۱- Introduction

۲- Sustainable control objectives in freeway traffic control

۳- The modelling framework for sustainable freeway traffic control

۴- Sustainable freeway control strategies

۵- Remarks on sustainable freeway traffic control

۶- Future steps towards a greener mobility

References

Abstract

Sustainability is a key point in the design and management of mobility and traffic systems, which affects also the development of traffic control strategies for freeway networks. According to sustainability-related concepts, freeway traffic controllers should be devised not only for maximally exploiting the road capacity and decreasing vehicles travel delays, but also for reducing pollutant emissions, fuel consumptions, accidents, noise, and so on. This paper analyses the state of the art of freeway traffic control strategies characterised by sustainability-related objectives, in particular referred to traffic emissions and traffic safety, by providing a classification of the research papers in this area. The final part of the paper highlights the main research challenges for modelling and control techniques brought by the introduction of emerging information and communication technologies, that are becoming more and more widespread and are transforming the concept of vehicles in intelligent and connected agents, able to measure the traffic state and to implement specific traffic control policies.

Introduction

Nowadays, the greater awareness about the dangerous effects produced by myopic policies aimed only at pursuing short-term benefits has brought the issue of sustainable development to the centre of the political agenda of many countries worldwide. In recent years, in fact, the theme of sustainability has been addressed considering various fields of the human activity and proposing several definitions and targets (as those proposed in Kates, Parris, & Leiserowitz, 2005 and Giovannoni & Fabietti, 2014). Although concerning different aspects, such definitions agree that only the actions aimed at achieving the optimal relation between the humans and the environment can ensure a fair development of contemporary and future society. Yet, the concept of sustainability is extremely complex, since it requires the fulfilment of a mix of often conflicting objectives. The creation of sustainable cities, the promotion of a more equitable economic growth and the environmental safeguard represent just some of the objectives identified in United Nations (2017) to accomplish the 2030 Agenda for Sustainable Development (United Nations General Assembly, 2015). The implementation of the 2030 Program requires a rethinking of transportation systems in a more open-minded and environmentfriendly perspective. In this sustainable vision, the transport system should enhance the social equity and ensure a safer mobility by increasing the access to services and to the most disadvantaged areas, without damaging the environment and people’s health. This ambitious journey towards sustainable mobility starts from the awareness that the transport system, in particular the road sector, is today one of the leading sources of greenhouse gases and pollution, involving serious consequences both for human health and for the environment (Hoek, Brunekreef, Goldbohm, Fischer, & Brandt, 2002). A survey developed by the World Health Organization, on the basis of 2012 data, revealed that 3.7 millions of premature deaths may be attributed to environmental pollution. Most of these deaths and diseases are caused by the prolonged exposure to substances resulting from the use of fossil fuels.