Operational Impacts of Converting Four-lane Roadways to Three-lane Cross Sections PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Operational Impacts of Converting Four-lane Roadways to Three-lane Cross Sections PDF full book. Access full book title Operational Impacts of Converting Four-lane Roadways to Three-lane Cross Sections by Karen Lynn Giese. Download full books in PDF and EPUB format.
Author: Karen Lynn Giese Publisher: ISBN: Category : Languages : en Pages : 144
Book Description
This study investigated and compared the simulated operational measures of effectiveness for similar traffic volumes, left-turn percentages, and access point densities for a case study roadway with a four-lane undivided and a three-lane cross section. The objective of this study was to quantify the operational impacts of this type of conversion. Actual four- lane undivided to three-lane conversions have shown decreased crashes and crash rates, produced small reductions in average arterial travel speed (similar to the CORSIM results), and resulted in large reductions in the number of speeding vehicles. Four analysis tools were reviewed and the CORSIM model was chosen to complete a sensitivity analysis that included five simulations for each combination of four average daily traffic levels, three left-turn volumes, and six access point densities. The arterial level of service (LOS) decreased from LOS C to D when the average daily traffic was 20,000 vehicles per day (the largest volume considered). The timing of the two-phase signalized intersections within the simulated corridor was optimized and did not experience a change of more than 5.5 seconds per vehicle in average stopped delay (i.e., no overall intersection LOS change). In general, a statistically significant difference in average arterial travel speed was found when four-lane undivided roadways were compared to similar three-lane roadways. The magnitude of the difference, however, ranged only from 0.5 to 3.9 miles per hour.
Author: Karen Lynn Giese Publisher: ISBN: Category : Languages : en Pages : 144
Book Description
This study investigated and compared the simulated operational measures of effectiveness for similar traffic volumes, left-turn percentages, and access point densities for a case study roadway with a four-lane undivided and a three-lane cross section. The objective of this study was to quantify the operational impacts of this type of conversion. Actual four- lane undivided to three-lane conversions have shown decreased crashes and crash rates, produced small reductions in average arterial travel speed (similar to the CORSIM results), and resulted in large reductions in the number of speeding vehicles. Four analysis tools were reviewed and the CORSIM model was chosen to complete a sensitivity analysis that included five simulations for each combination of four average daily traffic levels, three left-turn volumes, and six access point densities. The arterial level of service (LOS) decreased from LOS C to D when the average daily traffic was 20,000 vehicles per day (the largest volume considered). The timing of the two-phase signalized intersections within the simulated corridor was optimized and did not experience a change of more than 5.5 seconds per vehicle in average stopped delay (i.e., no overall intersection LOS change). In general, a statistically significant difference in average arterial travel speed was found when four-lane undivided roadways were compared to similar three-lane roadways. The magnitude of the difference, however, ranged only from 0.5 to 3.9 miles per hour.
Author: Keith K. Knapp Publisher: ISBN: Category : Left-turn lanes Languages : en Pages : 112
Book Description
At and above 1,750 vehicles per hour, the simulation indicated a reduction in arterial level of service. Therefore, at least in Iowa, the feasibility of a four-lane undivided to three-lane conversion should be questioned and/or considered much more closely when a roadway has (or is expected to have) a peak-hour volume of more than 1,750 vehicles. Assuming that 10 percent of the daily traffic occurs during the peak-hour, these volume recommendations would correspond to 15,000 and 17,500 vehicles per day, respectively. These suggestions, however, are based on the results from one idealized case xi study corridor analysis. Individual operational analysis and/or simulations should be completed in detail once a four-lane undivided to three-lane cross section conversion is considered feasible (based on the general suggestions above) for a particular corridor. All of the simulations completed as part of this project also incorporated the optimization of signal timing to minimize vehicle delay along the corridor. A number of determination feasibility factors were identified from a review of the past research, before-and-after case study results, and the simulation sensitivity analysis. The existing and expected (i.e., design period) statuses of these factors are described and should be considered. The characteristics of these factors should be compared to each other, the impacts of other potentially feasible cross section improvements, and the goals/objectives of the community. The factors discussed in these guidelines include - roadway function and environment - overall traffic volume and level of service - turning volumes and patterns - frequent-stop and slow-moving vehicles - weaving, speed, and queues - crash type and patterns - pedestrian and bike activity - right-of-way availability, cost, and acquisition impacts - general characteristics, including - parallel roadways - offset minor street intersections - parallel parking - corner radii - at-grade railroad crossings xii The characteristics of these factors are documented in these guidelines, and their relationship to four-lane undivided to three-lane cross section conversion feasibility identified. This information is summarized along with some evaluative questions in this executive summary and Appendix C. In summary, the results of past research, numerous case studies, and the simulation analyses done as part of this project support the conclusion that in certain circumstances a four-lane undivided to three-lane conversion can be a feasible alternative for the mitigation of operational and/or safety concerns. This feasibility, however, must be determined by an evaluation of the factors identified in these guidelines (along with any others that may be relevant for a individual corridor). The expected benefits, costs, and overall impacts of a four-lane undivided to three-lane conversion should then be compared to the impacts of other feasible alternatives (e.g., adding a raised median) at a particular location.
Author: Thomas M. Welch Publisher: ISBN: Category : Left-turn lanes Languages : en Pages : 34
Book Description
In recent years, many traffic engineers have advocated converting four-lane undivided urban streets to three-lane two-way left turn facilities. A number of these conversions have been successfully implemented. Accident rates have decreased while corridor and intersection levels of service remained acceptable. This conversion concept is yet another viable alternative "tool" to place in our urban safety/congestion toolbox.
Author: Marcus Brewer Publisher: Transportation Research Board ISBN: 0309223598 Category : Technology & Engineering Languages : en Pages : 90
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.
Author: Douglas W. Harwood Publisher: Transportation Research Board ISBN: 9780309068659 Category : Transportation Languages : en Pages : 80
Book Description
This synthesis report will be of interest to officials and staff of municipal, regional, and statewide transportation agencies responsible for roadway design and traffic control. It will be of special interest to those concerned with intersections and driveways on divided highways where larger vehicles encounter narrow medians. It will also be of interest to other professionals who interact with these agencies to mitigate such problems. This report presents state-of-the-practice information about current median design policies and practices, describes the traffic operational and safety problems encountered in designing for larger vehicles at divided highway intersections, and identifies alternative improvement techniques that can be used in new construction or reconstruction projects to avoid introducing traffic operational and safety problems. This TRB report focuses on 10 alternative cross sections widely used on arterial highways in urban, suburban, and rural environment.
Author: Kay Fitzpatrick Publisher: ISBN: Category : Technology & Engineering Languages : en Pages : 144
Book Description
TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 299: Recent Geometric Design Research for Improved Safety and Operations reviews and summarizes selected geometric design research published during the 1990s, particularly research with improved safety and operations implication.
Author: James A. Bonneson Publisher: Transportation Research Board ISBN: 9780309060677 Category : Technology & Engineering Languages : en Pages : 148
Book Description
The objective of this research project was to develop a methodology for evaluating alternative midblock left-turn treatments on urban and suburban arterials. The methodology had to be applicable to three common midblock left-turn treatments: the raised-curb median, the flush median with two-way left-turn lane (TWLTL) delineation, and the undivided cross section. The methodology developed for this research focuses on the evaluation of midblock street segments on urban and suburban arterials. The basis for NCHRP Report 395.
Author: Karen Lynn Giese
Author: Karen Lynn Giese
Author: Keith K. Knapp
Author: Woochul Lee
Author: Thomas M. Welch
Author: Marcus Brewer
Author: Douglas W. Harwood
Author: Kevin N. Balke
Author: Kay Fitzpatrick
Author: James A. Bonneson
Author: