A New Concept for Air Quality Modelling in Street Canyons

We present an analytical model that predicts concentrations in street canyons assuming a uniform distribution within a street, dimensioned by its length and width and the height of the surrounding built-up area. Using the Prandtl-Taylor hypothesis, the concentration in the street is determined from a mass flux balance between a horizontal advective flux, a turbulent diffusive vertical flux and a continuous road transport emission source. The model does not necessarily assume re-circulation of the flow in the street canyon, but rather considers the turbulent intermittency in the shear layer shed from the upwind roof level as the driving force. This concept is in agreement with recent measurements and observations. The model has been applied to compute benzene concentrations based on hourly emissions obtained for 1963 streets and road segments in the City of Antwerp, Belgium. The results are compared with diffusive sampler measurements carried out at 101 locations in several streets of Antwerp, during 4 periods of 5 days in 1998. When averaged over periods of 5 days, the calculated benzene concentrations show a very good agreement with the results obtained by the diffusive sampler measurements.     

城市道路交通可持续发展模式及其评价

首先在已建立的城市道路交通系统可持续发展评价指标体系的基础上提出了两种交通规划模式，即供需平衡模式和环保模式，然后讨论了基于这两种模式的规划方案的具体生成方法，最后，给出了各种发展模式自动评价系统的实现过程。     

城市道路交通安全GIS系统的研究

GIS系统是有效提高城市道路交通安全管理的水平 ,减少事故的发生 ,使事故对道路通行的影响最小化 ,并有效合理分配交通流的重要手段。笔者在研究城市道路交通安全GIS系统的基础上 ,讨论了数据的来源、专题信息图层的构建 ;提出了系统开发的主要技术 ;介绍了道路交通安全信息的采集、查询和更新 ,交通事故信息的分析与预测 ,交通事故管理等功能 ;并提出了基于道路交通安全GIS系统事故管理的一些新方法。     

高温气冷堆新燃料运输事故频率分析

商用高温气冷堆核电站是中国未来可能发展的第四代核电站,其新燃料元件和运输容器有显著的特点.探索了将概率安全评价(PSA)方法引入放射性物品运输的辐射风险评价中,首先用故障树方法分析了高温气冷堆新燃料元件公路运输的潜在事故频率,经过事故情景分析、力学分析和临界分析,选择了货包辐射水平升高和临界两种潜在事故予以分析.结果表明,货包辐射水平升高的事故频率很低;临界事故的频率极低,在后续的风险评价中可忽略.     

北京市交通扬尘PM2.5排放清单及空间分布特征

为建立一种自下而上的交通扬尘PM_2.5排放清单方法,对北京市不同区域、不同类型道路的路面积尘负荷进行了采样和实验室分析,对各类路网的道路车流量和车辆类型进行了调查和统计,建立了北京市道路交通扬尘PM_2.5排放清单,并对其空间分布进行了分析. 结果表明:北京市城区快速路、主干道、次干道、支路和胡同的交通扬尘PM_2.5排放因子分别为(0.05±0.03)(0.09±0.05)(0.11±0.05)(0.16±0.14)和(0.27±0.20)g/(km·辆),相应各类型道路的交通扬尘PM_2.5排放强度分别为(7.21±4.66)(5.27±3.03)(3.34±1.49)(2.84±2.49)和(0.54±0.40)kg/(km·d);郊区高速路、国道、省道、县道、乡道和城市道路的交通扬尘PM_2.5排放因子分别为(0.10±0.03)(0.50±0.33)(0.39±0.37)(0.41±0.41)和(0.65±0.31)(0.19±0.08)g/(km·辆),各类型道路交通扬尘的PM_2.5排放强度分别为(3.82±1.31)(10.00±6.58)(3.93±3.74)(1.64±1.63)(0.65±0.31)和(0.74±0.32)kg/(km·d). 北京市道路交通扬尘PM_2.5的年排放量为13 565 t,从空间分布上看,郊区交通扬尘PM_2.5年排放量、单位道路长度排放量以及排放因子均高于市区,而城区单位行政区面积的交通扬尘PM_2.5排放量高于远郊区县. 从交通扬尘PM_2.5排放的空间分布特征看,在继续加强城区交通扬尘控制的同时,应采取措施控制远郊区县公路的扬尘排放. 自下而上的交通扬尘PM_2.5排放清单提高了排放的时空分辨率,能够识别路网中高排放的区域和路段,为交通扬尘总量管理和减排目标考核提供了一种技术手段.      

Mortality from road traffic accidents in a rapidly urbanizing Chinese city: A 20-year analysis in Shenzhen, 1994–2013

Objective: This study aimed to describe the trends of motorization and mortality rates from road traffic accidents and examine their associations in a rapidly urbanizing city in China, Shenzhen.

Methods: Using data from the Shenzhen Deaths Registry between 1994 and 2013, we calculated the annual mortality rates of road traffic accidents, in addition to the age- and sex-specific mortality rates and their annual percentage changes (APCs) for the period of 2000–2013. We also examined the associations between mortality rate of road traffic accidents and traffic growth with Spearman's rank correlation analysis and a log-linear model derived from Smeed's law.

Results: A total of 20,196 deaths due to road traffic accidents, including 14,391 (71.3%) male deaths and 5,805 (28.7%) female deaths, were recorded in Shenzhen from 1994 to 2013. The annual mortality rates in terms of deaths per population and deaths per vehicle changed in similar patterns, demonstrating an increase since 1994 and peaking in 1997, followed by a steady decrease thereafter. The decrease in mortality was faster in individuals aged 20 year or older compared to those younger than 20 years. The mortality rates in term of deaths per population were positively correlated with the total number of vehicles per kilometer of road but negatively correlated with the motorization rate in term of vehicles per population. The estimated model for deaths due to road traffic accidents in relation to the total population and the number of registered vehicles was ln (deaths/10,000 vehicles) = ?1.902 × ln (vehicles/population) ? 1.961. The coefficient was statistically significant (P < .001) and the coefficient of determination was 0.966, indicating a good model fit.

Conclusions: We described a generally decreasing trend in the mortality rates of road traffic accidents in a rapidly urbanizing Chinese city based observations in the 20-year period from 1994 to 2013. The decreased mortality rate may be explained by the expansion of road network construction, improved road safety regulations and management, as well as more accessible ambulance services in recent years. Nevertheless, road traffic accidents remain a universal problem of great public health concern in the whole population.     

Analysis of posttraumatic stress disorder in children with road traffic injury in Wenzhou,China

Objective: Road traffic accidents are the leading health threat to children and cause significant long-term mental health problems. This study aimed to characterize posttraumatic stress disorder (PTSD) in children suffering from road traffic injuries (RTIs) in Wenzhou, China.

Methods: We conducted a retrospective study of 537 children (aged 1 to 13 years old) with RTIs. The epidemiological features, PTSD incidence, clinical manifestation, and risk factors were analyzed based on a customized PTSD risk factor questionnaire. The outcome factors were also evaluated by means of the logistic regression method.

Results: The PTSD incidence was 24.77% in children with RTIs. The incidence of PTSD was related to the personality, family environment, and family care of the children. It was found that early psychological intervention and reasonable family care from the family might promote physical and mental welfare as well as contribute to the development of more effective treatments to prevent PTSD.

Conclusion: For susceptible children, in addition to dealing with the somatic injury, psychological intervention and family care should be carried out as early as possible.     

从道路设计角度改善交通空气质量的可行性分析

道路交通是重要大气污染源之一,随着机动车数量的增加,其排放污染物对环境空气质量和人体健康的影响日益严重。影响道路环境空气质量的主要因素包括机动车排放、扩散状况和受体分布。道路设计能够从道路线形、道路设施及配置等方面影响到机动车运行排放水平并改变污染物扩散,从而影响到公众的污染物暴露水平。从道路线形、地形位置、路边设施(声屏障、树木绿化)等方面综述了道路设计要素对路边空气质量影响的研究现状,表明了从量化道路设计指标角度改善交通空气质量的可行性;在美国道路建设和环境符合性方面的政策分析基础上,分析了我国道路建设总流程中环境考虑要素,以期为进一步完善我国道路设计导则提供参考。     

The use of navigation systems in naturalistic driving

Objective: In this study, we assessed the use of portable navigation systems in everyday driving by applying in-vehicle naturalistic driving.

Method: Experienced users of navigation systems, 7 females and 14 males, were provided with a specially equipped vehicle for approximately 1 month. Their trips were recorded using 4 cameras, Global Positioning System (GPS) data, and other sensor data. The drivers’ navigation system use data were coded from the video recordings, which showed how often and for how long the system was activated and how often and for how long a driver operated the system.

Results: The system was activated for 23% of trips, predominantly on longer and unique trips. Analyses of the percentage of time for which the speed limit was exceeded showed no evidence of differences between trips for which the navigation system was used or not used. On trips for which the navigation system was activated, participants spent about 5% of trip time interacting with the device. About 40% of interacting behavior took place in the first 10% of the trip time, and about 35% took place while the car was standing still or moving at a very low speed; that is, 0–10 km/h.

Conclusion: These results shed light on how and when drivers use navigation systems. They suggest that although drivers regulate their use of such systems to some extent, they often perform risky tasks while driving.     

Identification methods of key contributing factors in crashes with high numbers of fatalities and injuries in China

Objectives: In China, serious road traffic crashes (SRTCs) are those in which there are 10–30 fatalities, 50–100 serious injuries, or a total cost of 50–100 million RMB (U.S.$8–16 M), and particularly serious road traffic crashes (PSRTCs) are those that are more severe or costly. Due to the large number of fatalities and injuries as well as the negative public reaction they elicit, SRTCs and PSRTCs have become of great concern to China during recent years. The aim of this study is to identify the main factors contributing to these road traffic crashes and to propose preventive measures to reduce their number.

Methods: 49 contributing factors of the SRTCs and PSRTCs that occurred from 2007 to 2013 were collected from the database “In-depth investigation and analysis system for major road traffic crashes” (IIASMRTC) and were analyzed through the integrated use of principal component analysis and hierarchical clustering to determine the primary and secondary groups of contributing factors.

Results: Speeding and overloading of passengers were the primary contributing factors, featuring in up to 66.3 and 32.6% of accidents, respectively. Two secondary contributing factors were road related: lack of or nonstandard roadside safety infrastructure and slippery roads due to rain, snow, or ice.

Conclusions: The current approach to SRTCs and PSRTCs is focused on the attribution of responsibility and the enforcement of regulations considered relevant to particular SRTCs and PSRTCs. It would be more effective to investigate contributing factors and characteristics of SRTCs and PSRTCs as a whole to provide adequate information for safety interventions in regions where SRTCs and PSRTCs are more common. In addition to mandating a driver training program and publicization of the hazards associated with traffic violations, implementation of speed cameras, speed signs, markings, and vehicle-mounted Global Positioning Systems (GPS) are suggested to reduce speeding of passenger vehicles, while increasing regular checks by traffic police and passenger station staff and improving transportation management to increase income of contractors and drivers are feasible measures to prevent overloading of people. Other promising measures include regular inspection of roadside safety infrastructure and improving skid resistance on dangerous road sections in mountainous areas.