Mohammad Sadra Sharifi

Traffic flow characteristics of heterogeneous pedestrian stream involving individuals with disabilities

Walking facilities such as walkways and stairs are important infrastructure that must be designed to accommodate pedestrian behavior to be effective. Heterogeneity in pedestrian composition is one important factor generally overlooked in guidelines and handbooks for walking facility design. Specifically, individuals with different types of disabilities are often overlooked because of the lack of available data. In response, a controlled large-scale research project was conducted at Utah State University to study the performance of various walking environments under heterogeneous pedestrian streams involving individuals with visual and mobility impairments. These environments included a passageway, types of angles (right and oblique), bottlenecks, queuing areas, and stairs. The goals of this study were (a) to investigate macroscopic characteristics of heterogeneous pedestrian streams in various walking environments by using traffic flow fundamental diagrams and (b) to analyze the walking speeds of different pedestrian groups with consideration of congestion. The performance of facilities was evaluated by using macroscopic parameters estimated from calibrated traffic flow models. Speed analyses showed similarities and differences between the behaviors of pedestrian groups. Exploring traffic flow characteristics of a heterogeneous pedestrian stream in various walking facilities may improve the planning and design of such facilities.

Analysis of Walking Speeds Involving Individuals with Disabilities in Different Indoor Walking Environments

AbstractWalking facilities are important infrastructures in communities. These facilities should be designed to accommodate the needs of all types of pedestrians. Unfortunately, existing design guidelines fail to offer adequate consideration for individuals with disabilities owing to a lack of empirical data. To address this knowledge gap, a controlled large-scale research project was conducted at Utah State University (USU) to study the walking behavior of people with various types of disabilities in various indoor walking facilities. These facilities included a passageway, different types of angles (right and oblique), bottleneck, and stairwells. The purpose of this paper is twofold: to examine the impacts of individuals with disabilities on crowd walking speed, and to study the impacts of different indoor walking facilities on the movements of various pedestrian groups. Results show that the presence of individuals with disabilities in a crowd significantly reduces the overall crowd speed. Statistical ...

Time Headway Modeling and Capacity Analysis of Pedestrian Facilities Involving Individuals with Disabilities

Walking infrastructure should be designed to be effective for the needs of all pedestrian groups. Unfortunately, individuals with disabilities are often ignored in pedestrian facility analysis and design because of the lack of data on their walking behavior. A large-scale controlled walking experiment involving individuals with disabilities was conducted at Utah State University to observe individual pedestrian walking behavior on various walking facilities, including a passageway and a bottleneck. The purpose of this study was twofold: to model the time headway between individual types by using a mixed distribution model and to estimate passageway and bottleneck capacities and identify the impact of involving individuals with disabilities on capacity estimation. Analysis revealed that visually impaired individuals and individuals using nonmotorized wheelchairs and walkers caused the minimum capacity reduction on passageways and bottlenecks, whereas individuals using motorized wheelchairs caused the maximum capacity reduction in these areas. The findings are expected to improve the estimation of the facility capacity required to meet a preferred level of service for heterogeneous populations.

Link-Based Stochastic Loading Methods for Weibit Route Choice Model

The multinomial logit route choice model is known to have some drawbacks in traffic loading because of the independently and identically distributed assumption with the Gumbel distributed random error term. This assumption results in the models inability to handle the route overlapping and heterogeneous perception variance problems. This study proposed a new traffic loading technique for handling both route overlapping and heterogeneous perception variance problems. Specifically, a modified Dials STOCH algorithm and a link-based commonality factor were combined with the weibit route choice model to create the link-based C-weibit stochastic loading method. Numerical examples show the features of this stochastic loading method. The Chicago, Illinois, sketch network was used to demonstrate the applicability of the C-weibit stochastic loading method in a real transportation network.

Modeling Different Groups of Pedestrians With Physical Disability, Using the Social Force Model and Fractional Order Potential Fields

Modeling individuals with physical disabilities in a crowd has previously been in the form of a pure adjustment to velocity representing an entire group. However, current research involving individuals with various types of disability has shown interactions are far more complex and varying. These types comprised of mechanical and electric wheelchair, vision impaired, and various other mobility-related disabilities. Preliminary results have shown that each group varies not only in velocity, but also in composition of their environment. Further results show other differences in interaction within a crowd. This paper provides for some preliminary differences found in the study of individuals with disabilities within a crowd and how those differences change pedestrian interaction. Using the nature of Fractional Order Potential Fields (FOPF), this paper will provide some results for how pedestrian interaction can be adjusted to fit the varying differences found within each disability group.Copyright

Exit Choice Behavior of Pedestrians Involving Individuals with Disabilities During Building Evacuations

Pedestrian evacuation studies are critical in obtaining information about evacuation scenarios and in preparing to face the challenges of actual evacuations. Studies have examined evacuation policies, exit choice modeling, and evacuation curve analysis. Some studies have addressed the evacuation behavior of individuals with disabilities (IWDs), although this important aspect of evacuation seems to be missing from modeling of the exit choice in many studies. In modeling of the exit choice for evacuation, many studies have been found to be based on the stated preference survey method, where evacuees are asked to choose an exit based on descriptions, without an actual experiment taking place. This study focuses on the discrete choice model of the exit choice in the room for both IWDs and individuals without disabilities (IWODs). The results demonstrate that the presence of IWDs in the group plays a crucial role in the exit choice for all evacuees. The results demonstrate that there are significant differences in exit choice between IWDs and IWODs. Current evacuation policies have been found to be more focused on visual signs, while this study demonstrates that these visual signs are of little importance to individuals with visual disabilities.