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The European Union is promoting a circular economy in which waste management plays an essential role. Although many studies focusing on the use of recycled materials in the manufacture of asphalt mixtures for roads have been developed, studies related to the use of recycled materials for the construction of bike lanes are scarce. In this context, the main objective of this research is to explore the behaviour of asphalt mixtures with high replacement rates of recycled materials—reclaimed asphalt pavement (RAP) and ceramic waste—by natural aggregates for the construction of bike lanes. A total of six types of asphalt mixtures were designed by combining the content of the recycled materials and natural aggregates, with replacement rates ranging from 50% to 100%. The asphalt mixtures were characterized by determining the bulk and maximum density; the void content in the mixture; and the aggregate, stability, and deformation. In conclusion, the mixture C50R50, which consists of a full replacement of natural fine and coarse aggregates by 50% ceramic waste aggregate and 50% RAP, is proposed as the most appropriate sustainable solution. In this way, the use of this asphalt mixture allows for boosting the use of recycled aggregates as well as minimizing the consumption of virgin bitumen due to its residual bitumen content. Compared to the reference asphalt mixture consisting of 100% of natural aggregates, C50R50 is a more open mixture, with higher void content and somewhat more brittleness. Even so, the mixture C50R50 could be good enough for use in low traffic roads.

[EN] Pavement management systems can be used to efficiently allocate limited maintenance budgets to better align with pavement deterioration. However, pavement deterioration is subject to uncertain factors that complicate the prediction of future pavement conditions accurately, entailing differences in the optimum maintenance strategy. This paper addresses this challenge by introducing a method to aid local engineers in optimising the scheduling of maintenance activities under uncertain pavement deterioration conditions. Markov chains are used to simulate the variability of life-cycle performance. Moreover, a multi-objective optimisation of an urban network is carried out to find the maintenance programme that minimises the mean life-cycle cost, maximises the mean user benefit, and minimises the standard deviation of life-cycle cost. This third objective enables the optimisation routine to minimise the possibility of unintentionally increasing the life-cycle cost due to system variability. This approach results in a reduction of the life-cycle cost variability by up to 62%, provides pavement strategies that benefit road users as a result of better pavement conditions, and reduces the risk of resorting to costly future maintenance activities., This work was supported by the Spanish Ministry of Science and Innovation with the European Regional Development Fund (grants BIA2017-85098-R and RTC-2017-6148-7).

[EN] Road safety is a major public health concern in our society. Effective road design and accurate safety analyses must be a component of programs focused on reducing and eliminating roadway injuries and deaths. Various methodologies exist to determine the expected number of crashes on rural two-lane rural roads. This research compares different procedures which allow for the estimation of the number of crashes on homogeneous road segments. In this effort, a total of 27 two-lane rural road sections located in North Carolina were considered, resulting in 59 homogeneous road segments composed of 350 horizontal curves and 375 tangents along 150 km of road. Four methods were applied to the selected roadways: the Highway Safety Manual predictive method, two jurisdiction-specific Safety Performance Functions (SPFs), and a SPF which includes a consistency parameter. This research found that the use of SPFs which incorporate a consistency parameter allows highway engineers to consider human factor impacts on road safety assessment. The use of a consistency parameter can also simplify the crash estimation process. Analysis methods which only included local geometric variables provided unreliable results due to the calibration of only the specific road elements instead of their relationship with other road elements along homogeneous road segments., This research was subsidized by the Spanish Ministry of Science, Innovation, and Universities through "Ayudas a la movilidad predoctoral para la realizacion de estancias breves en centros de I+D 2017" (EEBB-I-17-12154) and 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 above mentioned Spanish Ministry and the European Social Fund. In addition, the authors would like to thank the North Carolina Department of Transportation, which provided traffic and crash data.

[EN] Pavement condition assessment is a critical step in road pavement management. In contrast to the automatic and objective methods used for rural roads, the most commonly used method in urban areas is the development of visual surveys usually filled out by technicians that leads to a subjective pavement assessment. While most previous studies on automatic identification of distresses focused on crack detection, this research aims not only to cover the identification and classification of multiple urban flexible pavement distresses (longitudinal and transverse cracking, alligator cracking, raveling, potholes, and patching), but also to quantify them through the application of Convolutional Neural Networks. Additionally, this study also proposes a methodology for an automatic pavement assessment considering the different stages developed in this research. This methodology allows for a more efficient and reliable pavement assessment, minimizing the cost and time required by the current visual surveys., The study presented in this paper is part of the research project titled SIMEPU Sistema Integral de Mantenimiento Eficiente de Pavimentos Urbanos, funded by the Spanish Ministries of Science and Innovation and Universities, as well as the European Regional Development Fund under Grant No. RTC-2017-6148-7. The authors also acknowledge the support of partner companies Pavasal Empresa Constructora, S.A. and CPS Infraestructuras, Movilidad y Medio Ambiente, S.L. and the Valencia City Council.

The use of micromobility vehicles is considerably growing in cities worldwide. As a result, crashes involving these vehicles are also increasing, with single-bicycle crashes accounting for a significant percentage. In most infrastructure-related crashes, the road surface was slippery. In this context, the study of pavement skid resistance is crucial to improve micromobility safety. In this research, the British pendulum tester was used to test the skid resistance of 5 different types of pavements on 17 bike lane locations in Valencia (Spain). Additionally, micromobility users’ speed was collected to analyse users’ behaviour. The results showed that asphalt, concrete, and rough painted tile pavements had the greatest skid resistance, whereas painted cobble and smooth painted tile pavements presented poor skid resistance. These values were compared with the limits set by the few guidelines that includes skid resistance thresholds. Moreover, skid resistance variability was also studied, with asphalt pavement being the most homogeneous. Based on the results of the research, several recommendations are proposed for the pavement to be used in the micromobility facility according to its typology. To this end, the investigatory level of skid resistance and the minimum braking distance required were also defined for each type of pavement and bike lane. The findings of this study contribute to the consideration of micromobility safety from the construction stage to the pavement management.

[EN] The analysis of road safety is critical in road design. Complying to guidelines is not enough to ensure the highest safety levels, so many of them encourage designers to virtually recreate and test their roads, benefitting from the evolution of driving simulators in recent years. However, an accurate recreation of the road and its environment represents a real bottleneck in the process. A very important limitation lies in the diversity of input data, from different sources and requiring specific adaptations for every single simulator. This paper aims at showing a framework for recreating faster virtual scenarios by using an Industry Foundation Classes (IFC)-based file. This methodology was compared to two other conventional methods for developing driving scenarios. The main outcome of this study has demonstrated that with a data exchange file in IFC format, virtual scenarios can be faster designed to carry out safety audits with driving simulators. As a result, the editing, programming, and processing times were substantially reduced using the proposed IFC exchange file format through a BIM (Building Information Modeling) model. This methodology facilitates cost-savings, execution, and optimization resources in road safety analysis., This research was funded by the Spanish Center for Industrial Technological Development (CDTI), as well as the European Regional Development Fund, grant number EXP-00091379/ITC-20161077.

[EN] In Spain, a new challenge is emerging due to the increase of many recreational bicyclists on two-lane rural roads. These facilities have been mainly designed for motorized vehicles, so the coexistence of cyclists and drivers produces an impact, in terms of road safety and operation. In order to analyze the occurrence of crashes and enhance safety for bicycling, it is crucial to know the cycling volume. Standard procedures recommend using data from permanent stations and temporary short counts, but bicycle volumes are rarely monitored in rural roads. However, bicyclists tend to track their leisure and exercise activities with fitness apps that use GPS. In this context, this research aims at analyzing the daily and seasonal variability of the Strava Usage Rate (SUR), defined as the proportion of bicyclists using the Strava app along a certain segment on rural highways, to estimate the Annual Average Daily Bicycle (AADB) volume on rural roads. The findings of this study offer possible solutions to policy makers in terms of planning and design of the cycling network. Moreover, the use of crowdsourced data from the Strava app will potentially save costs to public agencies, since public data could replace costly counting campaigns., This research was funded by the Ministry of Science, Innovation, and Universities, grant number TRA2016-80897-R and the General Directorate of Education, Research, Culture and Sport of the Valencian Government, grant number GV/2017/038

Various studies have been recently conducted to predict pavement condition, but most of them were developed in a certain region where climate conditions were kept constant and/or the research focused on specific road distresses using single parameters. Thus, this research aimed at determining the influence of pavement structure, traffic demand, and climate factors on urban flexible pavement condition over time. To do this, the Structural Number was used as an indicator of the pavement capacity, various traffic and climate variables were defined, and the Pavement Condition Index was used as a surrogate measure of pavement condition. The analysis was focused on the calibration of regression models by using the K-Fold Cross Validation technique. As a result, for a given pavement age, pavement condition worsens as the Equivalent Single Axle Load and the Annual Average Height of Snow increased. Likewise, a cold Annual Average Temperature (5&ndash, 15 &deg, C) and a large Annual Average Range of Temperature (20&ndash, 30 &deg, C) encourage a more aggressive pavement deterioration process. By contrast, warm climates with low temperature variations, which are associated with low precipitation, lead to a longer pavement service life. Additionally, a new classification of climate zones was proposed on the basis of the weather influence on pavement deterioration.

The aim of this study is to analyze the influence of horizontal geometric design and vehicle operation on fuel consumption and gas emissions produced by passenger cars. Continuous speed data were collected along 15 two-lane rural road sections. Different horizontal alignment indexes and operational variables were obtained. Fuel consumption and gas emissions were estimated by applying the VT-Micro model. The results showed that Curvature Change Rate and average speed have a significant impact on average fuel consumption and gas emissions. Finally, different regression models were calibrated based on these variables to estimate fuel consumption [l/100 km] and emissions [gr/km]. These results could be the basis to incorporate environmental sustainability principles into road design guidelines, since currently they do not take into account the environmental impact related to highway geometric design.

[EN] Road crashes are mainly caused by three concurrent factors: infrastructure, vehicle, and human factors. The interaction between the infrastructure and human factors leads to the concept of geometric design consistency. Recently, a global consistency model was developed based on the difference between the inertial operating speed profile and the operating speed profile. The first was defined as the weighted average operating speed of the previous road section based on distance, and represents drivers¿ expectancies, whereas the second represents road behavior. However, drivers¿ expectancies are related to short-term memory which declines gradually and depends on time. Thus, a time-based inertial operating speed would allow a more accurate estimation of the phenomenon. This research analyzes different periods of time and weighting distributions to identify how drivers¿ expectancies should be estimated. A set of 71 homogeneous road segments located in Italy were considered in the study. As a result, 25 seconds and a convex parabolic distribution should be used to calculate the inertial operating speed profile. This new way of estimating drivers¿ expectancies showed better results than those obtained based on distance. Finally, the proposed consistency model was compared with the previous models and was found to be able to assess more accurately the geometric design consistency. Therefore, the proposed consistency model is a useful tool for engineers to estimate the number of crashes so that they can incorporate road safety considerations into the geometric design of either new two-lane rural roads, or improving the existing ones., This research was subsidized by the Spanish Ministry of Economy, Industry, and Competitiveness through ‘‘Ayudas a la movilidad predoctoral para la realizacio´n de estancias breves en centros de I+ D 2015.’’ The study presented in this paper is also part of the research project entitled ‘‘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 ‘‘Azienda Nazionale Autonoma delle Strade’’ (ANAS) and the ‘‘Automobile Club Italia’’ (ACI), who provided traffic and crash data, respectively

[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] Highway vehicles driving on rural roads account for more than 50% of all CO2 emissions produced by the transportation sector in Europe. Although the policy measures to mitigate Greenhouse Gas emissions are increasing, these do not include policies aimed at reducing emissions by means of highway geometric design, which significantly influences drivers¿ speeds and accelerations and, consequently, plays a major role on fuel consumption and emissions. Therefore, the main objective of this research is to study the influence of the geometric design consistency on vehicle CO2 emissions. To do this, continuous speed data were collected on 47 homogeneous road segments by means of Global Positioning System devices. Vehicle CO2 emissions were estimated by applying the VT-micro model, whereas geometric design consistency was assessed considering different global consistency models. As a conclusion, vehicle CO2 emissions decreases as the consistency level of a homogeneous road segment increases. Specifically, a good consistency road segment has been found to present an emission rate 20-30% lower than a poor-consistent one. Therefore, the design of consistent roads allows, in addition to maximize road safety, to help to achieve more environmentally sustainable highways, reducing CO2 emission production., The presented study 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 Ministryof Economy, Industry, and Competitiveness and the European Social Fund. In addition, authors 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.

[EN] Calibration factors are applied in the Highway Safety Manual predictive method for rural two-lane, two-way roadway segments to adjust the estimate for local conditions. This research aims to evaluate and recommend improvements related to the estimation of these calibration factors. An aggregated and disaggregated analysis was performed to study the influence of different calibration factors on the prediction of the number of crashes in North Carolina. As a result, those calibration factors based on both types of road elements (horizontal curves and tangents) led to overestimating and underestimating the number of crashes on tangents and horizontal curves, respectively. Furthermore, the calibration factors based on fatal-and-injury crashes allowed a more accurate estimation of the predicted number of crashes than those calibrated considering all severity levels. Therefore, it is recommended to apply a different calibration factors for each type of road element and each type of crash severity., This research was subsidized by the Spanish Ministry of Economy, Industry, and Competitiveness through "Ayudas a la movilidad predoctoral para la realizacion de estancias breves en centros de I+D 2016." In addition, the authors would like to thank the North Carolina Department of Transportation (NCDOT), which provided traffic and crash data.

[EN] Road crash occurrence is closely related to the geometric design consistency, which can be defined as how drivers¿ expectancies and road behavior fit. To this regard, the crash rate on a road segment increases as its consistency level decreases. To assess this phenomenon, inertial consistency models were recently developed. These models are based on the difference between the inertial operating speed, which represents drivers¿ expectancies, and the operating speed, which represents road behavior. The higher the difference between both speeds, the higher the likelihood of crash occurrence. This research aims to validate and calibrate these consistency models on American two-lane rural roads. For this, a total of 194 homogeneous road segments and 977 horizontal curves along 665 km in North Carolina (US) were used. As a result, the geometric design consistency was identified as a major factor of crash occurrence. The higher the difference between drivers¿ expectancies and road behavior, the higher the crash rate. Likewise, the greater the consistency level, the greater the percentage of horizontal curves without reported crashes. A Safety Performance Function was also calibrated to estimate the number of crashes on a road segment. Consistency thresholds were defined and tested to identify where these crashes are more likely to take place. Finally, the results obtained in this study were compared with those obtained previously on Spanish highways. To this regard, the crash rate on an American highway was 1.85 times greater than those observed on a Spanish highway under the same risk exposure and consistency conditions. Therefore, different tools were developed to enhance the assessment of road safety to the geometric design of both new two-lane rural roads and improvements of existing highways., This research was subsidized by the Spanish Ministry of Economy, Industry, and Competitiveness through “Ayudas a la movilidad predoctoral para la realización de estancias breves en centros de I+D 2017” (EEBB-I-17-12154). The study presented in this paper is also 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 North Carolina Department of Transportation (NCDOT), which provided traffic and crash data.

[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.

La seguridad vial es una de las mayores preocupaciones de la sociedad actual. De hecho, anualmente mueren en las carreteras alrededor de 1,2 millones de personas y 50 millones resultan heridas.Entre los diferentes factores que están presentes en la producción de un accidente de tráfico cabe destacar el factor humano, el vehículo y la infraestructura. Concretamente, en los últimos años se ha estudiado profundamente la interacción entre el factor humano y el factor infraestructura a partir del concepto de consistencia del diseño geométrico de carreteras, que se puede definir como el grado de adecuación entre las expectativas de los conductores y el comportamiento de la carretera.En este sentido, un diseño consistente asegura que elementos geométricos sucesivos actúen de forma coordinada produciendo una conducción harmoniosa libre de sorpresas. Por el contrario, un diseño inconsistente puede producir sorpresas en los conductores provocando maniobras erráticas o conflictivas que incrementan la probabilidad de ocurrencia de accidentes.Sin embargo, todavía son muy pocas las guías o normas de diseño geométrico de carreteras que incluyen la evaluación de la consistencia en el proceso de diseño o mejora de carreteras.En esta tesis se desarrollan dos modelos de consistencia, uno global y otro local, basados en la definición básica de consistencia a través de la diferencia entre la velocidad de operación inercial, que representa las expectativas de los conductores, y la velocidad de operación, que representa el comportamiento de la carretera. Estos modelos permiten estimar el número de accidentes con víctimas en diez años en las carreteras convencionales españolas e identificar dónde es más probable que ocurran dichos accidentes.Finalmente, se propone una nueva metodología para el diseño y mejora de carreteras convencionales que incorpora los modelos calibrados con el fin de que los ingenieros sean capaces de diseñar carreteras más seguras., Road safety is one of the major concerns in our society. In fact, around 1.2 million people die and 50 million are injured in road crashes every year.Road crashes are mainly caused by three concurrent factors: infrastructure, vehicle, and human factor. Specifically, the interaction between the infrastructure and human factor has been thoroughly studied in recent years through the concept of geometric design consistency, which can be defined as how drivers' expectancies relates to road behavior.To this regard, a consistent road provides a harmonious driving free of surprises, which is associated with a low number of road crashes. On the contrary, an inconsistent road might present numerous unexpected events to drivers, leading to an anomalous behavior and increasing the likelihood of crash occurrence.However, few geometric design guidelines include a consistency evaluation during the design of both new two-lane rural roads and improvements of existing highways.This Thesis Dissertation presents a global consistency model and a local consistency model based on the geometric design consistency concept through the difference between the inertial operating speed, which represents drivers' expectations, and the operating speed, which represents road behavior. These models allow estimating the number of crashes with injuries in ten years on Spanish two-lane rural roads and identifying where these crashes are most likely to occur.Finally, a new methodology for the design and improvement of two-lane rural roads based on the calibrated models is proposed. This process will allow highway engineers to design safer roads., La seguretat viària és una de les majors preocupacions de la societat actual. De fet, anualment moren a les carreteres al voltant de 1,2 milions de persones i 50 milions resulten ferides.Entre els diferents factors que estan presents en la producció d'un accident de tràfic cal destacar el factor humà, el vehicle i la infraestructura. Concretament, en els últims anys s'ha estudiat profundament la interacció entre el factor humà i el factor infraestructura a partir del concepte de consistència del disseny geomètric de carreteres, que es pot definir com el grau d'adequació entre les expectatives dels conductors i el comportament de la carretera.En aquest sentit, un disseny consistent assegura que elements geomètrics successius actuen de manera coordinada produint una conducció harmoniosa lliure de sorpreses. Al contrari, un disseny inconsistent pot produir sorpreses en els conductors provocant maniobres erràtiques o conflictives que incrementen la probabilitat d'ocurrència d'accidents.No obstant això, encara són molt poques les guies de disseny geomètric de carreteres que inclouen l'avaluació de la consistència en el procés de disseny o millora de carreteres.En aquesta tesi es desenvolupen dos models de consistència, un global i un altre local, basats en la definició bàsica de consistència a través de la diferència entre la velocitat d'operació inercial, que representa les expectatives dels conductors, i la velocitat d'operació, que representa el comportament de la carretera. Aquests models permeten estimar el nombre d'accidents amb víctimes en deu anys a les carreteres convencionals espanyoles i identificar on és més probable que tinguin lloc aquests accidents.Finalment, es proposa una nova metodologia per al disseny i millora de carreteres convencionals que incorpora els models calibrats per tal que els enginyers siguin capaços de dissenyar carreteres més segures., TESIS

[EN] Road crashes are mainly caused by three concurrent factors: infrastructure, vehicle and human factor. The interaction between infrastructure and human factor leads to the concept of geometric design consistency, which can be defined as how driver¿s expectations and road behavior fit. This paper presents a new global consistency model based on the difference between the inertial operating speed profile (Vi) and the operating speed profile (V85). The first one is calculated as the weighted average speed of the previous road section and represents drivers¿ expectations, whereas the second one represents road behavior. A set of 71 homogeneous two-lane rural road segments located in Italy were used in the calibration of the model. As a result, a Safety Performance Function based on this new consistency model was proposed in order to estimate the number of crashes in an entire road segment. Finally, the new model was compared with previous global consistency models, concluding that the new consistency parameter better explains the phenomenon than the previous ones. Therefore, the new consistency model is a useful tool for the engineers which allows estimating the number of crashes and incorporate road safety to the geometric design of both new two-lane rural roads and improvements of existing highways., This research was subsidized by the Spanish Ministry of Economy and Competitiveness through "Ayudas a la movilidad predoctoral para la realizacion de estancias breves en centros de I+D 2015." The study presented in this paper is also 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 and Competitiveness and the European Social Fund. In addition, the authors would like to thank the Azienda Nazionale Autonoma delle Strade (ANAS) and the Automobile Club Italia (ACI), which provided traffic and crash data, respectively.

Road crashes are mainly caused by three concurrent factors: infrastructure, vehicle, and human factors. The interaction between infrastructure and human factor leads to the concept of geometric design consistency. Recently, a global consistency model was developed based on the difference between the inertial operating speed profile and the operating speed profile. The first one was defined as the weighted average speed of the previous road section based on distance and represents drivers’ expectancies, whereas the second one represents road behavior. However, drivers’ expectancies are related to Short-Term Memory which is gradually in decline and depends on time. Thus, a time-based inertial operating speed would allow a more accurate estimation of the phenomenon. This research analyzes different periods of time and weighting distributions to identify how drivers’ expectancies should be estimated. A set of 71 homogeneous road segments located in Italy were considered in the study. As a result, 25 seconds and a convex parabolic distribution should be used to calculate the inertial operating speed profile. This new way to estimate drivers’ expectancies presented better results than those obtained based on distance. Finally, the proposed consistency model was compared with the previous ones. As a conclusion, this model could assess more accurately the geometric design consistency. Therefore, the proposed consistency model is a useful tool for engineers to estimate the number of crashes and incorporate road safety to the geometric design of both new two-lane rural roads and improvements of existing highways.

[EN] The most important factors for road crash occurrence are infrastructure, vehicle, and human factors. In fact, infrastructure and its interaction with human factor have been thoroughly studied in recent years through geometric design consistency, which can be defined as how drivers¿ expectations and road behavior relate. Global consistency models were calibrated in the last decade to assess road safety on an entire homogeneous road segment. However, none of them include the underlying consistency phenomenon in their formulation. Recently, a new model was developed based on the difference between the inertial operating speed profile, which represents drivers¿ expectancies, and the operating speed profile, which represents road behavior. While the operating speed represents the estimated operating speed for every location along the road, the inertial operating speed aggregates for every station the operating speed effect along some distance already covered by drivers. The authors hypothesized that this `aggregation effect¿ was connected to drivers¿ expectancies, which proved to be true based on the best model fitted. However, the exact distance (or time) that should be considered to estimate the inertial operating speed still remains unknown. This paper aims to complete this model, analyzing how the inertial operating speed varies depending on different distances and periods of time. This impact is measured considering the reliability of the corresponding consistency model. The paper also covers how the inertial operating speed should be determined along the final distance or time. For this, a total of 184 homogeneous road segments along 650¿km in Spain were used., 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 Department of Housing, Public Works and Spatial Planning of the Valencian Regional Government and the Traffic Department of the Spanish Government, which provided traffic and crash data, respectively.

[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.

[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.

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.