The annual Hajj presents diversified negative experiences to millions of pilgrims worldwide. The negative experiences and recommendations to overcome them as per pilgrims' feedback are yet to be analyzed from an aggregated perspective in the literature, which we do in this paper. To do so, first, we perform a large-scale survey (n=988) using our comprehensive questionnaire. Then, we perform both quantitative (e.g., clustering) and qualitative (e.g., thematic) analyses on the survey data. Our quantitative analysis reveals up to seven clusters of negative experiences. Further, going beyond the quantitative analysis, our qualitative analysis reveals 21 types of negative experiences, 20 types of recommendations, and nine themes connecting the negative experiences and recommendations. Accordingly, we reveal associations among the negative experiences and recommendations based on the themes in thematic analysis and present the associations through a tripartite graph. However, we have some limitations in this study, such as fewer female and young participants. In future, we plan to collect more responses from female and young participants and extend our work by analyzing linkages in the tripartite graph by augmenting the edges within the graph with appropriate weights. Overall, the findings of this study are expected to facilitate the prioritization of tasks for the management personnel in charge of the Hajj pilgrimage.

Mass gatherings (such as Hajj/Umrah), owing to their immensity, often present a variety of difficulties to the attendees. To have a comprehensive understanding of the difficulties as well as their potential remedies, surveying a good number of attendees is unavoidable and this can be facilitated through engaging data collectors. A crucial part here is identifying the integrity of the data collectors, which is yet to be explored in the literature to the best of our knowledge. To address this gap, in this study, we first perform a mass-scale data collection over Hajj/Umrah pilgrims through online (n = 236) and in-person (n = 752) surveys, where we cover a substantial part (n = 712) through paid data collectors (n = 53). We critically investigate data collection activities of the data collectors through focused group discussions involving expert reviewers. We explore two computing techniques to unveil the integrity of the data collectors from two different perspectives. Our study finds out influential (religious and socio-geographical) aspects that impact the data collection process. Besides, we find that the collaborative participation of expert reviewers is obligatory to scrutinize the data collectors' integrity. Additionally, our explored computing techniques, namely conflict analysis and learning-based analysis, can identify up to 74% and 99% of the unreliable data collectors respectively. We observe that, although these computing-based filtering can indicate the integrity up to a certain level, human-in-the-loop is unavoidable for concluding on the integrity. To the best of our knowledge, this is the first study of its kind (i.e., integrity analysis of the data collectors) in the literature.

Even though traffic signal scheduling is one of the fundamental problems addressed in Intelligent Transportation Systems, most of the related existing studies solved this problem in the contexts of lane-based and homogeneous traffic. These studies ignored various distinctive contexts prevalent in developing countries, such as non-lane-based (i.e., designated lanes are not followed) and heterogeneous (i.e., motorized and non-motorized) traffic. Therefore, in this study, we propose a new methodology incorporating chronological implementations of multi-objective optimization and appropriate simulations to develop an efficient traffic signal scheduling system appropriate for non-lane-based and heterogeneous traffic. First, we explore NSGA-II: Non-dominated Sorting Genetic Algorithm with binary and real encoding-based populations.We propose two novel objective functions considering the non-lane-based heterogeneous nature of traffic. Among the two encoding-based implementations, we find that real-encoded NSGA-II performs the best in providing an optimal traffic signal schedule on a numerical simulator. Further, we integrate the real-encoded NSGA-II in DhakaSim, which is a microscopic traffic simulator that realizes distinctive contexts of developing countries. Afterward, we conduct extensive simulations over three road networks from Dhaka, Miami, and Riyadh. Our simulation results show that the proposed method can lead to a 163.1% increase in average speed and a 56.1% reduction in average waiting time across Dhaka city’s road network during peak traffic hours, compared to traditional fixed-time signal scheduling currently used in some parts of the city. Besides, our proposed methodology confirms improved average speed and average waiting time over the road networks of Miami and Riyadh, underscoring the approach’s generalizability. These results highlight the effectiveness of the proposed multi-objective signal optimization framework for non-lane-based heterogeneous traffic and its potential to improve urban traffic flow in diverse, congested settings significantly.

Even though the traffic systems in developed countries have been analyzed rigorously and operated efficiently, the same does not generally hold for developing countries due to inadequate planning, design, and operations of their transportation systems. Because of inherent differences between internal infrastructures, the strategies deployed in developed countries may not be amenable to developing ones. Besides, developing countries’ traffic systems are not well-studied in the literature to the best of our knowledge. For example, it is yet to explore how a developed country’s lane-based traffic flow would perform in the context of a developing country, which generally experiences non-lane-based traffic. As such, by using our newly developed traffic simulator ‘RoadBird’, we investigate outcomes of both lane-based and non-lane-based traffic from the contexts of both developing and developed countries. To do so, we run simulations over real road topologies (extracted from the GIS maps of major cities such as Dhaka, Miami, and Riyadh), considering different scenarios such as lane-based or non-lane-based flows, homogeneous or heterogeneous traffic, with or without pedestrians, etc. We also incorporate various car-following and lane-changing models to mimic traffic behaviors and investigate their performances. While the lane changing dilemma remains an open research question, our experimental evidence indicates: 1) lane-based approaches will not necessarily perform better in the case of currently-adopted non-lane-based scenarios, and 2) non-lane-based strategies may benefit system performance in lane-based scenarios while having heavy mixed traffic. Nonetheless, we reveal several new insights for on-road experiences both in developing and developed countries.