Integrated modelling chain for tailored traffic policy interventions

Urbanization brings a set of challenges that demand innovative and comprehensive solutions. Among these, sustainable mobility and air pollution mitigation are the most pressing ones, both tackled by the European Green Deal that advocates for Europe's climate neutrality by 50. The EU framework only sets the target goal for air quality and pollutant emissions, but the single member states are empowered to define their mobility strategy and define national and local policies. Therefore, a proper design and implementation of strategic initiatives must be tailored to the needs of local settlements and communities. Numerical models offer the possibility to test realistic strategies and evaluate their benefits by simulating realistic scenarios, including individuals’ and communities’ behavioural changes in response to strategy implementation. This study proposes an integrated modelling chain developed within the I-CHANGE (Individual Change of Habits Needed for European Green Transition) EU Horizon 2020 project to estimate the role and impact of behavioural change for the mitigation of CO2, greenhouse gases, short-lived climate forcers and air pollutants associated with road traffic. The modelling chain is modular and suitable to simulate the current status and hypothetical policy scenarios: it composes of an activity-based model, deriving the traffic flow generated by the citizens’ daily habits, an emission model, extrapolating the emission inventory of the target atmospheric compounds which are finally used by a dispersion model to derive the air pollutants concentration and spatial distribution. Rooted in numerical models at the state-of-the-art and well-consolidated analytical methods, citizens sustain the chain will and stakeholder needs to frame the necessary policy interventions. ntions. The outcome of the modelling chain is twofold: (i) bringing evidence on the efficiency of designed mitigation strategies and (ii) demonstrating to the public that mitigation can be pursued, incentivizing the necessary behavioural change it might require.  

The methodology here presented is applied to evaluate four policy scenarios tested in the city of Bologna (IT), Dublin (IE) and Hasselt (BE). The output allows to elaborate potential advantages and disadvantages in terms of mobility, air quality and behavioural change the cities would face. Specifically, the policy scenarios envision new bicycle infrastructure in designated areas (policy 1), Low Emission Zones in the city centre (policy 2), time-based restrictions on car and private vehicle usage near schools (policy 3) and flexible working hours/working from home schemes (policy 4). Depending on the scenario, policies implementation can introduce notable impacts on (local) concentrations. Specifically, policy scenarios tend to lead to lower peaks of pollutant concentration levels in the areas where policies are implemented, counterbalanced by minor concentration increases in other areas. These insights facilitate evidence-based policy adjustments, enabling decision makers to address the complexities of urban development while fostering resilient, inclusive, and environmentally conscious communities.