Resumen de Anàlisi quantitatiu de la velocitat dels vehicles a motor participants en atropellaments en zona urbana. Modelització de la sensibilitat de la variable evitabilitat a les variacions de la velocitat específica del vehicle i de la velocitat màxima permesa de la via
Road traffic accidents lead to a number of significant problems, which are clearly reflected in the social costs (injuries, repercussions, deaths, etc.) and economic costs (prevention, healthcare, lost profits, etc.).
This search analyses the road traffic accidents involving pedestrians occurring in urban areas in order to extract conclusions on their causes, as well as the conditions of the road, people and vehicles involved.
The main goal is focused on a quantitative analysis of the influence had by motor vehicle speed in urban areas and how a change to the specific speed of the vehicle and/or the maximum speed limit influence the preventability of the accident itself.
Achieving this goal is based on four stages, which are defined as secondary objectives but which also contribute significant value within the search.
1) Historic report on how mobility and accident rates have undergone various changes over time and in different scenarios. 2) Presentation of the knowledge held by a professional community - road traffic accident reconstruction experts - for its inclusion in the scientific debate. The data have been extracted (collected, deduced, calculated, etc.) using techniques inherent to the discipline, and listing and cataloguing them is essential to this search. 3) Design of a database containing all the significant variables allowing them to be inter-related for analysis of a road traffic accident.
At most, this includes up to 250 records per case, distributed among highly distinct categories. 4) Categoric definition of the ¿preventability¿ concept, an essential variable in the road traffic accident reconstruction discipline. The concept of ¿preventability¿ in the field of this study is defined as the endogenous potential of the subject driver to avoid contact between a mechanical traction vehicle and a pedestrian exposed to the risk stemming from interaction between: a) the relative positions and prior speed of the pedestrian and vehicle; b) the perceptive and reactive capacity of the driver; and c) the surrounding environmental circumstances. Determining these significant variables enables the design of a preventability algorithm and preventability indices based on the maximum speed limit and the initial speed of the vehicle.
Achieving the secondary objectives culminates in statistical models that can explain aspects related to the concept of preventability and its sensitivity to the speed involved in road traffic accidents involving pedestrians. Preventability modelling has been measured for three variables, i.e.: preventability, the preventability/vehicle speed index, and the preventability speed/maximum speed limit index.
Six fundamental variables have been used to explain measurements relating to preventability: initial vehicle movement speed, maximum speed limit, risk exposure time of the pedestrian, maximum preventability speed, pedestrian movement speed and driver reaction time.
The statistical models chosen depend on the type of variable to be explained: a logistic regression model has been used for the preventability variable (this being a dichotomous variable (0/1)) that allows the effect of each explanatory variable on the response variable (preventability) to be explained.
In contrast, multiple linear regression models have been used for the preventability indices because these are capable of modelling continuous numeric variables in the response.
The main contribution from the search is focused on modelling the influence had by motor vehicle speed in urban areas and how a change to the speed might influence the preventability of the accident itself. Modelling the sensitivity of preventability to speed, whether the initial movement speed or maximum speed limit.
