Feasibility algorithms for two pickup and delivery problems with transfers

International audienceThis presentation follows the PhD thesis of Renaud Masson [1] on the Pickup and Delivery Problem with Transfers (PDPT). The motivating application is a dial-a-ride problem in which a passenger may be transferred from the vehicle that picked him/her up to another vehicle at some predetermined location, called transfer point. Both the PDPT and the Dial-A-Ride Problem with Transfers (DARPT) were investigated. An adaptive large neighborhood search has been developed to solve the PDPT [2] and also adapted to the DARPT [3]. In both algorithms, multiple insertions of requests in routes are tested. E ciently evaluating their feasibility with respect to the temporal constraints of the problem is a key issue

Transfers in the on-demand transportation: the DARPT Dial-a-Ride Problem with transfers allowed

International audienceToday, the on-demand transportation is used for elderly and disabled people for short distances. Each user provides a specific demand: a particular ride from an origin to a destination with hard time constraints like time windows, maximum user ride time, maximum route duration limits and precedence. This paper deals with the resolution of these problems (Dial-a-Ride Problems - DARP), including the possibility of one transshipment from a transfer point by request. We propose an algorithm based on insertion techniques and constraints propagation

A dynamic ridesharing dispatch and idle vehicle repositioning strategy with integrated transit transfers

We propose a ridesharing strategy with integrated transit in which a private on-demand mobility service operator may drop off a passenger directly door-to-door, commit to dropping them at a transit station or picking up from a transit station, or to both pickup and drop off at two different stations with different vehicles. We study the effectiveness of online solution algorithms for this proposed strategy. Queueing-theoretic vehicle dispatch and idle vehicle relocation algorithms are customized for the problem. Several experiments are conducted first with a synthetic instance to design and test the effectiveness of this integrated solution method, the influence of different model parameters, and measure the benefit of such cooperation. Results suggest that rideshare vehicle travel time can drop by 40-60% consistently while passenger journey times can be reduced by 50-60% when demand is high. A case study of Long Island commuters to New York City (NYC) suggests having the proposed operating strategy can substantially cut user journey times and operating costs by up to 54% and 60% each for a range of 10-30 taxis initiated per zone. This result shows that there are settings where such service is highly warranted

Workload Equity in Vehicle Routing Problems: A Survey and Analysis

Over the past two decades, equity aspects have been considered in a growing number of models and methods for vehicle routing problems (VRPs). Equity concerns most often relate to fairly allocating workloads and to balancing the utilization of resources, and many practical applications have been reported in the literature. However, there has been only limited discussion about how workload equity should be modeled in VRPs, and various measures for optimizing such objectives have been proposed and implemented without a critical evaluation of their respective merits and consequences. This article addresses this gap with an analysis of classical and alternative equity functions for biobjective VRP models. In our survey, we review and categorize the existing literature on equitable VRPs. In the analysis, we identify a set of axiomatic properties that an ideal equity measure should satisfy, collect six common measures, and point out important connections between their properties and those of the resulting Pareto-optimal solutions. To gauge the extent of these implications, we also conduct a numerical study on small biobjective VRP instances solvable to optimality. Our study reveals two undesirable consequences when optimizing equity with nonmonotonic functions: Pareto-optimal solutions can consist of non-TSP-optimal tours, and even if all tours are TSP optimal, Pareto-optimal solutions can be workload inconsistent, i.e. composed of tours whose workloads are all equal to or longer than those of other Pareto-optimal solutions. We show that the extent of these phenomena should not be underestimated. The results of our biobjective analysis are valid also for weighted sum, constraint-based, or single-objective models. Based on this analysis, we conclude that monotonic equity functions are more appropriate for certain types of VRP models, and suggest promising avenues for further research.Comment: Accepted Manuscrip

Transportation network companies as cost reduction strategies for paratransit

Paratransit service is an auxiliary type of public transportation provided for people with disabilities and older adults. Federal ADA regulations require all transit agencies receiving federal funding to provide paratransit service, but the per trip cost to transit operators is extremely expensive. Many transit agencies are looking for ways to reduce costs without limiting services. For many agencies, this results in providing the minimum services as required by ADA regulations. However, Boston’s Massachusetts Bay Transit Authority (MBTA) has taken a different approach to cost reduction by entering into one of the first partnerships with transportation network companies. In September 2016, MBTA’s paratransit service, The Ride, began a partnership with both Uber and Lyft as a cost reduction strategy for paratransit provision. Since the beginning of the partnership, MBTA has been able to reduce costs of providing paratransit while maintaining the same level of service. This report will examine the benefits and limitations of such partnerships between transit agencies and transportation network companies, using MBTA’s The Ride partnership as an example for potentially successful partnerships throughout the United States.Community and Regional Plannin

The Travel Behavior and Needs of the Poor: A Study of Welfare Recipients in Fresno County, California, MTI Report 01-23

The passage of the Personal Responsibility and Work Opportunity Reconciliation Act of 1996 fundamentally transformed the provision of social assistance in the United States. Gone is Aid to Families with Dependent Children (AFDC), a program that entitled needy families with children to an array of benefits and public services. In its place is Temporary Assistance to Needy Families (TANF), a program that abolishes federal entitlements, provides flexible block grants to the states, mandates tough new work requirements, and imposes a five-year lifetime limit on the receipt of public assistance. Current welfare programs mandate employment for most recipients and offer temporary financial aid and short-term employment assistance to help recipients transition into the labor market. As a result of this fundamental restructuring of the U.S. welfare system, millions of welfare recipients are required to enter the paid labor market. Public agencies must establish programs to transition recipients into the labor market or risk dramatic increases in poverty rates. A growing number of studies suggest that reliable transportation-whether automobiles or public transit-is essential to linking welfare participants to employment opportunities. The purpose of this study is to: Understand the travel behavior of welfare participants; Examine strategies by which welfare participants overcome their transportation barriers; Identify the transportation needs of welfare participants living in the Central Valley; Examine the relationship between access to reliable transportation and employment status; and Develop a set of policy and planning recommendations to improve the transportation options of welfare recipients and other low-wage workers living in smaller, more rural, metropolitan areas

Analyzing the Effects of Transit Network Change on Agency Performance and Riders in a Decentralized, Small-to-Mid-sized US Metropolitan Area: A Case Study of Tallahassee, Florida, MTI Report 12-04

On July 11, 2011, StarMetro, the local public transit agency in Tallahassee, Florida, restructured its entire bus network from a downtown-focused radial system to a decentralized, grid-like system that local officials and agency leaders believed would better serve the dispersed local pattern of population and employment. The new, decentralized network is based on radial routes serving the major arterial roads and new crosstown routes linking the outer parts of the city, where population and employment is growing. Local officials and agency staff hoped the change would increase transit’s attractiveness and usefulness to the community. One year after the service restructuring, overall performance results are similar to those experienced in other cities that have implemented major service changes. Overall ridership and productivity are lower than before the service restructuring, due to the short time frame for rider adjustments and longer-than-anticipated headways, but new ridership has appeared in previously un-served or under-served corridors and neighborhoods. The service restructuring resulted in longer walks to bus stops, due to the removal of stops from many neighborhoods and their relocation to major roads, but overall transit travel times are shorter due to more direct routing. No particular neighborhoods or community groups disproportionately benefited from or were harmed by the change. The service restructuring was supported by some segments of the community who viewed the older system as ill-suited to the increasingly decentralized community, while it was opposed by other community stakeholders who worried about the loss of service in some neighborhoods and issues of access and safety, particularly affecting elderly and disabled riders, at new stop locations. StarMetro’s extensive public outreach efforts and ongoing service adjustments have reduced the intensity of the opposition to the service restructuring over time, although some segments of the community continue to voice their concerns about the effects of the change on transit-dependent, disabled, and elderly riders