Experimental Assessment of Off-Tracking Reduction Using a Split Fifth-Wheel Coupling during Intersection-Type Turning of a Scaled Tractor–Semitrailer

This article presents an experimental investigation of off-tracking in a tractor–semitrailer during intersection-type turning maneuvers, which typically involve quarter-circle turning paths at urban junctions. Two coupling configurations are examined: a conventional fifth-wheel coupling (CFWC) and a split fifth-wheel coupling (SFWC). A scaled articulated vehicle prototype is developed to conduct controlled low-speed turning tests across multiple radii representative of intersection maneuvering conditions. The measured trajectories of the tractor and semitrailer are compared with predictions from a previously developed zero-speed kinematic model adapted for the present configuration. Maximum off-tracking is quantified for both coupling systems, and agreement between measured and simulated trajectories is evaluated using a normalized root-mean-square error metric.

Results show that the SFWC consistently reduces off-tracking relative to the CFWC across all tested radii, while the kinematic model predicts the measured off-tracking profiles with mean-normalized errors below 0.1. The study is positioned as an experimental assessment of a previously proposed SFWC concept and kinematic formulation, rather than as a new coupling concept or a new modeling method. The findings provide controlled experimental evidence on the influence of coupling configuration on low-speed off-tracking behavior, while the practical implementation of the SFWC is identified as requiring further full-scale mechanical design, articulation limit, and durability studies.