| 2. |
Characteristics and Forms of the
Urban Climate . |
||
|
|||
.
|
2.8.1 The
Road as Pollutant Source
The growth in individual motorized traffic (IMT) – which can be expected to continue increasing in the future with the common market of the European Community and the opening of the borders to the East – places new demands on transportation policy. In many places, people today already speak of a collapse in traffic conditions on the roads, particularly in built-up areas. This increase in traffic is connected with a substantial burden on the environment, especially through noise (STAEDTEBAULICHE LAERMFIBEL, 1994, 2001, 2007) and air pollution. With this in mind, discussion about the "traffic of tomorrow" has recently been strengthened. The introduction of pollutants into the atmosphere is not, however, only important on the local and regional levels. Owing to new realizations about the air chemistry in the stratosphere and the effect of greenhouse gases on the world climate, this aspect has attained a fully new, global dimension (see also Chapter 2.12). The automobile dominates person and cargo traffic in the Federal Republic of Germany. As such, in 2002 about 78% of the 917 billion total person-kilometers were driven with passenger cars, and nearly 70% of the 509 billion total ton-kilometers were driven with trucks. Figure 2/15 shows the proportion of pollutant emissions attributed to road traffic in the Federal Republic of Germany in reference to the year 2002. The amount of pollutants produced by traffic was 37% of carbon monoxide (CO), 42% of nitrogen oxide (as NO2), 11% of NMVOC, and 18,5% of the greenhouse gas carbon dioxide (CO2). In November 1990 the 35th Conference of Environmental Ministers decided upon the following reduction goals for traffic emissions in the former West Germany (Table 2/2). Important consequences have the pollutants coming from traffic in connection with a new guideline of the EU because all limit values there are valid in all EU countries. When the declared limit values are reached there must be to install a air pollution abatement plans and it is allowed to reduce traffic to reduce air pollution too.
Table 2/2: Reduction goals for traffic emissions in the former Federal Republic of Germany (reference year 1987). Resolution of the 35th Conference of Environmental Ministers; values in parentheses: technical reductions achievable in the EC (reference year 1987; optimistic assumptions) The limit values are listed in the 22rd order to the Federal Emission Protection Law (2007). In a lot of street canyons in german cities the limit values for NO2 and PM10 are exceeded und this will be true also in the year 2010. The immissions situation of a location is formed partially by local emissions and their source altitude (very close to the ground for auto traffic), but also by local propagation conditions, in which wind and vertical temperature distribution play an important role (see Chapter 2.7). Figure 2/16 shows the air hygiene situation in the region of Stuttgart in the presence of low wind velocity and an inversion hindering the vertical air exchange with higher air layers. |
| . | |
| . . |
|
|
|||
| . | |||
|
|
|||
| Fig. 2/16: Obstructed air exchange with concentrated pollutants during a low-altitude inversion | |||
| . | |||
|
|
|||
|
