汕尾市新港大桥桥型方案比选

大跨度桥型方案比选。应在技术可行的前提下,对桥梁的经济性、美观性和创新性进行系统的分析、论证与比较,力争找到一个既能突出当地经济特色、人文思想及价值观念,又能表达现当代桥梁的技术水平及蕴涵未来桥梁的发展趋势的最佳方案。     

基于动态网格模型的航线自动生成算法

为了充分利用电子海图信息,进行航线设计,提出了基于动态网格模型的航线自动生成算法。采用一个判断网格模型中方格可航性的快速算法,对方格的可航性进行分类;给出了一个有效地使用8个字节表示邻接方格8个方向的编码方法,使邻接方格的连通性与字节的逻辑操作相对应;提出了网格路径权序列均匀度概念,给出了距离等长路径的优选方法,分析了路径与所对应的实际航路长度的差异;基于二分查找法,求出航线上所有转向点的路径方格序列。研究结果表明:基于动态网格模型所生成的航线可避开危险的障碍物,是合理、安全的。     

The effect of attitudes toward cars and public transportation on behavioral intention in commuting mode choice—A comparison across six Asian countries

This study investigated the contribution of psychological factors in explaining the choice of transportation mode in six Asian countries. Data were collected from 1118 respondents in Japan, Thailand, China, Vietnam, Indonesia, and the Philippines. The dependent variable was the intention to use one of three modes for work travel after getting a job: car, public transit, or other modes. The explanatory variables were three attitude factors taken from a previous study, including: 1/symbolic affective, reflecting affective motives of travel mode use; 2/instrumental, referring to functional attributes of travel modes; and 3/social orderliness which represents for environmental friendliness, safety, altruism, quietness et cetera. Several logit model estimates were made using the samples from the six countries separately and together. We obtained three main findings. First, attitude variables about the car were all significant determinants for the entire sample from Asian countries. Second, the social orderliness aspect of public transit was a common concern of respondents from developing countries in selecting this mode for work trips. Third, in countries in which the intent to use a car was not very high, attitude factors about the car were found to be significant determinants of the behavioral intention to commute by car but were less significant in countries in which the desire to use a car was high.     

Modelling parking choices considering user heterogeneity

We examine car driver’s behaviour when choosing a parking place; the alternatives available are free on-street parking, paid on-street parking and parking in an underground multi-storey car park. A mixed logit model, allowing for correlation between random taste parameters and estimated using stated choice data, is used to infer values of time, both when looking for a parking space and for accessing the final destination. Apart from the cost of parking, we found that vehicle age was a key variable when choosing where to park in Spain. We also found that the perception of the parking charge was fairly heterogeneous, depending both on the drivers’ income levels and whether or not they were local residents. Our results can be generalised for personalised policy making related with parking demand management.     

Behavior-consistent information-based network traffic control for evacuation operations

The evacuation operations problem aims to avoid or mitigate the potential loss of life in a region threatened or affected by a disaster. It is shaped to a large extent by the evolution of evacuation traffic resulting from the demand–supply interactions of the associated transportation network. Information-based control is a strategic tool for evacuation traffic operations as it can enable greater access to the affected population and more effective response. However, comparatively few studies have focused on the implementation of information-based control in evacuation operations. This study develops a control module for evacuation operations centered on addressing the demand–supply interactions by using behavior-consistent information strategies. These strategies incorporate the likely responses of evacuees to the information provided in the determination of route guidance information. The control module works as an iterative computational process involving an evacuee route choice model and a control model of information strategies to determine the route guidance information to direct evacuation traffic so as to approach a desired network traffic flow pattern. The problem is formulated as a fuzzy logic based optimization framework to explicitly incorporate practical concerns related to information dissemination characteristics and social equity in evacuation operations. Numerical experiments highlight the importance of accounting for the demand–supply interactions, as the use of behavior-consistent information strategies can lead evacuee route choices to approach the operator-desired proportions corresponding to the desired traffic pattern. The results also indicate that while a behavior-consistent information strategy can be effective, gaps with the desired route proportions can exist due to the discrete nature of the linguistic messages and the real-world difficulty in accurately modeling evacuees’ actual route choice behavior.     

Will a driving restriction policy reduce car trips?—The case study of Beijing,China

A driving restriction policy, as one of the control-and-command rationing measures, is a politically acceptable policy tool to address traffic congestion and air pollution in some countries and cities in the world. Beijing is the first city in China to implement this policy. A one-day-a-week driving restriction scheme was expected to take 20% of cars off the road every week day. Using household survey and travel diary data, we analyze the short-term effect of this driving restriction policy on individual travel mode choice. The data also allow us to identify which demographic groups are more likely to break the restriction rule. The estimates reveal that the restriction policy in Beijing does not have significant influence on individuals’ decisions to drive, as compared with the policy’s influence on public transit. The rule-breaking behavior is constant and pervasive. We found that 47.8% of the regulated car owners didn’t follow the restriction rules, and drove “illegally” to their destination places. On average, car owners who traveled during peak hours and/or for work trips, and whose destinations were farther away from the city center or subway stations, were more likely to break the driving restriction rules. Therefore, Beijing is probably in need of more comprehensive and palatable policy instruments (e.g., a combination of congestion tolls, parking fees, fuel taxes, and high-speed transit facilities) to effectively alleviate traffic congestion and air pollution.     

浅谈公路环评解译工作中遥感影像的选择

对目前公路环评解译工作中常用的TM、SPOT5、QUICK BIRD等影像在分辨率、波谱特征和经济性等方面进行了对比,得知TM影像在分辨率、波谱特性、价格方面均满足公路环评工作的需要,是适合公路环评工作的卫星影像。并以神池至河曲高速公路所在地区的TM影像为例,运用Chavezetal提出的最佳指数法得到了该区域解译的最优波段组合。     

Port privatization under Cournot vs. Bertrand competition: a third-market approach

By incorporating port competition into a third-market model consisting of two exporting firms and one importing country, we demonstrate the endogenous choice of port structures (i.e. privatization or public ownership) under either Bertrand or Cournot competition. In contrast to previous studies on port competition, we analyze the port strategy in view of all trading countries (i.e. importing country and exporting countries). We find that regardless of transport cost, the port ownership strategy alters according to exporting firm’s competition mode. Under Bertrand competition, the choice of port ownership structure depends on the degree of imperfect substitutability. However, under Cournot competition, all trading countries choose same ownership structures of each port. By comparing equilibrium of each competition mode, we show that welfare of exporting country under Cournot competition is higher than under Bertrand competition if goods are sufficiently substitutes. In contrast, importing country prefers Bertrand competition to Cournot competition when the competitive pressure is sufficiently high.     

厦门东通道海底隧道土建工程设计

正在建设的厦门东通道海底隧道长约6km，采用钻爆暗挖方案修建，它是我国大陆第一座大断面的水底隧道。设计借鉴了国内外已建或规划中的水底隧道的成果和经验，‘突出“以人为本、安全第一”的总体思路，考虑了对付各种突发性灾害的处置预案，以确保工程结构具有100a的安全性和耐久性。     

Analysing Demand for Suburban Trips: A Mixed RP/SP Model with Latent Variables and Interaction Effects

We analyse mode choice behaviour for suburban trips in the Grand Canary island using mixed revealed preference (RP)/stated preference (SP) information. The SP choice experiment allowed for interactions among the main policy variables: travel cost, travel time and frequency, and also to test the influence of latent variables such as comfort. It also led to discuss additional requirements on the size and sign of the estimated model parameters, to assess model quality when interactions are present. The RP survey produced data on actual trip behaviour and was used to adapt the SP choice experiment. During the specification searches we detected the presence of income effect and were able to derive willingness-to-pay measures, such as the subjective value of time, which varied among individuals. We also studied the systematic heterogeneity in individual tastes through the specification of models allowing for interactions between level-of-service and socio-economic variables. We concluded examining the sensitivity of travellers’ behaviour to various policy scenarios. In particular, it seems that contrary to political opinion, in a crowded island policies penalising the use of the private car seem to have a far greater impact in terms of bus patronage than policies implying direct improvements to the public transport service.