title: Latent risk and trend models for the evolution of annual fatality numbers in 30 European countries.
abstract: In this paper a unified methodology is presented for the modelling of the evolution of road safety in 30 European countries. For each country, annual data of the best available exposure indicator and of the number of fatalities were simultaneously analysed with the bivariate latent risk time series model. This model is based on the assumption that the amount of exposure and the number of fatalities are intrinsically related. It captures the dynamic evolution in the fatalities as the product of the dynamic evolution in two latent trends: the trend in the fatality risk and the trend in the exposure to that risk. Before applying the latent risk model to the different countries it was first investigated and tested whether the exposure indicator at hand and the fatalities in each country were in fact related at all. If they were, the latent risk model was applied to that country; if not, a univariate local linear trend model was applied to the fatalities series only, unless the latent risk time series model was found to yield better forecasts than the univariate local linear trend model. In either case, the temporal structure of the unobserved components of the optimal model was established, and structural breaks in the trends related to external events were identified and captured by adding intervention variables to the appropriate components of the model. As a final step, for each country the optimally modelled developments were projected into the future, thus yielding forecasts for the number of fatalities up to and including 2020.
authors.affiliation: BRSI, Belgian Road Safety Institute, Belgium. Electronic address: emmanuelle.dupont@ibsr.be.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Dupont
authors.affiliation: SWOV Institute for Road Safety Research and VU University Amsterdam, The Netherlands.
authors.forename: Jacques J F
authors.initials: JJ
authors.lastname: Commandeur
authors.affiliation: IFSTTAR, French Institute of Science and Technology for Transports, Development, and Networks, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Lassarre
authors.affiliation: SWOV Institute for Road Safety Research and VU University Amsterdam, The Netherlands.
authors.forename: Frits
authors.initials: F
authors.lastname: Bijleveld
authors.affiliation: BRSI, Belgian Road Safety Institute, Belgium.
authors.forename: Heike
authors.initials: H
authors.lastname: Martensen
authors.affiliation: NTUA, National Technical University of Athens, Greece.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Antoniou
authors.affiliation: NTUA, National Technical University of Athens, Greece.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Papadimitriou
authors.affiliation: NTUA, National Technical University of Athens, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Yannis
authors.affiliation: Hasselt University, Transportation Research Institute, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Hermans
authors.affiliation: ASPB, Agència de Salut Pública de Barcelona, CIBER de Epidemiología y Salud Pública (CIBERESP), Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain.
authors.forename: Katherine
authors.initials: K
authors.lastname: Pérez
authors.affiliation: ASPB, Agència de Salut Pública de Barcelona, CIBER de Epidemiología y Salud Pública (CIBERESP), Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Santamariña-Rubio
authors.affiliation: La Sapienza University of Rome, Research Centre for Transport and Logistics, Italy.
authors.forename: Davide Shingo
authors.initials: DS
authors.lastname: Usami
authors.affiliation: La Sapienza University of Rome, Research Centre for Transport and Logistics, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Giustiniani
mesh_terms: D000063:Accidents, Traffic / Q000401:mortality* / Q000639:trends; D005060:Europe; D006801:Humans; D015233:Models, Statistical; D008962:Models, Theoretical; D012306:Risk; D012449:Safety
keywords: Exposure; Forecasting; Latent risk model; Risk; Stochastic trend model; Structural time series models