40 research outputs found
Assessment of the impact of speed limit reduction and traffic signal coordination on vehicle emissions using an integrated approach
Towards a more refined insight in the critical motivating features of choice : an experimental study among recreational rope skippers
Objective: The question whether choice is a motivation and engagement-enhancing practice is a much debated subject, both theoretically as well as in practice. Therefore, the present study examined the impact of different types of choice on engagement and intended perseverance.
Design: and method: In a sample of Belgian rope skippers (n = 159; M-age = 17.17; SDage = 8.43) an experimental field design was implemented, in which three different choice conditions were compared to a no-choice comparison group.
Results: Results indicated that being offered choice with regard the type of exercises (i.e. option choice) were mixed, with choice yielding a clear engagement and perseverance-enhancing effect compared to a no choice control group in cases the offered options differed clearly from one another (i.e., high contrast option choice), while no benefits were observed in case choice options leaned closely to one another (i.e. low contrast option choice). Athletes' involvement in the order of exercises during a training session (i.e. action choice) tended to enhance athletes' engagement, but not their intentional perseverance, compared to a no choice control group. Finally, all experimentally offered choices yielded a positive effect on two aspects of autonomy need satisfaction, that is, perceived choice and felt volition. These two variables functioned as a chain of mechanisms through which different types of choice related to athlete engagement and intended perseverance. These effects emerged irrespective of rope-skippers' dispositional indecisiveness.
Conclusion: The discussion highlights the importance of a nuanced discussion regarding the topic of choice, thereby contrasting the different pros and cons associated with each type of choice
A novel approach to screen and compare emission inventories
A methodology is proposed to support the evaluation and comparison of different types of emission inventories, and more specifically the comparison of bottom-up versus top-down approaches. The strengths and weaknesses of the methodology are presented and discussed based on an example. The approach results in a “diamond” diagram useful to flag out anomalous behaviors in the emission inventories and to get insight on possible explanations. In particular, the “diamond” diagram is shown to provide meaningful information in terms of: discrepancies between the total emissions reported by macro-sector and pollutant, contribution of each macro-sector to the total amount of emissions released by pollutant, and the identification and quantification of the different factors causing the discrepancies between total emissions. Its main strength as an indicator is to allow investigating the relative contribution of activity and weighted emission factors. A practical example in Barcelona is used for testing and to provide relevant information for the analyzed emission datasets. The tests show the capability of the proposed methodology to flag inconsistencies in the existing inventories. The proposed methodology system may be useful for regional and urban inventory developers as an initial evaluation of the consistency of their inventories.JRC.H.2-Air and Climat
Potential of variable speed limits for emission and noise reduction on the E313 motorway to Antwerp, Belgium
Urban PM2.5 Atlas: Air Quality in European cities
Many European cities suffer from poor air quality and regularly exceed both the European standards prescribed by the Air Quality Directive and the guidelines recommended by the World Health Organization. This is particularly the case for fine particulate matter (PM10) for which both the daily and yearly average limit values are regularly exceeded in many cities and several regions in Europe. Similar conclusions hold for PM2.5 where few cities manage to keep concentrations below the levels recommended by the WHO.
Actions have been proposed and taken at the international, national and urban scales to reduce air pollution. While they have undoubtedly resulted in an overall improvement of the air quality over the years, there are still problems which are localised in specific regions and many cities. A key issue is thus to determine at which scale to act in order to abate these remaining air pollution problems most effectively. Central to this for cities, is a quantitative assessment of the different origins of air pollution in the city (urban, regional, national and transboundary) to support the design of efficient and effective air quality plans, which are a legal obligation for countries and regions whenever exceedances occur.
The “Screening for High Emission Reduction Potentials for Air quality” tool (SHERPA) has been developed by the Joint Research Centre to quantify the origins of air pollution in cities and regions. In this Atlas, both the spatial (urban, country…) and sectoral (transport, residential, agriculture…) contributions are quantified for 150 European urban areas in Europe, where many of the current exceedances to the air quality EU limit values and WHO guidelines are reported.
There is a need to provide information to improve air quality policy governance, to support authorities in choosing the most efficient actions at the appropriate administrative level and scale. In particular, actions at the local level focusing on the urban scale and at national/international level needs to be carefully balanced. Key conclusions are:
• For many cities, local actions at the city scale are an effective means of improving air quality in that city.
The overall conclusion is that cities have a role to play by taking actions at their own scale. It is important to emphasise that the emissions in cities contribute significantly to country and EU overall PM concentrations, reinforcing the important role of cities in reducing the air pollution through a multilevel approach.
• Impacts of abatement measures on air quality are city specific
The impact of a given abatement measure on air quality differs from city to city, even for cities that are located in the same country. Actions taken at different scales or in different activity sectors therefore lead to impacts on air quality that are city-specific. The diversity of possible responses to abatement measures stresses the need to take into account these city-specific circumstances when designing air quality plans. Actions that are efficient in one city might not be efficient in others.
• Sectoral measures addressing agriculture at country or EU scale would have a clear benefit on urban air quality.
Although agricultural emissions are limited in the "city" as defined here, agriculture considerably impacts air quality in many EU cities. The extent of the impact of agriculture on air quality is indicative of the potential of EU- or country-wide measures addressing this sector. Moreover, other sectoral measures can have an important potential at the urban scale even though they are applied at EU or country scale. This is the case of road transport where the EURO norms are, in practice, most effective in the areas where traffic is most important, i.e. cities.JRC.C.5-Air and Climat
Impact of passenger car NOX emissions on urban NO2 pollution – Scenario analysis for 8 European cities
Residents of large European cities are exposed to NO2 concentrations that often exceed the established air quality standards. Diesel cars have been identified as a major contributor to this situation; yet, it remains unclear to which levels the NOX emissions of diesel cars have to decrease to effectively mitigate urban NO2 pollution across Europe. Here, we take a continental perspective and model urban NO2 pollution in a generic street canyon of 8 major European cities for various NOX emission scenarios. We find that a reduction in the on-road NOX emissions of diesel cars to the Euro 6 level can in general decrease the regional and urban NO2 concentrations and thereby the frequency of exceedances of the NO2 air quality standard. High NO2 fractions in the NOX emissions of diesel cars tend to increase the urban NO2 concentrations only in proximity of intense road traffic typically found on artery roads in large cities like Paris and London. In cities with a low share of diesel cars in the vehicle fleet such as Athens or a high contribution from the NO2 background to the urban NO2 pollution such as Krakow, measures addressing heavy-duty vehicles, and the manufacturing, energy, and mining industry are necessary to decrease urban air pollution. We regard our model results as robust albeit subject to uncertainty resulting from the application of a generic street layout. With small modifications in the input parameters, our model could be used to assess the impact of NOX emissions from road transport on NO2 air pollution in any European city
Urban NO2 Atlas
The Atlas shows, for selected cities, the likely effects of the implementation of “Traffic Policies” intended to reduce urban NO2 concentrations.
As NO2 pollution in urban areas is mainly caused by traffic, the analysis focuses on assessing the relative contribution to the NO2 concentration in ambient air from different types of vehicles.
The results, obtained for a selected number of cities in Europe show that, depending on the size of the selected “Inner Area” (by this name, we mean the area over which traffic measures are applied), one could reduce on average up to 40% the NO2 urban background concentrations. Of this average reduction, roughly 15% is linked to passenger diesel cars, 13% to trucks and 6% to vans (mostly diesel); while the remaining share is associated to other type of vehicles (buses, gasoline cars, etc…).
This Atlas provides a first indication of the relative effectiveness of mobility policies aimed at reducing urban NO2 pollution concentrations in European cities. However, considering the specific assumptions in the applied approach, as on traffic flows, fleet composition, emission factors, size of the “Inner Area”, etc…, the results may not be as accurate as they would be when using detailed local data.
The SHERPA-City methodology and tool applied in this Atlas can be used by local authorities to assess a broad range of air quality measures, including technological (e.g. fleet renewal, new technologies) and soft measures (i.e. promotion of walking and cycling). Such measures can be assessed alone or in combination.JRC.C.5-Air and Climat
Energy savings in light rail through the optimization of heating and ventilation
This paper discusses the potential for energy savings in heating and ventilation of light rail vehicles. We present the results of a detailed monitoring campaign on one articulated tram in Ghent, Belgium. The results give insight in the energy use for heating and ventilation in light rail as a function of ambient weather conditions. After several months of monitoring, changes in the HV strategy were implemented and the monitoring was continued. Based on this monitoring data, an energy-use model was constructed for HV both before and after the heating and ventilation strategy changes. These models then served as input for a Monte Carlo simulation, providing average energy savings over 1 year as a result of the optimized heating and ventilation strategy
On the correlation between the forecast avalanche danger and avalanche risk taken by backcountry skiers in Switzerland
Rule-based decision frameworks are widely recommended to estimate the avalanche risk while planning a ski tour. However, these frameworks were developed relying primarily on accident data and usually did not consider backcountry travel data. Hence, they are not risk-based. Here, we address this gap and calculate the risk taken during backcountry touring in avalanche terrain and correlate it to the expected avalanche conditions as described in a public avalanche forecast. For this, we rely on 784 reported avalanche accidents and more than 2.1 million movement points in potential avalanche terrain, based on GPS tracks recorded in Switzerland for 14 winter seasons. Combining this data with the respective avalanche forecast, we show that risk increases fourfold from danger level 1-Low to 2-Moderate, and from 2-Moderate to 3-Considerable. Furthermore, at 2-Moderate and 3-Considerable, in the critical elevations and aspects specified in the avalanche forecast, the risk is nearly six times higher compared to locations outside this, so-called, core zone. For danger level 1-Low, where the Swiss avalanche forecast does not provide any information about the critical elevations and aspects, we derived a risk-based core zone. Within this core zone too, the risk is about six times higher than outside. These findings suggest an adaption of the rule-based decision frameworks to reflect the observed risk better. The proposed framework considers the strong influence of the elevation and reduces the effect of the aspect, compared to former decision frameworks. We emphasize that this new decision framework cannot replace on-site risk assessment. However, it allows backcountry users to come closer to the goal of achieving a minimum of avalanche risk while allowing a maximum of freedom of movement