Making or breaking - Key success factors in the air cargo market

This introductory paper considers a number of major evolutions in the air freight market. In the first instance, it describes the heterogeneous environment in which air cargo services are performed. Subsequently, it looks at some of the most notable developments in air freight. Lastly, it deals with the market structure and with possible future strategies.     

Localisation of freight consolidation centres serving small road hauliers in a wider urban area: barriers for more efficient freight deliveries in Gothenburg

This paper discusses the negative impacts of freight transport growth, especially in and around urban areas. Over time, a growing number of road freight vehicles have delivered less freight over longer distances, while average load factors have been reduced. This development is unsatisfactory, as transport capacity that could have been used more efficiently is lost. To mitigate negative impact, it has been suggested that freight consolidation and better planned localisation of freight consolidation centres (FCCs) would improve city logistics. Based on primary data, this paper investigates the potential to establish urban FCCs intended for small road hauliers (SRHs) delivering goods to the retail sector in a wider geographical area, the Gothenburg region in Sweden. While the findings show that a large majority of SRHs could reach potential FCC locations in a short time, congestion affects deliveries and several factors, many of which were observed already in the 1970s, restrict FCC establishments. Under present conditions, there is little scope for SRHs to successfully deliver goods to retailers in the Gothenburg region from FCCs; therefore, a more efficient urban transport system from a business or societal perspective is unlikely. Policy makers need to take into consideration the different segments, requirements, and characteristics of different cities before venturing into costly FCC projects.     

Driver behaviour,truck motion and dangerous road locations – Unfolding from emergency braking data

Road vehicles equipped with measurement, computing, data storage and data communication capabilities can be utilised as probe-vehicles. Data received from such vehicles can provide valuable traffic and traffic safety information in respect of the covered routes and the connecting road network. In this study, trucks negotiating their normal daily haulage trips were used as probe-vehicles and the data recording their vehicular emergency events, such as abrupt braking events, detected by their on-board vehicular safety systems were analysed. The motivation for such an analysis is manifold. The aspect emphasized here is that the recorded vehicular emergency actions and events can be seen as surrogate safety events. Some of these surrogate safety events mark traffic incidents and therefore can be used as input by the surrogate safety assessment methodology. Though the vehicular emergency data used herein provides only sparse spatial and temporal coverage of the road network investigated, its analysis led to some interesting findings about interactions between drivers, trucks and roads.     

On the use of RFID in the management of reusable containers in closed-loop supply chains under stochastic container return quantities

This paper studies a closed-loop supply chain that uses containers for transporting products from a supplier to a retailer. At the retailer, used containers are collected and returned to the supplier. The supplier inspects returned containers, and either repairs and reuses or disposes them. This paper studies the case where the fraction of containers that are returned to the supplier is stochastic, and where an RFID system can be used to support the tracking of container positions in the supply chain. The use of RFID leads to improved information on the return of containers and better return predictability as well as higher return rates, which we model as an increase in the mean return rate of containers and a reduction in return variance. The paper first develops a mathematical planning model for this scenario, and it then studies how the use of RFID impacts the performance of the system. In addition, it analyzes under which conditions the use of RFID is economical, and in which situations traditional container systems should be preferred.     

The lead-time reliability paradox and inconsistent value-of-reliability estimates

The value-of-reliability (VOR) reflects the savings in inventory-system costs from more reliable (less variable) lead times. Previous studies have revealed that more reliable, but positively skewed, lead times could actually increase optimal safety inventory when the probability of satisfying all demand during a replenishment cycle drops below 70%. Researchers claim that this paradox affects most firms and that it explains the inconsistent VOR estimates found in the transportation economics literature. Our investigation reveals that firms interested in high product availability may safely ignore the paradox and that less lead-time variability consistently increases VOR, the paradox notwithstanding.     

Integrated Berth Allocation and Quay Crane Assignment Problem: Set partitioning models and computational results

Most of the operational problems in container terminals are strongly interconnected. In this paper, we study the integrated Berth Allocation and Quay Crane Assignment Problem in seaport container terminals. We will extend the current state-of-the-art by proposing novel set partitioning models. To improve the performance of the set partitioning formulations, a number of variable reduction techniques are proposed. Furthermore, we analyze the effects of different discretization schemes and the impact of using a time-variant/invariant quay crane allocation policy. Computational experiments show that the proposed models significantly improve the benchmark solutions of the current state-of-art optimal approaches.     

Performance evaluation of China's air routes based on network data envelopment analysis approach

Air routes are among the most important elements of civil aviation transport. Airlines' operations are mainly dependent on the structure and layout of air routes. This paper first divides the production process of air routes into two stages, allocation and transport, based on air route operational characteristics. Then, two network data envelopment analysis (DEA) models are proposed to analyze the efficiency of the system, allocation, passenger transport, and freight transport of 477 air routes. The research result demonstrates that the different constraints on intermediate measure in the network DEA models do affect the air routes’ efficiency significantly; Most air routes have high allocation efficiency and passenger transport efficiency, while they have low freight transport efficiency. Furthermore, the efficiencies of 82 airports are also analyzed after aggregating the efficiencies of the air routes.     

海运运价指数研究综述

海运运价指数反映航运市场水平的动态变化,对贸易成本有重要影响。结合近些年海运运价指数的文献研究进展,首次对波罗的海干散货运价指数(BDI)、波罗的海原油运价指数(BDTI)以及中国出口集装箱运价指数(CCFI)三个海运运价指数的影响因素、波动周期性和指数预测方法研究领域的成果进行归纳整理和对比分析,为航运公司、船舶中间商的经营决策提供参考。影响因素主要从供需关系下的运输成本、航运市场、经济环境三个因素展开,波动周期结合各航运市场的特征并分析原因,预测方法则围绕线性模型与非线性模型进行比较,在文献述评的基础上指出目前研究的不足与未来的研究方向。     

货车集结参数的研究

全站的货车集结参数与每个去向的货车集结参数不等,这一现象说明货车集结参数的计算方式存在一些不合理性。经过分析推理,提出新的计算公式,并用集结参数的物理意义验证其正确性。将该公式应用于六盘水南站,说明其实际合理性。     

Relay network design in freight transportation systems

This paper provides techniques, heuristics, and algorithms for the location of a minimal number of relay points on a highway network that satisfies the driver-distance constraint––a driver leaving a distribution center does not travel for more than t miles before which he/she returns back to the originating point or rests before moving on further. Straight Route and Detour versions are considered. Empirical evaluations of the proposed heuristics on road networks are performed. The results indicate that the Straight Route version is computationally efficient but locates a larger number of relay points than the Detour versions.