Heavy-duty trucks, in particular class 8 tractor-trailer combinations for freight, are a major contributor to the total greenhouse gas (GHG) emissions in transportation systems worldwide. Diesel fuel vastly dominates this market due to its relatively low operating cost. However, both GHG and air pollutant emissions from diesel combustion are significant, which raises doubts about the long-term sustainability of this mode of transportation. A possible short-term opportunity to address this problem is to blend diesel with hydrogen by retrofitting existing fuel injection systems and fuel storage onboard the trucks. Thus, a life cycle assessment is conducted to evaluate the overall environmental and economic impacts of implementing hydrogen and diesel dual-fuel solutions in heavy-duty trucks. The results show a significant reduction in emissions, proportionally to the diesel displacement ratio. Importantly, the use of hydrogen fuel is also shown to provide potential cost savings in this highly cost-sensitive application for hydrogen pricing below C$4/kg. Hence, waste hydrogen available at low cost can facilitate immediate emission reduction and operational cost savings for existing truck fleets, and act as an economical bridge solution for sustainable heavy-duty freight. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.