Variation in Speed Distributions with Local Truck Proportion in Mixed Freeway Traffic: A Shapley Decomposition
Year: 2026
Type: article
Abstract: Variations in the overall speed distribution of mixed freeway traffic may reflect changes in vehicle-type weights, vehicle-type-specific speed distributions, or both. Using the highD vehicle trajectory dataset, we analyzed 50-m × 30-s spatiotemporal cells, with 60-s cells used for sensitivity analysis. Fixed-effects spline models estimated associations between local truck proportion (TP) and speed-distribution measures while adjusting for local traffic flow rate and recording–direction–location fixed effects. Standardized mixture distributions and a two-factor Shapley decomposition separated changes in the overall distribution into vehicle-type weight and within-type components. For the adjusted TP = 0.25 versus TP = 0.15 contrast, the differences in mean speed, the 25th percentile speed (P25), and the interquartile range were −2.51, −6.64, and +5.50 km/h, respectively, with the widening concentrated mainly on the lower-speed side. The directions of change were consistent at the 60-s scale. For mean speed, P25, the 50th percentile speed (P50), and the interquartile range, the vehicle-type weight component exceeded the within-type component in absolute magnitude at both temporal scales, as supported by recording–direction cluster bootstrap results. Distinguishing these components clarifies the statistical sources underlying changes in the overall speed distribution.
Source: Applied Sciences
DOI: 10.3390/app162010152
Authors: Haidong Li, Bo Hu, Honghui Shen, Xiaomeng Wang
Language: English
Subfield: Control and Systems Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,896
OpenAlex ID: W7221755084