A hedging policy for carriers’ selection under availability and demand uncertainty

We address a stochastic dynamic distribution problem where a family of products needs to be shipped from a warehouse to a distribution center (DC). Uncertainty is on carriers’ availability and demand at the DC. Internal, external and spot carriers must be optimally selected to minimize the expected discounted cost of transportation, inventories and shortages. We numerically prove that an optimal selection policy, SDMBSP, is based on three thresholds of the available inventory in the DC. A simulation model is proposed and proves the robustness of the SDMBSP and its outperformance over two other carrier selection policies.     

Urban spatial structure,employment subcenters,and freight travel

Metropolitan areas in the U.S. have become increasingly polycentric. Large employment subcenters have emerged outside of central cities, competing against the traditional city center for labor and businesses. The existing literature on land use and transportation focuses on passenger travel, providing little insight into the impact of polycentric metropolitan development patterns on freight activity. In this study, we use the Los Angeles region as a case study to examine the relationship between urban spatial development patterns and freight travel. Using the National Employment Time Series (NETS) data, we identify employment subcenters in metropolitan Los Angeles. We characterize freight activities associated with the subcenters using data from the Southern California Association of Governments (SCAG). We develop a regression model that estimates freight activity as a function of geographic characteristics, such as whether a location is in an employment subcenter, measures of nearby employment, access to the highway network, and proximity to intermodal freight facilities. The results indicate that employment is an important driver of freight activity; however, employment subcenters have an independent effect on freight activity. The results of this study suggest that further research on urban spatial structure and freight activity should assess the effects of employment subcenters and how their particular employment composition and characteristics are associated with freight activities at the metropolitan level. Such an approach would lead to more precise policy recommendations for urban goods movement.     

Appropriate indicators of rail freight activity and market share: A review of UK practice and recommendations for change

Growth in rail freight activity features strongly in contemporary transport policy at both the United Kingdom (UK) and European Union (EU) scale. Specifically, the British government set an 80% growth target between 2000 and 2010, with lower (but still substantial) growth estimates being identified in late-2005. This paper assesses the appropriateness of the forms of measurement adopted for rail freight activity and argues that achieving stated growth targets or estimates will not necessarily mean that policies encouraging modal shift from road to rail have succeeded. Additional or alternative means of monitoring the level of rail freight activity are discussed, since this is an issue of fundamental importance to policy implementation and evaluation.     

Stochastic resource allocation for containerized cargo transportation networks when capacities are uncertain

We consider the stochastic resource allocation problem for containerized cargo transportation with uncertain capacities and network effects, in which a freight operator needs to allocate a certain amount of capacity to each product to maximize the expected profit. We formulate the problem as a constrained stochastic programming model and provide theoretical results that completely characterize the optimal solution to the model under a special case. Under a general case, we build an approximation model of the problem and propose a sampling based algorithm to solve the approximation model. A number of numerical experiments are offered to test the algorithm.     

铁路集装箱运价策略研究

在市场经济环境下,运输价格是客户选择运输方式的重要因素,但目前我国铁路集装箱运输在运价方面还存在一些问题。通过分析铁路集装箱运输的特殊性,并将其运价划分为3类,提出对不同附加值的货物采用不同的运输费率、实行折扣运价和合理确定运行基价等建议,并建立了铁路集装箱最优运价模型。     

Multi-criteria decision-making for complex bundling configurations in surface transportation of air freight

Airlines typically carry out freight transportation in a hub and spoke structure, where the movements between the outstations and the hub are served by trucks. To transport freight efficiently, air carriers must consider bundling options for shipments that are delivered at outstations and have to be moved to the hub. There are three options when it comes to bundling freight: on ‘through unit load devices’ (T-ULD) (all freight for the same flight at the hub), on ‘mixed unit load devices’ (M-ULD) (freight for different flights at the hub) and loose freight in trucks. The optimal freight bundling configuration for carriers, taking into account their main KPIs (key performance indicators), is unknown. This research formulates the problem as a multi-criteria decision-making (MCDM) problem, allowing carriers to decide which configuration is optimal for a given outstation. The selected KPIs (cost, (un)loading time, and quality) are formulated as mathematical functions. A new MCDM, called best worst method (BWM), is then used to identify the best configuration with respect to the three KPIs. The proposed methodology is applied to KLM Cargo to identify the best configuration for the selected outstations that supply freight to the KLM hub at Schiphol Airport. This case study shows that there are different optimal freight bundling configurations for different outstations and that trucking costs and freight handling tariffs are among the key factors in deciding which configuration is optimal.     

An ex ante evaluation of mobile depots in cities: A sustainability perspective

Today, a large share of cost, congestion, and emission in cities is attributed to light goods vehicles like carrier vans distributing to the last mile. The aim of many policy agendas is to reach cleaner cities with less disturbance from the distribution vehicles. Several suggestions have been put forward and tested in research and practice, such as access restrictions, multimodal transport, and use of cleaner vehicles. In this paper, we develop a case for a more sustainable freight distribution within cities using an ex ante case study. The idea of the mobile depot is built on the iteration between historical transitions within cities and contemporary developments in urban freight distribution, and then analyzed ex ante both quantitatively in calculations and qualitatively in two stakeholder workshops. The idea is integrated and multimodal, based on a mobile depot (e.g., a bus, truck, barge, or tram) that circles the city and connects to low emission last mile delivery options such as LEVs (Light Electrical Vehicles) or cargo bikes. We found that such a system can be environmentally and socially better for the city context, while maintaining economic viability above a certain utilization rate of the mobile depot for the transport operators.     

Searching for policy priorities in the formulation of a freight transport strategy: a canonical correlation analysis of freight industry attitudes

An efficient and effective freight transport strategy can be aided by early professional contributions from key stakeholders. One broad group who have historically been given limited opportunity to influence the drafting of a freight strategy, are commercial road users and shippers who manufacture and distribute goods. Utilising a data set collected in Australia in 1996 from a sample of organisations involved directly and indirectly in road freight transportation, views were sought on road infrastructure changes, new road infrastructure, non-road infrastructure needs and transport policies. An optimal scaling approach using non-linear canonical correlation is implemented to search for structural relationships between the underlying policy and infrastructure dimensions and the various industry categories. This framework provides a powerful mechanism for identifying differences among stakeholders in terms of their support for or opposition to specific policies. Results reveal the considerable differences in attitudes associated with the component parts of the freight industry.     

Utilizing urban form characteristics in urban logistics analysis: a case study in Lisbon,Portugal

Within the realm of urban logistics, Macário (2013) developed a hypothesis, denominated the Logistics Profile (LP) concept that suggests homogeneous groups of urban zones with respect to three dimensions, which could be used to analyze freight movement policy: (1) the social and built environment; (2) characteristics of the goods/products being moved; (3) characteristics of the deliveries at the receiver establishment. The concept was expected to ease the transferability of best practices in city logistics, by analyzing similarities and differences between zones. This research uses a quantitative methodology to apply the LP concept, and assess its potential, using the city of Lisbon as a case study. The analysis is focused on: (a) the extrapolation of freight trip generation per establishment and delivery characteristics from a sample of commercial establishments to the population within the case study, (b) proposing a methodology to test the LPs, (c) testing the existence of proposed LPs. Freight trips have been extrapolated using a Multiple Classification Analysis (MCA) model. Freight delivery characteristics were attributed to establishments from a sample-based probability distribution. LPs were tested using a two-step cluster analysis. Some LPs have been matched with clusters of case-study zones, subject to case study particularities. Profile overlap was not an issue and occurrences were expected. The testing showed that Logistic Profiles have the potential for being used as a departure point for urban freight planning and policy analysis.     

Channel coordination,trade credit and quantity discounts for freight cost

In this paper we consider vendor-buyer channels subject to trade credit and quantity discounts for freight cost. We deal with the problems of determining the vendor’s credit period, the buyer’s retail price and order quantity while still maximizing profits. We focus on how channel coordination can be achieved using trade credit and how trade credit can be affected by quantity discounts for freight cost. We show that profits for both parties increase under channel coordination when the credit period is kept within an appropriate range. This range becomes wider as the discount for freight rates increases.     

A meta-model for passenger and freight transport in Europe

On the basis of the outcomes of five disaggregate national models for passenger transport, four national models for freight transport and two European transport models, a fast and approximate meta-model for passenger and freight transport in Europe has been developed. The meta-model for passenger transport includes a detailed segmentation of the population, which makes it possible to investigate the impact of policies on many different groups of the population. The meta-model for passenger and freight transport has been applied for a reference scenario for 2020 and to simulate many elements of the European Commission's Common Transport Policy. These policy measures were also assessed in terms of the consequences on the internal and external cost of transport.     

A time-period choice model for road freight transport in Flanders based on stated preference data

This paper presents one of the first models explaining the choice of time-period in road freight transport. Policies that would shift some fraction of the trucks from peak to earlier and later periods will contribute to the reduction of congestion. Therefore there is an increasing interest in modelling the time-period sensitivity of road freight transport to changes in travel time and cost by period. The model developed here is based on a stated preference survey amongst receivers of goods in Flanders and was implemented in the strategic freight transport model of the Flemish authorities.     

Are freight pipelines a pipe dream? A critical review of the UK and European perspective

Freight pipelines represent a novel way for the movement of freight transport and offer an alternative to conventional transport modes. The aim of this paper is to examine the potential for this transport mode within the UK and Europe. Firstly, the latest technological developments are identified, building on the last major review by Howgego and Roe (1998). There is then an analysis of the policy landscape towards freight pipelines, as successful implementation will require the support of policy makers. Finally, some of the major benefits and issues with freight pipelines are highlighted. We conclude that there are still opportunities for the use of freight pipelines, but that further research is yet required to fully understand the supply chain, logistics and other related activities that the introduction of this technology may influence. This is because systems which are presently in commercial operation have exhibited excellent characteristics, although they have not been more widely adopted.     

Price planning for time-definite less-than-truckload freight services

Price planning simultaneous determines the service demand (with associated prices) and an operational plan to maximize a carrier’s profit. We modeled this integral-constrained concave program in the link formulation and proposed an implicit enumeration embedded with Lagrangian Relaxation upper bounds to determine the optimal prices. Computations on Taiwan’s time-definite less-than-truckload freight market showed that the carrier needs to simultaneously re-evaluate its network capacity while determining prices. The common practice of distance-based pricing that sets price by a base rate over direct shipment distance underestimates operating cost, specifically operating losses for short distance shipments.     

考虑模糊不确定性的物流联盟收益核算

由于受到天气、油价、货运量、物流时效性等因素的影响,物流行业常存在模糊不确定性,使得在对物流成本及收益进行核算时,很难用精确实数来表示相关的参数。考虑物流联盟中的预期回货率及预期回程装载率等参数常需要用模糊数值来表示,基于物流成本的会计科目及基本核算理论,提出一种简单、实用的模糊不确定环境下物流联盟成本及收益核算方法,并通过实例分析,验证所提出方法的有效性。研究结果表明,该方法实用性较强,符合物流联盟的真实情况,可以有效运用于解决物流联盟的收益分配问题。     

An integrated modeling framework for design of logistics networks with expedited shipment services

This paper studied an integrated logistics network problem that determines optimal supplier locations, assignments of these suppliers to terminal facilities, expedited shipment configurations, and inventory management strategies in an uncertain environment. We studied the problem structure and proposed mathematical models to determine the optimal network design that minimizes the expected total system cost. We developed a customized solution approach based on Lagrangian relaxation that can solve these models efficiently and accurately. Numerical examples are conducted to draw managerial insights into how problem settings and key parameter values affect the optimal design results.     

Dual sourced supply chains: the discount supplier option

In this paper, we examine the dynamics of a supply chain that has the option of using two suppliers – one reliable, and the other unreliable. We characterize the unreliable supplier with long lead-time mean and variance. Although the use of the unreliable supplier might potentially warrant higher inventory and transportation costs, it is attractive because of the willingness of the supplier to provide a discount on the purchase price. We analyze the cost economics of two suppliers in a broader inventory-logistics framework, one that includes in-transit inventories and transportation costs. In this broader perspective, we provide a simple heuristic and sample exchange curves to determine: (i) if the order should be split between the suppliers; and (ii) if the order is split, the amount of discount and the fraction ordered to the secondary supplier to make order-splitting a worth-while policy. ©     

A multi-objective genetic algorithm approach to design optimal zoning systems for freight transportation planning

This paper contributes to the existing research on freight transportation, spatial and land use planning by investigating an improved spatial aggregation technique to delineate desirable freight traffic analysis zones. Zoning is a process of spatially aggregating several predefined basic spatial units (BSUs) into multiple zones. It plays a vital role in the transportation planning and decision-making process and is well-documented as the modifiable areal unit problem (MAUP). MAUP involves aggregating BSUs to obtain optimal zones satisfying specific criteria and constraints. This paper proposes an improved spatial aggregation methodology to develop a freight traffic analysis zone system by applying the multiobjective optimization concept using a genetic algorithm. The decision variables, namely, (i) Freight trip density; (ii) Number of establishments; (iii) Employment density; and (iv) Compactness, are chosen to represent the elements of freight, passenger traffic, and land use. The problem is formulated as a multiobjective network partitioning problem. The four objectives aim to create zones with better homogeneity and compactness. It is solved using a genetic algorithm with a weighted distance metric approach to prioritize the four objectives. Results show that zones resulting from the improved methodology are superior to the existing zones in terms of homogeneity of decision variables and compactness. The findings are expected to help the decision-making process of urban, transportation, and land-use planners in selecting appropriate freight traffic zone delineation strategies for a given region.     

Regional disparity analysis of Chinese freight transport CO2 emissions from 1990 to 2007: Driving forces and policy challenges

Freight transportation and logistics act as the artery of the national economy. With a booming economy, China's freight transport sector has experienced dramatic growth in recent decades and has become a key driving force of China's CO₂ emissions. Therefore, effective and efficient mitigation policies in the freight transport sector are critical for China to promote CO₂ emission mitigation strategies. In contrast to other countries, China's challenge stems not only from technical issues but also from regional socioeconomic disparities, which in turn require the implementation of locally oriented policies. For this reason, an analysis based on regional disparity is of vital importance for future policy making. However, to date, there have been few pertinent studies on the freight transportation sector. To fill this gap, this paper aims to conduct an in-depth comparative study of CO₂ emission characteristics and the driving forces in the freight transport sector in China's three regions (covering 31 provinces) from 1990 to 2007. The log mean Divisia index method (LMDI) is employed to analyse the driving forces, and the Gini coefficient is used to investigate regional inequity. Additionally, regional disparity is explored in-depth based on the analytical results and practical concerns. The results highlight that economic structure is a key driving force for emissions change and reveal significant regional disparity and inequity in freight transport emissions. The results are critical for future policy-making to address regional concerns.     

Reliable design of an integrated supply chain with expedited shipments under disruption risks

This paper studied the design of a two-echelon supply chain where a set of suppliers serve a set of terminals that receive uncertain customer demands. In particular, we considered probabilistic transportation disruptions that may halt product supply from certain suppliers. We formulated this problem into an integer nonlinear program to determine the optimal system design that minimizes the expected total cost. A customized solution algorithm based on Lagrangian relaxation was developed to efficiently solve this model. Several numerical examples were conducted to test the proposed model and draw managerial insights into how the key parameters affect the optimal system design.