UIC Leaflet 452: Conditions for Shunting and Formation of Freight Trains

What is UIC Leaflet 452?

UIC Leaflet 452 is an operational and technical standard titled “Freight trains – Formation and shunting.” In the complex world of Freight Traffic, trains are often composed of a diverse mix of Rolling Stock from multiple countries and owners.

The leaflet provides the mandatory rules that railway staff and terminal operators must follow when assembling a train or performing Shunting operations (moving wagons to form a consist). Its primary goal is Operational Safety, specifically preventing excessive longitudinal forces that could lead to wagon “climbing” or derailment in curves.

Safety Requirements for Shunting

Shunting is one of the most hazardous activities in rail operations. UIC 452 dictates the limits for impact speeds and weight distribution:

• Impact Speed Limits: When wagons are “humped” or shunted, the speed at which they strike other stationary wagons must be controlled to protect the Buffer and Draw Gear.
• Compatibility Checks: Rules for ensuring that wagons with specific characteristics (e.g., long wheelbases or specialized couplings) are compatible with the curves of the shunting yard.
• Load Stability: Ensuring that the way a wagon is loaded does not make it prone to derailment during the sudden “jerks” associated with shunting.

Train Composition and Consist Ordering

UIC 452 outlines how wagons should be ordered within a train to maintain stability during braking and acceleration. This is critical for Logistics Management and safety:

• Weight Distribution: Heavy wagons should ideally be placed closer to the locomotive to prevent a “bellows” effect (where heavy rear wagons crush lighter front wagons during braking).
• Braking Regime: Ensuring that all wagons in the consist have compatible braking systems (e.g., all set to “G” for freight or “P” for passenger/fast freight).
• Long/Short Wagon Mixing: Specific restrictions on placing very long wagons (like those in Combined Transport) next to very short ones in sharp curves.

Technical Reliability and Buffing Forces

The leaflet interacts closely with vehicle design standards. It assumes that wagons are built to withstand a certain level of longitudinal compression. If a shunting operation exceeds these limits, the Structural Integrity of the wagon could be compromised, leading to invisible damage that manifests as a derailment later during high-speed transit.

Comparison: Hump Shunting vs. Flat Shunting (UIC 452)