Inland cargo flow modelling considering shipment time variability on cross-border transport

This paper formulates an inland cargo flow model that considers the additional costs incurred because of variability in shipment times at borders and seaports. Using the proposed model, five scenario analyses for cross-border haulage between Lao PDR and seaports in Thailand and Vietnam are carried out in order to assess the impact of improving border and seaport reliability. These scenario analyses show that improving shipment time variability at seaports has more impact on cost reduction compared to improving border reliability. As for seaport choice, both cases of seaport and border reliability indicate similar trends. Cargo volumes decrease at Laem Chabang seaport in Thailand and increase at Vietnamese seaports as reliability at each identified bottleneck is improved.     

基于非洲陆锁国腹地的门户港前景分析

非洲范围内陆锁国腹地的门户港发展前景分析具有独特性,须考虑区位条件、地缘政治、政局稳定性、竞争形势、陆锁国运输需求分布等多种要素,与国内一般的港口竞争研究和发展前景研究有所不同。阐述非洲区域陆锁国腹地的门户港发展前景研究思路及所涉及的要素,并结合实例阐述某门户港发展前景,以期为类似咨询项目的开展提供研究思路,也可为海外相关港口投资机会的研究提供参考。     

Structural equation modeling of user satisfaction of bus transit service quality based on stated preferences and latent variables

Few studies have been conducted on the service quality (SQ) of bus transit in developing countries. This paper presents a structural equation modeling (SEM) approach to identifying the relationships among major attributes that affect the SQ of bus transit in the city of Dhaka in Bangladesh. Specifically, 22 bus transit SQ attributes, drawn from 655 questionnaires, are used to develop different SEM models for the city. Along with stated preferences, the effect of three latent variables on SQ is analyzed. Among the developed models, the best model is selected by using different statistical approaches. With the best model, selected attributes are rated according to their relative importance on SQ. Acknowledging limited resources of a developing nation, this study gives a clear way ahead to planners, operating companies and transport managers to design appropriate transport policies which will ensure more effective services to current bus users as well as attracting new passengers.     

谈农村公路工程造价的控制

农村公路项目工程造价控制工作贯穿于项目建设的全过程,在这期间,着重立项、设计阶段,不忽视招投标与施工结算阶段,加强项目完结后的评价工作,这是行之有效的方法。     

Modelling with joint choice of ports and countries of origin and destination: application to Colombian ports

Literature has focused on studying port choice independently or as an element of a supply chain without considering the joint selection with the country of origin/destination of the imports/exports. However, the characteristics and location of a port may make it more attractive to mobilise more freight from/to some particular countries rather than others, making the port choice decision dependent on the country of origin/destination of the cargo. This article proposes advanced econometric models to evaluate simultaneously port choice and the country of origin/destination choice for Colombian imports and exports. Findings suggest that for imports and exports domestic freight rate is the most important variable for the joint choice process. Also, for exports, maritime transit time is more relevant than for imports, while for the frequency of shipping lines the opposite is true. The existence of a trade agreement and the gross domestic product per capita also have a significant influence on the election of a country for exports/imports.     

The value of transportation accessibility in a least developed country city – The case of Rajshahi City,Bangladesh

Little appears to be known about the capitalization of transportation accessibility in South Asian housing markets, which typically differ from those of industrialized countries. This study starts addressing this gap by providing empirical evidence about the nature and the magnitude of the value of accessibility as reflected by residential rents in Rajshahi City, Bangladesh. Results of our SARAR spatial hedonic model estimated on 526 observations from a random sample collected via in-person interviews indicate that the rent of a multi-unit dwelling decreases by 0.0239% for every 1% increase in network access distance to the nearest major road. Moreover, proximity (within 400 m) to a primary school and to a healthcare facility commands rent premiums of respectively 93.55 BDT ($1.40) and 109.45 BDT ($1.64). Surprisingly, whether access roads are paved or not does not statistically impact rents, probably because of the dominance of walking, rickshaws use, and biking, combined with the rarity of personal cars. Likewise, proximity to bus stops and to train stations is not reflected in rents of multi-family dwellings, likely because buses and trains in Rajshahi City only provide regional and national service. Differences in estimates of our spatial models between maximum likelihood (ML) and generalized spatial two-stage-least-squares illustrate the danger of relying on ML in the presence of heteroskedasticity. These results should be useful for planning transportation infrastructure funding measures in least developed country cities like Rajshahi City.     

山区通村公路低造价水泥混凝土路面结构研究

为充分利用筑路资源、节省工程造价、提高路面设计质量,从交通特征、土基强度、筑路材料等影响因素出发,提出了抛石水泥混凝土、小板块水泥混凝土、低强度水泥混凝土路面三种符合山区通村公路建设资源特点的路面结构形式。采用有限元软件对推荐的路面结构进行了力学分析,并对三种结构形式进行经济比较,确定出工程造价最低的路面结构类型。     

交通强国背景下农村公路建设发展思路研究

交通强国战略提出以来,虽然我国农村公路建设得到了高质量发展,但也存在一些不容忽视的问题。通过反思目前农村公路建设存在的问题,提出了在交通强国背景下,因地制宜完善农村公路建设保障机制、加快建设高质量的农村公路运输物流服务体系、着力构建高效率的农村公路综合交通网络、积极推进高标准的农村公路平安交通体系建设的发展思路。     

国际环境保护合作障碍分析

保护环境是世界各国共同的任务,只有进行广泛而有效的国际合作才能完成。而且保护全球环境是为了全人类的生存和持续发展,是一项造福于全人类的公益事业。共同的目的、共同的利益和共同的危机使得环境保护的国际合作尤显重要。但就目前来看,环境保护的国际合作仍存障碍。     

Lateral dynamics of motorcycles towing single-wheeled trailers

A motorcycle towing a single-wheel trailer may provide useful transport for light cargo on narrow tracks and off-road use, particularly in rural areas of developing countries. Four designs of such trailers are described. Linear models are derived for the lateral dynamics of an off-road motorcycle towing this type of trailer straight ahead at constant speed. The trailers were tested behind an instrumented motorcycle. Linear autoregressive models were fitted to the experimental data using system identification techniques. Analytical and experimentally derived models largely agreed on frequency, damping and shape of the weave, wobble and trailer sway normal modes. The trailers made the motorcycle's steering heavier but the analytical models did not predict this. The location of the articulation axes between the motorcycle and the trailer were found to be critical for stability. The best trailer design handled well with loads up to 200 kg and speeds up to 70 km/h.