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Methodological Note

The charts and analyses in the Data Mobility report and dashboards are created using Floating Car Data (FCD) provided by the VIASAT provider.

FCDs are generated by a device known as a “black box” (“black box” in English) that can be installed in vehicles for insurance purposes. These devices are equipped with GPS and can record the vehicle’s location and other data useful for reconstructing accidents (date and time, engine status, instantaneous speed, etc.). The technology also allows for reconstructing mobility demand with private vehicles in a specific area through the analysis of information characterizing movements as sequences of points, in a completely anonymous and aggregated form.

The penetration coefficient, or the share of monitorable vehicles by VIASAT using this type of equipment, is about 2% of the total circulating vehicle fleet in Italy.
The total number of monitored vehicles and trips is detailed in the dashboards for the respective years of analysis.

The databases used for the analyses consist of the trips made by vehicles passing through the 14 Italian metropolitan cities. Trips are defined as the trajectories of vehicles, reconstructed based on the points released by black box devices between an ignition point and a shutdown point. Two consecutive trips are considered aggregated if:

  • the intermediate stop is less than 5 minutes throughout the territory;
  • the intermediate stop is less than 30 minutes within service areas along the main roads.

The expansion coefficients to the universe of the monitored sample are given by the ratio between the circulating vehicle fleet and the “resident” monitored sample. A vehicle’s residence is determined based on the share of stops within different municipalities.

The indicators are presented by movement component and refer to average values of the weekday in the month of October for the different years under analysis.

Indicators used, in order of appearance in the report sheets for each city:

  • Number of cars per 100 inhabitants: the motorization rate is derived from the circulating fleet (2022 data provided by ACI) related to the population of the capital city or metropolitan city under examination (2022 data provided by ISTAT)
  • Average trip length: sum of all distances in km traveled by vehicles related to the number of trips. Distribution in classes 0-5 km; 5-20 km; >20 km
  • Average trip speed: sum of all distances in km traveled by vehicles related to the sum of all actual travel times expressed in km/h. Distribution in classes 0-15 km/h; 15-30 km/h; >30 km/h
  • Average trip duration: sum of all actual travel times expressed in minutes related to the number of trips. Distribution in classes 0-15 min; 15-30 min; >30 min
  • Number of car trips: value of daily trips made by vehicles and expanded to the universe
  • Daily time spent driving: sum of all actual travel times related to the number of weekdays and the number of vehicles in the sample, expressed in minutes per day
  • Distances (total km traveled on the network in relation to the area): sum of all travel distances (understood as vehicles*km) at the average daily level related to the area in km² of the urbanized areas within the capital city or metropolitan city under examination
  • In the section “Change in movements on the territory“, the change in the number of movements is represented based on the origin (O) and destination (D) of the mobility matrix: exchanges between the capital city and other municipalities of the metropolitan city; exchanges between municipalities of the metropolitan city excluding the capital; crossings of the territory (O/D outside the metropolitan city).
  • Hourly profile: Hourly profiles are represented with the number of movements for each time slot per day of the week (including weekends); aggregated for the average hourly profiles of weekdays and holidays (Saturday and Sunday) for the years compared; and for territorial clusters divided as follows:
    • North: Turin, Venice, Milan, Genoa, and Bologna;
    • Center: Florence, Rome, and Naples
    • South: Bari, Cagliari, Catania, Messina, Palermo, and Reggio Calabria.
  • Monthly car usage: indicates the monthly usage rate of the vehicle and refers only to weekdays (e.g., the “occasional” usage class refers to car use equal to or less than 4 weekdays compared to the total weekdays of the month). For uniformity of days between 2019 and 2022, the same number of weekdays was considered in both years, excluding the first and thirty-first of October 2022. Percentages are obtained by calculating the number of vehicles belonging to each class compared to the total number of vehicles. Only vehicles residing in the capital city or municipalities of the metropolitan city under examination were considered.

Other indicators present in the chapter “Cities in comparison”:

  • Car trips per inhabitant: the so-called emission rate is obtained by relating the daily trips expanded to the universe with the resident population (provided by ISTAT) for the year and the area (municipality or metropolitan city) of reference
  • Short trips: percentage obtained from the sum of the number expanded to the universe of trips less than 5 km related to the total number expanded to the universe of total trips
  • Dependence on the car: coefficient given by the sum of all weekdays in which a vehicle was used related to the total monthly weekdays. If the coefficient is equal to 1, it means that on average in the area under examination, all vehicles were used every weekday of the month. The coefficient is calculated only for vehicles residing in the capital city or municipalities of the metropolitan city.
  • Daily car trips [additional indicator present in the interactive dashboard]: sum of all trips under examination related to the number of vehicles detected and the number of weekdays available.

It should be noted that, where not specified, the results refer to movements within the capital city.