Coherence analysis of road safe speed and driving behaviour from floating car data

In the Intelligent Transportation Systems, integration of different components of the classical driver-vehicleinfrastructure system is supported by advances in technology and communications. This study presents a general road safety analysis framework that exploits different types of data on traffic, geometry, and accidents to develop a Road Safety Analysis Center and an on-board Road Safety Driver Advisory. The Road Safety Analysis Center considers different sources of data: accident inventories, road geometry, and floating car data, which reveal drivers' behavior. Floating car data are also exploited to derive mathematically the longitudinal parameters of ancient roads, which are crucial to estimate safety conditions in curves. The critical points of the network are revealed by an aggregate analysis of accidents distribution on the roads, while the drivers' behaviour is addressed on a disaggregated level, by the evaluation of speeds distributions with a dense spatial detail. The comparison between speeds distributions, safety conditions, and accident occurrence is useful to individuate the portions of the network to be enforced with safety measures and support drivers with an advanced onboard speed advisory system. This methodology is applied to several extra-urban roads in the Latium region, Italy, to individuate roads with higher values of critical indices.