From Road to Laboratory: A Data-Driven Framework for Field-Aligned Simulation of Braking Dynamics Toward Sustainable Unit Load Packaging

Abstract

Modern distribution packaging is increasingly expected to meet both safety and sustainability targets. However, existing laboratory test methods for evaluating unit load stability still fall short of replicating the dynamic forces that occur during freight transportation. This study addressed that gap with an overarching objective to advance performance based and resource efficient packaging design by (1) characterizing field measured long duration horizontal forces across major freight modes, (2) developing a data driven method for generating unit load stability test profiles, and (3) proposing mode specific composite profiles that can be executed on common test equipment. Longitudinal acceleration data were collected in controlled settings using an instrumented box truck and in uncontrolled settings, multi-day commercial shipments spanning long-haul truck, container-on-train, and trailer-on-flatcar segments. Unit load response to braking events was evaluated in controlled tests using a repositionable unit load avatar designed to match the natural frequency range of typical commercial unit loads. Controlled braking tests and statistical analysis demonstrated that unit load elastic deformation is governed primarily by natural frequency, rise duration, and peak deceleration at the end of the rise phase, whereas steady state duration has statistically significant but comparatively minor influence. Analysis of the field data showed that the magnitude, duration, and occurrence of long duration longitudinal events differ systematically by mode and by segment of the route. Intermodal rail segments generated relatively high percentile longitudinal accelerations with shorter event durations, while over the road truck segments produced lower peak accelerations but substantially longer events, often exceeding several tens of seconds. These findings enabled the development of a simplified test profile structure that preserves deformation critical parameters while reducing steady state duration so that realistic profiles can be implemented within the stroke limits of conventional horizontal acceleration sleds. Building on these insights, the study introduced composite test profiles for long haul truck and rail operations that reflect the statistics of the most critical measured events. Collectively, the results support the inference that unit load stability can be evaluated using profiles that are both representative of actual transportation dynamics and operationally compatible with existing test systems. This can enable more precise specification of stretch wrap or other load stabilizers, reducing unnecessary material use and environmental burden while maintaining or improving load safety, and moves distribution packaging toward a more sustainable, performance-based engineering practice.