This on-road field investigation employed, for the first time, a completely automated, trigger-based data collection system capable of evaluating driver performance in an extended duration real-world commercial motor vehicle environment. The complexities associated with the development of the system, both technological and logistical and the necessary modifications to the plan of research are presented herein This study, performed in conjunction with an on-going three year contract with the Federal Highway Administration, examined the use of self-rating of alertness and temporal separation (minimum time-to-collision, minimum headway, and mean headway) as indicators of driver fatigue. Without exception, the regression analyses for both the self-rating of alertness and temporal separation yielded models low in predictive ability; neither metric was found to be a valid indicator of driver fatigue. Various reasons for the failure of self-rating of fatigue as a valid measure are discussed. Dispersion in the data, likely due to extraneous (non-fatigue related) factors (e.g., other drivers) are credited with reducing the sensitivity of the temporal separation indicators. Overall fatigue levels for all temporal separation incidents (those with a time-to-collision equal to or less than four seconds) were found to be significantly higher than for those randomly triggered incidents. On this basis, it is surmised that temporal separation may be a sensitive indicator for time-to-collision values greater than the 4-second criterion employed in this study. Two unexpected relationships in the data are also discussed. A "wall" effect was found to exist for minimum time-to-collision values at 1.9 seconds. That is, none of the participants who participated in this research effort exhibited following behaviors with less than a 1.9-second time-to-collision criterion. In addition, based upon the data collected for this research, anecdotal evidence suggests that commercial motor vehicle operators do not appear to follow the standard progression of events associated with the onset of fatigue. / Ph. D.

Med fler än en miljon omkomna i trafikolyckor världen över varje år är trafiksäkerhet ett ständigt aktuellt område. Studier på deprimerade patienter har visat att negativ sinnesstämning medför försämrad körförmåga. Dessa effekter är i hög grad outforskade och det är därför viktigt att undersöka om de förekommer även vid en mildare grad av nedstämdhet, så kallad dysfori, vilket i så fall skulle innebära att negativ sinnesstämning i likhet med trötthet och alkoholpåverkan utgör en allvarlig trafikfara. För att bättre förstå hur sinnesstämning påverkar körförmåga är det dock också relevant att undersöka om dysfori kan bidra till riskkompensation, det fenomen som inträffar när människor kompenserar för säkerhetsförändringar genom ett förändrat riskbeteende. I denna uppsats beskrivs en del av en körsimulatorstudie kring dysfori och bilkörning, där syftet var att undersöka om dysfori kan vara en orsak till riskkompensation. 15 studenter vid Linköpings universitet delades upp i en testgrupp med dysforiska försöksdeltagare (N = 5) och en kontrollgrupp (N = 10) med hjälp av Major Depression Inventory, ett instrument för att diagnostisera depression. Dessa fick sedan genomföra en körning i simulatorn Desktop T&D där time headway, time to collision, genomsnittshastighet och antal omkörningar mättes för de olika grupperna för att undersöka förekomsten av riskkompensation. Resultatet visade att inga signifikanta skillnader kunde observeras för något av måtten. Riskkompensation har i många studier visat sig vara ett komplext fenomen att undersöka och ett flertal metodologiska problem förelåg, särskilt på grund av svårigheten att mäta risk i en simulator med god validitet. Det är dock viktigt att fortsatta undersökningar görs för att bättre förstå riskkompensation, samt att fenomenet beaktas som en tänkbar inverkande faktor i framtida studier av körförmåga.

This diploma thesis deals with driver’s reaction time in regular road traffic. The theoretical part of this work focuses on reaction time, such as various definitions, structuring of reaction time, methods of measuring or publications made by other authors. The practical part of this diploma thesis includes proposal and realization of experiment, based on analysis of the current state by the author of this diploma thesis, which focuses on driver’s reaction time in regular road traffic (various traffic situations). At the end, the practical part presents the results evaluation based on various traffic situations or headway.

No description available.

Since the introduction of motor vehicles, the number of fatalities and accidents has been a concern for society.The number of fatalities on roads is amongst the most common causes of mortality worldwide (WHO, 2015).Even in industrialized countries the number of fatalities remains unacceptable. Therefore, in the last decades, anumber of approaches have emerged to support and boost traffic safety towards a system free from fatalities andserious impairment outcomes. ‘Sustainable Safety’ and ‘Vision Zero’ are well-known examples aiming to avoidfatalities within the traffic system and reduce injury severity when a traffic accident is inevitable. However, thenumber of fatalities and seriously injured accidents are still relatively high. More specifically, vulnerable roadusers remain involved in fatal and serious accidents even in industrialized countries. Therefore, further advancesin traffic safety studies are needed. This thesis aims at evaluating the impact of road characteristics, traffic rulesand information provision towards a safer traffic system. The thesis is composed of five scientific papers whichsummarizes the main contributions of this work. / <p>QC 20161109</p>

Η επιρροή του παράγοντα χρονοαπόσταση σε ένα σύστημα ακολουθίας οχημάτων μπορεί να προσδιορίσει την επικινδυνότητα του πλήγματος που υφίσταται το σύστημα. Με βάση μια παρ’ολίγον οπισθο-μετωπική σύγκρουση σε αυτοκινητόδρομο 3 λωρίδων, εξετάζεται ο ρόλος της χρονοαπόστασης μεταξύ των οχημάτων σε συνδυασμό με τους χρόνους αντίδρασης των οδηγών στην αντίληψη του επικείμενου κινδύνου. Το μοντέλο ακολουθίας οχημάτων κατά Brill, που συσχετίζει την χρονοαπόσταση, τον χρόνο αντίδρασης του οδηγού και την επιβράδυνση με τη συχνότητα των ατυχημάτων, χρησιμοποιείται ως κύριο εργαλείο για την εκτίμηση της ευαισθησίας της πιθανότητας ενός ατυχήματος. Μέσω της μικροσκοπικής ανάλυσης του βίντεο καταγραφής του ατυχήματος και της επεξεργασίας των δεδομένων και με πηγή έμπνευσης τα προγενέστερα επίμαχα ερωτήματα που θέτει και απαντά ο G. Davis και οι συνεργάτες του, προκύπτουν οι απαραίτητες πληροφορίες για την αριθμητική περιγραφή του ατυχήματος. Με τη χρήση έπειτα του λογισμικού προγράμματος OpenBUGS, το οποίο βασίζεται στη μέθοδο Monte Carlo Markov Chain, γίνεται προσομοίωση του προτύπου ατυχήματος και υπολογίζονται οι τιμές των παραμέτρων που επηρεάζουν τη μορφή του πλήγματος. Από τα αποτελέσματα προκύπτει ο βαθμός που ο συνδυαστικός παράγοντας χρονοαπόσταση και χρόνος αντίδρασης επηρεάζει το πλήγμα και αξιολογείται. Τέλος, με συγκεκριμένες επεμβάσεις επιχειρείται η βελτίωση ολόκληρου του συστήματος ακολουθίας οχημάτων. / The influence of time headway on a car-following system can determine the severity of a shockwave. Based on a near-miss rear-end collision on a 3-lane highway, this study examines the importance of time headway in combination with the driver’s reaction time upon perception of the upcoming hazard. The car-following model developed by Ed. Brill, relating driver’s reaction time, temporal headway and deceleration response to accident frequency, is used as a main tool for assessing the sensitivity of collision probability. Through a microscopic analysis of the video record and data processing and inspired by earlier critical questions that G. Davis and his associates have posed and answered, all the necessary information for the arithmetical description of the accident is extracted. Using the OpenBUGS software, and based on the Monte Carlo Markov Chain method, simulation of the collision prototype is achieved along with the calculation of other main parameters that affect the shockwave form. Simulation results, revealing the influence that the combined factor headway-reaction time has on a shockwave are derived and evaluated. Through certain modifications, the improvement of the whole car-following system is attempted.

Many car-following models predict a stable car-following behavior with a very small fluctuation around an equilibrium value g* of the net headway g with zero speed-difference Δv between the following and the lead vehicle. However, it is well-known and additionally demonstrated by data in this paper, that the fluctuations are much larger than these models predict. Typically, the fluctuation in speed difference is around ±2m/s, while the fluctuation in the net time headway T=g/v can be as big as one or even two seconds, which is as large as the mean time headway itself. By analyzing data from loop detectors as well as data from vehicle trajectories, evidence is provided that this randomness is not due to driver heterogeneity, but can be attributed to an internal stochasticity of the driver itself. A final model-based analysis supports the hypothesis, that the preferred headway of the driver is the parameter that is not kept constant but fluctuates strongly, thus causing the even macroscopically observable randomness in traffic flow.

<p>Pre obavljanja levog manevra, sa prioritetnog prilaza TWSC nesignalisane raskrsnice, vozač procenjuje interval koji se javlja u konfliktnom toku i bira onaj interval koji mu je najviše prihvatljiv. Vreme koje je potrebno za procenu prihvatljivog intervala je predstavljeno u vidu vremena čekanja u opsluzi vozila na raskrsnici. Sa pojavom prihvatljivog intervala, vreme čekanja u opsluzi vozila se završava, i tada počinje vreme za izvođenje manevra levog skretanja. Odluka o momentu početka izvođenja manevra levog skretanja je subjektivna i zasniva se na proceni vozača. Ispravna subjektivna procena uvek rezerviše bezbednosno vreme. U ovoj disertaciji je predstavljen razvoj detaljnog matematičkog postupka za proračun bezbednosnog vremena. Merenja na nesignalisanim raskrsnicama su dokazala primenjivost predloženog modela, mogućnost proračuna subjektivnog bezbednosnog vremena i visoko učešće bezbednosnog vremena u kritičnom intervalu (oko jedne trećine). Dobijeni rezultati su visoko saglasni sa HCM.</p> / <p>Before the left turn manoeuvre, from priority approach at TWSC unsignalized intersection, the driver estimates the interval occurring in the conflict flow and chooses the one which is most acceptable for him. The time required for evaluation of acceptable interval is presented by the service waiting time of vehicles at an intersection. With the appearance of an acceptable interval, service waiting time for vehicle ends, and then starts a time for performance of left turn manoeuvre. A decision about the moment of starting left turn manoeuvre is subjective and based on a driver&rsquo;s estimate. Correct subjective evaluation always reserves the safety time. This dissertation presents development of a detailed mathematical procedure for calculation form of safety time. Measurements at unsignalized intersections are proven applicability of the proposed model, possibility of calculation subjective safety time and high participation of safety time in critical gap (about one-third). The obtained results are highly consistent with HCM.</p>

Literature, while perceived as beneficial, is not widely used in the ESL arena. This study set out to investigate proven benefits of using literature in ESL through a review of the current research, at the same time establishing a link between literature and narrative based on `story grammar' which biological determinism claims the human brain is hardwired to use as a language learning tool. Hypothesizing that there would be no correlation between theory regarding the presence and application of literature in ESL as presented in the current research and the practice as found in the prominent ESL course, New Headway, the study set out to identify narrative input in New Headway's Elementary, Intermediate and Advanced Levels and analyzing the way in which narrative is used to teach language skills and communicative competence. Contrary to expectations a surprisingly high level of narrative was found and the narrative was exploited in full accordance with suggestions made in the current research. The findings indicate that the incorporation of narrative in New Headway is a pedagogically informed decision by the authors to exploit the benefits of literature while at the same time catering to a very heterogeneous audience of international ESL learners. Key terms: literature, narrative, story, biological determinism, ESL course books, New Headway / English Studies / M.Ed.

The connected vehicle technology presents an innovative way of sharing information between vehicles and the transportation infrastructure through wireless communications. The technology can potentially solve safety, mobility, and environmental challenges that face the transportation sector. Signal phasing and timing information is one category of information that can be broadcasted through connected vehicle technology. This thesis presents an in-depth study of possible ways signal phasing and timing information can be beneficial as far as safety and mobility are concerned. In total, three studies describing this research are outlined. The first study presented herein focuses on data collection and calibration efforts of the simulation model that was used for the next two studies. The study demonstrated a genetic algorithm procedure for calibrating VISSIM discharge headways based on queue discharge headways measured in the field. Video data was used to first compute intersection discharge headways for individual vehicle queue position and then to develop statistical distributions of discharge headways for each vehicle position. Except for the 4th vehicle position, which was best fitted by the generalized extreme value (GEV) distribution, the Log-logistic distribution was observed to be the best fit distribution for the rest of vehicle positions. Starting with the default values, the VISSIM parameters responsible for determining discharge headways were heuristically adjusted to produce optimal values. The optimal solutions were achieved by minimizing the Root Mean Square Error (RMSE) between the simulated and observed data. Through calibration, for each vehicle position, it was possible to obtain the simulated headways that reflect the means of the observed field headways. However, calibration was unable to replicate the dispersion of the headways observed in the field mainly due to VISSIM limitations. Based on the findings of this study, future work on calibration in VISSIM that would account for the dispersion of mixed traffic flow characteristics is warranted. The second study addresses the potential of connected vehicles in improving safety at the vicinity of signalized intersections. Although traffic signals are installed to reduce the overall number of collisions at intersections, rear-end collisions are increased due to signalization. One dominant factor associated with rear-end crashes is the indecisiveness of the driver, especially in the dilemma zone. An advisory system to help the driver make the stop-or-pass decision would greatly improve intersection safety. This study proposed and evaluated an Advanced Stop Assist System (ASAS) at signalized intersections by using Infrastructure-to-Vehicle (I2V) and Vehicle-to-Vehicle (V2V) communication. The proposed system utilizes communication data, received from Roadside Unit (RSU), to provide drivers in approaching vehicles with vehicle-specific advisory speed messages to prevent vehicle hard-braking upon a yellow and red signal indication. A simulation test bed was modeled using VISSIM to evaluate the effectiveness of the proposed system. The results demonstrate that at full market penetration (100% saturation of vehicles equipped with on-board communication equipment), the proposed system reduces the number of hard-braking vehicles by nearly 50%. Sensitivity analyses of market penetration rates also show a degradation in safety conditions at penetration rates lower than 40%. The results suggest that at least 60% penetration rate is required for the proposed system to minimize rear-end collisions and improve safety at the signalized intersections. The last study addresses the fact that achieving smooth urban traffic flow requires reduction of excessive stop-and-go driving on urban arterials. Smooth traffic flow comes with several benefits including reduction of fuel consumption and emissions. Recently, more research efforts have been directed towards reduction of vehicle emissions. One such effort is the use of Green Light Optimal Speed Advisory (GLOSA) systems which use wireless communications to provide individual drivers with information on the approaching traffic signal phase and advisory speeds to arrive at the intersection on a green phase. Previously developed GLOSA algorithms do not address the impact of time to discharge queues formed at the intersection. Thus, this study investigated the influence of formed intersection queues on the performance of GLOSA systems. A simulation test-bed was modeled inside VISSIM to evaluate the algorithm’s effectiveness. Three simulation scenarios were designed; the baseline with no GLOSA in place, scenario 2 with GLOSA activated and queue discharge time not considered, and scenario 3 with GLOSA activated and where queue dissipation time was used to compute advisory speeds. At confidence level the results show a significant reduction in the time spent in queue when GLOSA is activated (scenarios 2 and 3). The change in the average number of stops along the corridor was found not to be significant when the base scenario was compared against scenario 2. However, a comparison between scenarios 2 and 3 demonstrates a significant reduction in the average number of stops along the corridor, and also in the time spent waiting in queues