According to the “Brundtland definition” sustainability includes three pillars: economic, social and environmental, and in the past the economic and financial impacts have dominated the planning of transportation networks which was supported by cost-benefit analysis (CBA). Social and environmental issues have been partly considered by monetization or multi-criteria analysis. In particular the economic way of assessment, to monetize social and environmental impacts and add them to the generalized costs, presumes that these impacts can be traded-off perfectly. The emissions of CO₂, for instance, are fictitiously traded-off by a cost value for CO₂ multiplied with the estimated volume of emissions. The reports of the IPCC and the decisions adopted at the Climate Conferences make clear that GHG-emissions will lead to irreversible impacts which cannot be compensated by money payments in the future. Other long-term irreversibility in the transport planning concerns safety (losses of human life or health) or regional/urban structures leading to social disparities or car dependent mobility. Considering irreversibility implies a fundamental change of planning and decision support into the following directions: integrated systems assessment supplementing project assessment; target-based planning and decision support; new methodologies for integrating very long-term and irreversible environmental and climate impacts; consideration of social and regional equity; integration of innovative options for mobility and logistics and necessary conditions for their sustainable application; urban and regional planning with a clear preference for non-motorized transport and for avoiding an over-concentration of population; changing working locations and conditions for reducing commuting; integration of complementary infrastructures, like regenerative power supply, communication and control technologies, charging and fueling facilities. The idea behind the Special Issue is to collect ideas for methods and applications aiming at integrating irreversibility in transportation planning and decision support.
Keywords: target based infrastructure planning; integration of irreversible social and environmental aspects; wider scoping of transport infrastructure assessment; integration of complementary networks.