Branch-and-price for the pickup and delivery problem with time windows and scheduled lines

The Pickup and Delivery Problem with Time Windows and Scheduled Lines (PDPTW-SL) consists of routing and scheduling a set of vehicles, by integrating them with scheduled public transportation lines, to serve a set of freight requests within their time windows. This paper presents an exact solution approach based on a branch-and-price algorithm. A path-based set partitioning formulation is used as the master problem, and a variant of the elementary shortest path problem with resource constraints is solved as the pricing problem. In addition, the proposed algorithm can also be used to solve the PDPTW with transfers (PDPTW-T) as a special case. Results of extensive computational experiments confirm the efficiency of the algorithm: it is able to solve small- and medium-size instances to optimality within reasonable execution time. More specifically, our algorithm solves the PDPTW-SL with up to 50 requests and the PDPTW-T with up to 40 requests on the considered instances

NETWORK DESIGN FOR THE TEMPORAL AND SPATIAL COLLABORATION WITH SERVICE CLASS IN DELIVERY SERVICES

The COVID-19 pandemic has significantly impacted e-commerce and the delivery service sector. As lockdowns and social distancing measures were put in place to slow the spread of the virus, many brick-and-mortar stores were forced to close, leading to an increase in online shopping. This situation led to a surge in demand for delivery services as more people turned to the internet to purchase goods. However, this increase in demand also created several challenges for delivery companies. They experienced delays in delivering packages due to increased volume, limited staff, and disruptions to supply chains. It led to more competition and increased pressure on delivery companies to improve their services and delivery times. To overcome such competition, collaboration among small and medium-sized delivery companies can be a good way to compete with larger delivery companies. By working together, small and medium-sized companies can combine their resources and expertise to offer more extensive coverage and competitive prices than they could individually. This can help them to gain market share and expand their customer base. This study proposes a network design model for collaboration with service class in delivery services considering multi-time horizon. The problem to be considered is deciding which company is dedicated to delivering certain types of items, such as regular or refrigerated items, in designated regions in each time horizon. During the agreed-upon timeframe, the companies operate, using each other's infrastructure (such as vehicles and facilities) and sharing delivery centers for the coalition's benefit to improve efficiency and reduce costs. We also propose a multi-objective, nonlinear programming model that maximizes the incremental profit of participating companies and a linearization methodology to solve it. The max-sum criterion and Shapley value allocation methods are applied to find the best solution and ensure a fair distribution of profits among the collaborating group. The efficiency of the suggested model is shown through a numerical illustration

Environmental and energy performance of integrated passenger–freight transport

The first-last mile (FLM) transport of passengers and freight accounts for a significant share of total transport costs, pollution, and energy consumption. According to recent scientific literature and institutional inputs at the European level, operational innovations such as the combination of passenger and freight flows may be an effective approach for promoting sustainable and energy-efficient FLM transport. In this study, the energy and environmental performances of an integrated passenger and freight transport system based on the bus network of Zrenjanin (Serbia) were investigated with different future energy mix and transport policy scenarios. The operational aspects of the integrated system were designed through collaboration with territorial stakeholders and an analysis of local planning documents. The performance was evaluated and compared with current public transport and freight schemes considering vehicle fuel and technology, total mileage, and other relevant endogenous and exogenous factors. The results of our analysis indicate operational benefits and energy savings, mainly due to reduced total mileage and the predisposition to shift to the active modes for the last mile. However, most expected long-term energy savings are the result of technological development of vehicles and modal shifts induced by policy strategies

The model of goods delivery using multi depot vehicle routing problem at PT X

Vehicle Routing Problem (VRP) is a problem in shipping that focuses on distributing goods from a depot to customers. There are several developments from VRP, one of which is the Multi Depot Vehicle Routing Problem (MDVRP). The MDVRP model has the same goal as the VRP, which is to minimize travel costs. The difference between VRP and MDVRP depends on the depot used. In VRP, only one depot is used. Whereas in MDVRP, there is more than one depot used. This research discussed the delivery of goods to two depots. The aim of this research is to form a model for shipping goods using two depots, determine the total travel cost, and determine the optimal route to delivery of the goods. The data used in this research is secondary data. The result of this research is that the model for the MDVRP aims to minimize the total travel cost by using two depots and serving 10 customer locations. The total cost of the trip is IDR 390,000, with a total distance traveled as far as 300 km, and the optimal routes for delivering goods involve each depot making two trips. The first depot covers distances of 57 km and 48 km, and the second depot covers distances of 92 km and 103 km

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

A new approach to speed optimization of empty platform wagons in the Southeast region of Brazil / Uma nova abordagem para a otimização de velocidade de vagões de plataforma vazios na região Sudeste Do Brasil

Matching the demand for rail freight transportation depends on the railroad network structure and the availability of the rolling stock, locomotives and wagons. The distribution of wagons optimization helps reduce transportation costs, and the efficient allocation of assets is essential for rail competitiveness with other means of transportation. The present study aims to develop a mathematical model for optimizing the allocation of wagons and minimizing the distribution cost, adopted as empty transit time. The model also calculates the empty transit time of wagons according to demand distribution, and reduces the necessity for rail freight assets, because it also minimizes the wagon cycle. An algorithm was developed from the characteristics related to the distribution of freight wagons, using planned cycles adjusted by the demand distribution, and mathematical modeling was performed, applying integer linear programming to minimize the empty wagon transit time in a railway company. As a result, a weighted and optimized cycle was obtained to perform the sizing of wagons and meet the transportation plan, as well as minimizing the transit time between unloading and loading of goods. The new model presents a contribution to the operation, because, in addition to directing the optimal distribution of the assets using an integer linear programming algorithm, it also allows the planned wagon cycle adequacy, according to the demand of the respective period