Investigation of helmet use behavior of motorcyclists and effectiveness of enforcement campaign using CART approach

Use of the helmet is beneficial in reducing the severity of injuries and avoiding fatalities for motorcyclists, therefore, legislation exists in almost all countries. In practice, the situation is different regarding the helmet use, especially in the developing countries. This paper investigates the helmet use behavior of motorcyclists in Karachi, Pakistan. It determines the significant factors affecting the helmet use in Karachi (Pakistan) and recommending effective campaign measures to promote helmet use. It is vital in relation to the exponential growth of motorcycle users and poor enforcement of traffic rules. Repeated cross-sectional data collected before (n = 226) and after (n = 277) the helmet use enforcement campaign is analyzed using univariate and non-parametric classification and regression tree (CART) techniques. A significant number of motorcyclists do not hold a driving license and CART analysis highlighted the significance of this variable along with exposure to the road environment (measured as daily usage of motorcycle) to explain helmet use. Campaign effects are found temporary, therefore, serious efforts are required to design coherent and structured awareness and enforcement programs.     

基于分段变维的沥青路表纹理磨光行为分析（双语出版）

为了多尺度表征沥青路表纹理磨光行为，揭示其表面纹理磨光演化机理，首先基于沥青表面纹理的自仿相似特性，引入高差自相关函数，将常维分形扩展至分段变维分形，建立了表面纹理分段变维评价模型。其次，分别选取高磨光值的玄武岩和低磨光值的石灰岩成型沥青混合料试件，对其进行岩相鉴定，借助平板磨光机进行室内加速磨光试验，测量了不同磨光状态下的动摩擦因数，同时采用三维激光扫描仪获取了表面纹理信息。最后分析了断面轮廓分段变维高差自相关特性，并与摩擦因数进行了对比分析。结果表明：路面在大尺度范围内有明显的分段变维特征，高差自相关函数可以多尺度量化沥青混合料表面微观至宏观纹理特征，2种路表宏微观纹理界限波长为0.4 mm左右；截止波长可以作为评价普通磨光和差异磨光的指标，其中水平截止波长表示路面平均微凸体尺寸，垂直截止波长表示骨料平均高度；随着磨光转数的增加，受2种磨光机制影响的试件（玄武岩）表面纹理的水平截止波长变化甚微，而受普通磨光机制作用的试件（石灰岩）表面纹理的水平与垂直截止波长均下降明显；在道路设计和施工过程中，选取矿物组成成分更多、粒径分布更广、矿物质间硬度相差较大的集料，更容易受到2种磨光机制的影响，从而有助于沥青路表保持足够的表面纹理水平，延缓路面抗滑性能衰减速率。     

车队认知能力增强的通信区块间隙优化方法

为了在单车超越车队的过程中缩短超车车辆与车队间通信范围，减少车队通信压力，锁定影响车辆入队的关键车队区块，同时通过将待进入关键区块的车队进行间隙优化调整，为驾驶人提供定制化换道入队引导服务，提出了基于驾驶人超车风格特征参数的车队内信息传输关键区块锁定算法，通过分析影响驾驶人换道入队位置范围的关键因素，将驾驶人换道入队过程分为本车道速度调整过程与入队速度调整过程，利用非参数贝叶斯算法获取驾驶人超车换道特征数据并提出基于关键区块所在车队位置序列的车辆间隙优化调整策略。研究结果表明：超车车辆加速度、与前车预计碰撞时间、与车队相对速度是影响驾驶人换道入队范围的关键因素；通过非参数贝叶斯算法将超车车辆运行数据分类获取的驾驶人换道入队驾驶操作基元，可准确提供驾驶人行为特征关键参数；通过将驾驶人换道特征分为48个子类型，可锁定驾驶人换道入队范围且车队关键区块范围随着超车车辆与车队速度差值不同在各个特征类型上呈现不同变化趋势；针对驾驶人入队特征对待进入车队关键区块的车辆间隙进行优化调整，不仅可以为驾驶人提供可接受的驾驶辅助信息，同时减少了车队间隙产生过程中车辆加速度范围，提升了车队运行的舒适性。     

Stated preferences for investigating commuters' diversion propensity

A reasonable response to increasing traffic congestion may come from the rapidly developing traveler information systems. Such systems may be successful if they effectively influence drivers' enroute decisions; in this regard, a critical factor may be commuters' willingness to divert from their regular route in response to information about traffic congestion. This study evaluates the effects of real-time traffic information along with driver attributes, roadway characteristics and situational factors on drivers' willingness to divert.The empirical portion of this study is based on a survey of downtown Chicago automobile commuters. The stated preference approach was used to study commuters' diversion propensity. Drivers expressed a higher willingness to divert if expected delays on their usual route increased, if the congestion was incident-induced as opposed to recurring, if delay information was received from radio traffic reports compared with observing congestion, and if trip direction was home-to-work rather than work-to-home. Respondents were less willing to divert if their alternate route was unfamiliar, unsafe or had several traffic stops. Socioeconomic characteristics were also significant in predicting willingness to divert.     

The socio-cognitive links between road pricing acceptability and changes in travel-behavior

The objective of this study is to examine the effect of road pricing on people’s tendency to adapt their current travel behavior. To this end, the relationship between changes in activity-travel behavior on the one hand and public acceptability and its most important determinants on the other are investigated by means of a stated adaptation experiment. Using a two-stage hierarchical model, it was found that behavioral changes themselves are not dependent on the perceived acceptability of road pricing itself, and that only a small amount of the variability in the behavioral changes were explained by socio-cognitive factors. The lesson for policy makers is that road pricing charges must surpass a minimum threshold in order to entice changes in activity-travel behavior and that the benefits of road pricing should be clearly communicated, taking into account the needs and abilities of different types of travelers. Secondly, earlier findings concerning the acceptability of push measures were validated, supporting transferability of results. In line with other studies, effectiveness, fairness and personal norm all had a significant direct impact on perceived acceptability. Finally, the relevance of using latent factors rather than aggregate indicators was underlined.     

The effects of social networks on choice set dynamics: Results of numerical simulations using an agent-based approach

Activity-based analysis has slowly shifted gear from the analysis of daily activity patterns to the analysis and modeling of dynamic activity-travel patterns. In this paper, we address one type of dynamics: the formation and adaptation of location choice sets under influence of dyad relationships within social networks. It extends the dynamic model developed in earlier work, which simulates habitual behavior versus exploitation and exploration as a function of discrepancies between dynamic, context-dependent aspiration levels and expected outcomes. Principles of social comparison and knowledge transfer are used in modeling the impact of social networks through information exchange, adaptations of spatial choice sets and formation of common aspiration levels. We demonstrate model properties using numerical simulation with a case study of shopping activities.     

超细钢纤维对水泥砂浆强度影响的试验研究

通过试验对比研究不同体积率超细钢纤维、普通钢纤维对水泥砂浆抗折强度、抗压强度、压折比的影响。试验结果表明：超细钢纤维水泥砂浆的抗折强度随着钢纤维体积率的增大而提高,钢纤维体积率超过1.5%以后,超细钢纤维对水泥砂浆抗折强度的提高幅度要大于普通钢纤维,在钢纤维体积率为2.5%时,超细钢纤维水泥砂浆抗折强度达到最大值13.9MPa;超细钢纤维对水泥砂浆抗压强度的提高幅度略低于普通钢纤维;超细钢纤维水泥砂浆能明显降低水泥砂浆的压折比,提高砂浆韧性。     

停车费率对客运枢纽停车行为的影响研究——以苏州市汽车南站为例

基于对苏州市汽车南站的停车行为调查,分析停车收费、停车后的步行距离、停车场使用的方便程度以及停车目的等对停车行为的影响,确定停车者停车的效用函数,建立分析停车者停车行为的多项Logit模型,并验证模型的可行性。     

道路交通行为控制方法研究

交通控制一般分为交通系统控制和交通行为控制,其中交通行为控制涉及人的行为控制,是交通控制研究困难的主要原因之一。阐述行为控制的概念和方法,概括道路交通行为控制中存在的问题,借鉴管理学和经济学中对行为的研究方法,分析交通行为控制的对象及其特点属性,以＂交通人＂表达特性,承载假设和特点,同时在归纳行为过程及对行为产生影响的各种因素基础上,对行为的可控性进行探讨,并根据交通行为控制的六项原则,最终提出交通要素控制、交通行为约束和通行行为控制三大类交通行为控制方法,这对实际工作具有一定的指导意义。