Dynamic ride-sharing systems enable people to share rides and increase the efficiency of urban transportation by connecting riders drivers on short notice. Automated that establish ride-share matches with minimal input from participants provide convenience most potential for system-wide performance improvement, such as reduction in total vehicle-miles traveled. Indeed, may be designed match maximize system improvement. However, system-optimal not maximum benefit each individual participant....

Smartphone technology enables dynamic ride-sharing systems that bring together people with similar itineraries and time schedules to share rides on short-notice. This paper considers the problem of matching drivers riders in this setting. We develop optimization-based approaches aim at minimizing total system-wide vehicle miles incurred by system users, their individual travel costs. To assess merits our methods we present a simulation study based 2008 demand data from metropolitan Atlanta....

We develop a robust optimization framework for dynamic empty repositioning problems modeled using time-space networks. In such problems, uncertainty arises primarily from forecasts of future supplies and demands assets at different time epochs. The proposed approach models intervals about nominal forecast values limit on the systemwide scaled deviation values. A plan is defined as one in which typical flow balance constraints bounds are satisfied values, recoverable under limited set...

We study same-day delivery systems by formulating the dynamic dispatch waves problem (DDWP), which models a depot where requests arrive dynamically throughout service day. At any epoch (wave), information available to decision maker is (1) set of known, open that remain unfulfilled, and (2) potential may later in each wave, decides whether or not vehicle, if so, subset serve, with objective minimizing expected vehicle operating costs penalties for unserved requests. consider DDWP single...

We study the linked tactical design problems of fleet sizing and partitioning a service region into vehicle routing zones for same-day delivery (SDD) systems. Existing SDD studies focus primarily on operational dispatch do not consider system questions. Prior work has considered decision when may be partitioned dedicated to individual vehicles; such designs have been shown improve efficiency in related settings. Using continuous approximations capture average-case behavior, we first problem...

This paper presents a paired-vehicle recourse strategy for the vehicle routing problem with stochastic demands (VRPSD). In VRPSD, fleet of homogeneous capacitated vehicles is dispatched from terminal to serve single-period customer demands, which are known in distribution when planning, but only revealed certainty upon arrival. While most existing research this focuses on strategies where each operates independently, alternatively considers may be coordinated pairs. A tabu search heuristic...

Time considerations have been largely ignored in the study of vehicle routing problems with stochastic demands, even though they are crucial practice. We show that tour duration limits can effectively and efficiently be incorporated solution approaches build fixed, or a priori, tours for such problems. do so by assuming each must feasible all demand realizations, determine maximum given delivery solving optimization problem an adversary. A computational demonstrates approach, shows enforcing...

We present integer programming models of the service network design problem faced by less-than-truckload (LTL) freight transportation carriers and a solution approach for large-scale instances that result in practical applications. To accurately represent consolidation opportunities, use fine discretization time. Furthermore, simultaneously route empty trailers thus explicitly recognize efficiencies presented backhaul lanes. The can generate traditional designs commonly used LTL but also...

Abstract This paper defines the Home Health Nurse Routing and Scheduling (HHNRS) problem presents a rolling horizon approach for its solution. The HHNRS is dynamic periodic fixed appointment time routing with visit consistency constraints. A set of patients, revealed dynamically, must be visited according to prescribed weekly frequency over number weeks, where each assigned precise chosen from menu allowable appointments. Furthermore, visits repeat on same days times throughout patient's...

Ports-of-entry are critical components of the modern international supply chain infrastructure, particularly container seaports and airfreight hubs. The potential operational economic impact resulting from their temporary closure is unknown but widely believed to be very significant. This paper investigates one aspect this impact, focusing specifically on use inventory as a risk mitigation strategy for supplier, customer system in which goods transported through port-of-entry subject...

We study tactical models for the design of same-day delivery (SDD) systems. Same-day fulfillment in e-commerce has seen substantial growth recent years, and underlying management such services is complex. Although literature includes operational to SDD, they tend be detailed, complex, computationally difficult solve, thus may not provide any insight into SDD variables their impact on average performance system. propose a simplified vehicle-dispatching model that captures “average” behavior...

With the recent boom of gig economy, urban delivery systems have experienced substantial demand growth. In such systems, orders are delivered to customers from local distribution points respecting a time promise. An important example is restaurant meal system, where times expected be minutes after an order placed. The system serves by making use couriers that continuously perform pickups and deliveries. Operating rapid very challenging, primarily because high service expectations...