Vehicles, road traffic

Real-world emission rates of in-use motor vehicles (road traffic) can be quantified by measurements in road mnnels. The results reported for particle mass emissions in PMio varied from several mg veh km to some hundred mg veh km , with reduced amounts for the fine particle fraction PM2.5. The particles released mainly consist of EC, OC, soluble ions (NHj, S04 , NOs ) and mineral components (Si, Fe, Ca, Al, Mg). Trace metal emissions (Ba, Co, Cr, Cu, Mn, Ni, Pb, Sb, Sn, Sr, Ti, V, Zn) contribute usually for less than 1 % of total emissions in all size fractions. Observed particulate vehicle emissions could be attributed to several tailpipe and non-tailpipe sources. The main part of carbon emissions may be contributed to tail-pipe exhaust fraction, whereas the non-carbon emissions are most likely non-exhaust derived components. PMjo emissions are usually dominated by resuspended matter as well as by brake wear, whereas fine particles (PM2.5) are mainly derived from combustion processes. 

The reasons for the non-attainment of the PM10 limit values were also stated in the notifications of time extensions. In most cases, it was stated that non-attainment by 2005 could be attributed inter alia to a delay in the implementation of measures, or certain measures leading to a lower level of emission reductions than expected. An increase in road traffic is stated as a reason for non-attainment especially in eastern European countries. An increase of primary NO2 emissions due to an increasing share of diesel vehicles has been reported e.g. by France, Germany, Italy and UK. 

Compared to other cities, the modal split of Athens shows a rather high share of private vehicles. Freight transport is also mostly done by road traffic. Even though a ban on private diesel vehicles has been in place since 1992, emissions from traffic are of major importance. The measures proposed in the notification of time extensions and the air quality plan for Athens address the main sources and are aimed at improving public transport. Hence, if these measures are far-reaching enough, if they cover a substantial part of the relevant sources and are implemented in an effective way, a substantial decrease of the pollutant levels can be expected. 

The main sources are road traffic and natural sources. Various high impact measures such as a low emission zone and the renewal of the public transport fleet are foreseen in Lisbon [6]. Further measures might be implemented to reduce the share of diesel vehicles, and to increase the share of bicycles. 

Smit R, Ntziachristos L, Boulter P (2010) Validation of road vehicle and traffic emission model - a review and meta-analysis. Atmos Environ 44 2943-2953... 

From an emission point of view, in spite of the constant technical developments of less pollutant vehicles and the implementation of diverse mitigation strategies for PM [31], atmospheric pollution by road traffic has not diminished for pollutants such as N02. Also it has to be highlighted the poor understanding of the so-called non-exhaust emissions as a major source of urban PM. Several studies have shown that the importance of these non-exhaust emissions is comparable (or even higher) to that of emissions from vehicle exhaust systems [3, 32-34] (Fig. 2). 

Receptor models are widely used tools for apportioning concentrations of pollutants to different sources. They can be factor analytical methods (PMF, PCA, UNMIX, etc.) or chemical mass balance (CMB). On the one hand, these methods revealed to be very valuable to identify the main sources/categories of PM pollution (road traffic, secondary particles, fuel oil combustion, sea salt, etc.) but on the other hand they experienced difficulties in separating the contributions of collinear sources such as mineral dust (natural resuspension) and road dust (anthropogenic) or co-variant sources such as vehicle exhaust and road dust [34, 44, 45, 49, 55, 58, 110-113]). Significant improvements were made with the use of combination of models or constrained models such as the Multilinear Engine (ME-2). 

The rationale of introducing natural gas in road traffic is primarily to reduce emissions. Several factors should be considered when making a decision on putting up an alternative fuel system. LNG is prone to be preferred by heavy vehicles only when payload is important as is the case for large distribution fleets like buses and trucks that operate within reasonable distance from the filling station. Whereas CNG turns better out for small, light vehicles when the routes are not fixed, and payload is no issue. 

Gas analytical instruments for vehicle exhaust emission surveillance, evidential breath alcohol analysis in road traffic and calorific value determination of fuel gases are subject to legal control and require type approval and initial and subsequent verification. The national standards required in this part of gas analysis are provided by BAM. PTB uses in-house standards prepared by dynamic blending to ensure traceability of its type approval... 

The lungs are the main route of elimination (and of uptake) of volatile anaesthetics. Apart from this, they play only a trivial role in drug elimination. The route however, acquires notable medicolegal significance when ethanol concentration is measured in the air expired by vehicle drivers involved in road traffic accidents (via the breathalyser). 

In a study of children in Italy, exposure to exhaust from heavy vehicular traffic in metropolitan areas increased the occurrence of wheezing [332(111)]. In Kenya, children from the urban area were exposed more frequently to motor vehicle fumes on the way to school than rural children [49(111)]. In a study of asthmatic children in The Netherlands black smoke, particulates and ozone were associated with acute respiratory symptoms and medication use [328(111)]. A study of children less than 5 years of age in Birmingham, UK, showed an increased risk of hospitalisation for asthma for children living in areas with high traffic flow [333(111)]. A cross-sectional study of children in Munich, Germany, showed decreased pulmonary function and increased respiratory symptoms among children with high exposure to road traffic [334(111)]. 

To date the majority of on-road traffic is performed by vehicles equipped with internal combustion engines that use fuels derived from fossil fuels. The vehicles range from passenger cars to heavy duty trucks, and the engines used are either spark ignited or compression ignited reciprocating internal combustion devices. 

Road traffic — total traffic volumes — Measured in billion vehicle kilometers... 

Composition and size distribution of the emitted particles depend on the contribution of the individual emission sources related with road traffic—in particular combustion and non-tail-pipe emissions. Tailpipe emissions are vehicle exhaust emissions which are produced during fuel combustion (including additives) and released through the vehicle tailpipe (Rogge et al. 1993 Cadle et al. 1999). The particles derived from tail-pipe emissions are mainly composed of EC and OC, thus average total carbon emission rates are usually very close to the PM mass emission rates. Inorganic anions account for some percent of total tail-pipe emissions, the contribution of the elemental fraction is also in the order of few percent. 

The contribution of the various types of motor vehicles to the total line traffic-generated particulate matter was not quantified in this study. The traffic composition analysis indicated that petrol-driven passenger cars fitted with catalytic converters were the major contributor to traffic counts (about 60%). The daily traffic count ranged from 14,000 to 17,000 vehicles/h (15,500 1,200 vehicles/h). Results showed that traffic pattern on all days of a week had similar trend. Traffic count started to rise between 0700 and 1,300 h (mean 15,000 vehicles/h), before reaching maximum traffic count during 1,300-1,700 h (15,000-17,000 vehicles/h). Traffic counts then decreased between 1,700 and 2,000 h due to the diversion of vehicles towards other alternative routes as the Electronic Road Pricing (ERP)... 

During the process of dam-break evacuation, besides traffic capacity of motor vehicle, non-motor vehicle s traffic load also impacts on the travel time (or travel speed) (Wang Wei, Xu Jian, 1992), therefore, some scholars adopt half-theory and half-experience road resistance function method to calculate the travel time under the heavy mixed traffic situation (Zhang Xingxing, 2011). The major thought is as follows firstly determine the theoretical model of road resistance function based on the relationship of flow, speed and density. In such theoretical model, only consider the influence of traffic volume of motor vehicle, then correct non-motor vehicle s traffic volume, traffic lane number, traffic lane width and traffic disconnection (intersection) and calculation formula is shown below (Li Chaojie, 2007) (Wan Qing, Li Huiguo, 1995)... 

Employers should make road traffic safety a priority, enforcing policies that require use of safety belts and prohibit unsafe behaviors such as impaired driving and use of cell phones and other mobile devices that might distract the driver while the vehicle is in motion, the report concluded. 

An application of a lognormal distribution is conventional for loads due to the road traffic consisting of the sum of a number of identically distributed independent lorries, cars and special vehicles. Thus, the probability distribution of Uve load effects may be treated as a lognormal one as it is recommended by ISO 2394 1998 Eamon and Nowak (2004). According to JCSS (2000), Holicky and Markova (2007), the means and standard deviations of the imcertain-ties of action effects for columns may be defined as ONm = Mm 1.0 and = (tOm 0.1. ... 

In this thesis, the term "Road Safety" is often used instead of "Traffic Safety" because this thesis focuses on road traffic safefy only including road user safety and vehicle safety. The term Traffic Safety is a general term and could refer to the safety of all traffic modes air traffic, sea, rail and road. 

Exposure is an important dimension in road traffic fhat refers to the amount of travel in which accidents may occur. The more we travel on roads, the higher the probabdity of an accident to occur. Without traffic or mobility, there will be no accidents and no road safety problems. Many studies show that there is a correlation between vehicle trafEc volume and the total number of accidents. Moreover, traffic volume (mobility) is one of key issues, which is needed to promote the sustainability of transport in any country. 

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