A transverse fissure in rail is a progressive crosswise fracture that starts from a crystalline nucleus inside the rail head and grows at a right angle to the rail. Under 49 CFR 213.113 it is a named rail defect: from 5% of head area it needs remedial action, and at 100% only visual supervision or joint bars keep trains moving.
The classic cause is a hydrogen shatter crack left in rail that was not control-cooled at the mill. The defect gave its name to a whole field of rail inspection after a broken rail killed 29 people near Manchester, New York, in 1911. This guide covers what the defect is, why it forms, how ultrasonic testing finds it, what the FRA remedial action table requires, and how to tell it apart from the detail fracture, the defect it is most often confused with.
Contents: Definition · Causes · vs detail fracture · History · How common · Detection · 213.113 · Worked example · Limits · FAQ
What is a transverse fissure in rail?
A transverse fissure is an internal fatigue crack in the rail head, defined in 49 CFR 213.113(d)(15). The regulation's wording is the reference every track owner and test contractor works from:
"Transverse fissure means a progressive crosswise fracture starting from a crystalline center or nucleus inside the head from which it spreads outward as a smooth, bright, or dark round or oval surface substantially at a right angle to the length of the rail. The distinguishing features of a transverse fissure from other types of fractures or defects are the crystalline center or nucleus and the nearly smooth surface of the development which surrounds it." — 49 CFR 213.113(d)(15), eCFR
Three features in that definition matter in the field:
| Feature | What it means | Why it matters |
|---|---|---|
| Internal nucleus | The crack starts inside the head, not at the running surface | Nothing is visible on the rail until the fissure breaks out or the rail fails |
| Crosswise growth | The crack face is roughly perpendicular to the rail's length | The face is a good reflector for an angled ultrasonic beam travelling along the rail |
| Smooth, often banded surface | Fatigue growth leaves a smooth face, often bright or dark, sometimes with arrest marks | On a broken rail, the face and its nucleus identify the defect for the FRA accident report |
A transverse fissure is sized as a percentage of the rail head cross-sectional area it has weakened. That percentage drives the remedial action under 213.113(c), so sizing accuracy is a regulatory issue, not just a reporting detail.
Key takeaway: a transverse fissure is defined by where it starts (an internal nucleus) and how it grows (crosswise), and it is sized by percent of head area.
What causes a transverse fissure?
The classic cause is a shatter crack: a tiny internal crack formed by hydrogen in the steel when rail cools too quickly after rolling. Under repeated wheel loads and bending, a shatter crack can act as the nucleus that grows into a transverse fissure.
The research record on this is long and consistent:
- 1911 onward. J. E. Howard of the US Bureau of Standards first reported this type of failure in 1911, after the fatal Lehigh Valley wreck (as recounted in a 1932 AIME paper on rail steels).
- 1941. The Joint Investigation of Fissures in Railroad Rails at the University of Illinois found in rolling-load tests that "only shatter-cracked rails developed fissures", although not every shatter-cracked rail did. Bending moment pushed the cracks toward a transverse direction and sped their growth (Seventh Progress Report, AREA Bulletin vol. 42, 1941, TRID record).
- 1943. The same investigation examined control-cooled rails that had failed in service and reported that none of them contained shatter cracks. Their transverse fissures started instead from blow holes and welded spots (Ninth Progress Report, AREA Bulletin vol. 44, 1943, TRID record).
- 1972. AREA's rail failure statistics reported no new transverse fissure failures in control-cooled rail during 1971 (AREA Bulletin vol. 73, 1972, TRID record).
- 1970s. Mills began removing hydrogen by vacuum degassing, which made control cooling unnecessary. A 1974 trade article described hydrogen in molten steel as the "culprit that causes shatter cracks" (Railway Track and Structures, 1974, TRID record).
Control cooling means slowing the cooling of hot rails, for example in insulated boxes, so hydrogen can diffuse out before it forms cracks. Control cooling was developed in the 1930s, and AREA committees were still drafting standards for it in 1941. Rail rolled before mills adopted it is the population most at risk.
What about oxide inclusions?
Oxide and other non-metallic inclusions can also nucleate a transverse fissure, but the record does not support calling them "the leading cause". A 1957 AREA review of 32 failed control-cooled rails attributed 11 to transverse fissures, from shatter cracks, hot-torn steel and, in one case, an inclusion; 13 of the 32 were detail fractures from shelling (TRID record 11673). Inclusions, blow holes and weld spots are secondary nucleation sites. In modern clean, degassed rail steel, the surface-initiated detail fracture is the more common transverse defect (see the FRA data below).
| Nucleus | Era it dominates | Primary control |
|---|---|---|
| Hydrogen shatter crack | Rail rolled before control cooling | Control cooling, later vacuum degassing |
| Blow hole, hot tear, welded spot | Control-cooled rail (1940s–1950s reports) | Mill practice and quality control |
| Oxide or other inclusion | Any era; less common in clean modern steel | Steelmaking cleanliness |
| Surface rolling contact fatigue (shells, head checks) | Modern high-tonnage track | Grinding and lubrication; this produces a detail fracture, not a transverse fissure |
Key takeaway: the classic transverse fissure is a manufacturing defect, a hydrogen shatter crack in rail that was not control-cooled; service loading only grows it.
How is a transverse fissure different from a detail fracture?
A transverse fissure starts inside the head; a detail fracture starts at or near the running surface. Both grow crosswise and can look alike once the rail breaks, but the regulation separates them by origin. 213.113(d)(7) says detail fractures "should not be confused with transverse fissures, compound fissures, or other defects which have internal origins", and that detail fractures "may arise from shelled spots, head checks, or flaking".
| Transverse fissure (TF) | Detail fracture (DF) | Compound fissure (CF) | |
|---|---|---|---|
| 213.113(d) definition | (15) | (7) | (3) |
| Origin | Crystalline nucleus inside the head | At or near the head surface | A horizontal split head that turns up or down |
| Typical cause | Hydrogen shatter crack or internal flaw from manufacture | Rolling contact fatigue: shelling, head checks, flaking | Growth of a horizontal split head |
| Typical location | Often central in the head, though fissures can sit toward the gauge side | Usually the gauge corner of the high rail on curves | Head, from a horizontal plane |
| Main detection problem | Small nucleus gives a weak early echo | Masking: surface shells and head checks block the beam | Horizontal leg may be found first with 0° |
| 213.113 remedial row | Shared with DF | Shared with TF | Separate row, no joint-bar option |
| FRA accident cause code | T220 (combined with CF) | T207 | T220 (combined with TF) |
The "masking" problem often blamed on transverse fissures belongs mainly to detail fractures. Shelling and head checks sit on the surface, right where a detail fracture starts, and they reflect or scatter the ultrasonic beam before it reaches the crack below. A true transverse fissure under clean rail has no such shield. See EMA Industries' guide to how a detail fracture develops in rail and the companion page on compound fissures in rail.
Key takeaway: classify by origin. An internal nucleus means TF; a surface origin from shells or head checks means DF.
Which accidents made the transverse fissure famous?
The defining case is the Lehigh Valley Railroad wreck near Manchester, New York, on August 25, 1911. Train No. 4, running from Buffalo toward Philadelphia, derailed on a broken rail at the Canandaigua Outlet bridge, and cars fell from the bridge. Twenty-nine people died and about 62 were injured.
The Interstate Commerce Commission investigated (ICC accident report, ROSA P). The broken rail was found in seventeen pieces, and the investigation attributed the break mainly to transverse fissures, with piping in the rail as a second factor. It concluded that careful inspection of the rail in track would not have revealed the defects. Accounts of the investigation say the rail had been in service for less than a year. J. E. Howard of the Bureau of Standards reported the failure as an internal transverse fissure, and the case opened decades of research into the defect.
The original version of this article called the train the "Philadelphia Day Express". We could not confirm that name in the ICC record or in other sources, so this page uses the ICC's identification: Lehigh Valley train No. 4.
The Superior, Wisconsin derailment was a detail fracture, not a transverse fissure
The 1992 derailment at Superior, Wisconsin, is often cited in transverse fissure articles, but the NTSB found a different defect. At about 2:50 a.m. on June 30, 1992, a Burlington Northern freight train derailed approaching the Nemadji River bridge. A tank car of aromatic concentrates containing benzene fell into the river, and the vapor cloud led to the evacuation of more than 40,000 people from Superior, Duluth and nearby areas (NTSB/HZM-94/01, March 1994).
The NTSB stated the cause directly in its April 1, 1994 recommendation letter to the FRA:
"The derailment resulted when a preexisting crack (detail fracture) inside the rail caused the rail to break under the train load." — NTSB Safety Recommendation R-94-1 and -2
Metallurgical examination found six fatigue cracks, all detail fractures from shelling at the upper gauge corner of the rail head. The rail had been ultrasonically tested about six weeks earlier. The NTSB concluded that overlapping shelling cracks inside the head "prevented the penetration of the ultrasonic sound waves", so the defects could not be detected. The flaw sat inside the rail head, under a damaged surface; it was not "underground". This is the clearest published example of masking, and it is a detail fracture case.
Key takeaway: Manchester, 1911, is the classic transverse fissure case; Superior, 1992, is a masked detail fracture.
How common are transverse fissure derailments today?
Transverse and compound fissures together (FRA cause code T220) caused 576 reported train accidents from 2005 to 2014, about 21.6% of the accidents caused by rail, joint bar and anchoring defects (T2xx codes). That is the true denominator behind the "21.7%" figure that circulates online. It is not a share of all railway accidents.
We reproduced the figure from FRA's train accident dataset (data.transportation.gov, dataset byy5-w977, queried 24 October 2026, data through July 31, 2026). Counts change slightly as late reports are filed under 49 CFR 225.11, so the 0.1-point gap is expected.
| FRA data, all track types | 2005–2014 | 2016–2025 |
|---|---|---|
| T220 transverse/compound fissure accidents | 576 | 175 |
| All T2xx rail, joint bar and anchoring accidents | 2,667 | 1,640 |
| T220 share of T2xx | 21.6% | 10.7% |
| T220 share of all reported train accidents (2005–2014: 24,818) | 2.3% | not calculated |
| T207 detail fracture accidents, 2005–2014 | 457 | not calculated |
Three cautions apply when quoting these numbers:
- T220 combines transverse and compound fissures. FRA data can't separate the two, so no public count of "transverse fissure derailments" alone exists.
- Most T220 accidents are in yards. Of the 576 from 2005 to 2014, 304 were on yard track and 216 on main track.
- Older "transverse defect" totals usually add detail fractures. The original article's "1,181 derailments and $294 million, 2002–2011" matches T220 plus T207 combined: our query returned 1,179 accidents and $292.2 million in reported damage for those two codes in that period.
On main track the balance has shifted toward surface-initiated defects. From 2016 to 2025, T207 detail fractures caused 110 main-track derailments, against 57 for T220. University of Illinois researchers reported that transverse/compound fissures and detail fractures together accounted for over 65% of broken-rail freight derailments on Class I main lines from 2001 to 2010 (Liu et al., Journal of Transportation Engineering, 2014). For how the codes work, see FRA defect codes explained.
Key takeaway: quote T220 with its denominator and date range, and say that it includes compound fissures.
How does ultrasonic testing detect a transverse fissure?
A transverse fissure is found with an angled shear-wave beam, typically 70°, aimed along the rail into the head so the beam strikes the crack face nearly head-on. A straight 0° beam travels parallel to a transverse crack face and is a poor primary detector for it.
Rail test systems, whether a test car, a hi-rail unit or a walking cart, carry several probes, each covering a different defect orientation. The arrangement below is typical industry practice; channel layouts vary by system and owner procedure.
| Channel (typical) | Aimed at | Main defects found |
|---|---|---|
| 70° forward and backward | Rail head, along the rail | Transverse fissures and detail fractures |
| 70° skewed or offset toward the gauge corner | Gauge corner of the head | Detail fractures under shelled or head-checked surfaces |
| About 37–45° forward and backward | Head-web area and web, through to the base | Bolt hole cracks, web defects, some head-web separations |
| 0° straight beam | Vertically through head, web and base | Horizontal split heads, head-web separations, compound fissures; vertical split heads through loss of back-wall echo |
| Side-looking probes (some systems) | Head from the side or the lower head corner | Vertical split heads and gauge-corner defects |
One published system design uses 0°, 38° and 70° probes (US Patent 5,777,891). The 0° channel also works as a coupling check: when the back-wall echo disappears, the test either hit a horizontal defect or lost contact, and the operator must decide which.
When a test car flags a suspect, a qualified operator under 49 CFR 213.238 verifies it with hand-held equipment, sizes it as a percentage of head area and marks the rail. How often rail must be searched is set by 49 CFR 213.237, not by 213.113.
How well do test systems find transverse defects?
Field trials give realistic expectations. In a 1999 TTCI evaluation of six hi-rail test systems on 49 known defects, the systems found 75% of transverse defects overall: 66% of those at 20% of head area or less, and 96% at 21% or more. Transverse defects under shells were found about 62% of the time, against 77% for those not under shells (TTCI Technology Digest TD-99-006). These figures are from 1999 equipment and should be read as a historical baseline, not current performance.
Key takeaway: 70° channels find transverse fissures; 0° and 37–45° channels cover the other orientations; small and masked defects are the ones missed.
What does 49 CFR 213.113 require when a transverse fissure is found?
The track owner must verify the indication, then apply the remedial action in the 213.113(c) table for the defect's size as a percent of head area. Under 213.113(b), verification is due within four hours, or immediately when the defect would need action A, A2 or B. A person designated under 213.7 decides whether the track stays in service (213.113(a)).
Transverse fissures share one row of the table with detail fractures, engine burn fractures and defective welds:
| % of rail head cross-section weakened | Transverse fissure, detail fracture, engine burn fracture, defective weld | Compound fissure (for comparison) |
|---|---|---|
| 5% to less than 25% | C | B |
| 25% to less than 60% | D | B |
| 60% to less than 70% | A2, or E and H | B |
| 70% to less than 100% | A2, or E and H | A2 |
| 100% | A, or E and H | A |
Source: 49 CFR 213.113(c) remedial action table, eCFR, as revised by the 2014 Improving Rail Integrity final rule. The table is printed as an image in the CFR; check the current eCFR version before quoting it in a procedure.
What the letters require (summarized; each speed is "or the maximum allowable for the track class, whichever is lower"):
| Action | Requirement |
|---|---|
| A | Assign a person designated under 213.7 to visually supervise each operation over the defective rail |
| A2 | A designated person visually inspects the rail; trains may then run at up to 10 mph for up to 24 hours before another inspection |
| B | Limit speed to 30 mph, set by a designated person with at least one year of supervisory experience in track maintenance |
| C | Apply joint bars, bolted only through the outermost holes, within 10 days. On Class 3–5 track, 30 mph until the bars are on, then 50 mph. If the defect was found during a 213.237 search, 50 mph is allowed for up to 4 days; after that, 30 mph until barred. Bars not applied within 10 days: 10 mph |
| D | Apply joint bars, bolted only through the outermost holes, within 7 days. On Class 3–5 track, 30 mph or less (as authorized by a designated person with one year of supervisory experience) until the bars are on, then 50 mph. Bars not applied within 7 days: 10 mph |
| E | Apply joint bars bolted as required by 213.121(d) and (e) |
| H | Limit speed to 50 mph |
Transverse fissures and detail fractures allow the joint-bar option (E and H) even at 100% of head area. Compound fissures don't. The compound fissure row runs B, A2 and A with no joint-bar alternative, so a draft that offers joint bars for a compound fissure is wrong. The 2014 rule also lowered the A2/E-and-H threshold for this row from 80% to 60% of head area, citing evidence that detail fractures can grow by more than 5% of head area per MGT.
When a transverse fissure breaks a rail in service, it counts toward the service failure rate under 213.237(a), along with compound fissures, detail fractures and vertical split heads. In an FRA accident report, the cause code is T220. Class 6 and higher track uses 213.337 instead.
Key takeaway: TF follows the C → D → A2/E+H → A/E+H sequence; compound fissures follow B → A2 → A with no joint bars.
Worked example: sizing a transverse fissure and choosing the remedial action
Scenario. A Class 4 freight main line carries 28 MGT a year. A scheduled test flags a 70° indication in the head of the low rail on a tangent, with a clean running surface. Hand verification confirms a transverse fissure sized at 30% of head area.
Step 1: classify. The rail surface is clean and the reflector sits mid-head, so this is classed as a transverse fissure, not a detail fracture. It makes no difference to the remedy, because both share a row, but it matters for the record and for the cause code if the rail later fails.
Step 2: find the table row. 30% falls in "25% to less than 60%": action D. If the rail isn't replaced, joint bars bolted through the outermost holes must be applied within 7 days. Speed is held to 30 mph or less until they are on, then 50 mph (below this line's Class 4 limit of 60 mph). If the bars aren't on within 7 days, the limit drops to 10 mph.
Step 3: estimate the risk of waiting. The NTSB, applying a 1988 DOT study of detail fracture growth, estimated an average rate of about 2.5% of head area per MGT in the Superior case. This is an illustration, not a rule: the NTSB itself noted that crack growth is often not linear.
| Input | Value |
|---|---|
| Starting size | 30% of head area |
| Assumed growth | 2.5% of head area per MGT |
| Traffic | 28 MGT ÷ 365 days = 0.077 MGT per day |
| Growth per day | 0.077 × 2.5 = 0.19% of head area per day |
| Days to reach 60% (A2 / E and H row) | (60 − 30) ÷ 0.19 ≈ 156 days |
At that rate, the 7-day deadline leaves a wide margin. At the 5% per MGT rate cited in the 2014 rule, growth is 0.38% per day and 60% would be reached in about 78 days. Either way, a defect missed on one test can travel a long way up the table before the next one: 30 MGT at 2.5% per MGT is 75 percentage points of head area.
Step 4: record it. The 213.241 record needs the defect's location, type and size, and the initial remedial action and its date (49 CFR 213.241).
Key takeaway: the percentage of head area picks the action; tonnage between tests decides how much margin a missed defect has.
What are the limits of transverse fissure detection?
Ultrasonic testing can't guarantee that every transverse fissure is found. No regulation requires 100% detection, and the main limits are well documented:
- Small nuclei. An early fissure is a small reflector. In the 1999 TTCI trial, two-thirds of transverse defects at 20% of head area or less were found, against 96% of larger ones.
- Masking by surface damage. Shelling, head checks and spalling can reflect the beam before it reaches a defect. This mainly hides detail fractures at the gauge corner, as at Superior in 1992, but it can hide any head defect below a damaged surface.
- Coupling loss. Worn, corrugated or contaminated rail can break the probe's contact. Lost coupling produces untested rail, which 213.241(c)(6) requires the owner to record; it is not a negative result.
- Worn head profiles. On heavily worn rail, a fixed-angle probe may inspect a different volume of the head than intended.
- Operator judgment. Suspects are interpreted by people. Calibration, gate settings and verification practice all affect the outcome.
- Sizing uncertainty. Head-area sizing from UT is an estimate. A defect near a table boundary (25% or 60%) deserves a conservative call.
Methods the original article presented as solutions, such as laser-generated ultrasound, rotational laser vibrometry and AI pattern recognition, are research and development topics. They aren't a standard alternative to contact UT for 213.237 compliance today, and their claimed performance should be checked against published test data before anyone relies on it.
Key takeaway: treat a clean test as strong evidence, not proof, especially on shelled rail and for small defects.
How EMA Industries applies this
EMA Industries performs ultrasonic rail flaw testing for transit agencies, short lines and industrial track owners from its Southern California base, mobilizing nationwide. For transverse fissures, the deliverable that matters is a verified, located and sized indication, classed as TF or DF by origin, with the 213.113 action it triggers, plus a record of any untested rail where surface condition or coupling prevented a valid search. To plan a test program or verify suspect indications, contact EMA Industries.
Related reading: Detail fracture development in rail · Compound fissure in rail · FRA defect codes explained · 49 CFR 213.237 rail flaw detection requirements · Rail shelling and spalling · Head checks in rail
Frequently asked questions
What is the difference between a transverse fissure and a transverse defect?
"Transverse defect" is an umbrella term for any crosswise crack in the rail head. It usually covers transverse fissures, compound fissures, detail fractures and engine burn fractures. A transverse fissure is the specific type with an internal nucleus, defined in 213.113(d)(15).
Which probe detects transverse defects in the rail head?
A 70° shear-wave probe aimed along the rail is the standard channel for transverse fissures and detail fractures. Test systems typically add 70° channels aimed toward the gauge corner, 37–45° channels for the web and bolt holes, and a 0° channel for horizontal defects.
Can a transverse fissure be repaired with joint bars?
Under 213.113 the joint-bar option exists for transverse fissures at every size: joint bars within 10 days (C) or 7 days (D) for smaller defects, and joint bars with a 50 mph limit (E and H) at 60% or more. Compound fissures have no joint-bar option. Most owners replace the defective rail as the permanent repair.
Do transverse fissures still occur in modern rail?
They still occur, but far less often than in rail made before control cooling and vacuum degassing. FRA code T220 still records about 17 to 18 accidents a year (2016–2025), but that count includes compound fissures, and detail fractures now cause more main-track derailments.
What is the FRA cause code for a transverse fissure?
T220, "transverse/compound fissure", in the FRA accident cause codes reported on Form F6180.54. Detail fractures from shelling or head checks are T207. The defect names in 213.113 have no numeric codes of their own.
Sources
- 49 CFR 213.113, Defective rails, eCFR (definitions in (d), remedial action table in (c)); text read on Cornell LII and the govinfo 2024 CFR, October 2026
- 49 CFR 213.237, Inspection of rail, eCFR
- 49 CFR 213.238, Qualified operator, eCFR
- 49 CFR 213.241, Inspection records, eCFR
- 49 CFR 213.337, Defective rails (Class 6 and higher), eCFR
- 49 CFR 225.11, Reports of accidents/incidents, eCFR
- Track Safety Standards; Improving Rail Integrity, final rule (January 24, 2014), Federal Register
- NTSB Safety Recommendation R-94-1 and -2 (April 1, 1994), Superior, Wisconsin derailment
- NTSB/HZM-94/01, Derailment of Burlington Northern Freight Train No. 01-142-30, Superior, Wisconsin, June 30, 1992, TRID record
- ICC report of the accident on the Lehigh Valley at Manchester, NY, August 25, 1911, ROSA P
- FRA train accident data, dataset byy5-w977, data.transportation.gov, queried 24 October 2026
- Liu, Lovett, Dick, Saat and Barkan, "Optimization of Ultrasonic Rail-Defect Inspection for Improving Railway Transportation Safety and Efficiency", Journal of Transportation Engineering, 2014
- TTCI Technology Digest TD-99-006, hi-rail test system evaluation (1999)
- Moore, Seventh Progress Report of the Joint Investigation of Fissures in Railroad Rails, AREA Bulletin, 1941, TRID record
- Moore et al., Ninth Progress Report of the Joint Investigation of Fissures in Railroad Rails, AREA Bulletin, 1943, TRID record
- Investigation of Failures in Control-Cooled Railroad Rails, AREA, 1957, TRID record
- Rail Failure Statistics: Transverse Fissures and Performance of Control-Cooled Rail, AREA Bulletin, 1972, TRID record
- Producing 78-ft Rails in Canada, Railway Track and Structures, 1974, TRID record
- US Patent 5,777,891, rail test probe arrangement, Google Patents