1,721,098 research outputs found
Naturalistic driving data collection to investigate into the effects of road geometrics on track behaviour
Full text linkRoad designers assume that drivers will follow the road alignment with trajectories centred in the lane, and move at the design speed parallel to the road centreline (i.e., the horizontal alignment). Therefore, they assume that if the horizontal alignment indicates the “designed trajectory”, the driving path indicates the “operating trajectory”. However, at present, they do not have the necessary tools to measure the relationship between the designed alignment and possible vehicle trajectories. The paper has two objectives: (a) to develop an understanding of the root causes of differences between road alignment and vehicle trajectories; and (b) to define and calibrate a model that estimates the local curvature of trajectories on the basis of the designed horizontal alignment. The two objectives were pursued by carrying out a naturalistic survey using vehicles equipped with high precision GPS in real-time kinematics (RTK) mode driven by test drivers on road sections of known geometric characteristics. The results provide an insight into the effects of road geometrics on driver behaviour, thus anticipating possible driving errors or unexpected/undesired behaviours, information which can then be used to correct possible inconsistencies when making decisions at the design stage
Experimental Investigation into Driver Behavior along Curved and Parallel Diverging Terminals of Exit Interchange Ramps
Full text linkCurrent design manuals provide guidance on how to design exit ramps to facilitate driving operations and minimize the incidence of crashes. They also suggest that interchanges should be built along straight roadway sections. These criteria may prove ineffective in situations where there is no alternative to terminals being located along curved motorway segments.
The paper investigates driving behavior along parallel deceleration curved terminals, with attention paid to the difference in impact between terminals having a curvature which is the same sign as the motorway segment (i.e. continue design), and those having an opposite curvature (i.e. reverse design). A driving simulation study was set up to collect longitudinal and transversal driver behavioral data in response to experimental factor variations. Forty eight drivers were stratified on the basis of age and gender, and asked to drive along three randomly assigned circuits with off-ramps obtained by combining experimental factors like motorway mainline curve radius (2 values), terminal length (3), curve direction (2) and traffic conditions (2).
The motorway radius was found to be significant for drivers’ preferred speed when approaching the terminal. Terminal length and traffic volume do not have a significant impact on either longitudinal or transversal driver outputs. However, the effect of curve direction was found to be significant, notably for reverse terminals which do not compel drivers to select appropriate speeds and lane change positions. This terminal type can give rise to critical driving situations that should be considered at the design stage to facilitate the adoption of appropriate safety countermeasures
Factors influencing driver behaviour along curved merging interchange terminals
Full text linkProblem statement. To promote safe and comfortable driving operations, design manuals and policies call for merging terminal ramps to be built along straight roadway sections. However, this prescription may need to be overlooked when there is no alternative to terminals being designed along curves. This study aims to assess the impact of design factors on driver behaviour along curved acceleration terminals with continue or reverse curvature
prior to joining the motorway. Methodology. A driving simulation experiment was conducted to observe longitudinal and transversal driver behaviour when certain factors (i.e., radius, ramp length, motorway curve direction, and traffic conditions along the motorway segment) were manipulated. The forty-eight drivers involved were separated into groups based on age and gender. Results. The motorway radius has a significant impact on longitudinal performance, while traffic volume impacts on the merging point where vehicles enter the adjoining motorway lane. Compared to linear terminals, the merging abscissa need to be longer on curved ones so as to compensate for the blind spot and enable drivers to identify and accept gaps between vehicles in the traffic flow. The ramp-terminal connection type influences the speed at the beginning of the terminal, the position of the merging point and transversal driver behaviour. Conclusions. Although some limitations in the study were necessary to limit their impact on the experimental design, the results here may prove useful when considering the adoption of appropriate engineering countermeasures at the design stage of entry terminals along curved motorway segments
Archaeology & pilgrimage : studies around the rurAllure European project
No full textEngramma 204 collects researches and findings of several Italian and European scholars who have dealt with aspects related to ancient, Medieval and Modern pilgrimage along the main three European Routes (Via Romea Francigena, Via Romea Strata, Via Romea Germanica), or along other routes to the Holy Land. The issue is divided into three sections. The first one is dedicated to the European project rurAllure by Martín López Nores, José Juan Pazos Arias, Susana Reboreda Morillo, Óscar Penín Romero, which focuses on the enhancement of minor sites along the pilgrimage routes of Europe, and it is accompanied by an overview on the development of promotional activities for some Italian cases supervised by Alessia Mariotti. The second section presents a series of studies related to some contexts that are close to mineral springs or important waterways and were frequented by pilgrims throughout the centuries: these are articles by Paola Zanovello and Andrea Meleri's on the Euganean Hills (Padua), by Maddalena Bassani's on the sanctuary of Minerva Medica in Val Trebbia (Piacenza) and that at Timavo’s Sources (Monfalcone), by Jacopo Turchetto on the centuriation between Padua and Altino. Furthermore, the articles by Silvia González Soutelo, Miguel Gómez-Heras, and Laura García Juan on the Bagno Vignoni area (Siena), and by Alessia Mariotti and Mattia Vitelli Casella on the Argenta site (Po Delta). In the third and final section one can read two important contributions, the first by Ludovico Rebaudo, devoted to the study of manuscript evidences recorded during a pilgrimage to the Holy Land about archaeological remains in Anatolia; the second by Jacopo Tabolli, who presents an exhibition on votive bronzes left by pilgrims in the sanctuary at the ‘Sorgenti di San Casciano ai Bagni’ (Siena) that recently opened at the Palazzo del Quirinale in Rome
A preliminary investigation into the use of alkali-activated blast furnace slag mortars for high-performance pervious concrete pavements
No full textPervious concrete (PC) pavements are water control systems for infiltrating storm water, reducing runoffs, contrasting heat-island effects and noise diffusion in urban environments. Their poor strength and stiffness, which stem from their porosity, limit their application for use in sidewalks and residential streets. To overcome this limitation, the research aimed at developing an alkali-activated blast furnace slag binder (AA-BFS) which, when added to the concrete mixture, would enable it to attain the characteristics required for application in trafficked road pavements. A Portland cement (CEM-I) and a blast furnace cement (CEM-III/C) were included for comparison purposes. Standard and high-performance pervious concrete (HPPC) mortars were tested with the same mix ratio of binder, sand, and admixtures. The effects of a latex polymer admixture were also analysed. After 2, 7, and 28 days of curing, AA-BFS mortars exhibited the greatest flexural and compressive strengths. As expected, CEM-III/C needed more time to achieve strengths comparable to those recorded for CEM-I. The addition of latex failed to result in any discernible benefits in terms of the stress-strain behaviour of mortars. The results confirm that AA-BFS is a sustainable option for HPPC production
Sensorless SPMSM Control for Heavy Handling Machines Electrification: An Innovative Proposal
No full textThe electrification of road vehicles is a relatively mature sector, while other areas of mobility, such as construction machinery, are just beginning their transition to electric solutions. This work presents the design and realization of an integrated drive system specifically developed for retrofitting fan drives in heavy machinery, like bulldozers and tractors, utilizing existing 48 VDC batteries. By replacing or complementing internal combustion and hydraulic technologies with electric solutions, significant advantages in efficiency, reduced environmental impact, and versatility can be achieved. Focusing on the fan drive system addresses the critical challenge of thermal management in high ambient temperatures and harsh environments, particularly given the high current requirements for 3kW-class applications. A sensorless architecture has been selected to enhance reliability by eliminating mechanical position sensors. The developed fan drive has been extensively tested both on a braking bench and in real-world applications, demonstrating its effectiveness and robustness. Future work will extend this prototype to electrify additional onboard hydraulic motors in these machines, further advancing the electrification of heavy-duty equipment and improving overall efficiency and environmental impact
Humidity stress responses in pollen of anemophilous and entomophilous species
No full textPollen grains of 10 anemophilous and entomophilous species of angiosperms were kept at 4 relative humidities (RH) (15, 51, 79 and 98%) and their viability tested by fluorochromatic reaction after time lapses ranging from 6 to 144 h. Pollen viability in the anemophilous species decreased more rapidly than in the entomophilous ones with the exception of the dioecious palm Chamaerops humilis. The modes of anther and flower opening, times of anther exposure etc. were recorded; Cytological data are discussed and compared with these aspects of reproductive ecology. © 1994 Scandinavian University Press
Traffic crash pattern modification as a result of a 30 km/h zone implementation. A case study in Turin (Italy)
Full text linkThe strategy of 30 km/h zones, referred to in the international context as "traffic calming" measures, serves to safeguard pedestrians, cyclists and motorcyclists, collectively referred to as “vulnerable road users” (VRU). Its main function is to compel drivers to observe a maximum speed limit of 30 km/h. However, urban infrastructure transformations modify traffic collision patterns and the involvement of road users, with a spatial temporal redistribution of events. This work seeks to study the effects on collision distribution resulting from the introduction of a 30 km/h zone to the Mirafiori Nord area in the city of Turin in late 2008. Collision frequencies, based on data provided by the Italian National Institute of Statistics (ISTAT), were evaluated over the period 2006-2016. Road traffic collisions involving both VRU and motorized users (“noVRU”) were taken into account. Decreases in collision frequency were found for noVRU related crashes, while the VRU crash rate remained essentially unchanged with only minor fluctuations consistent with the regression to the mean phenomenon. The countermeasures, which sought to protect VRU, were however very effective for noVRU. As the effects of each structural modification spill over into neighboring areas, the analysis of collision frequency was extended to a study area greater than the one in which the 30 km/h zone was realized. In fact, due to the migration of events, the reduction in the collision frequency in the speed restricted zone was accompanied by an increase in the
same frequency in the immediate surrounding area
DEVELOPMENT OF A NOVEL INTELLIGENT SPEED ADAPTATION SYSTEM BASED ON AVAILABLE SIGHT DISTANCE
Full text linkRoads are designed without considering the improved performance of modern vehicles and the new onboard technologies available for assisted driving. In addition, vehicles frequently travel at speeds which exceed the maximum considered in road design. Hence, the need for speed and safety related countermeasures (e.g., field control, mobile or fixed speed cameras, traffic calming measures) is evident. However, these countermeasures are only partially effective and the proportion of crashes which are speed related remains significant.
This investigation is aimed at the development of a new Intelligent Speed Adaptation (ISA) system based on the available sight distance (ASD). In conditions of poor visibility, the system (i) inform drivers when they are travelling at inappropriate speeds, or (ii) generate warning sounds to the same effect, or (iii) intervene directly and compel drivers to adopt the speed which is most appropriate to the particular ASD. As reported in this methodological paper, the functionality of the new ISA system was tested at the driving simulator of the Politecnico di Torino (Italy) and the resulting estimated ASD value was validated and tested successfully. Future experimental investigations will be devoted to assessing the effectiveness of the system on driver speed behavior and decision making
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