Deconstructing development density: Quality, quantity and price effects on household non-work travel

Smart growth and transit-oriented development proponents advocate increasing the density of new land development and infill redevelopment. This is partly in order to reduce auto use, by reducing distances between trip origins and destinations, creating a more enjoyable walking environment, slowing down road travel, and increasing the market for transit. But research investigating how development density influences household travel has typically been inadequate to account for this complex set of hypotheses: it has used theoretically unjustified measures, has not accounted for spatial scale very well, and has not investigated potentially important combinations of measures. Using data from a survey of metropolitan households in California, measures of development density corresponding to the main hypotheses about how density affects travel—activity density affecting distance traveled, network load density affecting the speed of auto travel, and built form density affecting the quality of walking—are tested as independent variables in models of auto trip speed and individual non-work travel. Residential network load density is highly negatively correlated with the speed of driving, and is also highly correlated with non-work travel, both singly and in combination with other measures. Activity density and built form density are not as significantly related, on their own. These results suggest that denser development will not influence travel very much unless road level-of-service standards and parking requirements are reduced or eliminated.     

动态设计在新七道梁特长公路隧道建设中的尝试

根据兰临高速公路新七道梁隧道施工中围岩开挖和支护变形的实际情况,通过对隧道支护、衬砌结构进行动态设计的尝试,取得了预期的建设成果;提出了隧道建设动态管理的几点建议,对今后的公路隧道建设管理有一定的借鉴作用。     

新型废胶粉改性沥青混合料的路用性能试验研究

文章针对我国道路沥青温度敏感性大的问题,通过在沥青中掺入不同剂量的废旧橡胶粉进行沥青改性及路用性能指标检测试验,研究橡胶粉的剂量对基质沥青性能的影响。试验结果表明,橡胶粉的最佳剂量为15%。     

东巴凤公路灾害的防范与治理

文章分析了广西东巴凤公路目前在修建和养护中出现的病害成因,提出了防护与治理的相关性建议,为类似公路灾害的防护与治理提供参考。     

动力学法监测路基压实技术的应用

针对路基压实质量较难检测的现状,以连续测试路基结构抗力变化信息为特色的动力学检测方法应用于路基压实质量监督工作中.通过路基结构在形成过程中抗力的变化来评价压实状态的变化,实现了在压实过程中连续实时的质量监控.     

A list of accident scenarios for three legs skewed intersections

The term ‘scenario’ is used in the safety field to designate a prototype or a model of an accident process characterised by chains of facts, actions, causal relations and consequences in terms of damage to people and property. The prototypical scenarios, properly realized, provide a basis on which to consider the action to be taken, but also a concrete backup for accident information for use in information campaigns or training. The objective of this study is to define the prototypical accident scenarios for a particular configuration of road intersection: the skewed intersection. Limited sight distance at skewed intersections leads to safety issues. A non-skewed intersection provides the best operating conditions as drivers can easily sense the direction in which they are travelling, estimate the speeds of the opposing traffic and smoothly complete a maneuver in shorter time. In skewed intersections, instead, the ability of drivers to recognize any conflicting vehicles diminishes in comparison to right-angle intersections. The logical-deductive approach used in this paper for the determination of accident scenarios is based on an analysis of a large database of incidents, which occurred on several roads in eastern Sicily on 35 skewed intersections at three-legs. The skew angle of the minor leg of all the intersections studied is between 15° and 20°. This research allowed to develop accident scenarios related to particular configurations of intersections, compatible with the Italian rules. Prototypical scenarios are constructed using samples of accidents occurring on a particular type of study area, especially when they are based on files from in-depth investigations. The method used is an inductive approach, based on an examination of each case, grouping together similar cases and building a prototypical scenario using this case grouping. From the in-depth analysis of database accidents 9 prototypical accident scenarios have been identified for the skewed intersections.     

Factors with the greatest influence on drivers' judgment of roundabouts safety. An analysis based on web survey in Italy

The aim of this paper is to identify the roundabout geometric characteristics affecting the safety perception while the typical maneuvers (entry, circulation, exit) are being carried out. The tool used was an on-line questionnaire, filled out by about 1.650 respondents. Four different dimensionality reduction methods (Cluster Analysis, Correspondence Analysis, Exploratory Factor Analysis and Confirmatory Factor Analysis) were used to analyze the data collected from the survey, in order to examine the key factors affecting the safety perception during the typical roundabout maneuvers. The considerations arising from the final model are the following: 1) the respondents' opinions regarding the safety perception of maneuvers are not preconceived ideas, but they originate from specific safety perceptions due to roundabout geometric configurations; 2) the users prefer definitely single lane roundabouts; this is an important confirmation of most results in the literature; 3) it was quantified the extent of the relationship between the safety perception of the typical roundabout maneuvers and the following aspects: a) maneuver type, b) geometric characteristics of the roundabouts design elements. This is the innovative aspect of the present research whose results have implications regarding theory, infrastructure and the application of new safety technologies.     

基于山区复杂路段下的车辆主动限速控制系统研究

山区复杂路段交通事故频发,行车安全问题亟待解决,因此研究该路段下的主动限速控制技术具有重要意义。本文阐述了主动限速控制系统的原理与构成,并且对车辆的运行安全车速进行了分析与建模,提出了主动限速的控制策略。最后通过对该系统软硬件进行了调试,初步验证了其可行性比较合理,能够指导驾驶人的行车安全。     

基于层次分析法的东海二桥建设方案模型

洋山港二期正式投入运营,东海二桥也正在规划当中,关于东海二桥的建铁路桥、公路桥还是公路铁路两用桥的争议一直没有停止过,不同的专家给出了不同的答案。本文在分析影响东海二桥建设方案选取的通过能力、投资额、营运安全和环保等四个因素的基础上,通过建立层次分析模型并求解,得出东海二桥最佳建设方案。