Quantifying uncertainty in short-term traffic prediction and its application to optimal staffing plan development

•A hybrid PSO-ELM model is improved for interval prediction of short-term traffic.•The reliability and sharpness of the prediction intervals are considered.•The improved PSO-ELM model is compared with five other models.•A comprehensive optimal staffing plan development framework is proposed.•Performances of staffing plans from prediction intervals and point predictions are compared.