Testing demand responsive shared transport services via agent-based simulations

Demand Responsive Shared Transport DRST services take advantage of Information and Communication Technologies ICT, to provide on demand transport services booking in real time a ride on a shared vehicle. In this paper, an agent-based model ABM is presented to test different the feasibility of different service configurations in a real context. First results show the impact of route choice strategy on the system performance

The importance of information flows temporal attributes for the efficient scheduling of dynamic demand responsive transport services

The operation of a demand responsive transport service usually involves the management of dynamic requests. The underlying algorithms are mainly adaptations of procedures carefully designed to solve static versions of the problem, in which all the requests are known in advance. However there is no guarantee that the effectiveness of an algorithm stays unchanged when it is manipulated to work in a dynamic environment. On the other hand, the way the input is revealed to the algorithm has a decisive role on the schedule quality. We analyze three characteristics of the information flow (percentage of real-time requests, interval between call-in and requested pickup time and length of the computational cycle time), assessing their influence on the effectiveness of the scheduling proces

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

Usage Analysis of Milwaukee County\u27s Paratransit System: the Case of Potawatomi Casino and Veteran Affairs Medical Center Destinations

In order to protect the rights of seniors and Persons with Disabilities (PWDs), the United States government, through Congress, enacted the Americans with Disabilities Act (ADA) in 1990. The Act ensures that there is equity for persons with disabilities in all aspects of public services including employment, education, transportation, accommodation, commercial facilities and businesses and communication (Federal Register, 2010). In this study, we focus on the problem of transportation of PWDs, specifically in Milwaukee County in Southeast Wisconsin. The study was initiated as a collaborative effort between UWM’s Industrial and Manufacturing Engineering team, UWM’s Director of the Rehabilitation Research Design & Disability (R2D2) Center, Milwaukee County Office of Persons with Disabilities team and the MCTS-Paratransit Department Team. MCTS wanted to explore effect that increased ADA bus ridership would have on the paratransit system performance such as bus utilization by PWDs, PWD average waiting time as well as the average time in system. Since the MCTS network is large, the team determined to pilot the study on the most used routes by PWDs in Milwaukee County that serve the two most visited destinations, namely, the Potawatomi Hotel & Casino and Milwaukee Veterans Affairs Medical Center. We formulated three study objectives to achieve this broad goal. First, we sought to understand the current status of ridership for R14 which serves the Casino, and R23 and RBlue both of which serve the V.A. Medical Center. We used both observational data to determine destination accessibility. In this study, destination accessibility is defined as the ease with which PWDs can access the location from the bus stop. Therefore, we made travel observations to both destinations in the winter, thereby considering the worst case scenario in the winter season. In addition, ridership by bus was compared to the ADA paratransit system, which is offered through MCTS’s Transit Plus Program. Observations results indicated that while the V.A. medical center was accessible, the Casino was not accessible to PWDs. Lack of accessibility was determined to be predominantly due to poor bus stop design as well as the distance from the bus stop to the Casino entrance. In addition, ridership results indicated that paratransit ridership outweigh ADA ridership on the fixed bus route service by a ratio of 3 to 1. Ridership to the V.A. on the fixed bus route system is twice the bus ridership to the Casino. Though the reasons to access these two destinations are distinctively different—medical care versus entertainment, we observed that the unfriendly environment in the Casino bus stop might the largest contributor to the low ridership on route R14. The study results also found that while fixed bus route ridership significantly changes by seasons, this effect was not significant for ridership on the ADA paratransit service. The second objective sought to simulate the current fixed bus ADA usage. This was done to create a baseline on which potential changes to the system could be incorporated and their effects determined. In the third objective we make a potential alteration to the system, where a few potential riders who use the ADA paratransit through Transit Plus are switched to use the fixed bus route. In this study, PWDs who use the ADA paratransit are deemed potential for fixed bus route if they geographically reside less than 0.5 miles away from the route bus stop. Therefore, two simulation models, I and II were developed and implemented. The first model simulated the current annual ridership of R14 to the casino. Due to study time constraints, only ridership to the Casino was simulated. The results of Model I indicated that the annual average ridership was about 7 per day. The 95% confidence interval of the passenger waiting time was [10.22, 13.09] minutes, which was evidently in the summer. Winter average waiting time confidence interval turned out to be [8.96, 12.96]. On the other hand, since all buses can only accommodate at most two PWDs on wheel chair or scooter, we were interested to know if this constraint increased the waiting time for PWDs using these mobility devices. The results showed that the 95% confidence interval of the average waiting time for PWDs using wheel chairs was at most (summer) [10.58, 13.22]. Simulation model II, an extension of model I incorporated potential PDW riders who currently use ADA paratransit into the fixed bus route in model I. The simulation process involved a combination of three software—Batch Geo, ArcGIS as well as ProModel. The results indicated very little effect of additional riders on the waiting time. For instance, the 95% confidence interval of the average waiting time for non-wheelchair users was [9.88, 14.15] minutes, while the interval waiting time for wheelchair riders was [9.44, 13.20]. In the other hand, the 95% confidence interval for the average time in system for all passengers (with or without a wheel chair) was estimated as 29.87 to 38.34 minutes. Finally, the bus utilization by PWDs in this study was measured as the percentage of the number of bus runs in the simulation carrying at least one PWD to the total bus runs. The average utilization was found to be 6.5%. This percentage is an indicator of that MCST has potential to increase fixed bus route ridership by persons with disabilities, especially if challenging issues such as low bus frequency, less geographical coverage of the bus network (to cover areas where most Casino ADA visitors reside), public transport awareness, bus driver training and most of all, increased accessibility of the Casino destination

Transport poverty meets the digital divide : accessibility and connectivity in rural communities

Peer reviewedPublisher PD

Predictive positioning and quality of service ridesharing for campus mobility on demand systems

Autonomous Mobility On Demand (MOD) systems can utilize fleet management strategies in order to provide a high customer quality of service (QoS). Previous works on autonomous MOD systems have developed methods for rebalancing single capacity vehicles, where QoS is maintained through large fleet sizing. This work focuses on MOD systems utilizing a small number of vehicles, such as those found on a campus, where additional vehicles cannot be introduced as demand for rides increases. A predictive positioning method is presented for improving customer QoS by identifying key locations to position the fleet in order to minimize expected customer wait time. Ridesharing is introduced as a means for improving customer QoS as arrival rates increase. However, with ridesharing perceived QoS is dependent on an often unknown customer preference. To address this challenge, a customer ratings model, which learns customer preference from a 5-star rating, is developed and incorporated directly into a ridesharing algorithm. The predictive positioning and ridesharing methods are applied to simulation of a real-world campus MOD system. A combined predictive positioning and ridesharing approach is shown to reduce customer service times by up to 29%. and the customer ratings model is shown to provide the best overall MOD fleet management performance over a range of customer preferences.Ford Motor CompanyFord-MIT Allianc

A Multistage Stochastic Programming Approach to the Dynamic and Stochastic VRPTW - Extended version

We consider a dynamic vehicle routing problem with time windows and stochastic customers (DS-VRPTW), such that customers may request for services as vehicles have already started their tours. To solve this problem, the goal is to provide a decision rule for choosing, at each time step, the next action to perform in light of known requests and probabilistic knowledge on requests likelihood. We introduce a new decision rule, called Global Stochastic Assessment (GSA) rule for the DS-VRPTW, and we compare it with existing decision rules, such as MSA. In particular, we show that GSA fully integrates nonanticipativity constraints so that it leads to better decisions in our stochastic context. We describe a new heuristic approach for efficiently approximating our GSA rule. We introduce a new waiting strategy. Experiments on dynamic and stochastic benchmarks, which include instances of different degrees of dynamism, show that not only our approach is competitive with state-of-the-art methods, but also enables to compute meaningful offline solutions to fully dynamic problems where absolutely no a priori customer request is provided.Comment: Extended version of the same-name study submitted for publication in conference CPAIOR201

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