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.




Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities


Book Description

TRB' National Cooperative Highway Research Program (NCHRP) Report 674: Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities explores information related to establishing safe crossings at roundabouts and channelized turn lanes for pedestrians with vision disabilities. Appendices B through N to NCHRP Report 674 were published as NCHRP Web-Only Document 160.




Traveler Response to Transportation System Changes


Book Description

From a transportation and community perspective, objectives of pedestrian and bicycle facility improvements have evolved to include numerous aspects of providing viable and safe active transportation options for all ages, abilities, and socioeconomic groups. Pedestrian and bicycle facilities appear overall to benefit the full spectrum of society perhaps more broadly than any other provision of transportation. A challenge in non-motorized transportation (NMT) benefit analysis is to adequately account for all the different forms in which pedestrian and bicycle facilities provide benefit. In this report, new as well as synthesized research is presented. This chapter examines pedestrian and bicyclist behavior and travel demand outcomes in a relatively broad sense. It covers traveler response to NMT facilities both in isolation and as part of the total urban fabric, along with the effects of associated programs and promotion. It looks not only at transportation outcomes, but also recreational and public health outcomes. This chapter focuses on the travel behavior and public health implications of pedestrian/bicycle areawide systems; NMT-link facilities such as sidewalks, bicycle lanes, and on-transit accommodation of bicycles; and node-specific facilities such as street-crossing treatments, bicycle parking, and showers. Discussion of the implications of pedestrian and bicycle "friendly" neighborhoods, policies, programs, and promotion is also incorporated. The public health effects coverage of this chapter, and associated treatment of walking and bicycling and schoolchild travel as key aspects of active living, have been greatly facilitated by participation in the project by the National Center for Environmental Health--part of the Centers for Disease Control and Prevention (CDC). This pivotal CDC involvement has included supplemental financial support for the Chapter 16 work effort. It has also encompassed assistance with research sources and questions, and draft chapter reviews by individual CDC staff members in parallel with TCRP Project B-12A Panel member reviews (see "Chapter 16 Author and Contributor Acknowledgments". TCRP Report 95: Chapter 16, Pedestrian and Bicycle Facilities will be of interest to transit, transportation, and land use planning practitioners; public health professionals and transportation engineers; land developers, employers, and school administrators; researchers and educators; and professionals across a broad spectrum of transportation, planning, and public health agencies; MPOs; and local, state, and federal government agencies. This chapter is complemented by illustrative photographs provided as a "Photo Gallery" at the conclusion of the report. In addition, PowerPoint slides of the photographs in full color are available on the TRB website at http://www.trb.org/Main/Blurbs/167122.aspx.




NCHRP Report 674


Book Description




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.




Incorporating Safety Into Long-range Transportation Planning


Book Description

"TRB's National Cooperative Highway Research Program (NCHRP) Report 546 examines where and how safety can be effectively addressed and integrated into long-range transportation planning at the state and metropolitan levels. The report includes guidance for practitioners in identifying and evaluating alternative ways to incorporate and integrate safety considerations in long-range statewide and metropolitan transportation planning and decision-making processes"--Publisher's description.




Design and Performance of Earth Retaining Structures


Book Description

Proceedings of the 1990 Specialty Conference on Design and Performance of Earth-Retaining Structures, held in Ithaca, New York, June 18-21, 1990. Sponsored by the Geotechnical Engineering Division of ASCE. This Geotechnical Special Publication contains 50 papers on the design and performance of earth-retaining structures. Topics include historical perspectives, wall selection, contracting practices, waterfront structures, gravity walls, mechanically stabilized systems, cast-in-place walls, soil nailing, tied-back excavations, and seismic design. Papers survey the current state of the practice for earth retention and support, detail the rapid and profound changes to design and construction practices in the past 20 years, and forecast technological developments that are likely to carry the practice into the next century. Sixteen invited papers by international experts address aspects of each of the general topics, including trends in ground movements, effects of material selection and construction practices, and advances in design analyses and procedures. Other papers address specific case histories of various types of earth-retaining structures, provide results of performance monitoring, compare predicted to actual performance, and assess the impacts of construction practice and design procedures on performance.




Stabilization of Existing Subgrades to Improve Constructibility During Interstate Pavement Reconstruction


Book Description

This synthesis will be of interest to state department of transportation (DOT) construction, geotechnical, materials, and pavement system design engineers, engineering geologists, and research engineers, and others concerned with the constructibility of new pavements over existing subgrades. The synthesis describes current practice for the stabilization of existing subgrades to improve constructibility during interstate pavement reconstruction. It presents information regarding the methods available to evaluate and improve subgrade conditions for the purpose of meeting the constructibility requirements of a reconstruction project. This report of the Transportation Research Board presents data obtained from a review of the literature and a survey of the state DOTs. The synthesis reports on: subgrade evaluation methods including sampling, laboratory, and in-situ test methods, as well as assessment of existing drainage systems; constructibility factors such as existing and proposed pavement types, available equipment, and cost effectiveness of various subgrade stabilization techniques; methods of subgrade improvement including mechanical and chemical stabilization, use of recycled and waste materials, the use of geosynthetics in reinforcement and drainage applications; and construction methods with an emphasis on innovative approaches such as novel sequencing of construction traffic, use of lightweight equipment, and robotics. In addition, several case histories describing applicable pavement reconstruction projects are presented. Finally, suggestions to possibly improve the practice and the identification of research needs are also presented.




Binder Characterization and Evaluation


Book Description




Guardrail Performance and Design


Book Description

Barrier installations are warranted (or justified) only at highway locations where the consequence of an errant vehicle leaving the roadway is judged to be more hazardous than the impact with the barrier installation. A six degree-of-freedom mathematical model was found to be useful in describing dynamic behavior of a vehicle during impact. Predictions of vehicle and barrier behavior correlated with results obtained from full-scale crash tests. Crash conditions simulated with a computer were used to identify and evaluate vehicle static and dynamic as well as barrier parameters. Vehicle weight, yaw mass moment of inertia, and deformation constant were found to be significant.