Search

[EN] The presence of cyclists on Spanish rural roads is ever increasing and currently frequent, and thus becoming a serious safety concern. In rural environments, the risk of a crash is higher than in rural areas. The main cause is the higher speed of motor vehicles during overtaking manoeuvres. This manoeuvre is especially challenging when cyclists ride in groups as they may change size, length, shape, and speed along their route. These variables and those related to road cross-section can influence driver behaviour when overtaking a group of cyclists. To study this, instrumented bicycles were used to ride along five road segments with different geometric and traffic characteristics. Cyclists rode individually and in groups. Overtaking was evaluated by analysing the lateral distance, the speed, and other characteristics of the manoeuvre. Wider roads presented higher lateral clearances and overtaking speeds. Narrower roads had a high opposing lane invasion but a high level of compliance with the minimum lateral clearance. A higher clearance and lower speed of overtaking vehicles was registered when cyclists rode in line. Compliance with the 1.5 m clearance depended on the group configuration, being higher when cyclists rode in line. However, overtaking cyclists riding two abreast presented more accelerative manoeuvres, especially on narrow roads., This research is part of the research project TRA2016-80897-R, funded by MCIN/AEI/10.13039/501100011033 and the research project SPIP2017-02280, funded by the General Directorate of Traffic of Spain.

[EN] In recent years, cities are experiencing changes in the ways of moving around, increasing the use of micromobility vehicles. Bicycles are the most widespread transport mode and, therefore, cyclists¿ behaviour, safety, and comfort have been widely studied. However, the use of other personal mobility vehicles is increasing, especially e-scooters, and related studies are scarce. This paper proposes a low-cost open-source data acquisition system to be installed on an e-scooter. This system is based on Raspberry Pi and allows collecting speed, acceleration, and position of the e-scooter, the lateral clearance during meeting and overtaking manoeuvres, and the vibrations experienced by the micromobility users when riding on a bike lane. The system has been evaluated and tested on a bike lane segment to ensure the accuracy and reliability of the collected data. As a result, the use of the proposed system allows highway engineers and urban mobility planners to analyse the behaviour, safety, and comfort of the users of e-scooters. Additionally, the system can be easily adapted to another micromobility vehicle and used to assess pavement condition and micromobility users¿ riding comfort on a cycling network when the budget is limited., This research was funded by MCIN/AEI/10.13039/501100011033, grant number PID2019-111744RB-I00.

[EN] In Spain, the presence of cyclists' groups riding on two-lane rural roads in a single file or in parallel line is growing. The number of overtaking maneuvers to them is also increasing. This is one of the most dangerous interactions between motor vehicles and bicycles. However, the risk of these maneuvers has not been analyzed in depth. This research analyzes the objective and subjective risk of overtaking maneuvers to cyclists' groups. During this maneuver, the motorized vehicle overtakes the bicycles with a certain speed and lateral distance. These are the surrogate measures used to analyze the objective risk, whereas the subjective risk was analyzed based on the subjective risk perception that 10 cyclists riding instrumented bicycles (in different group configurations) indicated when every motor vehicle overtook them. Results show that the cyclists most exposed to the overtaking maneuver are those at the front and at the rear of the group. In relation to the configuration, the risk is higher in parallel lines, as the lateral clearance is lower compared with a single line. It is even higher when the overtaking maneuver is flying, which is usually performed at higher speeds and lower lateral clearance. The subjective risk perception increases with higher speed and lower lateral clearance, and is higher at the rear positions. Overtaking in which lateral distance is less than 1.5 m is perceived as the riskiest. These results provide scientific recommendations to enhance safety for cyclists' groups, and to integrate cycling with vehicular traffic on two-lane rural roads, The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study presented in this paper is part of the research project titled "Road safety countermeasures for two-lane rural roads with group of cyclists (Safe4Bikes)'' (SPIP2017-02280), subsidized by the Direccion General de Trafico (General Directorate of Traffic) of Spain. Document

[EN] Road safety is closely related to geometric design consistency, which is usually assessed by examining operating speed. Most consistency models only consider passenger car speeds, even though the interaction between passenger cars and heavy vehicles plays a pivotal role in road safety. This is due to the fact that there are too few models to estimate heavy vehicle speeds. This study aims to develop speed prediction models for heavy vehicles on horizontal curves of two-lane rural roads. To do this, continuous speed profiles were collected by using Global Positioning System (GPS) tracking devices on 11 road sections. Truck speeds were analyzed on 105 horizontal curves. The results showed that the radius of the horizontal curve and the grade at the point of curvature have a significant influence on heavy vehicle speeds. In this regard, vertical alignment only has a significant effect on truck speeds along upgrades. In addition, different trends were identified for loaded and unloaded trucks, so different speed models were calibrated for each of them. As a result, heavy vehicle speeds were adversely affected by grades greater than 3%. This phenomenon was larger for loaded trucks than for unloaded ones. Finally, the calibrated 85th and 15th percentile speed models were compared with those developed previously. As a conclusion, the use of the proposed models in this study was recommended on Spanish two-lane rural roads due mainly to the different characteristics of heavy vehicles around the world., The study presented in this paper is part of the research project titled ‘‘CASEFU - Estudio experimental de la funcionalidad y seguridad de las carreteras convencionales’’ (TRA2013-42578- P), subsidized by the Spanish Ministry of Economy, Industry, and Competitiveness and the European Social Fund. In addition, the authors would like to thank the companies SAV, SAEVI, and OAM, for their cooperation in field data gathering.

[EN] Mobility patterns and lifestyles have changed in recent years in cities worldwide, thanks to the strong rise in modes of travel commonly referred to as micromobility. In this context, e-scooters have experienced a great rise globally which has led to an increase of crashes involving this type of micromobility vehicle in urban areas. Thus, there is a need to study e-scooter users¿ behaviour and their interaction with cyclists. This research aimed at characterizing the meeting manoeuvre between micromobility users along diverse typologies of two-way bicycle track by using an in-strumented e-scooter. As a result, bicycle tracks having concrete or vegetated curb presented lower clearance distance (¿0.8 m) than those without edge elements (>1 m), with no statistically signif-icant differences found between the interaction with bicycles and e-scooters. Additionally, an online questionnaire was proposed to assess users¿ perceived risk during the meeting manoeuvre, concluding that micromobility users feel safer and more comfortable riding on pavements away from parked or moving motorized traffic, and on protected bicycle tracks., FundingThis research is part of the research project PID2019-111744RB-I00, funded by MCIN/AEI/10.13039/501100011033.

[EN] Free-flow speed variation of passenger vehicles along a road segment is one of the most used factors in road safety studies, as a surrogate measure to evaluate road design consistency. Free-flow speed may be measured when a road segment is already built but must be estimated during the design phase. Several studies have been carried out to calibrate models to estimate free-flow speed, with geometric features as explanatory variables. Currently, most free-flow speed models focus only on mean speed or speed in particular percentiles, such as the 85th or 95th. Moreover, most studies have assumed normality in the free-flow speed distribution without checking this hypothesis. The main objective of this study was to analyze the free-flow speed distribution on two-lane rural road curves and tangents. The research focused on two main issues: determining whether speed data were normally distributed at a specific site and analyzing the behavior of the mean and standard deviation of speed on curves and tangents. The study was based on continuous operating speed profiles, which were obtained from a database of more than 16,000 vehicles/km. A total of 63 horizontal curves and 78 tangents were analyzed. According to the results, the normal distribution is not the best distribution in most cases for describing free-flow speeds. In 46 of the curves and 64 of the tangents, free-flow speed cannot be assumed to be normally distributed. Therefore, some other distributions should be tested in further research., The study presented in this paper is part of the research project CASEFU-Estudio experimental de la funcionalidad y seguridad de las carreteras convencionales, subsidized by the Spanish Ministry of Economy and Competitiveness and the European Social Fund. In addition, the authors thank the Center for Studies and Experimentation of Public Works of the Spanish Ministry of Public Works for subsidizing the field data collection, and the Infrastructure and Transportation Department of the General Directorate of Public Works of the Valencian Government, the Valencian Provincial Council, and the Ministry of the Interior, especially the General Directorate of Traffic of Spain, for their cooperation in gathering the field data.

[EN] In 2014, highway vehicles accounted for 72.8% of all Greenhouse Gases emissions from transportation in Europe. In the United States (US), emissions follow a similar trend. Although many initiatives try to mitigate emissions by focusing on traffic operations, little is known about the relationship between emissions and road design. It is feasible that some designs may increase average flow speed and reduce accelerations, consequently minimizing emissions. This study aims to evaluate the impact of road horizontal alignment on CO2 emissions produced by passenger cars using a new methodology based on naturalistic data collection. Individual continuous speed profiles were collected from actual drivers along eleven two-lane rural road sections that were divided into 29 homogeneous road segments. The CO2 emission rate for each homogeneous road segment was estimated as the average of CO2 emission rates of all vehicles driving, estimated by applying the VT-Micro model. The analysis concluded that CO2 emission rates increase with the Curvature Change Rate. Smooth road segments normally allowed drivers to reach higher speeds and maintain them with fewer accelerations. Additionally, smother segments required less time to cover the same distance, so emissions per length were lower. It was also observed that low mean speeds produce high CO2 emission rates and they increase even more on roads with high speed dispersions. Based on this data, several regression models were calibrated for different vehicle types to estimate CO2 emissions on a specific road segment. These results could be used to incorporate sustainability principles to highway geometric design., The study presented in this paper is part of the research project titled "CASEFU - Estudio experimental de la funcionalidad y seguridad de las carreteras convencionales" (TRA2013-42578-P), subsidized by the Spanish Ministry of Economy, Industry, and Competitiveness and the European Social Fund. In addition, the authors would like to thank the Center for Studies and Experimentation of Public Works (CEDEX) of the Spanish Ministry of Public Works for subsidizing the field data collection and the General Directorate of Public Works and Transportation of the Valencian Government, to the Road Department of the Valencian Provincial Council, and to the Spanish Ministry of the Interior, especially the General Directorate of Traffic of Spain, for their cooperation in field data gathering. Finally, we would like to thank Professor Hesham A. Rakha, Virginia Tech (USA), for providing the VT-Micro model and assessing the authors in its use to obtain outcomes.

[ES] La velocidad de operación es uno de los factores más estudiados en el análisis de la seguridad vial por su relación con la siniestralidad. En la fase de explotación es relativamente sencillo calcular la velocidad de operación a partir de datos empíricos, pero, en las fases de planeamiento y de proyecto, sólo será posible estimarla. Numerosos autores han modelizado la velocidad de operación de vehículos ligeros en curvas de carreteras convencionales considerando su velocidad mínima. Algunos a partir de observaciones en aquellos puntos de la carretera más significativos como el punto medio de la curva (velocidad mínima), otros a partir de datos continuos utilizando, por ejemplo, dispositivos GPS. La mayoría de los modelos que estiman esta velocidad se basan únicamente en el percentil 85 de la distribución o en su velocidad media. Además, la mayoría de los estudios asumen que sus datos se distribuyen según una normal sin, en muchos casos, comprobar dicha hipótesis. El objetivo de este estudio es analizar la distribución de la velocidad desarrollada por vehículos ligeros circulando en condiciones de flujo libre en curvas de carreteras convencionales. Para ello, la investigación se basa en determinar si los datos de velocidad de 63 curvas disponibles de una base de más de 16.000 vh·km se distribuyen según una normal, y en el análisis del comportamiento de la media y la desviación típica de la distribución de velocidades en curvas. Se ha concluido que la distribución normal no es la que mejor se ajusta al comportamiento de la velocidad en la mayoría de los casos., El estudio que se ha presentado es parte del proyecto de investigación “CASEFU – Estudio experimental de la funcionalidad y seguridad de las carreteras convencionales” (TRA2013- 42578-P), subvencionado por el Ministerio de Economía y Competitividad y el Fondo Social Europeo. Asimismo, los autores quieren agradecer al Centro de Estudios y Experimentación de Obras Públicas (CEDEX) del Ministerio de Fomento por subvencionar la investigación en la que se llevó a cabo la toma de datos, a la Dirección General de Obras Públicas, Transporte y Movilidad de la Conselleria de Vivienda, Obras Públicas y Vertebración del Territorio, a la Diputación de Valencia, y al Ministerio del Interior, especialmente a la Dirección General de Tráfico, por su colaboración en la toma de datos.

[ES] Muy diversas investigaciones previas han mostrado cómo la percepción del riesgo afecta el comportamiento de los conductores. Muchas de ellas van dirigidas a observar la diferencia de percepción entre conductores experimentados y noveles, o entre el riesgo objetivo y el percibido. Mientras que el riesgo objetivo puede ser obtenido a partir de las estadísticas de siniestralidad, el riesgo percibido es más complicado de evaluar. Existen diversos métodos, yendo desde la encuesta directa hasta técnicas de rastreo de la visión.En este estudio se presenta una nueva metodología para recoger datos de Percepción Subjetiva de Riesgo (PSR) de forma quasi-naturalística. Con esta metodología, los conductores pueden indicar de forma sencilla su percepción de confort tras recorrer cada una de las curvas que compone un trazado. Posteriormente, la correlación de estos datos con la geometría de las curvas y otras variables permite derivar sencillas reglas para obtener un diseño consistente de la carretera. Igualmente, si esta metodología es válida para ser llevada a cabo en un entorno simulado, permitiría evaluar carreteras en fase de proyecto, convirtiéndose en una valiosa herramienta para los ingenieros.Un total de 28 conductores participaron en la toma de datos, recorriendo el mismo tramo de carretera en la realidad y en entorno simulado, de 32 km. En ambos casos indicaron su percepción de PSR tras cada una de las curvas aisladas. En este estudio se muestran los resultados alcanzados, tanto en el entorno real como el simulado. Igualmente, se establecen conexiones y correlaciones entre ambos métodos, mostrando bajo qué condiciones el entorno simulado arroja valores válidos., Los autores quisieran agradecer a la Universitat Politècnica de València (UPV), que financió el proyecto de investigación “CONSIM - Desarrollo de un Modelo para la Evaluación de la Consistencia del Diseño Geométrico de Carreteras Convencionales mediante Simuladores de Conducción” (PAID 05-2012). Asimismo, agradecer también al Ministerio de Economía y Competitividad y al Fondo Social Europeo, que financiaron el proyecto de investigación “CASEFU - Estudio experimental de la funcionalidad y seguridad de las carreteras convencionales” (TRA2013-42578-P), del cual forma parte este estudio.

[EN] In recent years, the number of road-based studies using driving simulators is growing significantly. This allows evaluating controlled situations that otherwise would require disproportionate observations in time and/or cost. The Institute of Design and Manufacturing (IDF) of the Polytechnic University of Valencia (UPV) has developed, in collaboration with the Engineering Research Group Highway (GIIC) of the UPV, a low cost simulator that allows rapid implementation and effectively a new methodology for validation studies of different roads through the implementation in the simulator scenarios of existing roads. This methodology allows the development of new scenarios based on the analysis of a layers-file system. Each layer includes different information from the road, such as mapping, geometry, signaling, aerial photos, etc. The creation of the simulated scenario is very fast based on the geometric design software, making it easier to consulting firms using the system that can evaluate and audit a particular route, obtaining reliable conclusions at minimal cost, even if the road is not actually built. This paper describes the basic structure of the layers generated for developing scenarios and guidelines for the implementation thereof. Finally the application of this methodology to a case of success will be described., Authors would like to thank Polytechnic University of Valencia (UPV) that subsidizes the research project CONSIM (PAID 05-2012).

[ES] La velocidad de operación, definida como el percentil 85 de la distribución de velocidad de vehículos ligeros circulando en carreteras convencionales en condiciones de flujo libre, es una de las principales variables en la evaluación de la consistencia del diseño geométrico. De esta forma, los únicos vehículos considerados en el análisis son los vehículos ligeros, obviando la influencia de los vehículos pesados. Para la estimación de la velocidad de operación de estos vehículos el número de modelos existentes es mínimo. Por ello, el objetivo del trabajo que se presenta es el estudio experimental de la velocidad desarrollada por vehículos pesados en carreteras convencionales. El estudio no se centra únicamente en la velocidad de operación, sino en el estudio de la distribución completa de la velocidad, ya que los percentiles bajos están relacionados con el riesgo de alcance de vehículos ligeros. Se han analizado las diferentes variables que pueden influir con especial énfasis en las variables geométricas de la carretera. El estudio se ha basado en los datos obtenidos gracias a la colaboración de dos empresas, que han permitido la colocación de dispositivos GPS de 1 Hz en vehículos de su flota. Los GPS registraron de forma continua la velocidad desarrollada por los vehículos durante la realización de su ruta habitual. La influencia sobre el comportamiento de los conductores fue mínima al tratarse de un dispositivo de pequeño tamaño ubicado en el exterior del vehículo. Tras la restitución de la geometría de las carreteras objeto de estudio y el tratamiento de los datos de velocidad registrados, se analizó la influencia de las variables geométricas del trazado, especialmente en cuanto a alzado se refiere, en la velocidad. Se ha concluido que la pendiente no tiene una influencia significativa en la elección de la velocidad por parte de los conductores de vehículos pesados en curvas de carreteras convencionales, donde el principal control de la velocidad son los radios de las propias curvas., El estudio que se ha presentado es parte del proyecto de investigación “CASEFU – Estudio experimental de la funcionalidad y seguridad de las carreteras convencionales” (TRA2013- 42578-P), subvencionado por el Ministerio de Economía y Competitividad y el Fondo Social Europeo. Asimismo, los autores quieren agradecer a las empresas SAV y SAEVI, así como la Entidad Metropolitana para el Tratamiento de Residuos en Valencia, por su colaboración totalmente desinteresada en toma de datos.

[EN] The number of road safety studies that are based on driving simulators is growing significantly. The Polytechnic University of Valencia, Spain, developed a low-cost driving simulator for the assessment, training, and rehabilitation of drivers (SE2RCO). The main objective of this research was the validation of the driving simulator so that studies about road safety and highway geometric design that considered human factors could be performed. The validation was based on continuous speed profiles collected from 28 volunteers on a 30-km-long, two-lane rural road section. The same volunteers drove through the same road section built in SE2RCO. Speed data of 79 curves and 52 tangents were selected for the analysis. Comparison of the real and simulated speeds ensured the simulator's objective validity according to average and operating speeds. Two models were developed to predict field speeds from simulated speeds. Results showed that a simulated average speed lower than approximately 90 km/h was linked to a similar real average speed. For higher simulated speeds, the average speed in the real environment was lower than the simulated one. In addition, the actual operating speed was around 5 km/h lower than the operating speed in the driving simulator. Most volunteers assessed the quality and similarity of the virtual environment compared with the real world as medium or high and assessed the driving tasks similarly, thus achieving subjective validation of the simulator., The authors thank the Polytechnic University of Valencia, which subsidized the research project CONSIM-Desarrollo de un Modelo para la Evaluacion de la Consistencia del Diseno Geometric de Carreteras Convencionales Mediante Simuladores de Conduccion. The study presented here was also part of the research project titled CASEFU-Estudio Experimental de la Funcionalidad y Seguridad de las Carreteras Convencionales, which was subsidized by the Spanish Ministry of Economy and Competitiveness and the European Social Fund.

[ES] La cantidad de estudios de seguridad vial basados en simuladores de conducción está en continuo crecimiento. En este sentido, la Universitat Politècnica de València (UPV) ha desarrollado un simulador de conducción de bajo coste: SE2RCO (Simulador para la Evaluación, Entrenamiento y Rehabilitación de Conductores). El principal objetivo de la investigación es la validación de este simulador, con el fin de desarrollar estudios relacionados con la seguridad vial y el diseño geométrico de carreteras incorporando el factor humano. Dicha validación se ha realizado a partir de la observación en campo de los perfiles continuos de velocidad desarrollados por 28 voluntarios conduciendo su propio vehículo en un tramo de carretera convencional de 30 km. Los mismos voluntarios condujeron posteriormente en el simulador de conducción ese mismo tramo de carretera reconstruido en un entorno virtual. Un total de 79 curvas y 52 rectas fueron objeto de análisis. La comparación entre las velocidades desarrolladas en la realidad y las observadas durante la simulación permitieron llevar a cabo la validez objetiva del simulador de conducción. Los resultados mostraron que la velocidad media en el simulador y en la realidad era similar cuando la velocidad simulada era inferior a 87.3 km/h. En caso de ser superior, la velocidad media en la realidad era menor que en el simulador. En cuanto a la velocidad de operación, se observó que la velocidad real era aproximadamente 5 km/h menor que la simulada. Finalmente, estos resultados estuvieron apoyados por la percepción de los conductores, ya que la mayoría de ellos evaluaron la calidad del entorno simulado y el grado de similitud entre la tarea de conducción real y simulada como medio o alto, consiguiendo de esta manera la validez subjetiva del simulador de conducción., Los autores quisieran agradecer a la Universitat Politècnica de València (UPV), que financió el proyecto de investigación “CONSIM - Desarrollo de un Modelo para la Evaluación de la Consistencia del Diseño Geométrico de Carreteras Convencionales mediante Simuladores de Conducción” (PAID 05-2012). Asimismo, agradecer también al Ministerio de Economía y Competitividad y al Fondo Social Europeo, que financiaron el proyecto de investigación “CASEFU - Estudio experimental de la funcionalidad y seguridad de las carreteras convencionales” (TRA2013-42578-P), del cual forma parte este estudio.

[EN] The Vice-Rectorate for Studies, Quality and Acreditation and the Institute of Education Sciences promotes that education is based on competencies, either generic or specific. The School of Civil Engineering of the Universitat Politècncia de València has chosen the course “Caminos y Aeropuertos” to evaluate the generic competencies “Team working and leadership” and “Effective communication”, both oral and written. The course “Caminos y Aeropuertos” is a core subject in third year of the Deegree in Civil Engineering. The teaching methodology of this technical subject is based on the active participation of students through a diverse set of assignments. This paper explains the adaptation of the methodology to include the evaluation of generic competencies, having a high number of students (124). It is based on written exercises in teams of 1, 2 and 4 students, as well as on an oral presentation., [ES] Desde el Vicerrectorado de Estudios, Calidad y Acreditación de la Universitat Politècnica de València, junto con el Instituto de Ciencias de la Educación, se está llevando a cabo un proyecto para dar un giro hacia la formación basada en competencias. En la Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos, se ha elegido la asignatura "Caminos y Aeropuertos" como punto de control para la evaluación de las dimensiones competenciales "Trabajo en Equipo y Liderazgo" y "Comunicación Efectiva", incluyendo comunicación oral y escrita. “Caminos y Aeropuertos” es una asignatura de carácter troncal impartida en tercer curso del Grado en Ingeniería Civil, con una base claramente técnica. Desde su concepción, su docencia se ha diseñado con base en metodologías activas. No obstante, ha sido necesario modificar ligeramente su metodología docente para incluir la evaluación de las competencias mencionadas. En este trabajo se muestra cómo se ha adaptado la metodología docente y cómo se ha procedido a la evaluación de estas competencias dentro de una asignatura eminentemente técnica y con un alto número de alumnos matriculados (124). La metodología se basa principalmente en la realización de trabajos escritos de diferente entidad en grupos de 1, 2 y 4 personas y una exposición oral.

Overtaking is one of the most dangerous manoeuvres on two-lane rural highways. The most influential factors are related to drivers, so ITS and assistance systems are not yet common. This research is based on experimental data of overtaking manoeuvres collected using an instrumented passenger car, equipped with four cameras, laser rangefinders and a global positioning service (GPS) tracker. This vehicle was driven along four different road segments in the surroundings of Valencia (Spain) at a speed slightly slower than the operating speed of each segment. Overtaking time and speeds were measured. Unlike previous work, the influence of human factor was also considered. Age and gender of overtaking driver, as well as time spent following were used to characterise this influence. More than 200 manoeuvres were recorded and the influence of driver characteristics and delay on gap acceptance, manoeuvre duration and speed differences have been analysed. Results show differences in behaviour between age and gender groups, since young male overtaking drivers have shown a more aggressive behaviour. Overtaking times were around 1 s lower than other drivers, whereas average speed difference was 4 km/h higher. Collected data and their analysis have provided a basis to review design criteria and to develop future assistance systems., Authors would like to thank Spanish Ministry of Economy and Competitiveness that subsidizes the research project with reference code TRA2010-21736. Authors thank also Spanish General Traffic Directorate, Spanish Ministry of Public Works and Valencia Regional Governance for their collaboration during field study.

[EN] Passing is one of the most complex driving maneuvers performed on two-lane rural roads and has important effects on road safety and traffic operation. Passing is affected by driving behavior, road geometry, traffic volume, and traffic composition as well as external factors. Research was developed to compare the passing process under daytime and nighttime conditions. An experimental method was designed to collect video data of passing maneuvers on a two-lane rural road segment located near Valencia, Spain. Two methods were used: (a) external observations of four passing zones with six video cameras and (b) an instrumented vehicle equipped with video cameras and laser rangefinders, driven slightly below the operating speed along a segment of the same road so it would be passed by other vehicles. A total of 291 maneuvers were observed, up to 20% of which were at night. Macroscopic analysis results indicated that approximately 17% of passes were at night, even though passing frequency and passing demand decreased at night. Also, the behaviors of individual drivers who passed other vehicles were different at night and during the day. Maneuvers limited by the presence of an opposing vehicle were performed more quickly at night, even if the accepted gaps were longer. In this case, a more difficult perception of distances to opposing vehicles and of vehicle speeds explained the differences. In contrast, maneuvers limited by sight distance (without a visible opposing vehicle) were slower at night. This observation matched a traditional hypothesis: passing at night is safer because the headlights of an opposing vehicle allow a driver to anticipate the vehicle's position before it becomes visible., The authors thank the Spanish Ministry of Economy and Competitiveness for subsidizing the research project as well as the Spanish Ministry of Public Works and the Spanish General Traffic Directorate for collaboration during the field study.

The occurrence of road crashes depends on several factors, with design consistency (i.e., conformance of highway geometry to drivers' expectations) being one of the most important. A new consistency model for evaluating the performance of tangent-to-curve transitions on two-lane rural roads was developed. This model was based on the inertial consistency index (ICI) defined for each transition. The ICI was calculated at the beginning point of the curve as the difference between the average operating speed on the previous 1-km road segment (inertial operating speed) and the actual operating speed at this point. For the calibration of the ICI and its thresholds, 88 road segments, which included 1,686 tangent-to-curve transitions, were studied. The relationship between those results and the crash rate associated with each transition was analyzed. The results showed that the higher the ICI was, the higher the crash rate; thus, the probability of accidents increased. Similar results were obtained from the study of the relationship between the ICI and the weighted average crash rate of the corresponding group of transitions. A graphical and statistical analysis established that road consistency might be considered good when the ICI was lower than 10 km/h, poor when the ICI was higher than 20 km/h, and fair otherwise. A validation process that considered 20 road segments was performed. The ICI values obtained were highly correlated to the number of crashes that had occurred at the analyzed transitions. Thus, the ICI and its consistency thresholds resulted in a new approach for evaluation of consistency., The authors thank the Center for Studies and Experimentation of Public Works of the Spanish Ministry of Public Works, which partially subsidized the data collection, for obtaining the empirical operating speed profiles used in the validation process. The authors also thank the General Directorate of Public Works of the Infrastructure and Transportation Department of the Valencian government, the Valencian Province Council, and the General Directorate of Traffic of the Ministry of the Interior of the Government of Spain for their cooperation in data gathering.

Most studies on two-lane highway operations have focused on the percentage of following vehicles or the adjustment of the Highway Capacity Manual (HCM) procedure to local data. The HCM proposes the length of no-passing zones as a model parameter; however, the distribution and characteristics of passing zones are not addressed. In fact, only a few studies on the expected number of passes in a passing zone have been carried out. This research presents an analysis of the effectiveness of passing zones in terms of their length and traffic volume. Data were collected from four passing zones on a rural highway in Spain. The two-way traffic volumes ranged from 100 to 900 vehicles per hour (vph), and the passing zone lengths ranged from 265 to 1,270 m. More than 1,600 passing maneuvers were recorded. The operational effectiveness of the passing zones was obtained from the passing frequency and the passing rate. The results indicated that the longer the passing zone, the higher the passing frequency; however, the results stabilized with lengths above 1,100 m. Balanced flows with two-way traffic volumes between 600 and 700 vph optimized the number of passes. Nevertheless, the increase in the passing frequency with the traffic volume was lower than with the increase in following vehicles. The results were validated with data from another 12 passing zones. Finally, HCM adjustments based on the percentage of no-passing zones did not reliably represent the effectiveness of passing zones. Therefore, the effectiveness of every passing zone should be considered, and adjustment factors should be modified to maximize the passing opportunities for traffic volumes between 600 and 700 vph., The authors thank the Spanish Ministry of Science and Innovation, which subsidized the research project, and the Spanish Ministry of Public Works for its collaboration during the field study.

Methodologies based on naturalistic observation provide the most accurate data for studying drivers' behaviour. This study presents a new methodology to obtain naturalistic data related to drivers' behaviour in a road segment. It is based on the combination of using global positioning system data and drivers' questionnaires. The continuous speed profiles along a road segment and the characteristics of drivers, of their trips and the type of their vehicles can be obtained for a great amount of drivers. It has already been successfully used for several studies, such as the development of models to estimate operating speed profile in two-lane rural road segments; or the characterisation of driving styles. These operating speed models have been the key for the development of a new geometric design consistency model, allowing an easier road safety evaluation. Besides, knowledge on the human factors that influence speed choice may be useful for road safety media campaigns and education programs designers, and also for the improvement of intelligent driver assistance systems., The authors thank 'Centre for Studies and Experimentation of Public Works (CEDEX)' of the 'Spanish Ministry of Public Works' that partially subsidizes the research. We also wish to thank to the 'General Directorate of Public Works, Urban Projects and Housing' of the 'Infrastructure, Territory and Environment Department' of the 'Valencian Government', to the 'Valencian Provincial Council' and to the 'General Directorate of Traffic' of the 'Ministry of the Interior' for their cooperation in field data gathering.

[EN] To assist in the on-going effort to reduce road fatalities as much as possible, this paper presents a new methodology to evaluate road safety in both the design and redesign stages of two-lane rural highways. This methodology is based on the analysis of road geometric design consistency, a value which will be a surrogate measure of the safety level of the two-lane rural road segment. The consistency model presented in this paper is based on the consideration of continuous operating speed profiles. The models used for their construction were obtained by using an innovative GPS-data collection method that is based on continuous operating speed profiles recorded from individual drivers. This new methodology allowed the researchers to observe the actual behavior of drivers and to develop more accurate operating speed models than was previously possible with spot-speed data collection, thereby enabling a more accurate approximation to the real phenomenon and thus a better consistency measurement. Operating speed profiles were built for 33 Spanish two-lane rural road segments, and several consistency measurements based on the global and local operating speed were checked. The final consistency model takes into account not only the global dispersion of the operating speed, but also some indexes that consider both local speed decelerations and speeds over posted speeds as well. For the development of the consistency model, the crash frequency for each study site was considered, which allowed estimating the number of crashes on a road segment by means of the calculation of its geometric design consistency. Consequently, the presented consistency evaluation method is a promising innovative tool that can be used as a surrogate measure to estimate the safety of a road segment., The authors would like to thank the Center for Studies and Experimentation of Public Works (CEDEX) of the Spanish Ministry of PublicWorks for partially subsidizing this research.We also wish to thank the Infrastructure and Transportation Department of the General Directorate of Public Works of the Valencian Government, to the Valencian Provincial Council, and to the Ministry of the Interior, especially the General Directorate of Traffic of Spain, for their cooperation in field data gathering.

[EN] In the road design process, speed variation along the road segment is an important issue to consider in adapting road geometry to drivers' expectations. To achieve this objective, speed criteria are used to evaluate road consistency. Being able to estimate the operating speed in the design phase can lead to safer road alignment. With this objective, several researchers have developed operating speed models. Most of these models are based on collected spot speed data. They assume constant speed on curves and, therefore, deceleration that occurs entirely on the approach tangent. According to these assumptions, spot speed data are collected at the center of the horizontal curve and at the midpoint of the preceding tangent to obtain operating speed models. This paper presents a new methodology based on the use of Global Positioning System devices that allow continuous collecting and processing of speed data. With this new methodology, not only can new and more accurate operating speed models he developed, but cited hypotheses can also be checked. Observed speed continuous profiles allow studies that previously could not be done, especially as related to deceleration and speed variations. This study calibrated new speed models, including three for horizontal curves with a radius curve and the curvature change rate of a single curve as explanatory variables, and one for tangents that incorporates the curve speed model. Tangent-curve speed variations are evaluated, with comparison of Delta(85)V and Delta V(85), analysis of the deceleration length occurring on a curve, and development of two deceleration models., The authors thank the Center for Studies and Experimentation of Public Works of the Spanish Ministry of Public Works, which partially subsidized the research. The authors also thank the Infrastructure and Transportation Department, General Directorate of Public Works, Valencian Government, Spain; the Valencian Provincial Council; and the Ministry of the Interior, General Directorate of Traffic, Spain, for their cooperation in field data gathering.