Environmental Modelling & Software 16 (2001) 297–298 www.elsevier.com/locate/envsoft Note A strategic decision support tool for indicating airport sustainability Callum Thomas a , David Raper a , Paul Upham a,* , David Gillingwater b , Yingjie Yang b , Chris Hinde c a aric, Department of Environmental and Geographical Sciences, Manchester Metropolitan University, John Dalton Extension, Chester Street, Manchester M1 5GD, UK b Centre for Transport Studies, Civil and Building Engineering, Arnold Hall Building, Loughborough LE11 3TU, UK c Haslegrave Building, Department of Computer Science, Loughborough University, Loughborough LE11 3TU, UK Accepted 27 September 2000 1. Introduction Manchester Metropolitan and Loughborough Univer- sities in the UK are engaged in a 3-year project to model airport sustainability, using Manchester Airport as the main source of data and knowledge of airport system dynamics, with other regional UK airports acting as vali- dation sites. The purpose of the model is to supply stra- tegic decision support during the process of planning air- port growth and change. There is also potential for extending the model to assist in planning the regional distribution and integration of airports. The research pro- cess is described in Fig. 1. The main model entities defined are listed in Fig. 2. 2. Rationale The ability of an airport to increase its passenger throughput is subject to operational and environmental constraints. In the UK, potential environmental con- straints on aviation include land availability, noise exposure agreements and national air quality standards. For each constraint, there are options for mitigating impacts in the environs of the airport. Regarding breach of air quality standards (DETR, 1997), for example, a major mitigation option is the transfer of staff and sur- face access passengers from private to collective forms * Corresponding author. Tel.: + 44-161-247-3652; fax: + 44-161- 247-6332. E-mail address: p.upham@mmu.ac.uk (P. Upham). 1364-8152/01/$ - see front matter  2001 Elsevier Science Ltd. All rights reserved. PII:S1364-8152(00)00069-4 of transport that have fewer gaseous emissions per pass- enger km. The model will allow simulation of an airport’s growth over a number of years, showing selected environmental implications of different development options and modes of surface access. Files containing estimates of gaseous and noise emissions, for example, arising from the most favoured scenarios, would be input to more specific functional sub-models to assess bre- aches of environmental quality standards. 3. Model description Spatially, the model is bounded approximately within the three-dimensional zone of the conventional landing and take off cycle (i.e. when aircraft reach 3000 ft in altitude). In terms of the level of environmental assess- ment, the model focuses on loadings or stressors (e.g. emissions) rather than the impacts of those loadings. The indicator framework is consistent with physical sus- tainability theory in that it includes absolute as well as relative (per unit of business performance) measures of environmental loading. Since first and second thermo- dynamic laws mean that lower rates of material through- put in an economy lead to less resource depletion and less pollution, and higher rates to more of the same (Daly, 1973, pp. 14–15), sustainability requires measure- ment of absolute quantities of throughput. However, the exclusion of off-site impacts associated with the life cycles of products and services supporting an airport means that the model will indicate only aspects of the relative local sustainability of different ways of expanding an airport, together with use of operational capacity.