A rail can look perfectly sound and still have a serious defect hidden inside it. That is why 49 CFR 213.237 requires internal rail inspections on certain railroad tracks. The requirement adds another layer of protection beyond the routine inspection of visible track conditions.
The rule is not simply a schedule for running a rail-testing vehicle. It connects the timing of internal inspections with rail service failures, equipment performance, operator qualifications, and the actions required when part of a track cannot receive a valid search.
For railroad owners, track departments, and rail-testing personnel, those details matter. A test can be completed without every foot of rail necessarily receiving inspection credit. Likewise, a railroad can meet an inspection schedule and still face additional requirements if its service-failure rate remains too high.
The Rule Starts With the Condition of the Rail
The basic purpose of 49 CFR 213.237 is easier to understand when viewed from the rail itself. Some rail defects develop below the surface. They may not be obvious during a routine visual inspection, yet they can contribute to a broken rail. Internal rail testing provides a way to search for those hidden flaws before they become service failures.
The rule requires track owners to conduct internal rail inspections in addition to the inspections required under § 213.233. It also establishes service-failure limits for defined rail inspection segments.
That last point is important. The regulation does not treat testing as an isolated event. The track owner has to look at the results over time and maintain the applicable service-failure rate.
The inspection program also depends on the track category. Class 4 and 5 track follows one interval, while certain Class 3 track follows the same 370-day and 30 MGT limits. Other Class 3 track has a different schedule. That difference brings the first practical question into focus: when does the inspection clock actually run out?
The Inspection Clock Has Two Triggers
For the track categories covered by the shorter inspection interval, two limits matter: 370 days and 30 million gross tons (MGT).
Under 49 CFR 213.237, internal rail inspections on Class 4 and 5 track, and Class 3 track with regularly scheduled passenger trains or a hazardous-materials route, cannot exceed 370 days or 30 MGT between inspections, whichever is shorter.
The other Class 3 category works differently. Class 3 track without regularly scheduled passenger trains and not designated as a hazardous-materials route must be inspected at least once each calendar year, with no more than 18 months between inspections, or at least once every 30 MGT, whichever interval is longer. Even then, inspections cannot be more than five years apart.
| Track category | Inspection requirement |
|---|---|
| Class 4 and 5 | 370 days or 30 MGT, whichever is shorter |
| Class 3 with scheduled passenger trains or hazardous-materials route | 370 days or 30 MGT, whichever is shorter |
| Other Class 3 track | Annual/18-month and 30 MGT provisions, with a five-year maximum |
The rule also requires designated rail inspection segments for the applicable track. Those segments establish the milepost limits used to determine the individual inspection frequency.
The important point is simple: the applicable track category has to be identified before the inspection deadline can be determined.
Why Is 30 MGT Important?
MGT means million gross tons. It provides a way to measure traffic passing over a rail segment between inspections.
The opposite situation can occur as well. If the track has not reached 30 MGT but 370 days have elapsed, the calendar limit controls.
This is why both numbers belong in an inspection planning process. A scheduled test, however, is only part of the story. The more difficult question appears when the equipment cannot produce a usable search.
A Rail Test Is Not Automatically a Valid Search
The term “valid search” carries real weight in 49 CFR 213.237. The regulation defines a valid search as a continuous inspection for internal rail defects where the equipment performs as intended and a qualified operator interprets the equipment responses.
That definition has an important practical consequence. A rail-test vehicle can travel over a section of track without automatically giving that entire section inspection credit.
Suppose the operator identifies a portion where the equipment did not perform as intended. If the operator determines that a valid search could not be made over that length, the section cannot be treated as internally inspected under the applicable requirements.
The distinction protects against a common misunderstanding: the fact that a test vehicle physically passed over the rail does not, by itself, prove that the required internal search occurred.
The equipment must work as intended. The responses must also be interpreted by a qualified operator. Both conditions form part of the search.
When Part of the Rail Cannot Be Properly Searched
If a valid search cannot be made, the affected rail cannot simply remain on the inspection record as completed mileage. Under 49 CFR 213.237, the track owner must act before the applicable time or tonnage limit expires.
The available options are straightforward:
- Conduct a valid search over the affected section.
- Reduce operating speed to a maximum of 25 mph until a valid search can be made.
- Replace the rail that was not inspected.
The rule does not provide a fourth option that treats an unsuccessful search as a completed inspection. That matters most when a testing problem occurs close to the end of an inspection window.
A section that still lacks a valid search needs attention before the applicable deadline is reached. And the inspection process does not stop with finding defects. The regulation also asks how the rail performs in service.
Rail Service Failures Put the Inspection Results Into Context
The service-failure provisions are one of the more unusual features of 49 CFR 213.237 because they measure the outcome of the rail inspection program over time.
A service failure means a broken rail occurrence caused by a compound fissure, transverse fissure, detail fracture, or vertical split head. The regulation establishes different maximum service-failure rates depending on the track category and operating conditions.
| Track condition | Maximum service-failure rate |
|---|---|
| Class 4 and 5 track | 0.10 service failures per year per mile of track |
| Class 3, 4, and 5 track with regularly scheduled passenger trains or a hazardous-materials route | 0.09 service failures per year per mile |
| Where both passenger-train and hazardous-materials-route conditions apply | 0.08 service failures per year per mile |
These numbers should not be confused with the 30 MGT inspection interval. MGT helps determine when an inspection is due. The service-failure rate measures rail performance over a defined period.
The track owner calculates the rate over a 12-month period and must complete the calculation within 45 days after that period ends.
What Is Rail Track Inspection?
Rail track inspection is the examination of track and rail conditions that could affect safe train operation. Not every inspection serves the same purpose.
A visual inspection looks at visible track conditions. Internal rail testing searches for flaws within the rail that may not be apparent from the outside.
Under 49 CFR 213.237, internal rail inspection provides an additional safeguard for qualifying track. The process involves more than sending equipment over the rail. Equipment performance, operator qualification, inspection frequency, and the treatment of unsuccessful searches all matter.
This distinction helps explain why the regulation contains detailed requirements for the people and equipment involved in rail flaw detection.
The Equipment and the Operator Both Matter
Rail flaw detection depends on equipment capable of performing the required search. Under 49 CFR 213.237, inspection equipment must be capable of detecting defects between joint bars, including the area enclosed by the joint bars.
The operator is equally important. The person assigned to operate rail defect detection equipment must qualify under § 213.238 and demonstrate proficiency in the rail flaw detection process for each type of equipment assigned.
That requirement makes practical sense. The equipment produces responses, but someone qualified has to interpret them.
This is also why the operator's determination about a failed search has regulatory significance. A decision that a valid search could not be made can prevent that section from receiving inspection credit.
Defective Rail Must Be Clearly Marked
Once defective rail has been identified, it needs to remain easy to recognize in the field. The regulation requires a highly visible marking on both sides of the rail web and base.
Where permanent features make those areas inaccessible, the marking may be placed on or next to the rail head.
The requirement is simple, but its purpose is important. A detected defect should not become difficult to identify after the inspection vehicle has moved on. Clear marking supports the follow-up work needed to address the defective rail and helps personnel working on the track recognize the affected location.
Plug Rail Has Its Own Requirements
Plug rail can be easy to overlook when reviewing an internal inspection program. The regulation defines plug rail as rail removed from one track location and stored for future use as replacement rail somewhere else.
Under 49 CFR 213.237, replacement plug rail used on track subject to the internal testing requirements must have been tested for internal rail flaws.
For plug rail installed after March 25, 2014, the track owner must verify that the rail has not accumulated more than 30 MGT in its previous and new locations since the last internal rail flaw test before the next required test.
If non-compliant plug rail is in use after that date, trains operating over it cannot exceed Class 2 speeds until the rail receives the required testing.
The requirement prevents previously used rail from escaping the inspection process simply because it has moved to another location.
How § 213.237 Connects With Continuous Rail Testing
49 CFR 213.237 and § 213.240 address related parts of rail testing, but the provisions are not interchangeable.
Section 213.240 allows a track owner to elect continuous rail testing to satisfy internal rail inspection requirements under § 213.237 or § 213.339. When that process is used, the track owner must establish procedures for transmitting and analyzing test data, identifying suspect locations, prioritizing them, and conducting field verification.
The continuous-testing rule also addresses qualified operators, documentation, field verification, and annual reporting to FRA.
That distinction is worth keeping in mind when reviewing a railroad's testing program. Internal inspection requirements and continuous testing requirements can work together, but each provision has its own conditions.
A Practical Compliance Check
A useful review of 49 CFR 213.237 starts with the track segment rather than the testing machine.
- Identify the track classification and operating conditions.
- Confirm the designated inspection segment and applicable milepost limits.
- Track both elapsed days and accumulated MGT.
- Confirm that the inspection equipment can perform the required search.
- Verify the operator's qualification and equipment-specific proficiency.
- Record any portion where a valid search could not be made.
- Mark defective rail with the required visible marking.
- Address uninspected rail before the applicable limit expires.
- Monitor the 12-month service-failure rate.
- Complete required FRA notification when the performance target is not achieved.
This approach keeps the inspection program focused on the actual requirements rather than treating testing as a one-time event.
Final Thoughts
The most useful way to understand 49 CFR 213.237 is to look beyond the inspection date. The rule creates a chain of responsibilities.
The applicable track must be inspected within the required time or tonnage limits. The equipment must perform as intended. A qualified operator must interpret the responses. If part of the rail does not receive a valid search, that section cannot simply be counted as inspected.
The rule also looks at what happens after testing. Service-failure rates provide a longer-term measure of rail performance, and repeated failures can lead to more frequent testing or a lower track classification.
Key Takeaways
- Internal rail inspections help identify defects that routine visual inspections may not reveal.
- Track classification and operating conditions determine which inspection interval applies.
- Thirty MGT can trigger an inspection before the calendar-based limit is reached.
- The 370-day limit applies to specified Class 3, Class 4, and Class 5 track.
- A valid search requires functioning equipment and interpretation by a qualified operator.
- A section without a valid search cannot receive credit as internally inspected.
- The regulation provides specific options when an internal search cannot be completed.
- Service-failure rates provide a separate measure of rail inspection program performance.
- Repeated missed targets can require increased testing or reduced track classification.
- Accurate records and timely corrective action support a consistent rail safety program.
Frequently Asked Questions
How often are train tracks inspected?
Railroad tracks are inspected at frequencies established by the applicable FRA requirements. The exact schedule depends on track classification and operating conditions.
Under 49 CFR 213.237, certain Class 3, 4, and 5 track must receive internal rail inspections no more than 370 days or 30 MGT apart, whichever is shorter. Other Class 3 track follows a different schedule.
What are the requirements for railroad derails?
Railroad derail requirements are addressed by separate FRA rules and railroad operating procedures. A derail is a track-safety device used to protect against unauthorized or unintended movement into a protected area.
Its placement, use, inspection, and operation depend on the applicable railroad procedures and circumstances, rather than the internal rail inspection requirements in 49 CFR 213.237.
What is rail track inspection?
Rail track inspection involves examining track and rail conditions that could affect safe train movement. Different methods address different conditions.
Visual inspections focus on observable track defects, while internal rail testing searches for flaws within the rail. The internal inspection provisions in 49 CFR 213.237 address this specialized part of the overall track inspection process.
Who inspects railroad tracks?
Qualified railroad personnel and specialized rail-testing personnel perform different types of inspections. For internal rail flaw detection, 49 CFR 213.237 requires the person operating the rail defect detection equipment to qualify under § 213.238 and demonstrate proficiency with each type of equipment assigned.
The requirement places responsibility on both operator qualification and equipment performance.