EVALUATION OF ROAD SAFETY POLICIES AND MEASURES An application of dynamic models to traffic accidents involving vans in Spain during the period of 2000–2009 Aplicación de modelos dinámicos a los accidentes de tráfico con implicación de furgonetas en España en el período 2000–2009 Bahar Dadashova & Blanca Arenas Ramírez & José M. Mira McWilliams & Francisco Aparicio Izquierdo Published online: 11 January 2013 # Etrasa 2013 Abstract Four time series: number and severity of both van accidents and victims in Spanish roads have been analyzed using two main types of methodologies which are applied in the study of traffic accidents: demand for road use, accidents and their gravity (DRAG) and un- observed components model (UCM). Each model was estimated using explanatory and intervention variables that were divided into 9 groups. The explanatory varia- bles were included in the models depending on how significant their t-values were. The final models were chosen using fit statistics such as AIC and R 2 . Finally, predictions were obtained by both methodologies and the prediction errors were compared. None of the two methods was clearly better; it depended on which re- sponse variable was being predicted. Resumen En este trabajo se han analizado cuatro series temporales: número y severidad de accidentes de tráfico con furgonetas y las víctimas producidas en las carreteras españolas, mediante dos metodologías principales: DRAG y UCM. Cada modelo fue estimado con 9 grupos de variables explicativas y de intervención. Las variables explicativas incluidas en los modelos dependen del nivel de significación del estadístico-t. Los modelos finales fueron seleccionados usando los estadísticos de bondad de ajuste AIC y R 2 . Finalmente se han obtenido predic- ciones y se han comparado los errores de predicción de ambas metodologías. No es claro cuál de los modelos es mejor, ya que depende de la variable respuesta. Keywords DRAG . Unobserved components model . Traffic accidents . Prediction error Palabras clave DRAG . Modelos de componentes no observados . Accidentes de tráfico . Error de predicción Introduction Like the other EU countries, Spain has experienced a significant decrease in both the number of accidents and victims in the last few years, confirming positive changes in driver behavior due to the combination of surveillance and intervention measures such as the Penalty Point System and the Penal Code Reform enactment during the period studied [20]. Securitas Vialis (2012) 4:127–136 DOI 10.1007/s12615-012-9056-x B. Dadashova : B. Arenas Ramírez (*) : J. M. M. McWilliams : F. A. Izquierdo ETSII-UPM, Automobile Research Institute (INSIA), Madrid, Spain e-mail: barenas@etsii.upm.es