UIC IRS 50544-1 — Brakes: Braking performance
An industry or consortium reference: authoritative, but not a formal standard.
Issuing body: UIC (International Union of Railways) · Version: IRS 50544-1 (Ed. 1, 2025) · Published: 2025-03-01
Link verified August 5, 2026
Scope
Defines braking performance for railway vehicles and trains and the method for determining it: braked weight, braked-weight percentage (lambda), decelerations, and their conversion for operational use, including pointers for hand-wheel screw brakes and spring-loaded parking brakes. Successor to the long-serving UIC Leaflet 544-1 on braking power.
IRS 50544-1 is the reference the interoperable freight and passenger world still runs on when a train's braking capability has to be expressed as a single operational number: the braked weight established by calculation or test, and the braked-weight percentage that timetabling and braking tables consume. The IRS carries forward the leaflet 544-1 method — test train configurations, evaluation of stopping-distance measurements, correction factors, and the relationship between lambda and permissible speeds — which EN 14531 complements from the analytical side. It is used by vehicle engineers demonstrating braking performance for international traffic, by operators building braking tables, and alongside EN 14198 and the TSI braking clauses in any mixed UIC-brake consist.