Decoupling of Road Freight Transport and Economic Growth Trends in the UK: An Exploratory Analysis

Abstract

Between 1997 and 2004, gross domestic product increased in real terms in the UK by one‐fifth, while the volume of road freight movement remained stable. This suggests that the long‐awaited decoupling of economic and freight transport growth has begun, possibly leading to a new era of sustainable logistics. This paper reviews previous research on the decoupling issue and recent trends in gross domestic product/freight tonne‐km elasticities in Europe and the USA. It then examines 12 possible causes of the observed decoupling in the UK using published statistics from a wide range of British and European sources. This analysis indicates that around two‐thirds of the decoupling is due to three factors whose impact can be quantified: the increased penetration of the British road haulage market by foreign operators, a decline in road transport’s share of the freight market, and real increases in road freight rates. Several other factors, most notably the relative growth of the service sector, the diminishing rate of centralization, and the off‐shoring of manufacturing, appear to be having a significant effect, though this finding cannot be measured on the basis of available statistics. The paper concludes that, while the decoupling is in the right direction from a public policy standpoint, the net environmental benefits are likely to be quite modest.     

A Descriptive Framework for the Development and Operation of Liner Shipping Networks

Abstract

Successful mass transit solutions are rare in poor cities. When they appear they are lauded across the globe and too often copied uncritically. The latest exemplar of such best practice is the ‘Transmilenio’ rapid bus system in Bogotá. The article describes its main characteristics and applauds the improvements that it has already brought to urban transport in Bogotá. Naturally, the system is not without its flaws and these need to be drawn to the attention of those who might copy the Bogotá example. This is particularly important at the present time when the jewel of Bogotá has come under surprisingly strong local criticism over its cost, its ownership structure, its decreasing effectiveness and, fundamentally, because it has failed to solve the transport chaos of Bogotá. There is a real danger that ‘Transmilenio’ will stagnate as its popularity declines and as demands for a metro increase. Given the strengths of the system that would be something of a disaster and, most certainly, not in the interests of the poor.     

True Walking Distance to Transit

Abstract

People riding transit in the city of Detroit walk on average 0.8 miles (1.3 km) per round trip. The straight-line walking distance was found by buffering the bus stop locations and comparing them to the weighted US Census blocks. However, the true walking path follows the street pattern. Rather than undertaking network analysis, which would require connecting all addresses in the city with all bus stops, a Monte Carlo simulation was performed in geographic information system with random addresses. The simulation was performed over several addresses until convergence was achieved. The distances were converted to walking times and compared to the US National Household Transportation Survey.     

CBTC转换战略的实施

引进各种新信号技术系统是复杂而有风险的。美国运输技术中心公司（TTCI）认为逐步转换能使进程顺利并最大限度地提高可靠性。     

Optimization of crashworthy marine structures

History shows that ferry and RoPax collisions with tankers can be devastating for human life. This paper follows up such a scenario to contribute to rational increase of safety of marine structures. Through the coupling of multi-objective structural optimization and crashworthiness analysis, a conventional tanker structure is optimized for higher collision tolerance, accounting for the change in hull mass, so that the increase in safety is efficient. Two new concepts, proposed here, are deemed necessary for the successful execution of this task: a ‘two-stage’ optimization approach, reducing the number of needed collision simulations, and a rapid collision simulation approach that utilizes coarse FE mesh and reduces calculation time. Combining the obtained results with the state-of-the-art knowledge, a new insight about crashworthy design of tanker structures is also realized.     

Introduction to Special Issue on Tropical Coastal Management

In 1992, scientists at National Estuarine Research Reserve (NERR) sites proposed establishing a national coordinated monitoring program that would attempt to identify and track short-term variability and long-term changes in representative estuarine ecosystems and coastal watersheds. Known as the NERR System-Wide Monitoring Program (SWMP), it currently consists of monitoring water quality and atmospheric variables over a range of spatial and temporal scales. Additional monitoring of ecological resources and land-water use will follow in subsequent components of the program. Water quality monitoring at NERR sites includes measurements of pH, conductivity, temperature, dissolved oxygen, turbidity, and water level. The NERR sites use data loggers that record at 30-minute intervals and relay measurements to internal memory. Standardized protocols assure that sampling, processing, and data management techniques are comparable among sites. Statistical techniques are being used to identify periodicity in water quality variables. Periodic regression analysis indicated that diel periodicity in dissolved oxygen is a larger source of variation than tidal periodicity at sites with less tidal amplitude. Tidal periodicity, however, is more important at sites with a tidal amplitude greater than 1 m. This finding suggests that natural processes controlling dissolved oxygen levels differ among sites depending upon tidal amplitude. Water quality data from the NERR SWMP have also been used to investigate occurrence of hypoxia. Results from analysis of water quality at several reserves indicate that hypoxia occurs but that the percentage of time that dissolved oxygen was less than 28% saturation varied substantially among sites and between years. Most of the hypoxic events occurred in summer but were also observed in winter and fall when low dissolved oxygen is usually not considered a problem. Without continuous monitoring by the NERR SWMP, many low dissolved oxygen events would have been missed, thus underestimating the duration and potential impact of this type of water quality variability. The NERR SWMP provides a unique opportunity to increase our understanding of how various environmental factors influence estuarine processes. Only by understanding how estuaries function and change naturally over time will we be able to predict how these systems respond to changes in climate and human-induced perturbations.     

Subjective value of time in bus transit travel

A psychological scaling technique, magnitude estimation, is used to rate time spent on various elements of bus transit trips. Relative values of time are found for in-vehicle portions of trips, walking, waiting and transferring. Because magnitude estimation produces a ratio scale, results can be directly incorporated into modal choice analyses, route planning and evaluation procedures where monetary values of time are not necessarily required.     

Macroscopic traffic models for vehicle-follower automated transportation systems

The problem of distributing and routing vehicles in a large automated transportation network may be approached through the design of on-line control algorithms, particularly when the network contains many origin-destination pairs and alternate routes. To develop such algorithms, it is necessary to obtain models that accurately represent the dynamic behavior of vehicles on the guideway network. In this paper, models based on density, flow and average velocity variables are derived for the vehicle-follower longitudinal control scheme. Models suitable for use in analysis and simulation work are developed for links, merges, diverges, and stations. The proposed models are shown to compare favorably with simulation results that use explicit modeling of vehicle dynamic modeling of vehicle dynamic interaction.     

Vectorization and constraint grouping to enhance optimization of marine structures

Vectorization converts classical scalar optimization formulation, which strictly separates the objective from constraints, into a vector-based optimization, transforming constraints into objectives. Effectively, the search is not conducted anymore for a single optimum, but for a set of Pareto optima between the original objective and transformed constraints. Constraint grouping enhances handling of multiple constraints for vectorized problems, by combining several constraints within a single-objective function, thus reducing the computational time and computational difficulties of high-dimensional spaces created by vectorization. This paper formulates and investigates these two concepts with respect to design of marine structures. It analyses their effects on the possibility to improve the flexibility of optimization in a practical environment, by implementing them within a simple genetic algorithm. Obtained results of vectorization applied to realistic weight optimization problem are encouraging when compared with the results of the classical scalar form optimization, showing a significant improvement in magnitude as well as in reduced computation time needed to reach the optimum.     

VLCC级FPSO海上连接的模型试验及虚拟模拟(英文)

阐述了VLCC级.FPSO海上连接的模型试验和虚拟模拟,以及其研究结果如何应用于指导FPSO与SYMS存极浅水中的连接作业.模犁试验和虚拟模拟研究范围覆盖了各安装阶段,包括海上就位试验、就位及连接临时交义缆、系泊腿连接、压载灌浆直至达到风暴安全状态.模型试验不仅可以核实FPSO就何拖拉力要求,而且可以确定FPSO和安装驳船的运动幅值和系泊力大小.而虚拟模拟则可以虚拟模拟环境,通过虚拟模拟确认关键作业人员、作业执行方案和作业程序中潜在的问题.该文介绍的模型试验和虚拟模拟方法可以进一步推广到各种浮式平台的深水应用中.