Multi-lane factor for bridge traffic load from extreme events of coincident lane load effects

A novel framework for multi-lane factors (MLFs) for bridge traffic loading is proposed in this work. A general equation of MLF, consisting of a combination coefficient, a lane correction coefficient, and a share factor is established. The calculation methodology for lifetime MLF uses bivariate extreme-value theory based on coincident extreme lane loading events. Example application of the framework to a site using Weigh-In-Motion (WIM) data is demonstrated, in which traffic simulations and bivariate extreme value bootstrapping are implemented to calibrate the MLF model. For the site studied, statistical results of WIM data indicate the traffic loads in adjacent lanes are different but correlated. Calibration of the MLF model illustrates that the dependence between extreme coincident lane load effects is influenced by the correlation of traffic loads in adjacent lanes. Two key parameters, share factor and weight restriction, are found to have distinct influences on the calibrated values of MLFs, and so need to be considered in a site-specific assessment of multi-lane bridge traffic loading. The proposed general MLF framework provides a deep understanding of multi-lane traffic loading, and can be calibrated for any bridge or traffic stream.