A novel rare event approach to measure the randomness and concentration of road accidents.

Rafael Prieto Curiel,Steven Richard Bishop,Humberto González Ramírez,Yong Deng

doi:10.1371/journal.pone.0201890

Rafael Prieto Curiel, Steven Richard Bishop + Show 2 more

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https://doi.org/10.1371/journal.pone.0201890

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Abstract

BackgroundRoad accidents are one of the main causes of death around the world and yet, from a time-space perspective, they are a rare event. To help us prevent accidents, a metric to determine the level of concentration of road accidents in a city could aid us to determine whether most of the accidents are constrained in a small number of places (hence, the environment plays a leading role) or whether accidents are dispersed over a city as a whole (hence, the driver has the biggest influence).MethodsHere, we apply a new metric, the Rare Event Concentration Coefficient (RECC), to measure the concentration of road accidents based on a mixture model applied to the counts of road accidents over a discretised space. A test application of a tessellation of the space and mixture model is shown using two types of road accident data: an urban environment recorded in London between 2005 and 2014 and a motorway environment recorded in Mexico between 2015 and 2016.FindingsIn terms of their concentration, about 5% of the road junctions are the site of 50% of the accidents while around 80% of the road junctions expect close to zero accidents. Accidents which occur in regions with a high accident rate can be considered to have a strong component related to the environment and therefore changes, such as a road intervention or a change in the speed limit, might be introduced and their impact measured by changes to the RECC metric. This new procedure helps us identify regions with a high accident rate and determine whether the observed number of road accidents at a road junction has decreased over time and hence track structural changes in the road accident settings.

Highlights

According to the World Health Organization, during 2013, more than 1.2 million people died around the world due to a road accident, one of the most frequent causes of death, 2.8 times the mortality due to Malaria and 3.3 times the mortality due to violence
To help us prevent accidents, a metric to determine the level of concentration of road accidents in a city could aid us to determine whether most of the accidents are constrained in a small number of places or whether accidents are dispersed over a city as a whole
In Central London, 32% of the accidents happen in only 2.4% of the road junctions, and they get even more concentrated if we focus only on the Serious and Fatal categories

Summary

Introduction

According to the World Health Organization (with data available at https://bit.ly/2L89d9g), during 2013, more than 1.2 million people died around the world due to a road accident, one of the most frequent causes of death, 2.8 times the mortality due to Malaria and 3.3 times the mortality due to violence. Whilst the number of road accidents is a global concern, it is, possible to either reduce their frequency or their impact: in the UK, for example, the number of road fatalities decreased from an average of more than 3,400 each year between the year 2000 and the year 2004 to an average just above 1,800 fatalities each year between 2010 and 2013 (with data available at https://bit.ly/1JjD4iJ) This dramatic decrease in the number of fatalities in the UK indicates that accidents do not just occur and that through sensible policies, thousands of deaths around the world could be avoided. To help us prevent accidents, a metric to determine the level of concentration of road accidents in a city could aid us to determine whether most of the accidents are constrained in a small number of places (the environment plays a leading role) or whether accidents are dispersed over a city as a whole (the driver has the biggest influence)

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