Emissions Modelling with a Simple Transport Model
D Johnson, T Fowkes, T Whiteing, H Maurer, ITS, University of Leeds, UK
We report developments of the LEeds Freight Transport Model (LEFT), carried out as part of the EPSRC-funded ?Green Logistics? project. The developments provide better forecasts of freight volumes and their emissions based on a range of policies.
This paper reports recent developments of the LEeds Freight Transport Model (LEFT), carried out as part of the EPSRC-funded ?Green Logistics? project. This project examines the sustainability of logistics systems and supply chains and is currently being undertaken by a consortium of 6 UK universities, supported and steered by a range of project partners including the Department of Transport and CILT(UK).
The LEFT model uses logit models to provide estimates of the effect of macro-economically neutral scenarios on mode split (road, trainload and wagonload), average length of haul and total market size. The original version of the model, LEFT1, was a simple mode split model intended to give a rough idea of the magnitudes of the effects of various scenarios. This was developed into LEFT2, which was a spreadsheet based model that provided a near instantaneous estimate of the effect of macro-economically neutral scenarios on mode split, average length of haul and total market size.
LEFT3 adds in consideration of vehicle types used, making possible predictions regarding emissions. Disaggregation within LEFT3 is by 7 commodity groups, 9 distance bands and market type (via the need for road collection and delivery at one or both ends). Traffic can switch mode or distance band or disappear altogether or new traffic can be generated. The model was calibrated to 1998 values and data.
Our remit for the Green Logistics project is to deliver a range of enhancements to LEFT, in order to provide better future forecasts of freight volumes and their economic and societal impacts based on a wider range of sustainability initiatives implemented by governmental bodies and others. The paper outlines the developments in LEFT required to meet the objectives of the Green Logistics project, including:
? Recalibration to 2006 data. Rail data has been obtained and most road data we need is published, but work is currently underway interpreting and processing this data into a suitable format for use in the model. The parameterisation of the models must also be improved, eg. using the most up-to-date commodity specific values of time.
? For re-planning logistics chains, we really need Production/Consumption (P/C) data not Origin/Destination (O/D) data, which is usually what is available. P/C matrices establish trade links between places of production and intermediate or final consumption and permit a study of the effect of policies on the number and location of depots, and the pattern of their use, which would greatly strengthen the supply-chain modelling capability of LEFT. The paper reports our progress starting with the construction of a Gravity Model for Food Drink and Agriculture, using regional employment in those industries as the generator and regional population as the attractor with a simple separation function based on distance.
? Adding explicit consideration of externalities to the modelling framework with focus on air pollutants and greenhouse gases. An emissions module quantifies the external effects of freight traffic in physical measures (eg in kt of emissions) by vehicle type (road and rail) and delivers monetary estimates of the externalities.
Association for European Transport