Dissertations / Theses on the topic 'Traffic circles – Design and construction'

A traditional two dimensional (planar) statistical analysis was used to identify the clustering types of North Central Texas traffic fatalities occurring in 2001-2006. Over 3,700 crash locations clustered in ways that were unlike other researched regions. A two dimensional (x and y coordinates) space was manipulated to mimic a one dimensional network to identify the tightest clustering of fatalities in the nearly 400,000 crashes reported from state agencies from 2003-2006. The roadway design was found to significantly affect crash location. A one dimensional (linear) network analysis was then used to measure the statistically significant clustering of flow variables of after dark crashes and daylight crashes. Flow variables were determined to significantly affect crash location after dark. The linear and planar results were compared and the one dimensional, linear analysis was found to be more accurate because it did not over detect the clustering of events on a network.

Most vehicular tunnels, due to their restrictive and confined environment require continuous traffic surveillance and control. This is achieved by a variety of systems like closed circuit TV monitoring, personnel stationed in the tunnel, overheight & speed detectors and others. Traffic flow data were obtained from the Interstate 64(I -64) Hampton Roads Bridge-Tunnel. The data were analyzed and conclusions were drawn about traffic flow behavior at the different tunnel sections. During the operation of a tunnel, capacity reductions are often experienced due to temporary lane closures. These could result from incidences occurring in the tunnel area or due to regular maintenance activities. This work concentrates on the former case. A microcomputer model called Queue and User Cost Evaluation of Work Zones(QUEWZ) was employed in studying lane closure scenarios for the Virginia Tidewater Area Tunnels. In case of significant capacity reductions or complete blockages of directions of travel, it is desired to know beforehand the impact expected on the surrounding network. Traffic management actions like rerouting policies could be implemented and thus alleviate the problem. MASSVAC2, a computer simulation model for mass evacuation under emergency conditions was employed for analyzing different traffic management scenarios.
M.S.

Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Different types of live loading due to traffic may act on bridges. The focus of this study is on normal traffic loading according to the South African specification of TMH7. Heavy vehicles are not included in normal traffic loading. TMH7 represents the code of practice for the design of highway bridges and culverts in South Africa. The aim of the study is to provide an insight into the flexural analysis of skew bridges, under the effects of normal traffic loading. The need for the study arose since the specification of TMH7 does not explicitly specify application patterns for normal traffic loading. Only the intensity of normal traffic loading is specified and it should be applied to yield the most adverse effects. For these reasons, a set of so-called standard application patterns are investigated and developed through the course of this study. The envelope of the values from the standard application patterns are compared to the most adverse application pattern for flexural effects in certain design regions of the bridge deck. Flexure, as in the context of this study, translates into the bending and twisting of the bridge deck under loads. A number of numerical experiments are performed for typical single span and multi-span continuous carriageways, where the standard application patterns are compared to the most adverse application patterns. The results from the numerical experiments are documented and compared as the angle of skew of the bridge deck increases in plan-view. For this purpose, the development of effective and specialized software was necessary. It was found that the set of standard application patterns can be used as a preliminary approximation for the most adverse effects of normal traffic loading, for specific flexural resultants in certain design regions of a bridge deck. However, for a large number of secondary flexural effects, the set of standard application patterns did not represent a good approximation for the most adverse values.
AFRIKAANSE OPSOMMING: Verskillende tipes lewendige belasting, as gevolg van verkeer, kan op brûe inwerk. Die fokus van die studie is op normale verkeers-belasting volgens die Suid-Afrikaanse spesifikasie van TMH7. Swaar-voertuie word nie ingesluit by normale verkeers-belasting nie. TMH7 verteenwoordig die kode vir die ontwerp van padbrûe en duikers in Suid-Afrika. Die doel van die studie is om insig te verskaf in die buig-analise van skewe brûe, as gevolg van die werking van normale verkeers-belasting. Die rede vir hierdie studie ontstaan aangesien die spesifikasie van TMH7 nie eksplisiet aanwendingspatrone vir normale verkeers-belasting voorskryf nie. Slegs die intensiteit van normale verkeersbelasting word voorgeskryf en dit moet aangewend word om die negatiefste effekte te verkry. Vir hierdie redes word 'n versameling van sogenaamde standaard aanwendings-patrone deur die loop van die studie ondersoek en ontwikkel. Die omhullings-kurwe van die waardes wat deur die standaard patrone gelewer word, word vergelyk met die waarde van die aanwendings-patroon wat die negatiefste buig-effek in sekere ontwerp-areas van die brugdek veroorsaak. Buig-effekte, soos van toepassing op hierdie studie, verwys na buig en wring van die brugdek as gevolg van belastings. 'n Aantal numeriese eksperimente, vir enkel-span sowel as multi-span deurlopende brugdekke, word uitgevoer en die standaard aanwendings-patrone word vergelyk met die aanwendings-patrone wat die negatiefste waardes lewer. Die resultate van die numeriese eksperimente word gedokumenteer en vergelyk soos die hoek van skeefheid van die brugdek in plan-aansig toeneem. Vir hierdie doel is die ontwikkeling van effektiewe en gespesialiseerde sagteware dus nodig. Daar is gevind dat die standaard aanwendings-patrone, vir spesifieke buig-resultante in sekere ontwerp-areas van die brugdek, as 'n voorlopige benadering vir die negatiefste effekte van normale verkeers-belasting gebruik kan word. Dit was egter verder gevind dat vir 'n groot aantal sekondêre buig-effkte, die versameling standaard aanwendings-patrone nie as 'n goeie benadering vir die negatiefste waardes dien nie.

Information on transit ridership and operations is a necessary condition as far as efficient management is considered. Transit managements on the acquisition of such a data base can confirm predictions about scheduling, receive warnings about potential dangers and plan future operations on a much broader and precise base. Data from passenger counts provide essential information to marketing and scheduling personnel by identifying peak load-points and the such. Using manual collection methods for such data is expensive and prone to human errors. Automatic Passenger Counting (APC) systems are viewed as an improved and economical technique for data collection. Such systems monitor the progress of a particular vehicle -- its position, number of passengers getting on and off, times and distances between stops -- and make this data available for processing. These are state of the art systems, mostly microprocessor based and often embracing a modular structure. The Red Pine system is such a system with different dedicated modules for each bank of tasks. Multitasking software is seen to be an powerful tool for such systems and simplify the architecture of the system hardware. A CHMOS hardware design, suited for multitasking softwares is provided. Interfacing software for the Red Pine system has been developed and is explained. Debugging testing and simulation of the Red Pine hardware is detailed. Modifications have been recorded and improvements suggested.

Master of Science

Analysis of the right turn lane length of urban roads in left-hand traffic countries, such as Australia, UK and India (left-turn lane length in right-hand traffic countries such as USA), at signalised intersections encounters two main geometric features namely, deceleration length and storage length. The literature shows that in routine practice, the deceleration length is generally estimated by using constant deceleration rate. Many researchers consider this assumption for all design speeds unrealistic as it does not reflect the influence of the pavement condition. Hence, it may be desirable to consider the pavement’s condition in terms of its longitudinal coefficient of friction in the design analysis. In regard to the storage length, a large number of the current guidelines and models estimate the storage length of right-turn lane at signalised intersections under split phase. Hence, there is a need to examine other phase types and timings and integrate the signal timing as a part of the geometric design In this thesis, two analytical expressions have been analysed for the design of deceleration length. The first expression assumes a constant deceleration rate, and the second expression employs the concept of forces on a rotating wheel in which the coefficient of longitudinal friction between a vehicle’s tyres and the road surface is considered. The calculated deceleration lengths by these two expressions were compared with the recommended values in American and Australian standards as well as with the deceleration lengths that were obtained by a recent simulation study presented in the literature. It has been found that applying a constant deceleration rate of 2.74 m/s2 in the first expression provides the values of deceleration length comparable to most guidelines and studies. The second expression highlights the importance of using the pavement design in terms of the coefficient of friction to reduce the deceleration length in the case of limited space. A MATLAB based simulation programme has been developed to provide an estimate of the right-turn lane storage length for different traffic volumes in order to avoid the problems associated with blocking and overflow of right turn vehicles in 95% of cycles. In established intersections that cannot be modified due to physical constraints, the model is flexible enough to examine different signal phase types and timings and provides other solutions to reduce overflow and/or blockage situations. The simulation model also takes into consideration the leftover queue. The model results have been compared against an available analytical method in which similar signal phases and timings were investigated. The outcomes are similar to those of the analytical model in most of the signal phase types. The simulation model provides the flexibility to estimate the right-turn lane length for different combinations of through lane and right-turn lane traffic volumes. The developed simulation model has also been validated against the field data using three parameters, namely 95th percentile of maximum queue, overflow cycle percentage, and blockage cycle percentage. Comparing with the field observations yields a level of accuracy in the range of 78%-85%. Finally this simulation model has been used to optimise the green time in the case of split phase that demonstrates a large difference in traffic volumes of two opposite approaches; this could reduce the mean wait time by up to 28%.

Bicycle use is increasing in many parts of the U.S. Local and regional governments have set ambitious bicycle mode share goals as part of their strategy to curb greenhouse gas emissions and relieve traffic congestion. In particular, Portland, Oregon has set a 25% mode share goal for 2030 (PBOT 2010). Currently bicycle mode share in Portland is 6.1% of all trips. Other cities and regional planning organizations are also setting ambitious bicycle mode share goals and increasing bicycle facilities and programs to encourage bicycling. Increases in bicycle mode share are being encouraged to increase. However, cities with higher-than-average bicycle mode share are beginning to experience locations with bicycle traffic congestion, especially during peak commute hours. Today, there are no established methods are used to describe or measure bicycle traffic flows. In the 1960s, the Highway Capacity Manual (HCM) introduced Level of Service (LOS) measurements to describe traffic flow and capacity of motor vehicles on highways using an A-to-F grading system; "A" describes free flow traffic with no maneuvering constraints for the driver and an "F" grade corresponds to over capacity situations in which traffic flow breaks down or becomes "jammed". LOS metrics were expanded to highway and road facilities, operations and design. In the 1990s, the HCM introduced LOS measurements for transit, pedestrians, and bicycles. Today, there are many well established and emerging bicycle level of service (BLOS) methods that measure the stress, comfort and perception of safety of bicycle facilities. However, it was been assumed that bicycle traffic volumes are low and do not warrant the use of a LOS measure for bicycle capacity and traffic flow. There are few BLOS methods that take bicycle flow into consideration, except for in the case of separated bicycle and bicycle-pedestrian paths. This thesis investigated the state of BLOS capacity methods that use bicycle volumes as a variable. The existing methods were applied to bicycle facility elements along a corridor that experiences high bicycle volumes in Portland, Oregon. Using data from the study corridor, BLOS was calculated and a sensitivity analysis was applied to each of the methods to determine how sensitive the models are to each of the variables used. An intercept survey was conducted to compare the BLOS capacity scores calculated for the corridor with the users' perception. In addition, 2030 bicycle mode share for the study corridor was estimated and the implications of increased future bicycle congestion were discussed. Gaps in the BLOS methods, limitations of the thesis study and future research were summarized. In general, the existing methods for BLOS capacity are intended for separated paths; they are not appropriate for existing high traffic flow facilities. Most of the BLOS traffic flow methods that have been developed are most sensitive to bicycle volumes. Some of these models may be a good starting point to improve BLOS capacity and traffic flow measures for high bicycle volume locations. Without the tools to measure and evaluate the patterns of bicycle capacity and traffic flow, it will be difficult to monitor and mitigate bicycle congestion and to plan for efficient bicycle facilities in the future. This report concludes that it is now time to develop new BLOS capacity measures that address bicycle traffic flow.

This research is aimed at developing a probabilistic based model for heavy-duty pavement project evaluation. To achieve this objective studies were conducted in the area of traffic flow, traffic delay modelling, pavement deterioration, pavement condition monitoring, maintenance diaries, vehicle operating cost parameters and economic theories related to asset management. Extensive literature reviews on related topics were carried out as part of the process of developing this model. The major features of the model are its ability to assign random probabilities to various pavement maintenance options and calculate the probabilistic based whole of life cost for any pavement type, for a given design life. To accomplish the task of developing the model a simple traffic delay model was developed. Traffic delay and costs were alculated using the model for predetermined pavement and traffic conditions. Studies were conducted using this model to prove the validity of considering user costs as the predominant cost in any pavement project evaluation process. A probabilistic based whole of life costing model concept was developed along with a supporting traffic delay model and a range of spreadsheets to meet the objectives of this research. This concept was tested using a complete range of data and by making some realistic assumptions. The results obtained from this model are quite encouraging and are expected to provide the basis for a new innovative tool to pavement project engineers for the purpose of pavement project evaluation.

碩士
國立成功大學
資訊工程學系碩博士班
100
IEEE 802.16 version of the Worldwide Interoperability for Microwave Access (WiMAX) standard represents a new generation technology for high speed Broadband Wireless Access system. Its primary function focuses on resolving the bottleneck of lack of bandwidth and excessive equipment cost occurred in the last mile of communication systems. WiMAX 802.16e is developed for mobile wireless network, it could transmit data more efficiently by OFDMA. Several burst packing algorithms which lead to the restriction of WiMAX have been proposed for WiMAX system. In this work, a new concept Packing preprocessing was developed for the preprocedure of WiMAX packing algorithm. We use it for some specific purpose and choose the suitable algorithm to improve the performance. It could choose algorithm by analysis the input burst set. We proposed Basic packing Algorithm (BP) for the general input bust set. We also proposed Burst Combination packing Algorithm (BCP) and QoS-awared packing Algorithm (QP) for the switching algorithm. With the premise which is for evenly burst distribution, the algorithm will be selected between BP and BCP. With the premise which is for QoS- Guarantee, the algorithm will be selected between BP and QP. Ns2 simulator was used to evaluate the performance of this new concept and algorithms. Various scenarios were tested. The simulation results verify the improvement.

Commuter rail is increasingly popular as a means to introduce rail transportation to metropolitan transportation systems. The long-term benefits of commuter rail include the addition of capacity to the transportation system, providing a quality commute alternative, and shifting land use toward transit-oriented development patterns. The success of a commuter rail system depends upon cultivating a ridership base upon which to expand and improve the system. Cultivating this ridership is dependent upon offering a quality transportation option to commuters. Characteristics of commuter rail systems in the United States present challenges to offering quality service that must be overcome. Commuter rail has been implemented only on existing rail right-of-way (ROW) and infrastructure (depending upon condition) in the United States. Existing rail ROW does not often coincide with current commercial and residential demand centers and necessitates the use of a circulator system to expand the service boundary of commuter rail to reach these demand centers. The commuter rail circulator network design problem (CRCNDP) addresses a particular aspect of the commuter rail trip, seeking to improve the performance of the entire system through accurately modeling the portion of the trip from rail station to the final destination. This final leg includes both the trip on the circulator vehicle and the walking trip from the circulator stop to the final destination. This dissertation seeks to provide an innovative mathematical programming formulation and solution methodology for the CRCNDP and apply this method to a case study.

Submitted in fulfillment for the degree of Magister Technologiae: Engineering: Civil, Durban University of Technology, Durban, South Africa, 2013.
An increase in road traffic, poor road conditions and high numbers of road accidents are major challenges at the Port of Durban. Roads are considered as the most important transport mode at the Port of Durban. Road transport has taken almost 80% of the import and export cargo while railway transport is left with approximately 20%. It is estimated that 75 million lives in the world will be lost and 750 million people injured in road accidents in the first half of the 21th century. The Port of Durban is an important vehicle for facilitating economic growth of local, regional and national industries. For the Port to maintain global competitiveness with the current trend of globalization, it has to ensure that roads are well maintained, safe and have a smooth traffic flow with no delays. This study provides an overview of the road infrastructure within the Port of Durban in relation to road condition, safety, law enforcement and traffic. Existing and ongoing studies conducted in South Africa and abroad form part of the literature review. This study identifies factors that are affecting the condition of road infrastructure such as growth of container cargo, an increase in the dimension and weight of trucks, transport deregulation, port layout and handling equipments. Deregulation of road transport over the past years has resulted in an 80:20 split between road and rail transport putting more pressure on roads. Cost and time are the major deciding factors in the freight industry. Most customers prefer to use road transport due to the lower cost and reduced time compared to rail transport. There are eight major roads within the Port that connect the South, West and North of eThekwini Municipality namely Bayhead, Quayside, Maydon, Rick Turner, Wisely, South Coast, Bluff and Iran Roads. Asset verification and assessment of the condition of the existing eight major roads found that Quayside Road is in a better condition compared to the other roads. Maydon and South Coast Roads are low rated roads which are in a poor condition. Identification and assessment of the condition of 210 000m² of asphalt paved areas which included minor roads within the Port of Durban was also conducted. Most paved areas and roads fall under D (fair) category which is reasonable but maintenance work may be required within six months. Comparison between the condition of the eight major roads within the Port and outside the Port was investigated. The findings indicate that sections of roads outside the Port are in a better condition than sections within the Port. Traffic counts were conducted in order to determine the utilization of the existing eight major roads. Bayhead and South Coast Road are highly utilized roads. Road accident reports and death reports were analyzed on these roads. Most of the road accidents take place on South Coast Road. A questionnaire survey was conducted, targeting road users who travel on these roads within the Port. Feedback was obtained on the status of road conditions, safety and traffic within the Port of Durban. Findings of this survey revealed that most of the respondents don’t know where to report road defect/s within the Port. Approximately 37.5% of the road users felt not safe to drive on roads within the Port especially on South Coast Road. A high percentage of people (93%) witnessed accidents on these roads. Traffic signals within the Port are maintained by eThekwini Municipality and are very often non-functional. When road signs need to be repaired or replaced, it takes longer than expected. Also, there are limited parking areas around the Port resulting in trucks parking closer to the premises while waiting to collect or deliver cargo. This causes major traffic congestion, for example, on Maydon Road where most trucks park on the side of the road. Recommendations include assessment guidelines that could improve road condition, safety and traffic flow. Areas to be improved with regard to road infrastructure are also highlighted.
M

Indiana University-Purdue University Indianapolis (IUPUI)
Highway noise can cause annoyance, affect sleep patterns, and reduce the property value for people in the proximity. Current methods for analyzing the effectiveness of sound barriers only take loudness into consideration. This paper introduces new methods that can be used to analyze the effectiveness of the sound barriers. Our approach uses psychoacoustic measures including sharpness, roughness, fluctuation, strength, and annoyance. Highway noise is non-stationary, therefore each of these metrics are calculated over a short time. Finally analysis is performed the distribution and change over time. We used nth nearest neighbor algorithm to remove sounds that are not a part of the experiment. In the future, this data can be combined with human surveys to see if the change in sound quality due to the presence of sound barriers has a meaningful impact on people's lives.

This dissertation examines the use of statistical models for prediction. Examples are drawn from public policy and chosen because they represent pressing problems facing U.S. governments at the local, state, and federal level. The first five chapters provide examples where the perfunctory use of linear models, the prediction tool of choice in government, failed to produce reasonable predictions. Methodological flaws are identified, and more accurate models are proposed that draw on advances in statistics, data science, and machine learning. Chapter 1 examines skyscraper construction, where the normality assumption is violated and extreme value analysis is more appropriate. Chapters 2 and 3 examine presidential approval and voting (a leading measure of civic participation), where the non-collinearity assumption is violated and an index model is more appropriate. Chapter 4 examines changes in temperature sensitivity due to global warming, where the linearity assumption is violated and a first-hitting-time model is more appropriate. Chapter 5 examines the crime rate, where the independence assumption is violated and a block model is more appropriate. The last chapter provides an example where simple linear regression was overlooked as providing a sensible solution. Chapter 6 examines traffic fatalities, where the linear assumption provides a better predictor than the more popular non-linear probability model, logistic regression. A theoretical connection is established between the linear probability model, the influence score, and the predictivity.