Effective intervention in order to reduce freight transport impacts requires in-depth knowledge of the factors that determine the logistical decisions made by firms. Using data from 1999 shipper surveys, energy consumption is estimated for a sample of shipment and analyzed in relation to the logistical choices made by shippers to quantify the influence of logistical practices on freight transport energy consumption. The data Shipper surveys developed by INRETS describe both the journeys, in terms of the transport chains, and the principal characteristics of the shippers who send consignments. With a view to improving the method employed in this type of survey, two test surveys were conducted in France in 1998-99, each involving slightly more than 200 firms and 600 shipments. On the basis of these surveys different aspects of transport demand (consignments) were quantified and this demand can be related to the principal logistical characteristics of the shipping companies. Energy consumed for the transport of a shipment was estimated in four stages. Using published research it is possible to obtain an estimate of energy consumption which is fairly accurate for road transport but much less so for other modes (rail, waterways, sea and air). In order to exploit the surveys a simplified method for estimating the energy consumption for a consignment was implemented which made use of available variables. Average unitary consumptions, for each transport leg and transport chain are given. By using the average consumption data we have been able to assess the influence of some major logistical tendencies on transport energy consumption. Two major tendencies provide a good illustration of the potential of our approach: the grouping of consignments and the just-in-time approach. Thus, the average effect of grouping consignments is to reduce energy consumption by a factor of between 3 and 4 as a result of the combined effect of the reduction in consumption caused by the increase in the weight of the load and the increase in consumption caused by the lengthening of distances. Improvements to be incorporated into the new shipper survey are described. A new survey is being launched in France this year (2003); these data will enable a deep analysis and modelling of energy consumed in freight transport. For the covering abstract see ITRD E126595.
Abstract