About AAR Circular Letters
Circular letter summaries are produced monthly by Greenbrier Management Services Group.
AAR circular letters provide information of general applicability to the railroad industry, including proposed and final rules, revisions, standards and recommended practices, and calls for comments. These summaries provide the main points of circular letters issued in the prior month, as well as important implementation deadlines.
For access to the complete circular letter, please go to my.aar.org/circulars. Circular letters are a fee-based service provided by the AAR’s Transportation Technology Center Incorporated (TTCI). You may subscribe online at publications@aar.com or call 719.584.0538.
Implementation Circulars
C-14505
Revisions to Figure 14-B – Section 2 of the AAR Open Top Loading Rules Manual (OTLR)
Issued: February 3, 2025
Effective: February 3, 2025
The AAR’s Open Top Loading Rules Committee (OTLRC) has approved the following revisions to Figure 14-B of Section 2 OTLR manual. LR 3.5.137 – Section 2, Fig. 14-B:
- Added a new photo 5 to address the issue of J-hooks moving within the stake pockets allowing the strap to become loose and contact the commodity;
- Added a new verbiage, ‘For stake pockets that exceed the width of car deck, apply J-hook against the side sill.’
The implementation of these revisions is effective immediately and will be included in the next edition of the OTLR manual. In the interim, please insert the circular attachment for Figure 14-B in your Section 2 copy and be governed accordingly.
C-14506
Editorial Revisions to MSRP Section C, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2044, Safety Appliance Requirements for Freight Cars, Update to Appendix H1
Issued: February 4, 2025
Effective: February 4, 2025
The purpose of this circular letter is to notify the industry of editorial revisions to MSRP Section C, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2044, Safety Appliance Requirements for Freight Cars.
On January 29, 2025, Circular Letter C-14504 was issued to implement editorial changes in Appendix H1 Safety Appliances for Enclosed Vehicle-Carrying Cars and Vehicle-Carrying Superstructures applied to Flatcars. In Figures H1.1 and H1.2 of that revision, the dimension from the tip of the operating lever to the lowest sill step tread was inadvertently changed from 4 inches to 9 inches. The figures have been corrected to show the dimension at 4 inches. In addition to the Appendix H1 edits, a reference to Standard S-910 is hereby being edited to point to the correct Manual of Standards and Recommended Practices Section, i.e. Section C (see the change bar on page 347).
Revised Standard S-2044 is now implemented and effective immediately. This modification will be incorporated in the next issue of the Manual of Standards and Recommended Practices, Section C. Please update your library and be governed accordingly.
C-14513
AAR Manual of Standards and Recommended Practices (MSRP), Section K-II Locomotive Electronics and Train Consist System Architecture, Specification S-9170.V1.0
Issued: February 28, 2025
Effective: February 28, 2025
S-9170.V1.0 contains the interoperable functional and non-functional requirements for Precision Navigation Modules (PMNs). The functionality in this standard is intended to fulfill HOT (Locomotive) PLT requirements and act as the source of navigational truth for client subsystems, including PTC.
S-9170.V1.0 was Adopted in 2025 and is attached to this circular in PDF format. S-9170.V1.0 will be incorporated into the next issues of the MSRP Section K-II Locomotive Electronics and Train Consist System Architecture. In the interim, please insert the Circular in your copy of the MSRP Section K-II and be governed accordingly.
Solicitation Of Comments Circulars
C-14507
MSRP Section S, CASTING DETAILS, Specification M-203, Truck Side Frames, Cast Steel – Design and Testing, regarding updates to facility, equipment, and test approval
Issued: February 7, 2025
Effective: 30 days for comment.
The purpose of this circular letter is to solicit comments for revisions proposed to Section S, Specification M-203, Truck Side Frames, Cast Steel – Design and Testing, regarding updates to facility, equipment, and test approval. The Coupling System and Truck Castings Committee (CSTCC) proposed changes to section 8.0 of M-203 to clarify requirements for:
- static and dynamic test observation
- facility and equipment approval requirements and process
Additionally, an editorial change was made to Appendix B. Proposed revisions are highlighted with change bars in the attached file. See circular for full details.
C-14509
MSRP Section S, CASTING DETAILS, Specification M-212, Couplers and Yokes Secondhand Classification and Reconditioning, regarding scope updates and addition of locomotive coupler and yoke reconditioning activities
Issued: February 12, 2025
Effective: 30 days for comment.
The purpose of this circular letter is to solicit comments for revisions proposed to Section S, Specification M-212, Couplers and Yokes Secondhand Classification and Reconditioning, regarding updates to the scope, including the addition of locomotive coupler and yoke reconditioning activities.
The Specification for Quality Assurance, M-1003, Appendix A – Activity Code Guide activities B13 and B17 (for reconditioners of locomotive couplers and yokes) currently do not have entries in the “Technical Approval Required” column. CSTCC has agreed with the Locomotive Committee that Specification M-212 should be required for both activities. Since all reconditioners certified under activities B13 and B17 are already certified for activities B12 and B16 (reconditioners of freight couplers and yokes which do have M-212 Technical Approval Required) the change is essentially a formality. Upon implementation of revised M-212, CSTCC will request the Quality Assurance Committee to add M-212 to the Technical Approval Required Column of Specification M-1003 Appendix A activities B13 and B17.
Additional changes are also being proposed. See circular for full details.
C-14510
Circular 43, Rules Governing the Loading, Blocking, and Bracing of Freight in Closed Containers and Trailers in Intermodal Service (DP&FC)
Issued: February 24, 2025
Effective: 30 days for comment.
The purpose of this circular letter is to solicit comments for revisions proposed to Circular 43, Rules Governing the Loading, Blocking, and Bracing of Freight in Closed Containers and Trailers in Intermodal Service (DP&FC). Sections with Revisions or New Documentation:
B – General Rules
- Introduction Paragraph – Revised
- Inspection & Selection of Equipment; Items A. & B. – Revised
- Maximum Weights and Weight Distribution; Items A., B., & C. – Revised
- Hazardous Materials/Hazardous Substances; Item F. – New
- Weight Distribution for Concentrated Weight; Note & Item A. – Revised
The file attached to this circular replaces Circular 43-H.
C-14511
MSRP F, Sensors. New Publications: WILD Detector Validation Standard & Specification for Instrumented Wheel Sets for Measuring Vertical Impact Loads
Issued: February 26, 2025
Effective: 30 days for comment.
The Equipment Health Monitoring Committee (EHMC) is requesting comments on two proposed additions to MSRP, Section F that outline the requirements for instrumentation and the measurement of wheel/rail vertical loads and impact loads as a means of quantifying the accuracy and repeatability of wheel impact load detectors systems (WILD) whose data outputs, when approved by EHMC, will be used to create industry alerts in the Equipment Health Management System (EHMS). The documents included in this comment circular:
- S-6101B Industry Data Validation: Wheel Impact Load Detector (WILD)
- M-6101 Specification for Instrumented Wheel Sets for Measuring Vertical Impact Loads
C-14512
MSRP, Section M – LOCOMOTIVES AND LOCOMOTIVE INTERCHANGE EQUIPMENT: Recommended Practice, RP-509 –BRAKING RATIOS FOR LOCOMOTIVES
Issued: February 28, 2025
Effective: 30 days for comment.
Upon review of recently implemented revisions to MSRP, Section M, Recommended Practice, RP-509 BRAKING RATIOS FOR LOCOMOTIVES per circular letter C-14444 issued October 28, 2024, the Locomotive Committee (LC) has approved a request to replace the word ‘series’ with the term ‘locomotive model’ (along with a definition) within paragraph 2.1.
The revised RP-509 is attached to this circular letter for industry review and comment.
Upcoming Events
Spring 2025 AAR Technical Committee Meetings
AAR meetings that have been planned for the first half of 2025 are listed below. AAR Meeting Announcements can also be found online on the MxV Rail Technical Services web page: http://www.aar.com/standards/AARMeetingAnnouncements.html. Information for individual Technical Committee Meetings can be found online at https://cvent.me/erXMqo.
- Arbitration & Rules Committee: April 1-3 (College Station, TX)
- Contact: Nichole Fimple (202) 639-2143, nfimple@aar.org
- Asset Health Strategy Committee: March 5-6 (Charlotte, NC)
- Contact: Greg Deibler, (202) 639-2142, gdeibler@aar.org
- Automatic Equipment Identification Committee: February 24-25 (Jacksonville, FL)
- Contact: Greg Deibler, (202) 639-2142, gdeibler@aar.org
- Brake Systems Committee: March 4-6 (McDonough, GA)
- Contact: Heath Bushell, (719) 420-0425, brakes@aar.com
- Car Repair Billing Committee: March 18-19 (Chicago, IL)
- Contact: Bill Pzedpelski, (202) 639-2138, billp@aar.org
- Coupling System & Truck Castings Committee: February 12-13 (North Augusta, SC)
- Contact: Daniel Gutscher, (719) 251-1126, cstcc@aar.com
- Damage Prevention and Freight Claims Committee:
- March 18-19 (Pueblo, CO)
- DP&FC Conference: June 2-4 (Atlanta, GA)
- Contact: Kelsey Even, 719-225-0822, kelsey_even@aar.com
- Engineering Policy Committee: No Face-to-Face meeting scheduled at this time.
- Contact: Melody Sheahan, (202) 639-2146, msheahan@aar.org
- Equipment Engineering Committee: March 11-13 (Pueblo, CO)
- Contact: Jon Hannafious, (719) 251-6571, eec@aar.com
- Equipment Health Monitoring Committee: March 4-5 (Charlotte, NC)
- Contact: Greg Deibler, (202) 639-2142, gdeibler@aar.org
- Locomotive Committee: March 25-26 (Pueblo, CO)
- Contact: Mike Fore, (202) 639-2303, mfore@aar.org
- Open Top Loading Rules Committee: March 11-13 (Charlotte, NC)
- Contact: Rama Maram, (551) 689-3505, rama_maram@aar.com
- Quality Assurance Committee: February 25-27 (Pheonix, AZ)
- Contact: Don Guillen, (719) 251-6625, don_guillen@aar.com
- Railway Electronics Standards Committee: March 20 (Jacksonville, FL)
- Contact: Melody Sheahan, (202) 639-2146, msheahan@aar.org
- Signal Committee: No Face-to-Face meeting scheduled at this time.
- Contact: Melody Sheahan, (202) 639-2146, msheahan@aar.org
- Specially Equipped Freight Car Committee: February 11-12 (Jacksonville, FL)
- Contact: David Hendrixon, (719) 252-3439, david_hendrixon@aar.com
- Tank Car Committee: April 16-17 (Nashville, TN)
- Contact: Ken Dorsey, (202) 639-2262, kdorsey@aar.org
- Train Control Communications and Operations Committee: April 9 (Chicago, IL)
- Contact: Melody Sheahan, (202) 639-2146, msheahan@aar.org
- Wheels, Axles, Bearings & Lubrication Committee: March 18-20 (Elizabethtown, KY)
- Contact: Daniel Carter, (719) 248-0716, WABL@aar.com
- Wireless Communications Committee: March 18-19 (Jacksonville, FL)
- Contact: Melody Sheahan, (202) 639-2146, msheahan@aar.org
SAVE THE DATE! SEARS Spring 2025 Meeting.
Greenbrier is a Proud Sponsor | Savannah, GA | March 12–13
Learn more: https://www.serailshippers.com/event/sears-spring-2025-meeting/
Greenbrier’s Regulatory Services Group
Peace of mind for your business.
The Regulatory Management Group, led by James Rader, provides regulatory, engineering, process consulting and advocacy support to the railcar repair industry and the petrochemical rail shipper community.
- ASNT Level III Subscription Services
- DOT Compliance Assessments (Corporate and Plant)
- DOT Hazardous Materials Training (Corporate and Plant)
- Expert Witness Services in Rail-Related Litigation
- Federal Government Claims Mitigation (e.g. FRA and PHMSA)
- Nondestructive Testing Programs
- Quality Assurance Program Development
- Regulatory Counsel and Policy Advocacy
- Railcar Repair Management (Design Review, Drawings, Engineering and AAR Approval Administration)
- Tank Car Reliability and Maintenance Programs (49 CFR Subpart F of Part 180)
- Tank Car Maintenance Data Collection and Reliability Performance Analysis
- Welding Program Development
For inquiries about these summaries or any of our services, please reach out to: regulatoryservices@gbrx.com
About Greenbrier Management Services (GMS)
Greenbrier Management Services (GMS) is North America’s most comprehensive railcar management solutions provider. GMS manages nearly 400,000 railcars and has invested over 20 years in developing technology, processes, and people to provide the best railcar management products and services in the industry. GMS is powered by proprietary software and the best subject matter experts in the railcar business.
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