Knowledge about how implemented policy instruments have performed is important for designing effective and efficient policy instruments that contribute to reductions of greenhouse gas emissions. This paper carries out a meta-evaluation of ex-post evaluations of climate policy instruments in the freight transport sector. By analysing the outcomes and quality of evaluations, the aim is to identify whether estimated effects of policy instruments can be compared between evaluations and if the results are appropriate to use for evidence-based decision making. To analyse these aspects, commonly applied evaluation criteria are assessed and classified according to an assessment scale. We confirm that few ex-post evaluations are carried out and that there is a gap between evaluation theory and how ex-post policy evaluations are performed in practice, where evaluation criteria recommended in policy evaluation guidelines are found to often be neglected in evaluations. The result is a lack of systematic climate policy evaluation which hinders reliable conclusions about the effect of policy instruments. There is a need for more systematic monitoring and evaluation of implemented policy instruments and we suggest that evidence-based decision making can be improved by adjusting current policy evaluation guidelines and by introducing an evaluation obligation.

Microplastics from road traffic, mainly from tyre wear, are globally considered to be one of the largest sources of microplastic contamination in the environment. Plastics can either be deposited in the road vicinity, at the roadside and in ditches or spread via stormwater and air to the environment and receiving water bodies. In cold climates, microplastics, as well as other traffic-related pollutants, can be temporarily stored in snow and ice on and around roads and streets. The location and concentration of these pollutants is influenced by winter operations, where ploughing and skid control contribute to redistribution, and by melting and compaction of ice and snow. This creates reservoirs of microplastics and other pollutants, which are released into stormwater or surrounding soil during thaws, but also provides an opportunity to reduce the spread of microplastics by managing snow and ice appropriately. In the present report, a case study of microplastics in snow has been carried out in the municipality of Karlstad in Sweden, to get an idea of the potential variation, both in terms of concentration and total amounts in relation to traffic and the location of the sampling in the street environment. Microplastics have been analysed by pyrolysis GC/MS to identify tyre-specific polymers in combination with eight commonly occurring plastic types. In addition, six municipalities in different parts of the country responded to a questionnaire on microplastics in snow and urban snowmelt management. The results show that microplastics related to tyre wear (rubber polymers) tend to be present in higher concentrations on and near the carriageway. Other plastics show a less clear link to traffic. Along a salted bicycle lane, an elevated level of polypropylene, from which the brush of the sweep-salting machine is made, could be detected in the surface layer of the snow. In general, knowledge about microplastics in urban snow is low in the municipalities that responded to the survey.

Mikroplaster från vägtrafik, främst från slitage av däck, bedöms globalt vara en av de största källorna till kontamineringen av mikroplast i miljön. Plasterna kan antingen deponera i närområdet, vid vägkanten och i dikena eller spridas via dagvatten och luft till omgivning och recipienter. I kalla klimat kan mikroplaster, liksom andra trafikrelaterade föroreningar, komma att mellanlagras i snö och is på och kring vägar och gator. Var föroreningarna återfinns, och i vilka halter, som de påverkas av vinterdriften, där plogning och halkbekämpning bidrar till omfördelning, samt av smältning och kompaktering av is och snö. Detta skapar förråd av mikroplaster och andra föroreningar, som vid töväder frigörs till dagvatten eller omgivande mark men utgör även en möjlighet att minska spridningen av mikroplaster genom att hantera snö och is på ett anpassat sätt. I föreliggande rapport har en fallstudie av mikroplaster i snö genomförts i Karlstad för att få en bild av den potentiella variationen, både med avseende på koncentration och totala mängder i förhållande till trafik och var i gatumiljön proverna tagits. Mikroplaster har analyserats med pyrolys GC/MS för att kunna identifiera däckspecifika polymerer i kombination med åtta vanligt förekommande plasttyper. Vidare har sex kommuner i olika delar av landet besvarat en enkät om mikroplaster i snö och hantering av urbana snömassor. Resultatet visar att mikroplaster som kan relateras till däckslitage (gummipolymerer) tenderar att förekomma i högre halter på och nära körfälten. Övrig plast visar mindre tydlig koppling till trafik. Längs ett sopsaltat cykelstråk kunde en förhöjd halt av polypropen, som sopsaltmaskinens borste är tillverkad av, påvisas i snöns ytskikt. Generellt är kunskapen om mikroplaster i urban snö låg hos de kommuner som besvarade enkäten.

Microplastics are emitted to the environment from many sources, and transported via water, soil and air. The airborne component is less well studied and measurements often focus on particles larger than 10 μm, while smaller particles are worse from a health perspective and likely more abundant. Measurement studies do often not include tyre wear, which is a large source of microplastics in urban areas. To improve the understanding of the microplastics concentration in urban areas, simulations of emissions and concentrations of atmospheric tyre wear particles (TWP) over Stockholm are performed. The results show that TWP are ubiquitous in urban areas, with highest concentrations along busy highways and in poorly ventilated street canyons. Yearly average roof level concentrations of TWP-PM10 range from 0.2 μg m−3 in areas with moderate traffic to 1.2 μg m−3 close to busy highways. Average yearly concentrations at three selected street canyons range from 0.7 to 1.1 μg m−3. The modelled concentrations correspond to 4–6% of the total measured PM10 concentration. TWP emissions are expected to increase with increasing traffic in future, and possibly also with the increase in vehicle weight with electric vehicles and SUV:s.

There is mounting evidence that tire wear particles can harm natural systems, but worldwide trends in car weight and car usage, mean emissions are set to increase. To control tire wear emissions and help understand fate and transport, detailed characterisation of the particles, and the relationship between road surface properties and emission profiles is needed. This study deployed a suite of experiments utilising the advanced road simulator of the Swedish National Road and Transport Research Institute to compare seasonal tire types from three brands. An extraction method was developed for a coarse (>30 µm) fraction of tire and road wear particles (TRWP), and a comprehensive physicochemical characterisation scheme applied to both TRWP and tire-tread, including microscopy, energy-dispersive X-ray spectroscopy and pyrolysis-GC/MS. Road simulator dusts and hand-picked TRWP showed differences in shape, numbers, and mass between tire types and brands, and between asphalt and cement concrete road surfaces. Contrary to accepted perceptions, tactile analyses revealed that firm-elastic TRWP comprised only a minor proportion of TRWP. Fragile and chemically distinct tire-road-derived particles, termed here sub-elastic TRWP, comprised 39–100% of TRWP. This finding raises urgent questions about overall TRWP classification and identification features, resistance to weathering, and environmental fate. At the same time, differences in TRWP generation between tire formulations, and road surfaces, show potential for controlling emissions to reduce global impacts.

Microplastics from road traffic are mainly caused by tyre wear, which is globally considered to be one of the largest sources of microplastics. Tyre wear particles have been shown to occur in all media (road surface, air, soil, stormwater, lakes and rivers and coastal sediments) and are dispersed both by runoff and by atmospheric transport. To reduce the dispersion and possible effects of road traffic microplastics emissions, measures can be taken to prevent the formation of particles and to prevent their dispersion through treatment measures. This study focuses on street cleaning as a method to reduce emissions, but as many street cleaning methods are based on the use of plastic brushes, cleaning as a source of microplastics has also been considered. The study was carried out in collaboration with the municipality of Karlstad and included a review of how street cleaning is carried out in Karlstad in relation to uptake and dispersion of microplastics. 

Furthermore, a comparison between two cleaning machines (elevator and vacuum) has been made and a monitoring of microplastic amounts on the road surface during different phases of spring sweeping has been carried out. In order to estimate the amount of plastic torn from the brushes, weighing of the brushes has been carried out. In order to gain knowledge about the work of more municipalities on street sweeping from a microplastic perspective, a questionnaire study was sent out to six municipalities in different parts of the country. The results show that both cleaning machines have the capacity to reduce the amount of microplastics on the road surface. However, during spring sweeping, the amount of polypropylene (the most common plastic in the brushes) on the road surface increases. The distribution of analysed plastics differs significantly between the road surface and the material collected by the machines. This is thought to be due to the fact that the machines mainly collect coarser fractions, while finer fractions remain on the road surface. Knowledge of, and thus consideration of, microplastics in relation to operational measures such as street cleaning is currently low among the municipalities surveyed, but awareness exists, as does the need for support in implementing possible measures. 

The present study shows a complex problem picture and represents a first step in understanding how street cleaning can be used as a measure, but also indicates that the wear of plastic brushes leads to a net emission of microplastics.

Mikroplaster från vägtrafik har i huvudsak däckslitage som källa, vilket globalt bedöms vara en av de största källorna till mikroplaster. Däckslitagepartiklar har visat sig förekomma i alla medier (vägytan, mark, luft, dagvatten, sjöar och vattendrag och kustnära sediment). Partiklarna sprids både genom avrinning och genom lufttransport. För att minska spridning och eventuella effekter av vägtrafikens mikroplastutsläpp kan åtgärder vidtas för att dels förhindra bildningen av partiklar, dels för att förhindra spridningen genom reningsåtgärder. Denna studie fokuserar på gatustädning som metod för att minska emissionerna, men då många gatustädmetoder baseras på användning av plastborstar, har även städningen som källa till mikroplaster undersökts. Studien har genomförts i samverkan med Karlstads kommun och omfattat en genomgång av hur gatustädningen genomförs i Karlstad i relation till upptag och spridning av mikroplaster. 

Vidare har en jämförelse mellan två städmaskiner (elevator och vakuum) gjorts och en uppföljning av mikroplastmängder på vägytan under olika moment av vårsopning genomförts. För att uppskatta hur mycket plast som slits från borstarna har vägning av borstar genomförts. För att få kunskap om fler kommuners arbete med gatusopning ur ett mikroplastperspektiv, har en enkätstudie skickats ut till sex kommuner i olika delar av landet. Resultaten visar att båda städmaskinerna har kapacitet att minska mängden mikroplast på vägytan. Under vårsopningen framgår dock att mängden polypropylen (den vanligaste plasten i borstarna) ökar på vägytan. Fördelningen av analyserade plaster skiljer sig markant mellan vägytan och det material som maskinerna samlat in. Detta bedöms bero på att maskinerna huvudsakligen samlar in grövre fraktioner, medan finare fraktioner blir kvar på vägytan. Kunskapen om, och därmed också beaktandet av just mikroplaster i relation till driftåtgärder som gatustädning, är i dagsläget låg bland tillfrågade kommuner, men kännedom finns liksom behov av stöd i implementering av eventuella åtgärder. 

Föreliggande studie visar på en komplex problembild och utgör ett första steg i att förstå hur gatustädning kan användas som åtgärd, men indikerar också att slitage av plastborstar medför en nettoemission av mikroplaster.

Tyre and road wear particles (TRWP) are an important microplastics contributor to the environment, although direct observations along suggested pathways are virtually absent. There are concerns for both human health and ecosystems from TRWP exposure and leached chemicals. Due to great analytical challenges in detection and characterization, almost nothing is known about the physicochemical characteristics, occurrence, fate and transport of TRWP in the environment. Diverse tyre types exist for different seasons and vehicle profiles, and their formulations are undisclosed proprietary information.

Here we show TRWP dispersion in marine sediments, and a direct link between tyre formulation, tread hardness and TRWP emissions. Softer tyres with higher natural rubber and carbon black content generate higher particle wear. Sediment TRWP dominates the microplastics assemblage close to the city, while showing a much more steeply reducing concentration gradient with distance from the source, suggesting different transport behaviour compared to lower density microplastics. This implies that urbanized coastal ecosystems are impacted by the accumulating TRWP, with consequences for sediment ecosystems.

Gentle Remediation Options (GRO) are remediation measures involving plants, fungi, bacteria, and soil amendments that can be applied to manage risks at contaminated sites. Several studies and decision-support tools promote the wider range of benefits provided by GRO, but there is still skepticism regarding GRO implementation. Key issues that need to be better communicated are the various risk mitigation mechanisms, the required risk reduction for an envisioned land use, and the time perspective associated with the risk mitigation mechanisms. To increase the viability and acceptance of GRO, the phytomanagement approach implies the combination of GRO with beneficial green land use, gradually reducing risks and restoring ecosystem services. To strengthen the decision basis for GRO implementation in practice, this paper proposes a framework for risk management and communication of GRO applications to support phytomanagement strategies at contaminated sites. The mapping of the risk mitigation mechanisms is done by an extensive literature review and the Swedish national soil guideline value model is used to derive the most relevant human health exposure pathways and ecological risks for generic green land use scenarios. Results indicate that most of the expected risk mitigation mechanisms are supported by literature, but that knowledge gaps still exist. The framework is demonstrated to support the identification of GRO options for the case study site given two envisioned land uses: biofuel park and allotment garden. A more easily understandable risk management framework, as proposed here, is expected to act as a communication tool to educate decision-makers, regulatory bodies and other stakeholders for better understanding of risk mitigation mechanisms and preliminary timeframes of various GRO, particularly in the early stages of a brownfield redevelopment project. © 2021 The Authors

Recently, Europe is experiencing more frequent and greater floods compared to the last 500 years due to climate change among other factors. This has increased the associated risks, especially in urban areas, which poses a great challenge to all stakeholders. To protect traffic networks from possible floods, this paper uses QGIS, remote sensing data, and HEC-HMS model to assess flooding events and possible adaptation measures. Two case studies have been taken; 1) a 60-mm rainstorm that occurred in 2012 on a main road in the Northern part of Sweden (NB)); and 2) a 35-mm rainstorm that occurred in 2019 in the Southern part of Gothenburg (GO). The resulting flood hydrographs show that the peak reached are 0.5 m3/s and 3.8 m3/s in GO and NB, respectively. To adapt to these flood events, four adaptation measures were assessed namely afforestation, permeable pavements & green roofs, multi-use detention basins and culvert installation considering food production, biodiversity, prosperity, and the environment. The study has shown that afforestation is an effective flood risk mitigation measure to handle both moderate and extreme rain events. Well-maintained permeable surfaces and green roofs are effective in reducing flooding due to moderate rainfall, but not in reducing the impacts of extreme rainfall events. Well-designed multi-functional detention basins are good flood protection measures, however, if they are not well-maintained, their efficiency may be reduced by up to 90 %. Culverts are effective for frequent and limited rain events but extreme rain events may even increase flood risk and thereby contribute to damaging the infrastructure.

Tire wear particles (TWP) are assumed to be one of the major sources of microplastic pollution to the environment. However, many of the previously published studies are based on theoretical estimations rather than field measurements. To increase the knowledge regarding actual environmental concentrations, samples were collected and analyzed from different matrices in a rural highway environment to characterize and quantify TWP and other traffic-derived non-exhaust particles. The sampled matrices included road dust (from kerb and in-between wheeltracks), runoff (water and sediment), and air. In addition, airborne deposition was determined in a transect with increasing distance from the road. Two sieved size fractions (2–20 µm and 20–125 µm) were analyzed by automated Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM/EDX) single particle analysis and classified with a machine learning algorithm into the following subclasses: TWP, bitumen wear particles (BiWP), road markings, reflecting glass beads, metals, minerals, and biogenic/organic particles. The relative particle number concentrations (%) showed that the runoff contained the highest proportion of TWP (up to 38 %). The share of TWP in kerb samples tended to be higher than BiWP. However, a seasonal increase of BiWP was observed in coarse (20–125 µm) kerb samples during winter, most likely reflecting studded tire use. The concentration of the particle subclasses within airborne PM80-1 decreases with increasing distance from the road, evidencing road traffic as the main emission source. The results confirm that road dust and the surrounding environment contain traffic-derived microplastics in both size fractions. The finer fraction (2–20 µm) dominated (by mass, volume, and number) in all sample matrices. These particles have a high potential to be transported in water and air far away from the source and can contribute to the inhalable particle fraction (PM10) in air. This highlights the importance of including also finer particle fractions in future investigations.

To fulfil the global sustainable development goals (SDGs), achieving sustainable development is becoming urgent, not least in the transportation sector. In response to this, the sustainability framework Sustainability National Road Administrations (SUNRA) was developed to contribute to improving the sustainability performance of national road administrations across Europe. In the present study, the framework has been tested, applied and further developed to be applicable for target setting and follow-up at the project level at both the Swedish Transport Administration (STA) and at municipal levels. The aim was a framework relevant for investment, re-investments, maintenance and operation projects and also to make it more user applicable. The study also investigated how the framework can contribute to sustainability, identified drivers and barriers for applying the framework and examined whether the framework can be applied and adapted to projects of different complexities. The adaptations and developments were done in collaboration between researchers and practitioners. The results show that the framework could easily be used and adapted for investment, re-investment, maintenance and operation projects in the planning stage, as well as for small municipal establishments, construction or reconstruction of residential areas and frequent maintenance. The framework contributes to increased awareness on sustainability, and it provides a common structure and transparency on how infrastructure project goals/targets are set and fulfilled. The framework can also be applied to follow the fulfilment of the goals/targets and thereby adapt the project to better fulfil the goals. Identified barriers include the lack of obligations and lack of experience in using sustainability frameworks.