reliability analysis of centralized versus decentralized zoning strategies for paratransit services

Abstract ADA paratransit services are a very large and ever-growing industry providing door-to-door transportation services for people with disability and elderly customers. Paratransit system, however, just like all other public transportation systems, suffers from travel time variability due to various factors and as a result gives its customers unreliable services. Although service reliability is a very important aspect in transportation study, it has not received much attention in the paratransit research community. A quantitative study evaluating the paratransit service reliability under different zoning strategies is yet to be found. This research filled this gap. Statistical models were proposed to represent travel time variability. Simulation experiments based on real demand data from Houston, Los Angeles and Boston were performed to quantitatively compare the reliability performance of centralized and decentralized operating strategies under different travel time variability levels. Results showed that the decentralized strategy, compared to the centralized no-zoning strategy, substantially improves the reliability of paratransit in terms of on-time performance. This research provides a framework for paratransit agencies to evaluate the service reliability of different organizational strategies through the simulation method

Ridepooling and public bus services: A comparative case-study

This case-study aims at a comparison of the service quality of time-tabled buses as compared to on-demand ridepooling cabs in the late evening hours in the city of Wuppertal, Germany. To evaluate the service quality of ridepooling as compared to bus services, and to simulate bus rides during the evening hours, transport requests are generated using a predictive simulation. To this end, a framework in the programming language R is created, which automatically combines generalized linear models for count regression to model the demand at each bus stop. Furthermore, we use classification models for the prediction of trip destinations. To solve the resulting dynamic dial-a-ride problem, a rolling-horizon algorithm based on the iterative solution of Mixed-Integer Linear Programming Models (MILP) is used. A feasible-path heuristic is used to enhance the performance of the algorithm in presence of high request densities. This allows an estimation of the number of cabs needed depending on the weekday to realize the same or a better general service quality as the bus system

Overcoming Healthcare Transportation Barriers: A Case Study

Transportation remains a major barrier in receiving cancer treatment in Canada. The situation is especially alarming for those living in rural areas and in the light of COVID pandemic, poses another risk in the long list of health challenges to patients with pre-existing conditions. In this dissertation we set out find a solution to this problem by providing a framework for a personalized healthcare transportation system tailored to the needs of this population. A three-step approach is proposed. First, a review of literature and initiatives employed by global transportation providers is conducted to identify major methods used for healthcare industry. Second, a transportation strategy is proposed, and key performance indicators identified through analysis of data and interviews with industry best practices in order to determine key aspects of such operations having the most impact on the overall service level. Finally, a discrete event simulation is provided and tested through various scenarios to understand how such operations would behave in real life and how they react as the environment evolves through time. A case study of a major nonprofit organization for whom this strategy was originally outlined is provided for further context. In the end, the key findings from this research are formulated as a decision-making tool for future guidelines in managing similar operations. Keywords: Transportation; Strategy; Simulation; Healthcare; Ride Sharing; Breast Cance

Evaluating the performance of a dial-a-ride service using simulation

In this paper we study the effects of changes to a paratransit system operated as a dynamic dial-a-ride service. The scheduling of requests is limited by time window constraints and maximum ride time constraints; costs for customer discomfort in form of waiting time and excess ride time are considered in the planning of the service. The parameters defining these constraints and costs are evaluated based on simulations of a real-world scenario. Several different criteria, both regarding customer level of service and operational costs, are used to evaluate the simulation results. By showing which parameters have a large impact on the different evaluation criteria, we can give guidelines to operators of public transport of how to design their dial-a-ride services. Numerical results are presented and from these results conclusions are drawn regarding which parameters are most important in dynamic dial-a-ride services