventive measures against track failures and possible derailment.


History

The first rail inspections were done visually and with the Oil and Whiting Method (an early form of Liquid Penetrant Inspection). Many sources cite that the need for better rail inspections came after a derailment at
Manchester, New York Manchester is a town in Ontario County, New York, United States. The population was 9,406 at the 2020 census. The town was named after one of its villages, which in turn was named after the original Manchester in England. It was formed in 1822 f ...
, in 1911. That particular accident resulted in the death of 29 people and injuries to 60 others. The investigation of the accident revealed that the cause was a transverse fissure (a critical crack that lies perpendicular to the length of the rail) in the rail. Further investigation in the late 1920s showed that this type of defect was quite common. With increased rail traffic at higher speeds and with heavier axle loads today, critical crack sizes are shrinking and rail inspection is becoming more important. In 1927, Dr.
Elmer Sperry Elmer Ambrose Sperry Sr. (October 12, 1860 – June 16, 1930) was an American inventor and entrepreneur, most famous for construction, two years after Hermann Anschütz-Kaempfe, of the gyrocompass and as founder of the Sperry Gyroscope Company. ...
built a massive rail inspection car under contract with the
American Railway Association The American Railway Association (ARA) was an industry trade group representing railroads in the United States. The organization had its inception in meetings of General Managers and ranking railroad operating officials known as Time Table Conventi ...
. Magnetic induction was the method used on the first rail inspection cars. This was done by passing large amounts of the magnetic field through the rail and detecting
flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport ph ...
leakage with search coils. Since then, many other inspection cars have traversed the rails in search of flaws. In 1949 ultrasonic flaw detection was introduced by Sperry Rail Service (Named after Dr. Elmer Sperry), by the 1960s Ultrasonic Inspection Systems had been added to the entire Sperry Fleet. Rail inspection continues to advance to this day. Companies like Sperry Rail Service, Nordco Inc, Herzog Rail Testing, and many others continue to develop an ever-increasing array of technologies to detect internal flaws.


Defects and location

There are many effects that influence rail defects and rail failure. These effects include bending and shear stresses, wheel/rail contact stresses, thermal stresses, residual stresses, and dynamic effects. Defects due to contact stresses or rolling contact fatigue (RCF): *tongue lipping *head checking (gauge corner cracking) *squats - which start as small surface-breaking cracks Other forms of surface and internal defects: *
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
*inclusions *seams *shelling *transverse fissures *wheel burn One effect that can cause crack propagation is the presence of water and other liquids. When fluid fills a small crack and a train passes over, the water becomes trapped in the void and can expand the crack tip. Also, the trapped fluid could freeze and expand or initiate the corrosion process. Parts of a rail where defects can be found: *head *web *foot *switchblades *welds *bolt holes A majority of the flaws found in rails are located in the head, however, flaws are also found in the web and foot. This means that the entire rail needs to be inspected.


NDT methods

A list of methods used to detect flaws in rails: *
Ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
- the most popular method *Visual Inspection - Primarily using cameras to detect broken or cracked joint bars in bolted rail. *Liquid Penetrant Inspection (LPI) - used for manual inspection of joint bars and rail ends. *
Eddy current Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a mag ...
inspection - great for surface flaws & near-surface flaws * Magnetic Particle Inspection (MPI) - used for detailed manual inspection *
Radiography Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...
- used on specific locations (often predetermined) such as bolt holes and where
thermite welding Exothermic welding, also known as exothermic bonding, thermite welding (TW), and thermit welding, is a welding process that employs molten metal to permanently join the conductors. The process employs an exothermic reaction of a thermite composit ...
was used * Magnetic induction or
Magnetic flux leakage Magnetic flux leakage (TFI or Transverse Field Inspection technology) is a magnetic method of nondestructive testing that is used to detect corrosion and pitting in steel structures, most commonly pipelines and storage tanks. The basic princip ...
- earliest method used to locate unseen flaws in the railway industry *
EMAT Electromagnetic acoustic transducer (EMAT) is a transducer for non-contact acoustic wave generation and reception in conducting materials. Its effect is based on electromagnetic mechanisms, which do not need direct coupling with the surface of th ...
Electromagnetic Acoustic Transducer


Utilizing NDT methods

The techniques mentioned above are utilized in a handful of different ways. The probes and transducers can be utilized on a "walking stick", on a hand pushed trolley, or in a handheld setup. These devices are used when small sections of track are to be inspected or when a precise location is desired. Many times these detail-oriented inspection devices follow up on indications made by rail inspection cars or rail trucks. Handheld inspection devices are very useful for this when the track is used heavily because they can be removed relatively easily. However, they are considered very slow and tedious, when there are thousands of miles of track that need an inspection. Rail
inspection car A speeder (also known as a section car, railway motor car, putt-putt, track-maintenance car, crew car, jigger, trike, quad, trolley, inspection car, or a draisine) is a small railcar formerly used around the world by track inspectors and work cre ...
s and HiRail trucks are the answer to today's high mileage inspection needs. The first rail inspection cars were created by Dr. Sperry. Since then, many new models have rolled out. These rail inspection cars are basically their own train with inspection equipment on board. The probes and transducers are mounted on carriages located underneath the inspection car. Modern-day inspection cars now use multiple NDT methods. Induction and ultrasound methods can be used in rail inspection cars and operate at testing speeds of more than . Increased Camera systems for detection of broken joint bars or missing bolts. Eddy Current systems for the detection of near-surface defects. There are many manufacturers of road/rail inspection trucks, otherwise known as HiRail trucks. These HiRail inspection cars are almost all ultrasonic testing exclusively, but there are some with the capability to perform multiple tests. These trucks are loaded with high-speed computers using advanced programs which recognize patterns and contain classification information. The trucks are also equipped with storage space, tool cabinets, and workbenches. A
GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
unit is used with the computer to mark new defects and locate previously marked defects. The
Federal Railroad Administration The Federal Railroad Administration (FRA) is an agency in the United States Department of Transportation (DOT). The agency was created by the Department of Transportation Act of 1966. The purpose of the FRA is to promulgate and enforce rail saf ...
(FRA) requires that any indications of defects need to be hand-verified immediately. The GPS system allows a follow-up car to find precisely where the flaw was detected by the lead vehicle. One advantage to the HiRail trucks is that they can work around regular rail traffic without shutting down or slowing down entire stretches of track. However, because railroad management frequently orders HiRail trucks to be used to inspect tracks at speeds over , tracks reported as having been inspected are, in fact, not inspected. An NTSB report on the Amtrak derailment in Oregon in 2006 documented this fact.


The future of rail inspection

With increased rail traffic carrying heavier loads at higher speeds, a quicker more efficient way of inspecting railways is needed. Lasers inspect railway geometry, but one day they might be utilized as a form of non-contact evaluation of the rail. This most likely will be done with laser-optical transmitting transducers in ultrasonic testing. Eliminating contact with the rail could one day allow high-speed detection of flaws. (Testing of rail is currently able to be done at 80 km per hour with a Speno US-6 Ultrasonics train) Another need for the future is a complete rail inspection system. A step in this direction is a deeper investigation of the rail by using low-frequency eddy currents. Other advancements could include neural network analysis of signals to improve defect detection and identification and longitudinal guided ultrasonics. Improved rail quality, composition, and joining techniques could lead to better wear characteristics and a longer lifespan of the rail. Some investigation into banitic steels looks promising. A safe and portable means of filmless radiography could assist with onsite defect evaluation. These are just a few advancements in the process of being developed for future use.


Example trains

*
Doctor Yellow is the nickname for the high-speed test trains that are used on the Japanese Shinkansen ("Bullet Train") dedicated express passenger train routes. The trains have special equipment on board to monitor the condition of the track and overhead wire ...
(Japan) *
New Measurement Train The New Measurement Train (NMT), also known as the ''Flying Banana'', is a specialised train which operates in the United Kingdom to assess the condition of Rail tracks, track so that engineers can determine where to work. It is a specially conve ...
(United Kingdom)


See also

*
Maintenance of way Maintenance of way (commonly abbreviated to MOW) refers to the maintenance, construction, and improvement of rail infrastructure, including Railway track, tracks, ballast, grade, and lineside infrastructure such as Railway signal, signals and sign ...
*
Nondestructive testing Nondestructive testing (NDT) is any of a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage. The terms nondestructive examination (NDE), n ...
*
Rail tracks A railway track (British English and UIC terminology) or railroad track (American English), also known as permanent way or simply track, is the structure on a railway or railroad consisting of the rails, fasteners, railroad ties (sleepers, ...
*
Work train A work train or departmental train (engineering train in the UK) is one or more rail cars intended for internal non-revenue use by the railroad's operator. Work trains serve functions such as track maintenance, maintenance of way, revenue colle ...
* Track checker *
Track geometry car A track geometry car (also known as a track recording car) is an automated track inspection vehicle on a rail transport system used to test several parameters of the track geometry without obstructing normal railroad operations. Some of the p ...


References

*Cannon, D. F., Edel, K.-O., Grassie, S. L. & Sawley, K. "Rail defects: an overview." ''Fracture & Fatigue of Engineering Material & Structures''. vol. 26. no.10. pp. 865–886. Oct. 2003. *''Eddy Current Inspection''. GE Inspection Technologies Ltd. – Hocking. April 5, 2005. http://www.hocking.com/applications/rail/. *Federal Railroad Administration, Office of Safety Analysis. "Train Accidents by Type and Major Cause from Form: FRA F 6180.54. Jan.-Dec, 2004." April 6, 2005. http://safetydata.fra.dot.gov/officeofsafety/. *''G-Scan''. "Practical Application" Guided Ultrasonics (Rail) Ltd. April 6, 2005. http://www.guided-ultrasonics.com/rail/index.html. *Judge, Tom, engr. ed. "Looking for flaws in all the right places." ''Railway Age''. vol. 203. no.12. pp. 29–31. Dec. 2002. *Keefe, Kevin P. "Track classifications - Classifying and inspecting railroad track." ''Trains Magazine''. Sept. 10, 2002. *National Transportation Safety Board. April 6, 2005. www.ntsb.gov. *
Rail Inspection
'. NDT Resource Center. April 5, 2005.


External links

* * {{citation , url = http://www.railwaywondersoftheworld.com/rail-defects.html, chapter= "Detecting rail defects", title= Railway Wonders of the World, year = 1936, pages = 919–924, editor-first=Clarence , editor-last=Winchester illustrated description of the Sperry detecting system
Sperry Rail Defect Manual
1964 More information about the types of defects that can be found by the Sperry rail car
Holland Trackstar
Railway safety Permanent way