The CROSS-STORM project aims to develop a numerical–experimental procedure for assessing the risk of road accidents caused by crosswinds generated by thunderstorms. The methodology consists of three steps: defining the wind velocity field during a storm, calculating the aerodynamic loads acting on a vehicle exposed to thunderstorm outflows, and evaluating the dynamic response of the vehicle–driver system and the associated accident risk. Building on the experience gained within the ERC THUNDERR project, a wind-field model suitable for time-domain simulation of the non-stationary outflow will be developed. Aerodynamic coefficients for different road vehicles will be measured in the POLIMI wind tunnel, and used together with the simulated wind field to compute the resulting aerodynamic loads.

To reproduce driver reactions to these unsteady loads, an experimental campaign will be carried out on the new POLIMI Dynamic Driving Simulator, testing a sample of 20–30 drivers under various scenarios. The ultimate goal is to produce a risk map linking relevant factors—weather conditions, orography, and vehicle type—to specific accident-risk levels.

For the first time, a methodology is proposed that models wind fields of non-synoptic severe events and estimates accident risk by incorporating driver behaviour from simulator tests. This new approach shifts the focus from vehicle manufacturers to infrastructure managers and road users, enabling the evaluation of mitigation measures on motorway sections and supporting real-time risk-assessment algorithms. It may also guide optimal route selection, improving both safety and mobility.