AREMA vs FRA vs ASTM: Key Differences in Railway Standards

In the AREMA vs FRA vs ASTM comparison, only FRA writes binding law. Its 49 CFR Part 213 sets track limits and rail test intervals, such as 370 days or 30 MGT on Class 4 and 5 track. AREMA publishes recommended practice, and ASTM writes material and test-method standards that apply only when a contract or code cites them.

Those three names are only part of the picture for anyone buying or doing rail NDT in the United States. Weld acceptance comes from AWS documents and owner specifications, technician qualification from ASNT documents, transit track from FTA, state oversight and APTA, and freight car interchange from the AAR. This guide sets out what each body actually controls, which document wins when they overlap, and how to trace the governing documents for a real job.

This article covers US bodies only. For EN, ISO and other national rules, see our guide to global standards and regulations for ultrasonic rail testing.

Contents: Binding or voluntary · FRA · AREMA · ASTM · AWS and ASME · ASNT · Transit · AAR · Who governs what · Worked example · Limits · FAQ

AREMA vs FRA vs ASTM: which one is binding?

FRA rules are binding on their own; AREMA and ASTM documents become binding only when someone adopts them. A federal regulation applies to every railroad in its scope whether or not anyone signs a contract. A recommended practice or a test method applies when a railroad writes it into its own standards, a purchase order cites it, or a regulation incorporates it by reference.

The order of precedence on a job is usually simple. Federal regulation sets the floor. The railroad's own standards may be stricter, and the contract decides which voluntary documents, and which editions, apply.

Key takeaway: when two documents disagree, the regulation sets the minimum and the contract decides everything above it.

What does FRA regulate for track and rail testing?

FRA's Track Safety Standards in 49 CFR Part 213 set minimum, enforceable limits for track on the general railroad system, including geometry, rail defects and internal rail testing. Section 213.1(a) says the part "prescribes minimum safety requirements for railroad track that is part of the general railroad system of transportation," and owners may adopt stricter rules. A full walk-through of the part is in our FRA track safety standards guide.

The parts that matter most for rail NDT are these:

Does FRA use AREMA to set track geometry limits?

No. Part 213 states its own geometry limits in its own tables, and it doesn't cite AREMA anywhere. For example, 213.55 limits the tangent alinement deviation, measured as the mid-offset from a 62-foot line, to 5 in. on Class 1 track, 1 3/4 in. on Class 3 and 3/4 in. on Class 5. A full-text search of the 2025 Part 213 found no mention of AREMA or ASTM.

The only outside standard Part 213 incorporates by reference is an APTA wheel-profile standard (SS-M-015-06). Appendix D uses it for vehicle qualification simulations at high speed or high cant deficiency, which is far from routine rail testing.

FRA does mention AREMA's manual in two other places, and neither is in Part 213:

• Bridge worker safety. Under 214.103(c), walkways and railings that meet the Manual for Railway Engineering can stand in for fall protection in some cases.
• Bridge policy. Appendix A to Part 237, a policy statement, calls the MRE "the recommended specifications for the design and rating of bridges". It also says other specifications have been used successfully.

What do the other FRA parts cover?

Part 214 protects roadway workers, and Part 237 governs bridge safety programs. Part 214 applies to any crew fouling a track, whether railroad employees or contractors such as an NDT crew. It requires a job briefing under 214.315 and an on-track safety method before anyone fouls the track. Part 237 requires a bridge management program and an inspection of each bridge at least once each calendar year, with no more than 540 days between inspections (237.101).

Part 237 covers the structure. Rail flaw testing on a bridge deck still falls under 213.237 and 213.238.

FRA sets no NDT method. The word "ultrasonic" appears nowhere in Part 213. Section 213.237 requires "internal rail inspections" with equipment that can find defects between joint bars, and ultrasonic testing is how the industry meets that requirement.

Key takeaway: FRA tells the owner what condition the track must meet and how often to search the rail, not which code to test it to.

What does AREMA publish, and how is it used?

AREMA publishes the Manual for Railway Engineering, a set of recommended practices that railroads adopt into their own standards. It doesn't enforce anything. AREMA's own catalog describes the material like this:

"developed by AREMA technical committees and is published as a guide to railways in establishing their individual policies and practices." — AREMA, publications catalog

The MRE is organized in numbered chapters by subject (the 2026 edition is current). These are the chapters NDT buyers meet most often:

Chapter 4 is the rail NDT chapter. In the 2025 table of contents, its parts and items include:

• Part 2, Manufacture: 2.1 Specifications for Steel Rails.
• Part 3, Joining of Rail: 3.10, a quality assurance specification for electric flash-butt welding, and 3.13, Specification for the Quality Assurance of Thermite Welding of Rail.
• Part 4, Maintenance:
  • a recommended minimum performance guideline for rail testing
  • recommended qualifications for operators doing ultrasonic testing of rail
  • recommended procedures for those operators
  • recommended calibration rails for rail flaw detection systems

These are table-of-contents titles only. The text is paywalled, and AREMA doesn't allow its content to be fed into AI tools. Read the edition your contract names. Our AREMA standards guide explains how the manual is organized and updated.

Large railroads usually write AREMA practice into their engineering standards, and short lines often lean on it directly. The force still comes from the railroad's adoption or from a contract clause, not from AREMA.

Key takeaway: AREMA is the profession's best practice; it becomes a requirement only when a railroad or contract makes it one.

What do ASTM standards cover for railroads?

ASTM writes product specifications and test methods. It doesn't write railroad regulations, welding codes or welding procedures. An ASTM document tells a lab or an inspector how to make or test something. Whether the result is acceptable usually depends on the document that cites it.

These are the ASTM documents an NDT buyer is most likely to see on a rail or structural job. Each was checked on the ASTM store in October 2026.

The original version of this article said ASTM standards are "adopted into FRA rules". That isn't true for track: Part 213 cites no ASTM document. It also listed "welding procedures" under ASTM, but those are written by the employer or contractor and qualified under an AWS or ASME code. Our guide to the welding procedure specification explains how a WPS and PQR work.

Key takeaway: ASTM tells you how to test; the citing code, specification or contract tells you what passes.

Who sets weld acceptance for rail and structural welds?

AWS and ASME publish the welding codes, and which one applies depends on what is being welded. No single code covers every weld on a railroad. Naming the wrong one in a specification sends the inspector to the wrong acceptance criteria.

AWS D15.2 is titled Specification for Joining Railroad Rail and Related Rail Components. It covers thermite, flash and arc welding of rail, and it contains clauses on procedure qualification, welder qualification and inspection acceptance. The public preview shows the structure, but the acceptance values are paywalled, so they should be read from the contract edition.

AWS D1.1 doesn't govern rail welds. For structural work, our article on AWS D1.1 weld inspection criteria covers the static and cyclic acceptance tables.

Key takeaway: pick the weld code by the product (rail, car, bridge, building or vessel), then confirm the edition in the contract.

Who qualifies NDT technicians?

The employer does, using an ASNT document as the framework; neither ASNT nor FRA certifies a technician under SNT-TC-1A. ASNT's standards page calls SNT-TC-1A (2024) a "Recommended Practice" that gives employers guidance for in-house programs. It calls ANSI/ASNT CP-189 (2024) a standard that establishes minimum requirements for employer-based certification.

The practical difference:

• SNT-TC-1A is flexible. The employer writes its own written practice and sets its own hours and exams within the guidance.
• CP-189 is prescriptive. A contract that cites it is asking for a stricter, auditable program.

Rail flaw detection adds a federal layer. Under 213.238, a provider of rail flaw detection must have a documented training program, and each operator needs written authorization, at least 160 hours of supervised experience, and a demonstrated ability to run the specific equipment. That rule qualifies operators for 213.237 internal rail inspections. It doesn't replace an SNT-TC-1A written practice, and the employer still grants the qualification.

AREMA Chapter 4 adds a recommended qualification and procedure for ultrasonic operators, which a railroad can adopt on top of both. Our SNT-TC-1A requirements guide covers levels, hours and written practices.

Key takeaway: ask a bidder for its written practice, its 213.238 records where rail flaw testing is involved, and the document the contract names.

Who governs rail transit track?

Rail transit is overseen by FTA and a state safety oversight agency (SSOA), not by FRA, unless the line is commuter rail or shares track with the general railroad system. Part 213 excludes rapid transit in an urban area that isn't connected to the general system (213.3(b)(3)). FRA treats commuter railroads as part of the general system regardless of connection (Part 209 Appendix A).

FTA's rules are program rules, not track standards:

• Part 671: roadway worker protection for rail transit
• Part 673: public transportation agency safety plans
• Part 674: state safety oversight

None of the three sets a track geometry limit or a rail flaw test interval. Each state's SSOA adopts a program standard, and the agency's own track standards fill the gap.

That is where APTA comes in. APTA's voluntary standard RT-FS-S-002-02, Rail Transit Track Inspection and Maintenance, calls for ultrasonic rail flaw detection of mainline track at least once a year. An agency that adopts it takes on that interval.

In California, the CPUC's General Order 143-B uses Part 213's geometry subparts as a guideline for light rail. It doesn't list the internal rail testing subpart, so the CPUC rules don't adopt 213.237.

AREMA Chapter 12 (Rail Transit) and Chapter 11 (Commuter and Intercity Rail Systems) are the engineering references for these systems. Our mass transit rail inspection guide covers testing on transit track.

Key takeaway: on isolated transit, the agency's adopted standard, often APTA, sets the test interval; the federal rules set the safety program around it.

What does the AAR cover?

The Association of American Railroads writes the rules for freight equipment exchanged between railroads, not for track. AAR's Technical Services group maintains the interchange rules, mechanical standards and component specifications. Its Manual of Standards and Recommended Practices (MSRP) exists to promote the safe, uniform interchange of rail equipment, and its sections cover items such as trucks, brakes, wheels and axles, bearings and tank cars.

A search of the MSRP contents found no section on track structure or rail flaw testing. The AAR also doesn't inspect or enforce track. Its rules bind member railroads through the interchange agreement.

FRA does incorporate some AAR brake standards by reference in 49 CFR Part 232, among them S-469 freight brake performance (232.103) and S-486 single car air brake tests (232.305). That makes AAR relevant to car shops and wheel-and-axle NDT, but not to rail flaw testing.

Key takeaway: AAR matters for rolling stock; for rail in track, look to FRA, AREMA and the owner's standards.

Who governs what? A summary table

Use this table to find the first document to read for each kind of work. Each row assumes general-system freight track unless it says otherwise.

Worked example: which documents govern a thermite weld UT job on a short line?

A hypothetical short line, traced from the rail it buys to the record it files, shows how the bodies stack. The inputs are stated so each step can be checked.

Inputs:

Step 1: Is FRA in scope? Yes. The line is part of the general railroad system, so Part 213 applies (213.3) and Part 214 applies to the test crew (214.3). The crew needs a job briefing and an on-track safety method before fouling the track.

Step 2: Rail steel. The purchase specification may cite AREMA MRE Chapter 4 Part 2.1, ASTM A1, or both. Neither is a federal requirement. The mill certificate shows conformance to whichever the order named.

Step 3: Welding and CWR records. The railroad's CWR plan under 213.119 governs installation temperature and the records kept for the new welds. Its welding specification sets the weld kit, the welder qualification and the post-weld finishing. That specification may adopt AREMA Ch. 4 Part 3 item 3.13 and AWS D15.2:2022. The contract must say which edition applies, because D15.2 changed from a recommended practice to a specification in 2022.

Step 4: UT procedure and acceptance. No FRA rule prescribes a weld UT method. The test follows the contractor's written procedure, accepted by the railroad and aligned with its welding specification. Acceptance comes from that specification, or from D15.2's acceptance clause where it is adopted. ASTM E164 is a general weldment practice and doesn't govern rail welds unless the contract says so. The instrument check can follow ASTM E317 if the contract asks for it.

Step 5: Personnel. The technicians are certified by their employer to its SNT-TC-1A written practice, or to CP-189 if the contract specifies it. If the railroad counts this work toward its 213.237 internal rail inspection, the operators must also be qualified under 213.238.

Step 6: What happens if a weld fails. Say one weld shows a discontinuity in the transverse plane sized at 15% of the rail head cross-section. That exceeds the 5% individual threshold in 213.113(d)(6), so it is a defective weld. Under the remedial action table, a defective weld from 5% to under 25% of head area takes remedial action C:

• apply joint bars within 10 days
• until the bars are on, run no faster than 30 mph on Class 3 to 5 track
• after the bars are on, the limit is 50 mph or the class maximum, whichever is lower

On this 40 mph Class 3 line, trains run at 30 mph until the bars are applied, then back at 40. A rejection under the railroad's weld acceptance criteria may be stricter and call for cutting the weld out, whatever the 213.113 size.

Step 7: The next scheduled rail test. Other Class 3 track is tested at least once a calendar year or every 30 MGT, whichever is longer, never more than 5 years apart (213.237(c)). At 8 MGT a year:

• 30 MGT ÷ 8 MGT/yr = 3.75 years, which is longer than one year
• 3.75 years is inside the 5-year cap, so the internal rail test interval is 30 MGT, about 3.75 years

The new welds don't reset that interval. The owner's weld acceptance test and the federal rail search are separate obligations.

For the inspection itself, see our guide to aluminothermic weld inspection. To see where UT sits beside MT, PT and RT, see the comparison of non-destructive testing methods.

What this comparison does not settle

This comparison maps who controls what. It can't tell you what your contract says, or what a paywalled code contains. Several limits apply.

• Editions change. AREMA issues a new MRE each spring, AWS revised D1.1 in 2025 and D15.2 in 2022, and ASTM reapproves standards on its own cycle. Always read the edition named in the contract.
• Paywalled content isn't reproduced here. This article gives only the AREMA table-of-contents titles and the AWS and ASTM scope wording from the publishers' public pages. Clause numbers and acceptance values must come from your own licensed copy.
• Owner standards often govern. Many requirements on a real job come from the railroad's or agency's engineering standards, which are stricter than Part 213 and aren't public.
• State rules vary. Transit oversight differs by state, and this article only gives the California example.
• International work is out of scope. For EN, ISO and other national documents, use our global standards guide.
• This isn't legal advice. Jurisdiction questions, such as shared-use track, need the railroad's regulatory counsel or FRA.

How EMA Industries applies this

EMA Industries performs ultrasonic rail flaw testing for transit agencies, short lines and industrial track owners, plus rail weld inspection and NDT Level III services. It is based in Southern California and mobilizes nationwide. Before a weld or rail testing job starts, the scope should name the governing documents and editions, as in the worked example, so that the procedure, acceptance criteria and records match the owner's requirements. To scope a project, contact EMA Industries.

Related reading: 49 CFR 213.237 rail flaw detection requirements · FRA track safety standards · AREMA standards · Short line railroads in the USA

Frequently asked questions

Is AREMA a regulation or a guideline?

AREMA is a guideline. Its Manual for Railway Engineering is a set of recommended practices that railroads adopt into their own standards. FRA's Part 213 is the regulation, and it doesn't cite AREMA.

Do FRA regulations reference AREMA standards?

Not in the Track Safety Standards. Part 213 sets its own geometry and defect limits. FRA mentions AREMA's manual only in a few other places, such as bridge walkway rules in 214.103 and the bridge policy statement in Part 237 Appendix A.

Which ASTM standards apply to rail testing?

None is required by federal rule. ASTM A1 covers carbon steel tee rails at purchase, and E164, E317 and E797 are general UT practices that apply when a contract cites them. Rail flaw testing in track follows the owner's or provider's written procedure, with AREMA Chapter 4 as guidance.

What standard governs thermite weld inspection in the US?

The railroad's own welding specification governs thermite weld inspection. It usually draws on AREMA MRE Chapter 4 Part 3 and, where adopted, AWS D15.2/D15.2M:2022. Once a weld is in service, 49 CFR 213.113 sets the remedial action for a defective weld.

Does FRA certify ultrasonic rail testing technicians?

FRA doesn't certify anyone. Under 49 CFR 213.238, the rail flaw detection provider qualifies and authorizes its own operators, with at least 160 hours of supervised experience. Separately, NDT technicians are certified by their employer under an SNT-TC-1A written practice or to CP-189.

Sources

• 49 CFR Part 213, Track Safety Standards, eCFR (text read on Cornell LII and the govinfo 2025 CFR XML, October 2026)
• 49 CFR 213.55, Track alinement, eCFR
• 49 CFR 213.113, Defective rails, eCFR
• 49 CFR 213.237, Inspection of rail and 213.238, Qualified operator, eCFR
• 49 CFR Part 214, Railroad Workplace Safety, eCFR
• 49 CFR Part 237, Bridge Safety Standards, eCFR, including Appendix A
• 49 CFR Part 232, Brake System Safety Standards, eCFR
• 49 CFR Part 209 Appendix A, FRA jurisdiction, Cornell LII
• 49 CFR Part 674, State Safety Oversight and Part 671, Rail Transit Roadway Worker Protection, eCFR
• AREMA publications catalog and 2026 MRE listing, AREMA
• AREMA MRE Chapter 4 table of contents (2025), AREMA (titles only)
• ASTM A1-00(2026), Carbon Steel Tee Rails, ASTM store
• ASTM E164-24, E317-21 and E797/E797M-21, ASTM store
• AWS D15.2/D15.2M:2022 public preview, AWS
• AASHTO/AWS D1.5M/D1.5:2025 Bridge Welding Code, AWS
• ASNT standards and publications, ASNT (SNT-TC-1A and CP-189)
• APTA RT-FS-S-002-02, Rail Transit Track Inspection and Maintenance, APTA
• AAR standards and MSRP Section A-I, Association of American Railroads
• CPUC rail transit rules and regulations, California Public Utilities Commission