Improved Multi-lane Roundabout Designs for Urban Areas


Book Description

This research, undertaken 2008 to 2010, investigated the comparative safety of multi lane roundabouts versus signalized intersections, pedestrian facilities, vertical deflection devices and visibility to the right. Guidance for practical application of the relevant measures to enhance roundabout safety has been developed and is included in this document. The Dutch turbo roundabout was reviewed and considered to be feasible for application in New Zealand. For intersections with four arms or more, a well designed multi lane roundabout should be significantly safer for vehicle users than traffic signals. Several means of adequately catering for pedestrians and cyclists at multi lane roundabouts are feasible to implement in many cases. In the interest of road safety, a Roundabouts First policy is recommended for adoption by the NZTA. The legal use of flashing signal displays and part time signal operation are also recommended for consideration, which would potentially allow for Pelican type pedestrian crossing installations, and also for signalized roundabouts to operate with less vehicle delay during off peak periods.




Roundabouts


Book Description

TRB's National Cooperative Highway Research Program (NCHRP) Report 672: Roundabouts: An Informational Guide - Second Edition explores the planning, design, construction, maintenance, and operation of roundabouts. The report also addresses issues that may be useful in helping to explain the trade-offs associated with roundabouts. This report updates the U.S. Federal Highway Administration's Roundabouts: An Informational Guide, based on experience gained in the United States since that guide was published in 2000.




Alternative Types of Roundabouts


Book Description

This book presents a history of roundabouts, an introduction to their design, calculations of their capacity and traffic-safety features. It describes the key features of standard roundabouts and their limitations. Alternative types of roundabouts are a fairly recent development and have only been implemented in a few countries to date. The book illustrates a broad variety of these recent alternative types of roundabouts, as well as proposed types still in the development phase, explaining for each the specific needs it meets, its advantages and drawbacks. In closing, the book offers an outlook on the role of roundabouts in future street traffic.




Roundabouts in the United States


Book Description

"Research sponsored by the American Association of State Highway and Transporation Officials in cooperation with the Federal Highway Administration."




Recent Roadway Geometric Design Research for Improved Safety and Operations


Book Description

RB’s National Cooperative Highway Research Program (NCHRP) Synthesis 432: Recent Roadway Geometric Design Research for Improved Safety and Operations reviews and summarizes roadway geometric design literature completed and published from 2001 through early 2011, particularly research that identified impacts on safety and operations.




Roundabouts as Safe and Modern Solutions in Transport Networks and Systems


Book Description

This book offers a collection of guidelines that will be particularly useful to those making decisions concerning roundabouts as safe and modern solutions in transport networks and systems. The decision-making support systems described here will interest those who face the challenge of finding solutions to problems concerning modern transport systems on a daily basis. Consequently, the book is chiefly intended for local authorities involved in planning and preparing development strategies for specific transport-related issues (in both urban and regional contexts), as well as for representatives of business and industry who are directly engaged in the implementation of traffic engineering solutions. The guidelines provided in the respective chapters help to address the given problem soundly, and to simplify the selection of an appropriate strategy. The topics covered include traffic conditions and the performance of single-lane, two-lane and turbo roundabouts, road traffic safety analysis, analysis of road traffic safety improvements, surrogate safety measures at roundabouts, analysis of pedestrian behavior at pedestrian crossings with public transport vehicles, methods for assessing vehicle motion trajectory at single-lane roundabouts using visual techniques, making compact two-lane roundabouts effective for vulnerable road users, concepts for wireless electric vehicle charging near roundabouts, work zones, and temporary traffic control at roundabouts. Since the book also considers new approaches to theoretical models (including modeling roundabout capacity, models of critical gaps and follow-up headways for turbo roundabouts, and estimating roundabout delay while taking into account pedestrian impact), it will also appeal to researchers and scientists studying these problems. The book gathers selected papers presented at the 15th Scientific and Technical Conference “Transport Systems. Theory and Practice”, organized by the Department of Transport Systems and Traffic Engineering, Silesian University of Technology in Katowice, Poland on September 17–19, 2018.




Global Sensitivity Analysis


Book Description

Complex mathematical and computational models are used in all areas of society and technology and yet model based science is increasingly contested or refuted, especially when models are applied to controversial themes in domains such as health, the environment or the economy. More stringent standards of proofs are demanded from model-based numbers, especially when these numbers represent potential financial losses, threats to human health or the state of the environment. Quantitative sensitivity analysis is generally agreed to be one such standard. Mathematical models are good at mapping assumptions into inferences. A modeller makes assumptions about laws pertaining to the system, about its status and a plethora of other, often arcane, system variables and internal model settings. To what extent can we rely on the model-based inference when most of these assumptions are fraught with uncertainties? Global Sensitivity Analysis offers an accessible treatment of such problems via quantitative sensitivity analysis, beginning with the first principles and guiding the reader through the full range of recommended practices with a rich set of solved exercises. The text explains the motivation for sensitivity analysis, reviews the required statistical concepts, and provides a guide to potential applications. The book: Provides a self-contained treatment of the subject, allowing readers to learn and practice global sensitivity analysis without further materials. Presents ways to frame the analysis, interpret its results, and avoid potential pitfalls. Features numerous exercises and solved problems to help illustrate the applications. Is authored by leading sensitivity analysis practitioners, combining a range of disciplinary backgrounds. Postgraduate students and practitioners in a wide range of subjects, including statistics, mathematics, engineering, physics, chemistry, environmental sciences, biology, toxicology, actuarial sciences, and econometrics will find much of use here. This book will prove equally valuable to engineers working on risk analysis and to financial analysts concerned with pricing and hedging.




Roundabouts


Book Description

The roundabouts controlling traffic at the I-17/Happy Valley Road interchange represent Arizona's first application of modern roundabout traffic control in this manner. The construction of roundabouts at this interchange location served to alleviate past congestion and safety issues by reducing off-ramp queues and reducing speeds in the area of the I-17 off-ramp termini. The use of the roundabouts offered flexibility in addressing the complicated traffic interactions of the freeway on- and off-ramps, two-way frontage roads, and Happy Valley Road. Based on this milestone and the overall unique application of roundabout design and function at this particular interchange, the I-17/Happy Valley Road roundabouts were studied to help identify possible improvements that could be incorporated at this location and into future Arizona Department of Transportation roundabout initiatives. The anticipated benefits of the improvements include, but are not limited to, more efficient traffic operations, reduced costs (on average), increased capacity, and improved safety (due to overall slower speeds through the roundabout). The main objectives of this research project include literature review of other state guidelines; evaluation of the roundabouts' design parameters and operation as they relate to capacity and safety; collecting public opinion; and guidelines development. The deliverables of the research project include recommended improvements for the existing roundabouts involving geometric, striping, and signing modifications. Also, the research project culminates in guidelines for the selection, evaluation, and design of roundabouts which provide details on the facets of roundabout use as it relates to Arizona.




Pedestrian Facilities Users Guide: Providing Safety and Mobility


Book Description

This guide is intended to provide information on how to identify safety and mobility needs for pedestrians with the roadway right-of-way. Useful for engineers, planners, safety professionals and decision-makers, the guide covers such topics as: the Walking Environment including sidewalks, curb ramps, crosswalks, roadway lighting and pedestrian over and under passes; Roadway Design including bicycle lanes, roadway narrowing, reducing the number of lanes, one-way/two-way streets, right-turn slip lanes and raised medians; Intersections with roundabouts, T-intersections and median barriers; and Traffic calming designs.




Virtual Analysis and Evaluation of Roundabout Safety and Operational Features


Book Description

Roundabouts can be a solution to safety concerns present at other types of intersections. Recently in the United States, there has been an increase in conversion of problematic intersections to roundabouts to improve their safety. However, it is difficult to make these roundabouts, especially multi-lane roundabouts, safe to all ranges of users. Roundabout features such as advance warning and signage play an important role in determining driver performance as they navigate the roundabout. This research is an effort to evaluate new and existing roundabout safety and operational features such as signs and pavement markings and how they influence performance of drivers at multi-lane roundabouts. It evaluates the two-lane roundabout and the rotor turbo roundabout as an alternative geometric design to a multi-lane roundabout. Virtual scenario simulation by use of a driving simulator is employed to probe driver response to a variety of roundabouts features. The results indicate that lane keeping and speeding are still a problem in multi-lane roundabouts. The rotor turbo roundabout performs better in correctness of lane choice and navigation speed control. Yielding was not a significant problem in both kinds of roundabouts. Furthermore, it was found that roundabout signs and pavement markings used in the United States can be adopted for turbo roundabouts.