The Mechanical Reference Repository (MRR) centralizes and automates elements of the AAR Interchange Rule 88 and Running Repair Agent (RRA) processes in a single, easy-to-use application. Car mark owners, shop owners, and railroads can reduce the amount of time and manual work required to complete these processes.

Rule 88 establishes minimum mechanical requirements for the interchange of freight cars, as well as the process and documentation required when repairing, rebuilding, or otherwise modifying a freight car. The MRR Rule 88 module enables users to electronically submit Rule 88 applications and supporting documentation, view the status of their applications, manage updates, and store and search applications.

MRR also allows sponsoring railroads to submit associations with Running Repair Agents at specific locations for approval by the AAR. Approved associations are displayed in FindUs.Rail in real time and before they appear in printed quarterly updates.

Legal Disclaimer: Any actions taken in reliance on or pursuant to this website are subject to Railinc's Terms of Use, as set forth in, and all AAR rules. 

How To Begin Using MRR

Login to and select the View/Request Permissions link from the Launch Pad. Then select the Request button for Mechanical Reference Repository and select the applicable role.

New users will need to complete the following steps.

Railinc Company Identifier
Register for a reporting mark, or Railinc Company ID, using the Railinc Onboarding Application. There is a one-time setup charge for registering a company ID with Railinc.

Railinc Single Sign-On Account (SSO)
To access MRR, go to the Single Sign-On portal on Railinc's home page. Follow the instructions to register or log in. If you already have an SSO account, proceed to Step 3. Contact the Railinc Customer Success Center by email at or by phone at 877-724-5462 with questions.

More On This Page:

MRR Webinar Slides

Introduction to Rule 88 Process: Click here to download slides from this webinar.

Introduction to Running Repair Agent Process: Click here to download slides from this webinar.