The news media did a sensational job covering the safety risk to the public and the inconvience of the March 12, 2007 CSX Railroad derailment at Oneida, New York involving propane tank cars that exploded and burned. The derailment has been cleaned up and CSX is back in operation moving freight by rail. The subsequent investigation into the cause of the derailment revealed that a broken rail caused the derailment. News agencies learned that CSX had been moving additional placarded cars (hazardous materials) on the rail corridor (Chicago Main Line) because the Office of Homeland Security required elimination of hazardous material movements through Washington D.C.

The US Dept. of Transportation, Federal Railroad Administration Office of Safety polices the railroads adherence to Federal Safety Standards which cover 1) Freight Car Safety; 2) Track Safety; 3) Railroad Signal System Safety; 4) Train Operations Safety and; 5) Worker Safety.

Local, State and Federal public servants were compelled by the news media and the public at large to address the frequency of the CSX train derailments in New York. The primary east-west mainline freight corridor (Chicago Main Line) carries the more ton miles annually than any other rail line in New York. Federal Railroad Administration (FRA) Administrator - Joe Boardman, was prompted to immediately reschedule the FRA’s Track Geometry Car (T-16) which records the loaded track surface, alignment, and gage defects on CSX in New York. The FRA also rescheduled the Gauge Restraint Measurement Track Geometry Car (T-18) which induces horizontal force against the gage face of the rails to determine track structure strength or weakness. The public message is these measures will offer risk reduction, at least short term, and the inspections will also spill over onto other railroads in New York. CSX owns their own Track Geometry Cars and routinely tests the Chicago Main Line tracks as a method to identify defects which are repaired. The Track Geometry Cars rerouted immediately onto CSX from their current schedules throughout the US will not find internal rail defects that cause broken rails, or rolling stock (freight cars) wheel defects that can break a rail.

The segment of the Chicago Line where the derailment occurred is categorized as class 4 track (maximum freight speed 60-mph and maximum passenger speed 79-mph). FRA Track Safety Standards require rail owners to perform ultrasonic rail testing for internal defects for any class 3 track (maximum freight speed of 40-mph) or tracks carrying passenger service. The owner (CSX) must maintain these records for the FRA’s review. The industry standard for internal rail defects is 0.09 service failures per track mile. It would be interesting to know what the rail defect ratio per mile is on the Chicago Mail Line. Good engineering practice requires adjusting the rail testing schedule by CSX to reduce risk. When CSX began to reroute placarded cars over the Chicago Line they may have increased the ultrasonic rail testing frequency to reduce risk, or if the frequency of defect found per mile on the Chicago Line was increasing, the rail testing frequency may have been increased. Lines with accumulated tonnage of 1-billion ton miles and a continuously increasing rail defect ratio are candidates for a new rail relay and replacement. Some railroad coal lines serving the Powder River Basin in Wyoming have a rail life of about 7-years due to the very high cumulative tonnage.

So what causes rail breaks? Rail breaks occur more frequently during cold weather conditions and on rail lines like the Chicago Main Line which has continuous welded rail with no joints to accommodate contraction and expansion caused by temperature. The rail is under considerably large tensile force when it contracts (shrinks) due to the cold temperature. Rail anchors are used keep the rail from shrinking, but if the anchors don’t work the rail will break. If the rail has an internal defect, it is a weak point in the rail system and it will break. If a broken wheel or flat spot on a wheel of a freight car is present, the impact induced from the wheel unevenness can break the rail. By far, the most common cause of rail breaks are from internal rail defects. The enormous number of load cycles induced by every wheel of the freight cars on many freight trains is referred to as live load stress range. The magnitude of the stress and the quantity of the cycles cause fatigue growth of the original microscopic imperfections in the rail metallurgy. Studies have shown that the flaw growth is more rapid during periods of cold weather. Flaw growth of transverse defects is between about 5 and 10 percent per Million Gross Tons (MGT). Accumulated tonnages of 10 to 40 MGT can have 100% cross-sectional area sizes of flaw (rail break). A rail flaw does not need to grow to 100% of the rail cross-section to cause a rail break! The Chicago Line probably sees annual tonnage of at least 70 MGT (on both tracks – double main line). Anyone can readily see how nasty these internal rail flaws are. The flaw can grow rapidly since you can not find them when they are less than 2.5% to 5% in size of the rail cross-section area. If the tonnage figures stated above are relatively accurate, one would expect the Chicago Line to be ultrasonically rail tested twice a year. Since Amtrak is allowed to operate passenger service over CSX’s Chicago Line, and hazardous materials are also moved over the line, risk aversion is important and rail testing frequency is fundamental.

A tiny inclusion, like a hydrogen bubble of microscopic size, can accidentally be included in the steel metallurgy that makes up the rail ingot used to fabricate rail at the steel mill. These inclusions are present in rail and most never grow and propagate into large defects. But some of the inclusions/imperfections do grow into defects like transverse fissures, compound fissures, detail fractures, and head and web separations.

A transverse fissure is a progressive crosswise fracture starting from a distinctive crystalline center or nucleus inside the head from which it spreads outward and is nearly smooth, bright or dark round or oval surface substantially at a right angle to the rail length. A compound fissure is a progressive fracture originating in a horizontal split head which turns up or down in the head of the rail as a smooth, bright or dark surface progressing until substantially at a right angle to the rail length. A detail fracture means a progressive fracture originating at or near the rail head surface. These fractures are not of internal origin and grow from a surface defect like a shelly spot or head checks or faking.

How do you find internal defects in rail? Ultrasonic rail test cars are used. A series of diodes on an undercarriage of the test car slice non-destructive sectional views from different angles along the rail while traveling on the track. When a defect is found, the car is stopped and hand testing equipment is used to verify the defect. The rail at the location of the defect is color code painted and marked for the track maintenance of way forces. Good engineering practice dictates replacement of all rail defects rather than taking remedial action such as limiting operating speed or applying joint bars to be consistent with maintaining a minimum track quality level. Certain types of rail defects also dictate the minimum required remedial action. Most Railroad Companies require section gangs to immediately follow the internal rail testing car and change out all of the defective rails. Remedial action, such as slow orders, is only used until the rail can be replaced. Track Supervisors of adjoining sections will typically “pool” their M/W Forces and help each other get the rails changed out without prolonged periods of slow orders.

Defects are hardly ever found that are smaller than 2.5% of the rail cross-sectional area. Current technology does not allow the CSX Railroad to find and remove the small rail defects. The defects that are found must be removed in accordance with CSX protocol which is at minimum the same remedial action steps that FRA Track Safety Standards prescribe or more stringent steps. Some Railroads require the defective rails to be broken using a Buda Rail Bender at the point of the defect and a photo taken of the defect. Other companies have rigid requirements that scrap rail be kept separate and shipped to scrap dealers. Failure to have a rigid policy and enforcement can lead to a defective rail being reinstalled on the line with catastrophic consequences.

When a rail “breaks” on the Chicago Line, which has centralized traffic control and cab signal technology, the rail segment between signal control points automatically goes red. The locomotive engineer upon encountering a red signal must stop. The locomotive engineer may only proceed at a speed that will allow him to stop within ½ the distance needed to stop after the CSX dispatcher has confirmed there are no conflicting train movements. However, one must assume the rail broke under the train so the signal system could not have prevented the magnitude of derailment that did occur. The evidence reported by the news agencies indicate part of the trains freight cars wheel treads were damaged which would indicate they passed over a broken rail while the lead freight cars did not display this damage.

In addition to the ultrasonic rail testing program described above, CSX employs Track Inspectors whom specifically get over the track every week. It is rare for a track inspector to first discover a broken rail. Typically, the signal maintainer finds the broken rail because they are called out by the dispatcher to locate and fix the track circuit which has given a red block indication when no train or equipment is present on the dispatchers display panel.

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