Models of the Relationship between Transport and Land‐use: A Review

Abstract

A two‐way interaction between transport and land‐use has been one of the central research topics of transport studies. Thus, it is not surprising that there have been numerous approaches taken to investigate this reciprocal relationship. This paper critically examines the existing literature to see how effectively the current models represent this mutual interaction. This examination process intends to form a prototype reference that compares and contrasts the advantages and disadvantages of the various models. This undertaking is dealt with based on theoretical, methodological and operational characteristics of a respective model. Some conclusions and suggestions are also drawn.     

Do Road Planners Produce More ‘Honest Numbers’ than Rail Planners? An Analysis of Accuracy in Road‐traffic Forecasts in Cities versus Peripheral Regions

Abstract

Based on a review of available data from a database on large‐scale transport infrastructure projects, this paper investigates the hypothesis that traffic forecasts for road links in Europe are geographically biased with underestimated traffic volumes in metropolitan areas and overestimated traffic volumes in remote regions. The present data do not support this hypothesis. Since previous studies have shown a strong tendency to overestimated forecasts of the number of passengers on new rail projects, it could be speculated that road planners are more skilful and/or honest than rail planners. However, during the period when the investigated projects were planned (up to the late 1980s), there were hardly any strong incentives for road planners to make biased forecasts in order to place their projects in a more flattering light. Future research might uncover whether the change from the ‘predict and provide’ paradigm to ‘predict and prevent’ occurring in some European countries in the 1990s has influenced the accuracy of road traffic forecasts in metropolitan areas.     

Accompanied versus Unaccompanied Transport in Short Sea Shipping between Spain and Italy: An Analysis from Transport Road Firms Perspective

Short sea shipping (SSS) is called to play a key role in ensuring sustainable mobility in the European context. In the past years several studies tried to define the SSS requirements and also to identify the SSS lines that were economically viable. However, no studies approach the profile of their users—the road transport firms—and the organizational patterns adopted by them, in order to gain a better understanding of this transport modality. This research, on the basis of a sample of 81 international road transport firms that use SSS between Spain and Italy, analyses the profile of these firms and certain elements inherent to their relationship with the shipping firms, according to the two modalities of organizing their SSS transport operations: accompanied versus unaccompanied.     

Transport Network Design Problem under Uncertainty: A Review and New Developments

This paper aims to provide a state-of-the-art review of the transport network design problem (NDP) under uncertainty and to present some new developments on a bi-objective-reliable NDP (BORNDP) model that explicitly optimizes the capacity reliability and travel time reliability under demand uncertainty. Both are useful performance measures that can describe the supply-side reliability and demand-side reliability of a road network. A simulation-based multi-objective genetic algorithm solution procedure, which consists of a traffic assignment algorithm, a genetic algorithm, a Pareto filter, and a Monte-Carlo simulation, is developed to solve the proposed BORNDP model. A numerical example based on the capacity enhancement problem is presented to demonstrate the tradeoff between capacity reliability and travel time reliability in the NDP.     

Quality indicators and capacity calculation for RoRo terminals

Abstract

Road freight transportation has increased dramatically over recent years along with its impacts such as congestion, noise, and pollution. As a result, European and US governments have started policies to promote alternatives to road transportation, such as logistic chains containing a Short Sea Shipping (SSS) link. Road is, by definition, a more flexible means of transportation than shipping, which is usually cheaper. Therefore, to move traffic to SSS chains, it is necessary to provide fast, frequent, and reliable maritime transportation. In this sense, roll-on/roll-off (RoRo) vessels are the most convenient ships to be used, since they have smaller dwell times in port and, therefore, this is a kind of traffic likely to increase dramatically. The foreseeable increase of this kind of traffic must meet with an increase in the actual capacity by means of either improvement in performance and possible enlargements of existing terminals or the construction of new terminals. In that sense, this paper proposes a simple methodology to calculate the capacity of a RoRo terminal, whether already in operation or during its design process, and relate it to some quality standards by means of quality indicators, which should lead to the definition of Levels of Service similar to those already used in roads and airports. The paper ends by applying the methodology to a real terminal in Barcelona, Spain.     

Singapore motorisation restraint and its implications on travel behaviour and urban sustainability

The example of Singapore shows that rapid urban and economic growth does not have to bring traffic congestion and pollution. Singapore has chosen to restrain car traffic demand due to its limited land supply. Transport policy based on balanced development of road and transit infrastructure and restraint of traffic has been consistently implemented for the past 30 years. Combined with land use planning, it resulted in a modern transport system, which is free from major congestion and provides users with different travel alternatives. As the economic growth caused a substantial increase in demand for cars, several pricing policies were introduced with the aim of restraining car ownership and usage. Growth of the vehicle population is now controlled and potentially congested roads are subject to road pricing. These measures help to keep the roads free from major congestion, maintain car share of work trips below 25% and keep the transport energy usage low. Although Singapore conditions are in many aspects unique, its travel demand experience can provide useful lessons for other rapidly growing cities in Asia.

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在拥堵的高速公路上,合乘车辆（HOV）车道是一种高效环保的交通方式. 虽然HOV车道广受采纳,但该系统的利用效率受到质疑. 加州在全州范围内 采取了一项允许混合动力车辆使用HOV车 道的政策,以期通过鼓励驾驶员使用省油汽车来减少尾气排放,同时通过更有效地利用HOV车道的剩余通行能缓解交通拥挤. 加州橘县高速公路的路网用于研究 该政策的影响及有效性. 研究方法结合使用传统的规划模型来估计交通需求及校准的微观仿真模型来评价系统性能. 通过对系统整体性能、车道服务水平和空气质量 三方面的分析,结论表明此政策对在高峰时段没有剩余通行能力的HOV车道带来严重的负面影响. 为保证HOV车道服务质量不明显下降还能减少排放,该政策最多允许50 000辆在加州注册的混合动力车辆使用HOV车道.     

Performance characteristics of a supplementary stack-cooling system for fuel-cell vehicles using a carbon dioxide air-conditioning unit

In fuel-cell-powered vehicles, the fuel-cell system requires a thermal-management subsystem to dissipate heat released during the reaction of hydrogen with oxygen. When the stack generates power at a high rate, a large amount of heat is also generated. If cooling by the radiator is insufficient, a supplementary stack-cooling system is needed to maintain a safe operating temperature. In this study, the performance of a CO₂ air-conditioning unit for stack cooling was investigated under various conditions, and the relationship between cabin cooling and stack cooling was also studied. The coefficient of performance (COP) increased from 1.9 to 2.4, with an increase in cabin-air inlet flow rate from 0 to 8 m³/min. When the air-conditioning unit was turned off, the cooling capacity of the stack cooler was increased; correspondingly, as the cabin-cooling capacity was increased, that of the stack cooler decreased. With an increase in ambient-air inlet temperature from 38°C to 45°C, the COP decreased by 24%. Additionally, both the stack-cooling capacity and cabin-cooling capacity were decreased by about 12% and 16%, respectively, due to reduced heat transfer in the gas cooler as the ambient air inlet temperature was increased. It is expected that the experimental results can serve as a resource in designing a stack-cooling system using a CO₂ air-conditioning unit to enhance stack power generation and efficiency.     

Accelerated life prediction of fillet-type,gas-welded joints

In this paper, in order to save time and cost for the fatigue design and to develop the optimum approaches for accelerated life prediction of the fillet gas welded joints, the (Δσ)_R − N_f relationship was obtained from actual fatigue test data, including welding residual stress. Based on these results, the (Δσ_a)_R − (N_f)_ALP relationship derived from the method of statistical probability analysis was compared with the actual fatigue test data. From the result, the optimum statistical distribution for the accelerated life prediction was analyzed to be the lognormal distribution for the fillet-type, gas-welded joint. The mean accuracy of the accelerated life prediction was assessed to be 85∼95% of the actual test life at the 95% reliability level and ±15% standard deviation. Therefore, it is expected that the accelerated life prediction will provide a useful method for determining the criterion for fatigue design and for predicting a specific target life.     

Optimizing the shape of a bumper beam section considering pedestrian protection

This paper presents a design technique to optimize the shape of a vehicle bumper beam that satisfies both the safety requirements for a front rigid-wall impact and the regulations protecting pedestrians from lower leg injuries caused by bumper impacts. An intermediate response surface modeling (IRSM) technique was introduced to approximate the non-linear force-displacement curves obtained from the front impact analysis of a vehicle bumper. The accuracy of the IRSM model was tested by comparing its results with those of the non-linear finite element analysis. The maximum displacement error between the two models did not exceed 3%. Using pedestrian impact analyses based on the experimental arrangement of the Plackett-Burman design, the approximate functions describing the response values acting on the lower legs were calculated. The shape of the bumper beam was optimized by integrating the IRSM with the force-displacement model and the approximate functions on lower leg impact. The optimization results satisfied safety regulations on the maximum allowable displacement of the vehicle bumper, and also the regulations protecting pedestrians from lower leg injuries caused by bumper impacts.