Air Quality of Inner-city and Other Non-Motorway Roads Within the Netherlands: a National Overview, Forecast and Analysis
W Korver, J de Bruijn, Goudappel Coffeng, NL; K Krijgsheld, Ministry of Housing, Spatial Planning and the Environment, NL
A national overview and insight in the amount of PM10 and NO2 locations which exceeds the air quality standards within the Netherlands. And also an assessment of the possibilities for local governments to resolve the remaining problems.
Almost 50% of all road traffic occurs on other roads than the motorway network. A national overview of the actual air quality situation however is missing. The Dutch ministry of Housing, Spatial Planning and the Environment asked Goudappel Coffeng to do a study to for all non-motorway roads, with the following questions. To give a national overview and insight in the amount of PM10 and NO2 locations which exceeds the air quality standards for the actual situation and for the years 2010 and 2015, divided into: Number and size of the bottlenecks; classification of these bottlenecks in such a way that the impact of possible policy measures can be calculated; an assessment of the number of persons living in an area exceeding the air quality standards. And also to make an assessment of the possibilities for local governments to resolve the remaining locations exceeding the air quality standards.
Total road length within the Netherlands is 132,000 km. To calculate the local contribution of road traffic to the PM10 and NO2 concentrations for all these roads is an immense task. A number of simplifications had to be made. Only roads were selected which have the potential of exceeding the NO2 air quality standard. This was based on assuming a worst case approach: maximum share of heavy road traffic and stop and go traffic. Based on these criteria circa 5,000 km of roads (4% of all roads) were selected. Along these roads almost 900 thousands people are living in an area with the potential of exceeding the air quality standards. For these roads all kind of relevant geometric information is collected. Based on this it was possible to calculate for every selected location the levels of NO2 and PM10 concentrations and the contribution of the local road traffic within these concentrations.
Different variants were distinguished, these were: the actual situation, the situation in 2010 and 2015 without any extra policy measures, the situation in 2010 and 2015 with a high ambition policy scenario (a situation in which a maximum policy effort is assumed to reduce the emissions levels of road vehicles). And also a differentiation is made in which the see salt reduction for PM10 is applied.
Finally for three case studies (three cities) a number of local policy scenarios are evaluated on their impact on the air quality. These policy scenarios are divided into three levels (a light, a medium and a heavy package of local policy measures).
Circa 500,000 people live in an area in which the air quality exceeds the standard for NO2. Without any new policy measures this number decreases with 60% to 200,000 people and in 2015 towards 160.000 people. Assuming a maximum policy effort at the national level this could decrease in 2010 to 110,000 people and to even 24,000 people in 2015.
For the actual situation almost every selected location leads for PM10 to a level which exceeds the standard. Without any additional policy actions the number of people living in an area exceeding the PM10 average day standard decreases by 8% in 2010 and 10% in 2015. The deduction of sea salt leads to an improvement, the people exposed to a too high level of PM10 concentrations decreases in 2010 with 21% and in 2015 with 29%. Assuming a maximum policy effort at the national level the number of people living in an area where the PM10 standards are exceeded, decreases in 2010 to circa 550,000 (-33%) and to 340,000 in 2015. In general it can be concluded that PM10 concentrations will, despite a package of national policy measures, exceed the standards on many locations. It is important to notice that for the actual situation on a lot of locations the background concentration itself is already responsible for exceeding the standards.
The contribution of local traffic to the concentration levels is the highest for NO2. The share of local traffic in the NO2 concentrations amounts to 25%. Important to notice is that for those locations where the standards are exceeded the share of local traffic in the NO2 concentrations will increase; in the high ambition scenario in 2015 even to 40%. The contribution of local road traffic to the PM10 concentrations averages 10%. And this share remains more or less the same for the coming years, in both scenarios.
Locations with too high NO2 concentrations can be characterized by: most locations are found in the build up environment: measured in inhabitants exposed 93% of all locations, a very high share (>50%) of urban roads with buildings at both sides of the road (street canyons), high traffic intensities, relative high levels of freight traffic and low traffic speeds. Locations with too high PM10 concentrations can be characterized by (figures for the situation 2015 high ambition scenario): most locations are found in the build up environment: measured in inhabitants exposed 94% of all locations; a high share (37%) of urban roads with buildings at both sides of the road (street canyons), but at the same time other types of roads are important as well; traffic intensities are more or less average; the share of freight traffic is the same for locations which exceeds the standards and which don?t and low traffic speeds.
In general it can be said that locations with too high levels of NO2 concentrations can be influenced by a number of transport policy options (limiting freight traffic, increasing the traffic circulation, etc.). But that for those locations with too high levels of PM10 it is much more difficult to find an effective transport policy measure.
For the cities Rotterdam, Utrecht and Eindhoven three local transport policy packages were evaluated. Based on these case studies it can be concluded that there is not one successful local policy package. Local situation differ and therefore also the mix of transport policy measures differs. For reducing the NO2 concentrations limiting freight traffic is in general the most effective policy measure. And for reducing the PM10 concentrations limiting overall (passenger) traffic is in general the most effective policy measure.
Association for European Transport