Executive Summary

This report presents the results from a research project on the dynamic load allowance (DLA) for bridges subjected to autonomous truck platoons (ATPs). A brief overview of the project is presented followed by a comprehensive literature review on platooning configurations and their effect on bridges, the selection of candidate trucks to constitute an ATP, and DLA analyses. Next, the modelling of trucks, the road surface roughness generation in MATLAB, and its realization in Abaqus as 3D finite element modelling are presented in detail.

A comprehensive investigation was performed to identify the candidate truck using weigh-in-motion datasets published in the literature. Based on this review, the Federal Highway Administration (FHWA) Class 9 truck with five axles was selected for the platoons. A parametric study of the DLA was performed for a single span steel girder bridge for a single truck and for platoons with two or three trucks, with speeds ranging from 60 to 100 km/h, inter-truck spacings between 6 m to 10 m, and three road surface roughness profiles (ISO 8608 profile A, ISO 8608 profile B, and ISO 8608 profile C).

The results indicate that the resonance of the bridge can be excited by truck platoons for specific speed and inter-truck spacings, which can increase the DLA relative to that of a single truck. Combinations of platoon speed and spacing that result in resonance conditions and high DLA vary as a function of surface roughness. When resonance conditions are not encountered and inter-truck spacings are small, such that all platoon trucks are simultaneously on the span, the DLA is smaller compared to a single truck for smooth surface profiles. Large inter-truck spacings for 2-truck and 3-truck platoons result in high DLA but lower static loads, which can result in dynamic effects that are not within the current CSA S6, Canadian Highway Bridge Design Code guidelines, particularly for greater road surface roughness. ATPs on a smooth profile result in only marginal increases in DLA compared to a single truck and are within current CSA S6:19 guidelines.

Considering the results of the analyses conducted for this report, future work is recommended to compare the trends observed in DLA for different span lengths, bridge types, larger number of trucks, and multiple simultaneous presence effects.