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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Multi-Criteria Evaluation in Support of the Decision-Making Process in Highway Construction Projects

jia, jianmin 31 March 2017 (has links)
The decision-making process in highway construction projects identifies and selects the optimal alternative based on the user requirements and evaluation criteria. The current practice of the decision-making process does not consider all construction impacts in an integrated decision-making process. This dissertation developed a multi-criteria evaluation framework to support the decision-making process in highway construction projects. In addition to the construction cost and mobility impacts, reliability, safety, and emission impacts are assessed at different evaluation levels and used as inputs to the decision-making process. Two levels of analysis, referred to as the planning level and operation level, are proposed in this research to provide input to a Multi-Criteria Decision-Making (MCDM) process that considers user prioritization of the assessed criteria. The planning level analysis provides faster and less detailed assessments of the inputs to the MCDM utilizing analytical tools, mainly in a spreadsheet format. The second level of analysis produces more detailed inputs to the MCDM and utilizes a combination of mesoscopic simulation-based dynamic traffic assignment tool, and microscopic simulation tool, combined with other utilities. The outputs generated from the two levels of analysis are used as inputs to a decision-making process based on present worth analysis and the Fuzzy TOPSIS (Technique for Order Preference by Similarity to Ideal Situation) MCDM method and the results are compared.
12

Using naturalistic data to assess e-cyclist behavior

Dozza, Marco, Bianchi Piccinini, Giulio Francesco, Werneke, Julia 18 November 2020 (has links)
In Europe, the use of electric bicycles is rapidly increasing. This trend raises important safety concerns: Is their use compatible with existing infrastructure and regulations? Do they present novel safety issues? How do they impact other traffic? This study sought to address these concerns, using instrumented electric bicycles to monitor e-cyclists’ behavior in a naturalistic fashion. Data was collected from 12 bicyclists, each of whom rode an instrumented bicycle for two weeks. In total, 1500 km worth of data were collected, including 88 critical events (crashes and near-crashes). Analysis of these critical events identified pedestrians, light vehicles and other bicycles as main threats to a safe ride. Other factors also contributed to crash causation, such as being in proximity to a crossing or encountering a vehicle parked in the bicycle lane. A comparison between electric and traditional bicycles was enabled by the availability of data from a previous study a year earlier, which collected naturalistic cycling data from traditional bicycles using the same instrumentation as in this study. Electric bicycles were found to be ridden faster, on average, than traditional bicycles, in addition to interacting differently with other road users. The results presented in this study also suggest that countermeasures to bicycle crashes should be different for electric and traditional bicycles. Finally, increasing electric bicycle conspicuity appears to be the easiest, most obvious way to increase their safety.
13

Where do bicyclists interact with other road users?: Delineating potential risk zones in HD-maps.

Lackner, Bernd-Michael, Loidl, Martin 02 January 2023 (has links)
International crash statistics indicate a decrease of bicycle crashes, but at a slower pace compared to total crash numbers. The share of crashes with involved cyclists is above the modal share (see [1] for an overview). Depending on sources, types of analyses, and geographic regions, crash statistics suggest high rates of singlebike crashes and crashes between cyclists and other vulnerable road users (VRUs) [2], while cars are opponents in more than half of all fatal crashes in the European Union [3]. The design of th.e road environment is of particular relevance for crash risks. A study from London found three times higher injury odds for cyclists at intersections [4]. Connected and automated vehicles (CAV) are frequently said to increase the safety level in road traffic since they are less prone to human errors [5]. This might hold true in transport systems with little complexity, such as highways [6]. However, when it comes to complex situations in multimodal systems with multiple interactions between different road users, such as intersections in urban environments, existing solutions are not sufficient yet in terms of protecting VRUs. ... In order to contribute to the safety of VRUs in the interplay with CAVs in current systems, we propose a geospatial model, which delineates potential interaction risk zones from high definition (HD) maps and enriching these zones with additional information. These enriched risk zones are then provided as standardized OGC web service, which can be integrated in V2X systems. With this, we contribute to the visibility, and thus the safety of VRUs in connected transport systems. From a methodological point of view, the proposed model is a first step in integrating spatial context and semantic information explicitly into V2X communication. [From: Introduction]
14

E-Scooters appear on bike infrastructure: users and usage, conflicts and coexistence with cycling

Hardinghaus, Michael, Oostendorp, Rebekka 03 January 2023 (has links)
E-scooters are a rather new mode of transport. Nevertheless, in recent years lots of studies have been published. Replaced modes and consequential environmental impacts as well as specific injury pattern are important topics. Regarding shape, speed and usage, e-scooters are most similar to bikes. As a consequence, by law e-scooters use the same road space or infrastructure than bikes do. Concurrently, in recent years we experience a boom of cycling in cities and a significant expansion of the bike infrastructure. Requirements and frequency of usage on the bike infrastructure are growing in cities caused by increasingly diverse cyclists. At the same time, the bike infrastructure is subject new requirements and additional pressure due to the implementation of e-scooters. In Germany, allowing e-scooters on bike infrastructure can be seen as a paradigm shift since for the first time a motorized vehicle is allowed to use the infrastructure. On this background, interrelation between e-scooters and active mobility (walking and cycling) are very important for the future use of the infrastructure and the ongoing transformation of urban mobility. Hence, we use a multi-method approach to investigate these potential conflicts and draw conclusions for regulation as well as improvement in the system.
15

Safety evaluation of converging chevron pavement markings

Pratyaksa, Prabha 09 April 2013 (has links)
Chevron pavement markings have seen rising interest in the United States as a means to reduce speeds at high-speed locations and improve safety performance. In Atlanta, there are two freeway-to-freeway ramps where chevron markings are being used. A previous study analyzed before-and-after speed data at these ramps and found only a modest reduction on overall vehicle speeds. However, a cursory crash analysis indicated that the ramps had crash reductions of over 60%, suggesting that safety benefits exist even though vehicle speeds are not significantly affected. This research aims to evaluate the safety performance of chevron markings on the two ramps in Atlanta, GA in order to quantify the potential impact of the treatment on safety and to understand the mechanism by which the treatment influences safety. This thesis begins with a literature review covering topics in human factors in safety, past uses of different types of pavement markings, and methods in using crash databases and police reports in accident studies. Next, the thesis presents an in-depth before and after analysis of crash data from crash databases and police reports provided by the Georgia Department of Transportation. And finally, the thesis concludes with a summary of findings and a discussion of further research needs. The results verified that there were 73% and 61% crash reductions in the two study ramps. Chevron markings appear to have benefitted all types of crashes and that they are possibly serving as a warning to drivers of potential upcoming hazards. Unavailability of a number of police reports and errors in crash databases were limitations to this study, and ultimately, new sites should be selected carefully and further studies need to be performed to better understand the treatment's benefits.
16

Exploring Road Traffic Interactions Between Highly Automated Vehicles and Vulnerable Road Users

Fabricius, Victor January 2023 (has links)
Understandings of road traffic interactions are largely based on human-human interactions. However, the development of vehicles controlled by highly auto- mated driving systems (ADS) would introduce a radically novel type of road user. This compilation thesis explores encounters between these “autonomous vehicles” (AVs) and human vulnerable road users (VRUs) such as pedestrians and cyclists. The included publications are connected to three research questions. First, empirical studies are reviewed to highlight existing interactive be- haviors and communication cues. This is followed by a methodological question of how to investigate AV-VRU interactions. Finally, VRUs’ experiences from initial experiments on AV crossing encounters are presented. While road user trajectories and kinematic behaviors are viewed as primary mechanisms to facilitate traffic interactions, they might also be influenced by cues such as appearances, gestures, eye-gaze, and external human-machine interfaces (eHMI). Using the Wizard-of-Oz approach, we are able to explore VRU encounters with a seemingly highly automated vehicle. Compared to meeting an attentive driver, AV encounters resulted in a reported lower willingness to cross, lower perceived safety, and less calm emotional state, indicating that the absence of driver-centric cues could lead to interaction issues and impede acceptance of AVs. To further explore this, we included light-based eHMI to signal the driving mode and intent of the vehicle (e.g., intent to yield). Future research should continue to investigate how AVs may co-exist with human road users focusing on aspects such as behavioral adaptations, research methodologies, and the role of various eHMI.
17

Case studies of the transfer of road safety knowledge and expertise from western countries to Thailand and Vietnam, using an ecological road safety space model : elephants in traffic and rice cooker helmets

King, Mark Johann January 2005 (has links)
International organisations such as the World Health Organisation highlight the road crash problem in less motorised (or developing, or low income) countries like those in Southeast Asia and recommend the adoption of Western road safety measures. However, there are many differences between highly motorised and less motorised countries which raise questions about how successfully Western road safety knowledge and expertise can be transferred.----- A review of the statistical information on road crashes shows a great deal of uncertainty about both the scale and likely trajectory of road fatalities globally, in less motorised countries and in Asia. It is generally agreed, however, that Asia accounts for around half of all road fatalities, and analysis of the limited available data shows both that Southeast Asia is not an atypical region of Asia in road safety terms, and that Thailand and Vietnam are not atypical of Southeast Asian countries.----- A literature review of recommended practice approaches to road safety transfer in Asia shows that there are many economic, institutional, social and cultural factors which potentially influence the success of transfer. The review also shows that there is no coherent, comprehensive approach which either conceptualises these factors and their relationship to transfer outcomes, or uses an analysis of these factors to plan or modify transfer. To address this gap, this thesis develops a 'road safety space' model as a tool for conceptualisation and analysis, based on a biological metaphor which views the transfer of road safety measures from one context to another as analogous to the transfer of a species into a new ecological space. The road safety space model explicitly considers economic, institutional, social and cultural factors (from specific to broad) which influence the particular road safety issue which a particular road safety transfer effort seeks to address. A central contention of this thesis is that the road safety space model is both a feasible and useful tool to improve the process of road safety transfer to less motorised countries. Road safety space analysis is seen to have a role in a broader process of selection of road safety measures for transfer, along with knowledge of how the measures are considered to operate.----- The research reported in this thesis is comprised of three studies. Study 1 reviewed evaluations of road safety transfer to Thailand and Vietnam. Studies 2 and 3 were case studies of road safety transfer to Thailand and Vietnam respectively.----- Study 1 was an analysis of existing evaluations of road safety transfer to Thailand and Vietnam. The aims were to analyse the evaluations for their consideration of contextual factors, as described in the road safety space model, and to discuss whether the road safety space model assisted in understanding the reasons for success or failure of transfer. However, very few such evaluations exist, and those that were found generally lacked information on whether contextual factors were considered. This indicated the need for a more detailed, in-depth qualitative investigation of particular cases of road safety transfer, in order to investigate the feasibility and utility of the road safety space model.----- Two case studies (Study 2 and Study 3) were conducted to test whether the road safety space approach was both feasible and useful as a means of improving road safety transfer efforts. Study 2 was a case study of the development and implementation in Thailand of a road safety education program for school children, which involved the transfer of Western research and techniques. The transfer agents (i.e. those who effected the road safety transfer) were Australian consultants working for the Australian Road Research Board (ARRB). The transfer was funded by the World Bank and managed by the Thai Ministry of Education (MOE). Study 3 was a case study of the development and implementation of a motorcycle helmet wearing program in Vietnam, which involved the transfer of Western knowledge, techniques and technology. The transfer agents were staff of Asia Injury (AI), a non-government organisation (NGO), and the program was funded initially by a charitable fund, with the intention of becoming self-funding through operation of a helmet factory.----- The case studies employed background research into existing information on economic, institutional, social and cultural factors relevant to the road safety issues (road use behaviour of school children in Thailand and motorcycle helmet purchase and wearing in Vietnam), and collected data through interviews with key informants, analysis of secondary sources and observations. This information was used to derive the road safety space for each road safety issue, to identify the road safety space recognised and addressed by the transfer agents (ARRB and AI), and to determine which factors they missed, or were aware of but took no action on. The focus of this analysis was on the processes used in transfer, not on the road safety outcomes of transfer, although these provided information on the processes as well. Available evaluation information was used to draw links between the omissions and the success of the transfer processes. It was noted that information on how the transferred measures operate should come from a road safety space analysis in the originating country, although this raised questions about selection of country and time (when the measure was first introduced, or in its maturity).----- The feasibility and utility of the road safety space model were discussed. It was clear that the model provided information on the cases which was missed by the transfer agents. The questions examined next were whether this information could have been obtained from an exercise conducted before the transfer had commenced, whether the required effort and cost justified the potential benefits, and whether the information on the road safety space could have been useful for the transfer agents. Comparisons between the road safety spaces for the two cases showed some areas of commonality, e.g. perceptions of police corruption, but also many differences. It was considered likely that some broad factors could be generic, and the possibility was mooted that less motorised countries share issues with police enforcement. This requires further research, however, and at this stage it is better to treat each road safety space as a unique combination of contextual factors influencing the road safety issue of interest.----- It is concluded that the road safety space model is feasible if used in such a way as to minimise the research involved, and useful, although the degree of utility needs to be further explored in a prospective study. The limitation introduced by restricting informants to those who could speak English are discussed. An approach using road safety space analysis is recommended, emphasising analysis of the country to which the road safety measure is being transferred, supplemented by analysis of the originating country road safety space. Gaps in knowledge are identified for further research and development, in particular the theoretical and practical understanding of road use behaviours and their modification in less motorised countries in Southeast Asia. Elaboration of the model is also recommended, to take into account the influence of the type of measure transferred, the role of the transfer agent, the area of road safety (education, engineering or enforcement), and the time dimension (the time which might be needed for a transfer to show its effects).----- The findings of this research are likely to be applicable to road safety transfer in other less motorised regions of the world, however prospective testing is needed. They may also be relevant to issues of transfer for areas other than road safety, in particular public health and traffic engineering, where similar economic, institutional, social and cultural issues come together.
18

A model for the economic analysis of road projects in an urban network with interrelated incremental traffic assignment method

Lloyd, Evan Robert January 2005 (has links)
[Truncated abstract] In an urban network, any change to the capacity of a road or an intersection will generally result in some traffic changing its route. In addition the presence of intersections creates the need for frequent stops. These stops increase the fuel consumption by anywhere between thirty to fifty percent as evidenced by published standardised vehicle fuel consumption figures for urban and for country driving. Other components of vehicle operating costs such as tyre and brake wear and time costs will also be increased by varying amounts. Yet almost all methods in use for economic evaluation of urban road projects use open road vehicle operating costs (sometimes factored to represent an average allowance for stopping at intersections) for one year or sometimes two years in the analysis period and then make assumptions about how the year by year road user benefits may change throughout the period in order to complete the analysis. This thesis will describe a system for estimating road user costs in an urban network that calculates intersection effects separately and then adds these effects to the travel costs of moving between intersections. Daily traffic estimates are used with a distribution of the flow rate throughout the twenty-four hours giving variable speed of travel according to the level of congestion at different times of the day. For each link, estimates of traffic flow at two points in time are used to estimate the year-by-year traffic flow throughout the analysis period by linear interpolation or extrapolation. The annual road user costs are then calculated from these estimates. Annual road user benefits are obtained by subtracting the annual road user costs for a modified network from the annual road user costs for an unmodified network. The change in the road network maintenance costs are estimated by applying an annual per lane maintenance cost to the change in lane-kilometres of road in the two networks. The Benefit Cost Ratio is calculated for three discount rates. An estimate of the likely range of error in the Benefit Cost Ratio is also calculated
19

Trafikinformation i realtid i samband med vägarbete / Traffic Information in real time in connection with road work

Almqvist, Andreas, Simervir, Sandhu January 2012 (has links)
I rapporten har vi förklarat vilka problem som kan uppstå med dagens teknik och vilka eventuella lösningar som man kan förbättra med tiden. Med hjälp av Trafikverket har vi genomfört detta examensarbete. Vi hade fått tydliga direktiv från Trafikverket gällande examensarbetets syfte. Det gjorde det enkelt för oss att avgränsa arbetet efter de riktlinjer som var angivna och möjliga att genomföra. Studiens syfte var att förstå varför det inte går ge ut relevant trafikinformation. I dagsläget har man tekniken för ett väl fungerande system. Ett system där man enkelt kan få realtidsinformation i samband med trafiken, vägarbeten och eventuella hinder. I rapporten har vi även sammanfattat alla navigationssystem som man kan ha användning av som trafikant. Vi har gjort en omvärldsanalys på hur man i andra länder ger ut trafikinformation och hur de står sig jämtemot Sveriges trafikinformationssystem. För vårt examensarbete har vi använt oss av diverse olika rapporter och intervjuer. Detta tillsammans med personer som har kunskap inom området. Vi har även använt oss av åtskilliga hemsidor för att inhämta information. Rekommendationer för examensarbetet kommer att beskrivas genom fem teman. I rapporten har vi utfört en mängd olika intervjuer som vi sammanställt till teman. Teman var utformade efter det vi kände var mest relevant från intervjuerna. Våra teman speglar bilden av vad vi har lagt vikt med detta examensarbete. / In this report, we have explained the problems that may occur with today's technology and what possible solutions to improve with time. With the help of the Swedish Transport Administration, we have implemented this thesis. We got the clear directions from the Swedish Transport Administration regarding purpose of this thesis. This made it easy for us to delineate our work after the guideline that was definer. The study's purpose was to try to understand why you can´t give out the relevant traffic information. Today we have the technology create a well smooth operation system. A system where you can easily get real-time information related to traffic, road works and obstructions. In this report we have summarized all the navigation system that you could use as a road user. We have done an analysis of how other countries give out their traffic information and how good they are against the Swedish traffic information system. For our thesis we have used various of different reports and interviews. The interviews have been with people who have knowledge in the field. We have also used numerous websites to gather information. Recommendations for the thesis will be described through five themes. In this report, we have conducted a variety of interviews that we have compiled for themes. Themes were designed for what we felt was most relevant from the interviews. Our themes are a mirror image of what we thought was the most relevant part in our thesis.
20

Designing Multimodal Warning Signals for Cyclists of the Future

Nordmark, Anton January 2019 (has links)
Traffic is a complex environment in which many actors take part; several new technologies bring promises of reducing this complexity. However, cyclists—a particularly vulnerable road user group—have so far been somewhat put aside in these new developments, among them being Cooperative Intelligent Traffic Systems (C-ITS) and their aspects of human–computer interaction. This master’s thesis of industrial design engineering presents five multimodal collision warning signals for cyclists—future ones in these supposed C-ITS—using a novel application of bone conduction headphones (BCH) via sensations of both sound and touch. The thesis project was conducted as a complementary subset of the larger research project ‘V2Cyclist’ orchestrated by RISE Interactive. V2Cyclist set out to adapt the wireless V2X-protocol for cyclists by developing a physical prototype in the form of a bicycle helmet and corresponding human–computer interface. A significant part of the theoretical framework for this thesis was multiple resource theory: tasks in a different modality can be performed more effectively than in one already taxed attentively. Literature on human factors was also applied, particularly with regards to the perception of sound; evidence suggests that humans evolved a perceptual bias for threatening and ‘looming’ sounds that appear to encroach our peripersonal space; ethological findings point toward the association with low-frequency sounds to largeness. Sound design techniques usually applied to more artistic ends, such as synthesis and mixing, were repurposed for the novel, audiotactile context of this thesis. The thesis process was rooted in design thinking and consisted of four stages: context immersion, ideation, concept development, and lastly evaluation; converging and diverging the novel design space of using BCH in an audiotactile, i.e. bimodal way. The divergent approach generated a wide range of ideas. The later convergent approach did not result in one, definite design as further evaluation is required but also due to unknowns in terms of future hardware and network constraints. Given the plurality and diversity of cyclists, it may well follow that there is no optimal collision warning design in the singular. Hence, a range of five different solutions is presented. Each of the five multimodal collision warnings presents a different approach to conveying a sense of danger and urgency. Some warning signals are static in type, while others are more dynamic. Given the presumed rarity of collision warnings, multiple design techniques and rationales were applied separately, as well as in combination, to create different warning stimuli that signaled high urgency in an intuitive way. Namely, the use of: conventions in design and culture; explicitness in the form of speech; visceral appeal via threatening and animalistic timbres; dynamic and procedurally generated feedback; multimodal salience; crossmodal evocation of ‘roughness;’ size-sound symbolism to imply largeness; and innately activating characteristics of looming sounds. / Trafiken är en komplex miljö med många deltagare; diverse ny teknik gör anspråk på att underlätta denna komplexitet. Men, cyklister—en särskilt utsatt grupp av trafikanter—har hittills hamnat i skymundan för sådana utvecklingar. Vidare, aspekten av användbara gränssnitt för cyklister inom sådana uppkopplade och samverkande trafiksystem (C-ITS) har utforskats desto mindre. Det här examensarbetet inom Teknisk design presenterar fem multimodala kollisionsvarningar avsedda för cyklister—framtida sådana i dessa C-ITS—genom en ny och bimodal användning av benledande hörlurar via både ljud och vibrationer. Examensarbetet genomfördes i koppling till forskningsprojektet V2Cyclist, orkestrerat av RISE Interactive, vars projektmål var att anpassa det trådlösa kommunikationsprotokollet V2X för cyklister via en fysisk prototyp i form av en cykelhjälm och parallellt utveckla ett tillhörande användargränssnitt. En viktig del av det teoretiska ramverket för det här examensarbetet grundar sig på multiple resource theory: uppgifter kan utföras mer effektivt i en annan modalitet än i en som redan är belastad med uppmärksamhet. Mänskliga faktorer och teori om vår uppfattning användes; bevis pekar på att människor har evolutionärt utvecklat en bias för hotande ljud som upplevs inkräkta på vårt närmsta personliga revir; etologiska rön visar på en koppling mellan lågfrekventa ljud och ‘storhet.’ Tekniker inom ljuddesign vanligtvis använda till mer artistiska ändamål, såsom syntes och mixning, användes här till godo för att utforska den nya och bimodala designrymden. Processen för arbetet grundade sig i design thinking och bestod av fyra faser: kontextfördjupning, idégenerering, konceptutveckling, och utvärdering. En ny och tidigare outforskad designrymd beståendes av en bimodal, ljudtaktil användning av benledande hörlurar divergerades och konvergerades. Ett initialt utforskande angreppssätt gav upphov till en bred mängd av idéer. Ett senare renodlande angreppssätt gick, dock, inte hela vägen till endast en optimal lösning, då vidare utvärdering krävs men också på grund av okända teknologiska begränsningar. Dessutom, givet cyklisters stora mångfald, kan det möjligtvis följa att det inte finns någon enskild design av den optimala kollisionsvarningen. Ett spann på fem olika lösningar presenteras därmed. Fem koncept för multimodala kollisionsvarningar presenteras där varje variant uttrycker fara och kritiskhet på olika sätt. Vissa är statiska i typ, medan andra verkar mer kontinuerligt och dynamiskt. Det antogs att kollisionsvarningar sker sällan. Olika designtekniker och motiveringar har använts, ibland i kombination med varandra, för att skapa kollisionsvarningar vars avsikter omedelbart förstås: normer inom design och kultur gällande ljud; uttalad kommunikation i form av tal; anspråk på människors biologiska intuition via hotfulla och djurliknande klangfärger; dynamisk och procedurellt genererad feedback; multimodal effektfullhet; korsmodal känsla av grova texturer; size-sound symbolism för att antyda ‘storhet;’ samt de naturligt aktiverande egenskaperna hos looming sounds.

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