Francisco Aparicio Izquierdo

Evolution of the crashworthiness and aggressivity of the Spanish car fleet

This paper investigates the relationship between a passenger cars year of registration and its crashworthiness and aggressivity in real-world crashes. Crashworthiness is defined as the ability of a car to protect its own occupants, and has been evaluated in single and two-car crashes. Aggressivity is defined as the ability to protect users travelling in other vehicles, and has been evaluated only in two-car crashes. The dependent variable is defined as the proportion of injured drivers who are killed or seriously injured; following previous research, we refer to this magnitude as injury severity. A decrease in the injury severity of a driver is interpreted as an improvement in the crashworthiness of their car; similarly, a decrease in the injury severity of the opponent driver is regarded as an improvement in aggressivity. Data have been extracted from the Spanish Road Accident Database, which contains information on every accident registered by the police in which at least one person was injured. Two types of regression models have been used: logistic regression models in single-car crashes, and generalised estimating equations (GEE) models in two-car crashes. GEE allow to take account of the correlation between the injury severities of drivers involved in the same crash. The independent variables considered have been: year of registration of the subject car (crashworthiness component), year of registration of the opponent car (aggressivity component), and several factors related to road, driver and environment. Our models confirm that crashworthiness has largely improved in two-car crashes: when crashing into the average opponent car, drivers of cars registered before 1985 have a significantly higher probability of being killed or seriously injured than drivers of cars registered in 2000-2005 (odds ratio: 1.80; 95% confidence interval: 1.61; 2.01). In single-car crashes, the improvement in crashworthiness is very slight (odds ratio: 1.04; 95% confidence interval: 0.93; 1.16). On the other hand, we have also found a significant worsening in aggressivity in two-car crashes: the driver of the average car has a significantly lower probability of being killed or seriously injured when crashing into a car registered before 1985, than when crashing into a car registered in 2000-2005 (odds ratio: 0.52; 95% confidence interval: 0.45; 0.60). Our results are consistent with a large amount of previous research that has reported significant improvements in the protection of car occupants. They also add to some recent studies that have found a worsening in the aggressivity of modern cars. This trend may be reflecting the impact of differences in masses and travel speeds, as well as the influence of consumer choices. The precise reasons have to be investigated. Also, the causes have to be found for so large a discrepancy between crashworthiness in single and two-car crashes.

OPTIMIZACION DE CONSUMO DE COMBUSTIBLE DE VEHICULOS BASADA EN PROGRAMACION DINAMICA

In this paper, an optimization algorithm is proposed to calculate the optimal speed of a conventional vehicle taking into account fuel consumption, travel time and the vertical profile of the road. The optimization algorithm is based on the Dynamic Programming technique and obtains the global minimum of an objective function that involves fuel and time. By setting as target a predefined travel time, the algorithm calculates the optimal profiles for speeds and engaged gears for drive across a known highway. This travel is completed according to the established time and using the minimum possible fuel amount. The optimal speed profile is obtained by concatenating different vehicle speed transitions across the route. The fuel consumption is calculated using a quasi-static model for simulate the speed transitions of the vehicle. Using data of a real road, fuel savings of up to 5.2 % are obtained without modifying travel time. The algorithm can be implemented on a vehicle improving its efficiency.

ANÁLISIS DE SENSIBILIDAD EN EL CÁLCULO DE EMISIONES CONTAMINANTES DEL TRÁFICO DE MERCANCÍAS EN EJES DE TRANSPORTE

La competitividad en el transporte de mercancias espanol y mundial, junto con la preocupacion creciente por la reduccion de emisiones, ha provocado que se preste una gran atencion a la mejora de su eficiencia, tanto desde el punto de vista logistico como el medioambiental. Por ello, el trasvase modal tiene una relevancia creciente en las administraciones y en investigacion. En este trabajo se desarrolla un analisis de sensibilidad sobre un codigo de ordenador de simulacion estocastica, que estima la distribucion de probabilidad de las emisiones que se dejan de producir en la carretera como consecuencia del trasvase modal de mercancias al ferrocarril. El modelado estadistico proporciona el valor anadido esencial de la cuantificacion de las incertidumbres y comprende varias etapas que posteriormente se acoplan mediante el metodo de Monte Carlo, implementado en un codigo de simulacion escrito en lenguaje abierto R. El analisis de sensibilidad se realiza a traves de un experimento computacional cuyos resultados se analizan mediante la tecnica ANOVA, para estudiar el efecto, sobre las emisiones, de cambios en las distribuciones de probabilidad de las variables que determina las etapas del modelo, tanto de forma individual (efectos principales) como conjunta (interacciones). La metodologia se aplica como ilustracion al eje Madrid-Guipuzcoa para la estimacion de consumos y de las emisiones de CO, NOx, HC y de material particulado (PM). DOI: http://dx.doi.org/10.4995/CIT2016.2016.1989

Evaluation of the seat fastening in the frame of a road bus submitted to frontal impact

The collective intercity transportation by bus is currently a mean of locomotion much sought after by people. Security in accidents is a very important factor that must be taken into account in design of bus body structure, being the evaluation of passenger safety of this type of vehicle is an important subject that should be checked, because in many accidents occur disconnection between seats and fastening members causing serious passengers injury, often fatal. This work aims at evaluation the behavior of frame fixing of seats of intercity bus bodies, submitted to the frontal impact situation in a rigid wall of 100% offset, through evaluation by finite element method (FEM). This study uses a numerical model corresponding to the body structure and chassis, developed through flexible beam elements, combining with shell elements for the structure of the seats and its fastening members, with the objective of not missing the essential aspects of the problem, allowing the solution with a reduced computational time. The numerical model of bus body and seat was impacted against a rigid wall at a speed of 8.89 m/s, being its validation according to the deceleration curve established by Regulation 80. Then it was gotten the Von Mises stress in fastening members of the seat structure in bus body. It is also presented a proposal to improve the fastening of the seat structure, comparing the results of the stress gotten in the two types fastening submitted to the frontal impact.

Evaluation of the Effectiveness of Active Safety Systems in Vans with Respect to Real World Accident Analysis

This paper belongs to “F08: Vehicle Controls on Handling and Stability” topic. It is aimed to assess the potential influence of three active safety systems—the Antilock Brake System (ABS), the Brake Assist System (BAS) and the Electronic Stability Programme (ESP)—in collisions with vans involved, through the analysis of fatal real world accidents occurred in Spain. The methodology follows during this study is based on a retrospective accident analysis of the technical reports of the Spanish Traffic Directorate (DGT). A detailed database has been compiled by the INSIA—UPM accident analysis department, comprising 254 fatal accidents with vans involved, occurred in rural roads during 2009 and 2010. In case of fatal accidents, these reports prepared by the Spanish Traffic Police show a high quality data. This information has been analysed to identify major accidents and causes of accidents (HFF method), in order to identify reference accident scenarios, which take into account the active safety systems proposed. A sample of these accidents, selected from the most representative scenarios, has been re-analyzed and re-evaluated considering the assumed effect of each specific active safety system. Although the performance of active safety systems explains basically their behaviour in test conditions, they are not sufficient to assess their success in each real world situation. Active Safety systems interact with the driver, the vehicle and the environment. A full forecast of their potential is only possible by modelling the driver-vehicle-system-environment. This methodology has already been applied by authors to evaluate the effectiveness of active safety systems in case of pedestrian accidents. This study continues the same research line based on real world accidents analysis, applied to accidents involving vans. The findings show that a number of the collisions could have been avoided by implementing these systems. Even though comprising a small number of cases, it is an invaluable resource for monitoring real world performance of active safety systems.

Van Traffic Accident Analysis. A Holistic Approach

From 2003 on, the numbers of accidents and victims have decreased significantly in Spain: the number of deaths was in 2010 54 % below that of 2003. This has been to a great extent the results of several safety policy measures such as the penalty point system, surveillance and control campaigns and a considerable increase in the media of road safety-related issues. However, accidents with involvement of vans (LGV’s less than 3500 kg) have not followed this trend, and thus the contribution of this kind of vehicles to the global figures has risen. Within this context, INSIA has conducted an ambitious research project, developed with the purpose of an integrated analysis of the different factors which can explain the accidental behavior of this kind of vehicles. In this paper analyze in greater depth the validity of one of the initial hypothesis: “vans may have a different dynamic behavior from passenger cars, and thus accident rates may be higher if they are driven like a passenger car”. The basis of the working hypotheses are essentially related to the behavior of the vehicle with respect to safety distances, reaction times and braking capacities of the vehicle behind, and on the influence of loads.

Safety Management Evaluation in Bus and Coach Companies

Abstract In recent years, different initiatives have been carried out to develop Safety Management System guides or standards for coach and bus companies. They all consist of a set of safety and management requirements to be followed by organizations. However, none of them offers a complete set of tools to evaluate the safety level of the company and find the main weak points in order to improve them. The INSIA (Automotive Research Institute of Madrid, Spain) has developed a complete model that includes not only a set of elements that determine the safety level of the company but also a set of indicators and criteria to evaluate these elements by a team of auditors. The model allows companies to measure their safety level, find the weakest points and propose improvement actions.