Assessing the carbon emission effects of consolidating shipments

This paper studies the effect on carbon emissions of consolidation of shipments on trucks. By utilizing existing vehicle capacity better, one can reduce distance and thereby carbon emission reductions. Our analysis determines the emission savings obtained by a transport provider that receives customer orders for outbound deliveries as well as pickup orders from supply locations. The transport provider can improve the utilization of vehicles by performing the pickups and deliveries jointly instead of using separate trucks. We compare a basic setup, in which pickups and deliveries are segregated and performed with separate vehicles, with two consolidation setups: backhauling and mixing. We assume that the transport provider minimizes costs by use of a vehicle routing tool, and use a set of test in-stances derived from a standard VRP benchmark and an industrial solver to generate rout-ing plans for the three setups. To compare carbon emissions, we use a carbon assessment method that uses the distance driven and the average load factor. We find that emission savings are relatively large in case of small vehicles and for de-livery and pickup locations that are relatively far from the depot. However, if a truck visits many demand and supply locations before returning to the depot, we observe negligible carbon emission decreases or even emission increases for consolidation setups, meaning that in such cases investing in consolidation through combining pickups and deliveries may not be effective.