Examination Free-Flow Speed Distribution on Two-Lane Rural Roads

[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.García Jiménez, ME.; Pérez Zuriaga, AM.; Llopis-Castelló, D.; Camacho Torregrosa, FJ.; García García, A. (2016). Examination Free-Flow Speed Distribution on Two-Lane Rural Roads. Transportation Research Record Journal of the Transportation Research Board. 2556:86-97. https://doi.org/10.3141/2556-09S8697255

Validation of Low-Cost Driving Simulator Based on Continuous Speed Profiles

[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.Llopis-Castelló, D.; Camacho Torregrosa, FJ.; Marín-Morales, J.; Pérez Zuriaga, AM.; García García, A.; Dols Ruiz, JF. (2016). Validation of Low-Cost Driving Simulator Based on Continuous Speed Profiles. Transportation Research Record Journal of the Transportation Research Board. 2602:104-114. https://doi.org/10.3141/2602-13S104114260

PIME Aprendizaje Basado en Proyectos: Ingeniería de Carreteras e Ingeniería Geotécnica.

[ES] En los últimos años, la Universitat Politècnica de València (UPV) ha promovido, dentro de su programa de innovación educativa “Aprendizaje y Docencia” (A+D), la puesta en marcha de Proyectos de Innovación y Mejora Educativa (PIME). Durante el curso 2019/2020 se ha implantado un PIME basado en Aprendizaje Basado en Proyectos (ABP) que reúne a dos asignaturas consecutivas de tercer curso de Ingeniería Civil. En este artículo se muestran los resultados alcanzados en el primer semestre de implantación. Los alumnos han expresado claramente su interés y preferencia por este tipo de metodología. Han demostrado haber adquirido un aprendizaje en profundidad y ser capaces de adquirir conocimientos de forma autónoma, así como transferir estos a la realidad de la profesión mediante el desarrollo de su capacidad de trabajar en equipo y la posibilidad de realizar visitas de campo donde los conocimientos recibidos adquieren un carácter práctico. Además, han desarrollado las competencias esperadas, integrando aspectos académicos con otros sociales y éticos.[EN] In recent years, the Polytechnic University of Valencia has encouraged the implementation of Educational Innovation and Improvement Projects (PIME) within the "Learning and Teaching" (A+D) program. During the 2019/2020 academic year, a PIME based on Problem or Project Based Learning (PBL) was implemented, bringing together two consecutive subjects from the third year of Civil Engineering. This article shows the results achieved in the first semester after implantation. The students have clearly expressed their interest and preference for this kind of methodology. They have obtained an in-depth learning and they are prepared to acquire knowledge by themselves, as well as transferring it to professional practice by developing their ability to work as a team and the possibility of visit the studio area, so the knowledges acquire a practical character. They have also developed the expected skills , integrating academic aspects with other social and ethical oneGarrido De La Torre, ME.; Pérez-Zuriaga, AM.; Martínez-Ibáñez, V.; López Maldonado, G.; Cuadrado Tarodo, Á. (2020). PIME Aprendizaje Basado en Proyectos: Ingeniería de Carreteras e Ingeniería Geotécnica. En IN-RED 2020: VI Congreso de Innovación Educativa y Docencia en Red. Editorial Universitat Politècnica de València. 293-306. https://doi.org/10.4995/INRED2020.2020.11929OCS29330

Speed prediction models for trucks on horizontal curves of Spanish two-lane rural roads

Road safety is closely related to geometric design consistency, which is usually assessed by examining operating speed. Most of consistency models only consider passenger car speeds, even though the interaction between passenger cars and heavy vehicles plays a pivotal role on road safety. This is due to the 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 eleven road sections. As a result, 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 great influence on heavy vehicle speeds. To this regard, vertical alignment only has a significant effect on truck speeds developed along upgrades. In addition, different trends were identified for loaded and unloaded trucks. Several speed models were calibrated for both loaded and unloaded trucks. 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