modeling the WWSL: 12.4 NMRA Recommended Practices (RP)

Recommended Practices are only less mandatory than Standards by virtue of their slightly less critical subject matter with respect to interchange and/or the fact that deviation for specific reasons is permissable. Recommended Practices do not rise to the level of being a Standard, however, they provide details of various topics that have been found to be the best for interchangeability or operation

RP-1 Abbreviations - (4/2021)

RP-2 Standards Gauges - (12/10/2025 Revised)

RP-5 Electric Traction - General

RP-5.1 Electric Traction - Trolley Wire Frogs - (2/1982)
RP-5.2 Electric Traction - Curvature & Drawbars - (2/1982)

RP-7 Track Centers and Obstacle Clearances - (7/2017)

RP-7.1 Tangent Track Centers and Clearance Diagrams (1/2019)
RP-7.2 Curved Track Centers (7/2017)
RP-7.3 Curved Track Obstacle Clearances (7/2017)
RP-7.4 Interurban Track Centers and Obstacle Clearances (7/2017)
RP-7.5 Modifying Tangent Clearance Diagrams for Curved Tracks (7/2017)

RP-9 Electrical (1/24/2025)

RP-10 Trackwork - General - (7/2012)

RP-11 Curvature and Rolling Stock - (3/2018)

RP-12 Turnouts - General - (2/2015)

TN-12 Engineering Analysis and Geometric Design of Model Railroad Turnouts

RP-13.5 Guard Rail & Frog Relationship - (8/1981)
RP-13.6 Guard Rails - (8/1981)
RP-13.7 Frog & Wing Rails - (8/1981
)RP-13.8 Flangeway Flares - (8/1981)