Dosage optimization and bolted connections for UHPFRC ties

Concrete technology has been in changeful evolution since the Roman Empire time. It is remarkable that the technological progress became of higher magnitude from the second part of the XX Century. Advances in the development of new cements, the appearance of the fibers as a reinforcement for structural applications, and specially the grand progress in the field of the water reducing admixtures enabled the emergence of several types of special concretes. One of the lasts is the Ultra High Performance Fiber Reinforced Concrete (UHPFRC), which incorporates advances of the Self-Compacting Concrete (SCC), Fiber-Reinforced Concrete (FRC) and Ultra High Strength Concrete (UHSC) technology. This exclusive material requires a detailed analysis of the components compatibility and a high control of the materials and processes. Mainly patented products have been used for the few structural elements carried out so far today, but the costs makes doubtful the development of many other potential applications. In accordance with the previously explained, a simplification of the UHPFRC components and processes is needed. This becomes the first main goal of this Ph.D. thesis, which emphasizes in the use of local available components and simpler mixing processes. Moreover, the singular properties of this material, between ordinary concrete and steel, allow not only the realization of slenderer structures, but also the viability of new concepts unthinkable with ordinary concrete. In this field is focused the second part of the Ph.D. thesis, which develops a bolted connection system between UHPFRC elements. This research summarizes, first of all, the subfamilies belonging to the HPC-UHPC materials. Afterwards, it is provided a detailed comparison between the dosage and properties of more than a hundred of mixtures proposed by several authors in the last ten years of technology. This becomes a useful tool to recognize correlations between dosages and properties and validate or no preconceived ideas about this material. Based on this state of art analysis was performed the later development of mixtures, on Chapter 4, which analized the effect of use of simpler components and processes on the UHPFRC. The main idea was use local components available in the Spanish market, identifying the combinations that provide the best rheological and mechanical properties. Steam curing use was avoided since a process simplification is intended. Diferent dosages were developed to be adapted to various levels of performance, and always trying to be as economical as possible. The concretes designed were selfcompacting and mainly combined two fiber types (hybrid), as the flexural performance was of greater relevance. The compressive strength obtained varied in the range between 100 and 170 MPa (cube L=100 mm), and the flexural strength between 15 and 45 MPa (prism 100 x 100 x 500 mm). Some of the components introduced are very rarely used in UHPFRC, as limestone coarse aggregate or FC3R, a white active residue from the petrol industry. As a result of the research, some simple and practical tips are provided for designers of UHPFRC dosage. At the end of this chapter, five dosages are characterized as examples of useful concretes for different requirement applications. In a second part, the idea of a bolted joint connection between UHPFRC elements was proposed. The connection system would be especially useful for struts and ties elements, as truss structures. The possible UHPFRC failure modes were introduced and two different types of tests were designed and performed to evaluate the joint capacity. The geometry of the UHPFRC elements was modified in order to correlate it with the failure mode and maximum load reached. Also a linear finite element analysis was performed to analyze the UHPFRC elements connection. This supported the results of the experimental tests to deduce formulations that predict the maximum load for each failure mode. Finally, a real size truss structure was assembled with bolted joints and tested to verify the good structural behavior of these connections. To conclude, some applications designed and developed at the Universitat Politècnica de València with the methods and knowledge acquired on UHPFRC are abstracted. In many of them the material was mixed and poured in a traditional precast concrete company, providing adequate rheological and mechanical results. This showed the viability of simpler UHPFRC technology enabling some of the first applications in Spain with this material.Camacho Torregrosa, EE. (2013). Dosage optimization and bolted connections for UHPFRC ties [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34790TESI

DEVELOPMENT AND CALIBRATION OF A GLOBAL GEOMETRIC DESIGN CONSISTENCY MODEL FOR TWO-LANE RURAL HIGHWAYS, BASED ON THE USE OF CONTINUOUS OPERATING SPEED PROFILES

Road safety is one of the most important problems in our society. It causes hundreds of fatalities every year worldwide. A road accident may be caused by several concurrent factors. The most common are human and infrastructure. Their interaction is important too, which has been studied in-depth for years. Therefore, there is a better knowledge about the driving task. In several cases, these advances are still not included in road guidelines. Some of these advances are centered on explaining the underlying cognitive processes of the driving task. Some others are related to the analysis of drivers’ response or a better estimation of road crashes. The concept of design consistency is related to all of them. Road design consistency is the way how road alignment fits drivers’ expectancies. Hence, drivers are surprised at inconsistent roads, presenting a higher crash risk potential. This PhD presents a new, operating speed-based global consistency model. It is based on the analysis of more than 150 two-lane rural homogeneous road segments of the Valencian Region (Spain). The final consistency parameter was selected as the combination of operational parameters that best estimated the number of crashes. Several innovative auxiliary tools were developed for this process. One example is a new tool for recreating the horizontal alignment of two-lane rural roads by means of an analytic-heuristic process. A new procedure for determining road homogeneous segments was also developed, as well as some expressions to accurately determine the most adequate design speed. The consistency model can be integrated into safety performance functions in order to estimate the amount of road crashes. Finally, all innovations are combined into a new road design methodology. This methodology aims to complement the existing guidelines, providing to road safety a continuum approach and giving the engineers tools to estimate how safe are their road designs.Camacho Torregrosa, FJ. (2015). DEVELOPMENT AND CALIBRATION OF A GLOBAL GEOMETRIC DESIGN CONSISTENCY MODEL FOR TWO-LANE RURAL HIGHWAYS, BASED ON THE USE OF CONTINUOUS OPERATING SPEED PROFILES [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48543TESI

Influence of Lane Width on Semi-Autonomous Vehicle Performance

[EN] In the medium-term, the number of semi-autonomous vehicles is expected to rise significantly. These changes in vehicle capabilities make it necessary to analyze their interaction with road infrastructure, which has been developed for human-driven vehicles. Current systems use artificial vision, recording the oncoming road and using the center and edgeline road markings to automatically facilitate keeping the vehicle within the lane. In addition to alignment and road markings, lane width has emerged as one of the geometric parameters that might cause disengagement and therefore must be assessed. The objective of this research was to study the impact of lane width on semi-autonomous vehicle performance. The automatic lateral control of this type of vehicle was tested along 81 lanes of an urban arterial comprising diverse widths. Results showed that the semi-autonomous system tended to fail on narrow lanes. There was a maximum width below which human control was always required-referred to as the human lane width-measuring 2.5 m. A minimum width above which automatic control was always possible-the automatic lane width-was established to be 2.75 m. Finally, a lane width of 2.72 m was found to have the same probability of automatic and human lateral control, namely the critical lane width. Following a similar methodology, these parameters could be determined for other vehicles, enhancing the interaction between autonomous vehicles and road infrastructure and thus supporting rapid deployment of autonomous technology without compromising safety.García García, A.; Camacho-Torregrosa, FJ. (2020). Influence of Lane Width on Semi-Autonomous Vehicle Performance. Transportation Research Record. 2674(9):279-286. https://doi.org/10.1177/0361198120928351S27928626749Lu, Z., Zhang, B., Feldhütter, A., Happee, R., Martens, M., & De Winter, J. C. F. (2019). Beyond mere take-over requests: The effects of monitoring requests on driver attention, take-over performance, and acceptance. Transportation Research Part F: Traffic Psychology and Behaviour, 63, 22-37. doi:10.1016/j.trf.2019.03.018Dogan, E., Rahal, M.-C., Deborne, R., Delhomme, P., Kemeny, A., & Perrin, J. (2017). Transition of control in a partially automated vehicle: Effects of anticipation and non-driving-related task involvement. Transportation Research Part F: Traffic Psychology and Behaviour, 46, 205-215. doi:10.1016/j.trf.2017.01.012Shen, S., & Neyens, D. M. (2017). Assessing drivers’ response during automated driver support system failures with non-driving tasks. Journal of Safety Research, 61, 149-155. doi:10.1016/j.jsr.2017.02.009Du, X., & Tan, K. K. (2016). Comprehensive and Practical Vision System for Self-Driving Vehicle Lane-Level Localization. IEEE Transactions on Image Processing, 25(5), 2075-2088. doi:10.1109/tip.2016.2539683Du, X., & Tan, K. K. (2015). Vision-based approach towards lane line detection and vehicle localization. Machine Vision and Applications, 27(2), 175-191. doi:10.1007/s00138-015-0735-5Favarò, F., Eurich, S., & Nader, N. (2018). Autonomous vehicles’ disengagements: Trends, triggers, and regulatory limitations. Accident Analysis & Prevention, 110, 136-148. doi:10.1016/j.aap.2017.11.00

From the Vehicle-Based Concept of Operational Design Domain to the Road-Based Concept of Operational Road Section

[EN] Automated vehicles are designed to maintain both longitudinal and transverse control along a road section under certain favorable conditions. The conditions that ensure a safe operation of an automated vehicle are referred to as Operational Design Domain (ODD). So far, the concept of ODD has focused on the automated vehicle and how it is designed to operate autonomously and safely under certain conditions. However, Road Administrations and Operators would be probably more interested in formulating the concept of ODD from the road standpoint, identifying the sections that really allow an optimal and safe operation for all automated vehicles. Hence, this study introduces the concept of Operational Road Section (ORS) that is defined as a road section that is compatible with all automated vehicles¿ ODDs. This would result in very low disengagements of SAE Level 2 and 3 vehicles, and no disengagements at all of any SAE Level 4 vehicle, as long as their conditions do not vary. These road sections are determined as the overlapping of all the ODDs corresponding to all the automated vehicles traveling through a road segment. The concept of ORS will play a key role in the identification of the road features that promote a safe automated driving. With this information, Road Administrations and Operators could (a) establish improvement actions for extended automated operation and thus longer ORSs; and (b) manage driving restrictions to certain driving automation systems. Finally, a case study is presented showing the applicability of the ORS concept on a two-lane rural road segment.This research is part of the PIARC's Special Project "Smart Roads Classification," funded by World Road Association-PIARC.García García, A.; Llopis-Castelló, D.; Camacho-Torregrosa, FJ. (2022). From the Vehicle-Based Concept of Operational Design Domain to the Road-Based Concept of Operational Road Section. Frontiers in Built Environment. 8:1-8. https://doi.org/10.3389/fbuil.2022.90184018

Analysis of the Influence of Geometric Design Consistency on Vehicle CO2 Emissions

[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.Llopis-Castelló, D.; Camacho-Torregrosa, FJ.; García García, A. (2019). Analysis of the Influence of Geometric Design Consistency on Vehicle CO2 Emissions. Transportation Research Part D Transport and Environment. 69:40-50. https://doi.org/10.1016/j.trd.2019.01.029S40506

Development of a global inertial consistency model to assess road safety on Spanish two-lane rural roads

[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.Llopis-Castelló, D.; Camacho-Torregrosa, FJ.; García García, A. (2018). Development of a global inertial consistency model to assess road safety on Spanish two-lane rural roads. Accident Analysis & Prevention. 119(October 2018):138-148. https://doi.org/10.1016/j.aap.2018.07.018S138148119October 201

Calibration of the inertial consistency index to assess road safety on horizontal curves of two-lane rural roads

[EN] One of every four road fatalities occurs on horizontal curves of two-lane rural roads. To this regard, many studies have been undertaken to analyze the crash risk on this road element. Most of them were based on the concept of geometric design consistency, which can be defined as how drivers¿ expectancies and road behavior relate. However, none of these studies included a variable which represents and estimates drivers¿ expectancies. This research presents a new local consistency model based on the Inertial Consistency Index (ICI). This consistency parameter is defined as the difference between the inertial operating speed, which represents drivers¿ expectations, and the operating speed, which represents road behavior. The inertial operating speed was defined as the weighted average operating speed of the preceding road section. In this way, different lengths, periods of time, and weighting distributions were studied to identify how the inertial operating speed should be calculated. As a result, drivers¿ expectancies should be estimated considering 15¿s along the segment and a linear weighting distribution. This was consistent with drivers¿ expectancies acquirement process, which is closely related to Short-Term Memory. A Safety Performance Function was proposed to predict the number of crashes on a horizontal curve and consistency thresholds were defined based on the ICI. To this regard, the crash rate increased as the ICI increased. Finally, the proposed consistency model was compared with previous models. As a conclusion, the new Inertial Consistency Index allowed a more accurate estimation of the number of crashes and a better assessment of the consistency level on horizontal curves. Therefore, highway engineers have a new tool to identify where road crashes are more likely to occur during the design stage of both new two-lane rural roads and improvements of existing highways.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.Llopis-Castelló, D.; Camacho-Torregrosa, FJ.; García García, A. (2018). Calibration of the inertial consistency index to assess road safety on horizontal curves of two-lane rural roads. Accident Analysis & Prevention. 118(September 2018):1-10. https://doi.org/10.1016/j.aap.2018.05.014S110118September 201

How to incorporate automated vehicles on Road Safety Audits

[EN] Road Safety Audit (RSA) has proved to be one of the best road safety management procedures for design, construction, and maintenance of existing and new road infrastructure. At the beginning, the safety review only focused on motor vehicles and the human driver. Later, as well as nowadays, procedures are also applied to the needs for all vulnerable road users, taking into account that each of the groups (pedestrians, cyclists, motorcyclists) has its own specific requirements. The new and better capabilities of automated vehicles should be in accordance to road technical features, such as geometry, sight distance, signs, and markings. However, the corresponding standards were developed for human driving, and therefore they must be adapted to the new systems without losing compatibility with lower automation levels. While considerable research effort has been carried out for the digital infrastructure, only some studies have been carried out for the physical one with interesting findings that deserve to be incorporated into RSA procedures, such as: new available and required stopping sight distance; new automated speed as the maximum speed that allows the automated system to maintain the longitudinal and lateral control; readable road markings and road signs to facilitate recognition by both human drivers and connected and automated vehicles; etc. The main objective is to achieve the optimal performance of Advanced Driver Assistance Systems (ADAS). The main result of this study is a first proposal for a new chapter to be included in the checklists to carry out road safety audits for the different stages and road safety inspections.Camacho-Torregrosa, FJ.; García García, A.; Llopis-Castelló, D. (2021). How to incorporate automated vehicles on Road Safety Audits. Universidad de Burgos. 3113-3134. http://hdl.handle.net/10251/1913473113313

Time-Based Calibration of the Inertial Operating Speed to Enhance the Assessment of the Geometric Design Consistency

[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, respectivelyLlopis-Castelló, D.; Bella, F.; Camacho-Torregrosa, FJ.; García García, A. (2018). Time-Based Calibration of the Inertial Operating Speed to Enhance the Assessment of the Geometric Design Consistency. Transportation Research Record. 2672(38):223-232. https://doi.org/10.1177/0361198118782009S22323226723

New consistency model based on inertial operating speed profiles for road safety evaluation

[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.Llopis-Castelló, D.; Bella, F.; Camacho-Torregrosa, FJ.; García García, A. (2018). New consistency model based on inertial operating speed profiles for road safety evaluation. Journal of Transportation Engineering. 144(4):04018006-1-04018006-10. https://doi.org/10.1061/JTEPBS.0000126S04018006-104018006-10144