A classification yard where cars are pushed over an elevated hump and allowed to roll by gravity into designated classification tracks. Retarders control car speed during descent to prevent damage from collisions. Hump yards dramatically increase sorting throughput compared to flat switching.
A large rail facility where cars from inbound trains are sorted and grouped by destination to build outbound trains. Cars may be sorted using hump switching, flat switching, or a combination of both. Classification yards are the central nodes of the carload network.
A method of classifying cars in a yard where a locomotive pushes or pulls cars onto the correct track without the aid of a hump. Flat switching is slower than hump operations but is used at smaller yards or for fragile lading. It requires more locomotive movements and crew time per car sorted.
The process of grouping railcars destined for the same or nearby destinations together within a train so they can be set out as a single cut without additional classification. A blocking plan defines how a railroad arranges cars to minimize intermediate switching. Effective blocking reduces terminal dwell and improves network efficiency.
A braking device installed in classification tracks at a hump yard that applies friction to the wheels of descending cars to control their speed and ensure they couple gently with cars already in the classification track. Retarders are operated automatically by computer systems that calculate the required retardation based on car weight, wind, and track grade. They are essential for safe hump operations.