•We introduce the Shared Customer Collaboration Vehicle Routing Problem.•There are potential savings when carriers collaborate to serve shared customers.•Two alternative formulations are proposed and ...analyzed.•Extensive computational experiments are provided.•We quantify the potential benefits compared to the case when no collaboration exists.
This paper introduces a new vehicle routing problem that arises in an urban area where several carriers operate and some of their customers have demand of service for more than one carrier. The problem, called Shared Customer Collaboration Vehicle Routing Problem, aims at reducing the overall operational cost in a collaboration framework among the carriers for the service of the shared customers. Alternative mathematical programming formulations are proposed for the problem that are solved with a branch-and-cut algorithm. Computational experiments on different sets of benchmark instances are run to assess the effectiveness of the formulations. Moreover, in order to estimate the savings coming from the collaboration, the optimal solutions are compared with the solutions obtained when carriers work independently from each other.
•A minimal retailer density is needed to achieve positive cost savings.•There is a domain of retailer densities that never produce savings regardless site-parameters.•Emission savings is the most ...restrictive condition to satisfy.•The current monetary values of pollutants make the emission savings negligible.•Consolidation strategies alleviate the negative impact of access restriction policies on carriers.
This paper presents the necessary conditions to ensure a minimal profitability of carrier-led consolidation strategies in urban distribution. These conditions are shown by compact formulas obtained by continuous approximations representing the cost of the stakeholders involved: society, regular carriers, consolidation facility operator and environment. The domain of the retailer density variable that always produces negative effects on each stakeholder has been identified. The envelope of this domain does not depend on vehicle costs and other site-related parameters. On the other hand, there is a critical density of receivers that makes the carrier cost savings higher than the CF operator costs.
A key element to enhance urban distribution is the adequate management of parking space, particularly for loading and unloading operations. An in-advance booking system able to be adjusted to users ...needs can be a very useful tool for city councils. Such a tool should be fed with criteria for allocating requests to time slots. In this paper we discuss alternative criteria for the parking slot assignment problem for urban distribution and we propose the use of mathematical programming formulations to model them. Several models are proposed, analyzed and compared among them. Extensive computational experience is presented with a detailed analysis and comparison, which provides quantitative indicators of the quality of each of the proposed models.
•We define the parking slot problem assignment for urban distribution.•We propose alternative models according to different optimization criteria.•Extensive computational results are presented and analyzed.•Quantitative indicators of the quality of each model are introduced.
► We model the optimal design of interurban bus networks in city centers. ► The model uses a bi-level formulation. ► The objective function is a weighted sum of agency and operator costs. ► ...Metaheuristic Tabu Search is used to find a good solution of the problem. ► The methodology has been successfully applied to the large network of Barcelona.
This paper proposes a bilevel formulation for solving the Bus Network Design Problem (BNDP) of interurban services entering a major city. It is focused in interurban services because it is a growing problem in most of major cities, yet new in the literature. The layout of interurban bus routes and the locations of transfer stations in the main city are the key factors to provide a competitive public transportation service to commuters in a metropolitan area. The number of commuters in huge urban concentrations is growing due to the difficulties of living near the city center. The objective function of the first level is defined with the aim of reducing user and agency costs. In the second level the performance of users is addressed. Furthermore, a local search method based on the Tabu Search algorithm was carried out to guide the exploration in the solution domain. The results obtained in a set of test problems have demonstrated that the restart parameters of the algorithm play a significant role in the efficiency of the algorithm. Finally, implementation in the large network of Barcelona (Spain) reduces the total cost by 5% with regard to the present situation.
A novel model approach is proposed to estimate the spatiotemporal distribution of demand for free-floating carsharing. The proposed model is based on a Poisson regression model for right-censored ...data and estimates possibly time-varying demand rates of small subareas of a service region based on booking data with spatiotemporal information on pickups and dropoffs of cars. The approach allows operators to gain insights into the spatiotemporal distribution of demand for their service and to estimate the loss of demand due to unavailability of cars. Moreover, it can also be used as an input to improve the design of the service, through relocation techniques or to analyze the service with macrosimulation models. In addition, the approach is applied to a case study with real data.
In the last 20 years car sharing has been a growing trend in personal mobility. Multiple aspects of these systems have been already discussed: different forms of car sharing, user's preferences and ...behavior, or benefits estimation. Nevertheless, the management of these systems needs to be continuously improved to remain a competitive alternative. In this work, we propose a reservation scheme to manage rental reservations of a two-way station-based car sharing system. It allows the operator to better plan the necessary vehicles at each station, and encourages the drivers to make better use of the existing vehicles, by showing flexibility in the starting rental time. The reservation scheme is organized with an auction, where drivers bet for their preferred rental start time. Drivers participating in the auction are offered a reduced rental fare, which is then complemented with the reservation fee that results from the auction. The auction is solved under Vickrey-Clarke-Groves (VCG) mechanism for combinatorial auctions, which guarantees the desired properties for the operator and a fair assignment for the drivers. The proposed scheme is tested on instances inspired by the Mobility car sharing system in Zürich, Switzerland. The results show that operators could decrease their fleets with low to no impacts on the overall rental revenues, especially when drivers show flexibility in their rental start times. For certain levels of demand price elasticity, even positive impacts on the overall rental revenues can be expected. Moreover, reservation fees are proven to partially compensate for the decrease in rental revenues provided to the auction users.
Pick-up and delivery services are essential for businesses in urban areas. However, due to the limited space in city centers, it might be unfeasible to provide sufficient loading/unloading spots. As ...a result, this type of operations often interferes with traffic by occupying road space (e.g., illegal parking). In this study, a potential solution is investigated: Dynamic Delivery Parking Spots (DDPS). With this concept, based on the time-varying traffic demand, the area allowed for delivery parking changes over time in order to maximize delivery opportunities while reducing traffic disruptions. Using the hydrodynamic theory of traffic flow, we analyze the traffic discharging rate on an urban link with DDPS. In comparison to the situation without delivery parking, the results show that although DDPS occupy some space on a driving lane, it is possible to keep the delay at a local level, that is, without spreading to the network. In this paper, we provide a methodology for the DDPS design, so that the delivery requests can be satisfied while their negative impacts on traffic are reduced. A simulation study is used to validate the model and to estimate delay compared to real situations with illegal parking, showing that DDPS can reduce system’s delay.
This paper analyzes the logistic cost savings caused by the implementation of Urban Consolidation Centers (UCC) in a dense area of a city. In these urban terminals, freight flows from interurban ...carriers are consolidated and transferred to a neutral last-mile carrier to perform final deliveries. This operation would reduce both last-mile fleet size and average distance cost. Our UCC modeling approach is focused on continuous analytic models for the general case of carriers with different market shares. Savings are highly sensitive to the design of the system: the increment of capacity in interurban vehicles and the proximity of the UCC terminal to the area in relation to current distribution centers. An exhaustive collection of possible market shares distributions are discussed. Results show that market shares distribution does not affect cost savings significantly. The analysis of the proposed model also highlights the trade-off between savings in the system and a minimum market share per company when the consolidation center is established.
•An auction-based unified approach proposed for prebooked urban logistics facilities.•Heterogeneous carriers explicitly considered and social welfare optimized.•Online readjustment formulation and ...robust formulations to handle uncertain arrivals.•Theoretical and numerical analyses show advantages over the previous system.•Treatment for uncertainty yields social welfare close to the theoretical upper bound.
The proper management of urban loading/unloading facilities is crucial for both the efficiency of the logistic services and urban traffic systems. Thanks to the advances in technologies, such management can be achieved through prebooked systems. In this paper, we propose a comprehensive and unified auction-based approach to optimize the use of prebooked loading and unloading facilities, based on a previous work of the authors. The new proposed approach assigns parking spots to companies and computes the price of the service, to maximize the social welfare of the system. It has the following advantages over the previous system: (i) by employing an auction’s formulation based on the Vickrey–Clarke–Groves mechanism, the proposed system explicitly considers the heterogeneity in the penalty functions; (ii) uncertainty in the carrier arrivals due to traffic condition is handled explicitly with an online readjustment and two robust formulations.
The proposed auction system is tested on instances inspired by the logistic system in the city of Barcelona. Results show that compared to the previous work, the new approach exploiting the use of new information improves the social welfare by up to 22% with heterogeneous carriers. Results further show that the scenarios where demand is uniformly distributed over the time horizon present better utilities than the scenarios where demand is concentrated following a peak hour behavior. It is also shown that the proposed online readjustment formulation performs similar to the global offline optimum, and significantly improves the social welfare of the system when carriers fail to arrive at the allocated time due to traffic uncertainties.
Considering that the transport sector is responsible for 30% of the CO2 emissions in the EU, reaching up to 40% in urban areas, the efforts for technological improvements and innovation in ...transportation have been increasing during the last few decades. It is evident that urban freight distribution requires innovative solutions that are capable of improving the efficiency of transport whilst promoting innovative use of renewable energy, thus reducing energy consumption and associated GHG emissions while adopting and not stifling economic development. In this context, six Mediterranean cities (Barcelona, Bologna, Piraeus, Rijeka and Valencia)) collaborated with the purpose of contributing to the improvement of energy efficiency on urban freight transport as part of the SMILE Project (2015) (SMart green Innovative urban Logistics Models for Energy efficient mediterranean cities project), funded by the MED Programme. The SMILE project aims to improve the energy efficiency of Mediterranean cities through the promotion of innovative ‘green’ and cost effective solutions for urban freight logistics, addressing the target of green and smart urban development. This paper shows the results of the live test of smart city urban logistics solutions in the cities of Barcelona and Valencia that consisted of combining the use of electric tricycles and Transhipment terminals (or Urban Consolidation Centres) for the last-mile delivery of parcels and small shipments. A thoughtful analysis of the quantitative outcomes of the pilot test in both cities are presented from different perspectives: economical, operational, energy efficiency, environmental and social.
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