论四级公路的行车道宽度

探讨《公路工程技术标准》中四级公路的行车道宽度的不适应性,根据四级公路交通的实际情况提出建议值,可供工程技术人员参考和借鉴。     

基于800/900MHz频段的组合式电子收费车道设计

根据目前国内高速公路联网收费实际和技术条件,结合重庆市电子车牌项目作为省级区域国家级信息化试点的要求,提出了将基于800/900 MHz频段的组合式电子收费车道作为ETC(Electronic Toll Collection,电子不停车收费)快速通行手段的设计方案。该方案与目前MTC(Manual Toll Collection,人工半自动收费)的技术条件和实际环境兼容,并且投资成本低,具有较高的实用性和可操作性。     

自动调温阀拆除对柴油机危害的分析

文章叙述了柴油机冷却水自动调温阀的工作原理和调温特性,分析了调温阀拆除后冷却水温的变化及对柴油机性能的影响,并就维修中燃烧室组件的大量更换是否与调温阀的拆除有关进行了探讨。     

隧道与互通出口小净距路段换道可靠性研究

为分析高速公路隧道与互通出口小净距路段在不同交通流状况下的车辆驶出概率,提出了基于交通仿真的安全换道概率模型。首先,采用VISSIM标定仿真模型并进行正交试验,获取小净距路段在不同净距长度、交通量、驶出比例、大型车比例下的交通数据,在此基础上确定瞬时交通流密度及相应车流平均速度的计算方法,构建相应的分布模型,通过K均值聚类算法研究不同速度下的瞬时交通流密度大小和出现概率;同时引入可靠度方法并利用微分法来构建车辆安全换道概率模型,综合考虑车速、车流密度、目标车道临界可插入间隙等因素的不确定性,应用蒙特卡罗仿真法搭建求解概率模型的算法,并通过MATLAB对模型进行求解;针对分流车初始位置的不同,分别得到了不同交通量、大型车比例、净距长度下的换道驶出成功率,进而研究不同交通流状况组合下的净距长度。结果表明：交通量、大型车比例、净距长度对净距路段内侧车道车辆换道驶出成功率有显著性影响,研究结果可为规范的进一步完善提供参考。     

城市快速公交专用道道路线形设计分析

以汽车的动力特性和通过特性为理论依据,根据目前快速公交专用车辆大都采用低地板大型铰接底地板车辆的现状,结合其容量比一般普通公交大得多的特点,对快速公交专用道的道路线形设计进行分析,提出设计方法。     

Insights on disruptions as opportunities for transport policy change

Policy change is characterised as being slow and incremental over long time periods. In discussing a radical shift to a low carbon economy, many researchers identify a need for a more significant and rapid change to transport policy and travel patterns. However, it is not clear what is meant by rapid policy change and what conditions might be needed to support its delivery.Our contention in this paper is that notions of habit and stability dominate thinking about transport trends and the policy responses to them. We limit variability in our data collection and seek to design policies and transport systems that broadly support the continuation of existing practices. This framing of the policy context limits the scale of change deemed plausible and the scope of activities and actions that could be used to effect it.This paper identifies evidence from two sources to support the contention that more radical policy change is possible. First, there is a substantial and on-going churn in household travel behaviour which, harnessed properly over the medium term, could provide the raw material for steering behaviour change. Secondly, there is a growing evidence base analysing significant events at local, regional and national level which highlight how travellers can adapt to major change to network conditions, service availability and social norms. Taken together, we contend that the population is far more adaptable to major change than the policy process currently assumes.Disruptions and the responses to them provide a window on the range of adaptations that are possible (and, given that we can actually observe people carrying them out, could be more widely acceptable) given the current configuration of the transport system. In other words, if we conceptualise the system as one in which disruptions are commonplace, then different policy choices become tractable. Policy change itself can also be seen as a positive disruption, which could open up a raft of new opportunities to align policy implementation with the capacity for change. However, when set against the current framing of stability and habit, disruption can also be a major political embarrassment. We conclude that rather than being inherently problematic, disruption are in fact an opportunity through which to construct a different approach to transport policy that might enable rather than frustrate significant, low carbon change.     

单线隧道24 m仰拱栈桥施工技术研究

为了加快单线隧道施工进度,并确定24 m自行式液压栈桥施工流程和工艺,通过对24 m栈桥仰拱施工一次性浇筑、一次性浇筑24 m并加防裂网片、分区段12 m同步施工,3种施工方案进行分析,发现一次性浇筑及增加防裂筋施工工艺会出现仰拱断面开裂,分区段12 m同步浇筑既保证仰拱断面无裂纹,也加快了施工进度。文中同时提出多工作面施工理念,合理加快施工进度;通过微创微改在配套的矮边墙模板上焊接定位卡、堵头板采用钢木混合安装,反坡排水;安装移动水箱和预留水沟槽等工艺。     

Traffic noise studies in a tropical environment

This paper reports upon a survey of traffic noise annoyance in three residential districts of Trinidad, West Indies. Householder perceptions were solicited by means of a questionnaire survey and direct measurements of traffic noise levels were taken. The results were compared with surveys elsewhere. It was concluded that household status had little effect on annoyance perception, that at L₁₀ levels greater than 70 dB(A) at a dwelling facade the noise level is unacceptable. L₁₀ levels less than 65 dB(A) at the building facade are not perceived as annoying in the environment considered.     

Safety modeling for two‐way left‐turn lanes and a procedure to identify two‐way left‐turn lane segments with safety concerns

In the past, two‐way left‐turn lane (TWLTL) median treatments have been frequently used in Florida to inexpensively improve traffic and safety performances. In order to identify factors that may have significant impacts on safety operations in TWLTL sections and to identify TWLTL locations that present existing and future safety concerns, a research project was carried out and results are summarized in the paper. In the research, a three‐year crash history database with crashes and section characteristics from a total of 1688 TWLTL sections all over Florida was developed and used. A negative binomial regression model was developed to determine the statistical relationship between the number of crashes per mile per year and several variables such as traffic volume, access density, posted speed, and number of lanes. In regard to the methodology, in order to identify locations with safety concerns, several steps are needed: development of real crash data distribution, determination of statistical distribution models that better represent the actual crash data, determination of percentile values for the average number of crashes, estimation of crash rates for sections with the same characteristics, estimation of critical values for the variables corresponding to the percentile values for average number of crashes, calculation of tables of critical average annual daily traffic values, and generation of a list of TWLTL locations with critical safety concerns. Results presented in the paper have been used in real applications. Copyright © 2012 John Wiley & Sons, Ltd.     

基于驾驶人特性的双车道跟驰模型稳定性分析

为了研究交通拥堵问题，了解交通拥挤形成的过程及驾驶员自身特性对双车道交通流稳定性的影响.本文基于复杂网络聚类同步理论，对一类基于驾驶员特性的双车道跟驰模型的稳定性进行研究. 通过设计适当的控制器使得基于驾驶人特性的双车道车辆跟驰模型趋于稳定，并得到了模型稳定性的条件.此外，在双车道上的车辆受到随机外部扰动的情形下，利用具有外部扰动的复杂网络自适应H∞ 聚类同步理论，研究了外部扰动情形下基于驾驶人特性的双车道车辆跟驰模型的稳定性.最后，采用MATLAB仿真技术进行数值模拟，验证所设计控制器对双车道交通流稳定性的影响及不同的驾驶员性格特性对交通流运行的影响.