An-Najah Staff

Existing signal control strategies do not consider pedestrian flows in optimizing signal parameters, which may impose significant delays on pedestrians. This study aims to investigate the rationality and effectiveness of designing signal coordination for pedestrians. A numerical case study in Japan is analyzed. Field survey is conducted to collect the geometric characteristics, signal timings and vehicular traffic condition information. In a parallel approach, the performances of signal coordination for vehicular and pedestrian traffic are estimated by using the vehicular traffic simulation tool Synchro/SimTraffic and the pedestrian simulation tool NOMAD. The results showed that the coordination for the major pedestrian flow led to a significant reduction in average delay (15%). Generally, it is concluded that the effectiveness of pedestrian signal coordination is not guaranteed but depends on the relationship between pedestrian platoon dispersion and the signal cycle length.

Existing manuals do not provide clear specifications regarding the required crosswalk width under various pedestrian demand combinations and properties. Furthermore, they don’t offer any quantification regarding the effects of bi-directional flow and pedestrian flow composition upon capacity. This paper analyzes the effects of pedestrian age group and the interaction between bi-directional pedestrian flows on the capacity of signalized crosswalks. Three pedestrian age groups are defined: middle-age, pupils and elderly. A previous developed methodology for modeling pedestrian flows at signalized crosswalks is utilized to generate the fundamental diagrams of pedestrian flow. It is found that the maximum reduction in capacity occurs at roughly equal pedestrian flows from both sides of the crosswalk. Further, it is concluded that elderly pedestrians might cause a significant reduction in capacity up to 30%. © 2011 Published by Elsevier Ltd.

Among various pedestrian facilities, signalized crosswalks are the most complex and critical ones. Their geometry and configuration including width, position and angle directly affect the safety, cycle length and resulting delays for all users. Existing manuals do not provide clear and rational specifications for the required crosswalk width under different pedestrian demand combinations and properties. Furthermore, they do not consider the bi-directional flow effects on crossing speed and time when addressing pedestrian flow at signalized crosswalks. However, quantifying the effects of such interactions on the behavior of pedestrian flow is a prerequisite for improving the geometric design and configuration of signalized crosswalks. The objective of this paper is to develop a methodology for estimating the required crosswalk width at different pedestrian demand combinations and a pre-defined LOS. The developed methodology is based on theoretical modeling for total pedestrian platoon crossing time, which consists of discharge and crossing times. The developed models are utilized to generate the fundamental diagrams of pedestrian flow at signalized crosswalks. A comprehensive discussion about the effects of bi-directional flow and various pedestrian age groups on the characteristics of pedestrian flow and the capacity of signalized crosswalks is presented. It is found that the maximum reduction in the capacity of signalized crosswalks occurs at roughly equal pedestrian flows from both sides of the crosswalk. By utilizing existing LOS thresholds for pedestrian flow at signalized crosswalks, the required crosswalk widths for various pedestrian demand combinations are proposed for implementation.

Existing manuals do not provide clear specifications for the required crosswalk width under different pedestrian demand volumes and characteristics. However, optimizing crosswalk configurations including width is an important concern to improve the overall performance of signalized intersections. The objective of this paper is to develop a methodology for estimating minimum required crosswalk width at different pedestrian demand volumes considering bi-directional flow and different pedestrian age groups. The developed methodology is based on modeling total pedestrian platoon crossing time which consists of discharge and crossing times. Discharge time is modeled by using shockwave theory while crossing time is modeled by applying aerodynamic drag theory. The developed models are then calibrated for crosswalks with mainly elderly or pupil pedestrian platoons. A set of criteria based on pedestrian crossing speed is developed to identify the minimum required crosswalk width. Finally, different required crosswalk widths are proposed for different pedestrian demand volumes and directional split ratios considering the effects of pupil and elderly pedestrian platoons.

Existing optimization methodologies for intersection operations assumes a fixed geometric design, however the geometry and operational system should be simultaneously optimized to produce the best performance. Signalized crosswalks are complex and critical pedestrian facilities. Their geometry and configuration directly affect the safety, cycle length and resulting delays for all users. As crosswalks become wider or they are placed further upstream, the cycle length will increase due to the all-red time requirement, which deteriorates the overall mobility levels of signalized intersections. In contrast, when crosswalk width decreases, the required minimum pedestrian crossing time increases due to the bi-directional pedestrian flow effects, which leads to longer cycle length. Furthermore, existing manuals and guidelines do not offer any specification for the required crosswalk width under various pedestrian demand conditions. This study aims to propose new criteria for designing crosswalk width at signalized intersections, which can optimize the performance from the viewpoint of vehicular traffic and pedestrians. The proposed methodology considers pedestrian demand and its characteristics (such as bi-directional flow effects), vehicle demand and the geometric characteristics of the intersection. The concept of optimized crosswalk width is proposed and demonstrated through a case study. Moreover, a comprehensive discussion regarding the merits and drawbacks of existing strategies on positioning crosswalks is presented. It was found that at signalized intersections, which are characterized by low pedestrian and high vehicle demands, crosswalk width of 2 meters is appropriate to minimize cycle length and resulting delays for all users including pedestrians.