Browsing by Subject "kadut"

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  • Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka (Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka, 1981)
  • Kuja 
    Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka; Suomen Akatemian projekti (Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka, 1995)
  • Kuja 
    Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka; Suomen Akatemian projekti (Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka, 1995)
  • Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka (Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka, 1981)
  • Kupiainen, Kaarle (Finnish Environment Institute, 2007)
    Monographs of the Boreal Environment Research 26
    Vehicles affect the concentrations of ambient airborne particles through exhaust emissions, but particles are also formed in the mechanical processes in the tire-road interface, brakes, and engine. Particles deposited on or in the vicinity of the road may be re-entrained, or resuspended, into air through vehicle-induced turbulence and shearing stress of the tires. A commonly used term for these particles is ?road dust?. The processes affecting road dust emissions are complex and currently not well known.Road dust has been acknowledged as a dominant source of PM10 especially during spring in the sub-arctic urban areas, e.g. in Scandinavia, Finland, North America and Japan. The high proportion of road dust in sub-arctic regions of the world has been linked to the snowy winter conditions that make it necessary to use traction control methods. Traction control methods include dispersion of traction sand, melting of ice with brine solutions, and equipping the tires with either metal studs (studded winter tires), snow chains, or special tire design (friction tires). Several of these methods enhance the formation of mineral particles from pavement wear and/or from traction sand that accumulate in the road environment during winter. When snow and ice melt and surfaces dry out, traffic-induced turbulence makes some of the particles airborne.A general aim of this study was to study processes and factors underlying and affecting the formation and emissions of road dust from paved road surfaces. Special emphasis was placed on studying particle formation and sources during tire road interaction, especially when different applications of traction control, namely traction sanding and/or winter tires were in use. Respirable particles with aerodynamic diameter below 10 micrometers (PM10) have been the main concern, but other size ranges and particle size distributions were also studied. The following specific research questions were addressed: i) How do traction sanding and physical properties of the traction sand aggregate affect formation of road dust? ii) How do studded tires affect the formation of road dust when compared with friction tires? iii) What are the composition and sources of airborne road dust in a road simulator and during a springtime road dust episode in Finland? iv) What is the size distribution of abrasion particles from tire-road interaction? The studies were conducted both in a road simulator and in field conditions.The test results from the road simulator showed that traction sanding increased road dust emissions, and that the effect became more dominant with increasing sand load. A high percentage of fine-grained anti-skid aggregate of overall grading increased the PM10 concentrations. Anti-skid aggregate with poor resistance to fragmentation resulted in higher PM levels compared with the other aggregates, and the effect became more significant with higher aggregate loads. Glaciofluvial aggregates tended to cause higher particle concentrations than crushed rocks with good fragmentation resistance. Comparison of tire types showed that studded tires result in higher formation of PM emissions compared with friction tires. The same trend between the tires was present in the tests with and without anti-skid aggregate. This finding applies to test conditions of the road simulator with negligible resuspension.Source and composition analysis showed that the particles in the road simulator were mainly minerals and originated from both traction sand and pavement aggregates. A clear contribution of particles from anti-skid aggregate to ambient PM and dust deposition was also observed in urban conditions. The road simulator results showed that the interaction between tires, anti-skid aggregate and road surface is important in dust production and the relative contributions of these sources depend on their properties. Traction sand grains are fragmented into smaller particles under the tires, but they also wear the pavement aggregate. Therefore particles from both aggregates are observed. The mass size distribution of traction sand and pavement wear particles was mainly coarse, but fine and submicron particles were also present.
  • Stojiljkovic, Ana; Kauhaniemi, Mari; Kukkonen, Jaakko; Kupiainen, Kaarle; Karppinen, Ari; Denby, Bruce Rolstad; Kousa, Anu; Niemi, Jarkko V.; Ketzel, Matthias (Copernicus Publications, 2019)
    Atmospheric Chemistry and Physics
    We have numerically evaluated how effective selected potential measures would be for reducing the impact of road dust on ambient air particulate matter (PM10). The selected measures included a reduction of the use of studded tyres on light-duty vehicles and a reduction of the use of salt or sand for traction control. We have evaluated these measures for a street canyon located in central Helsinki for four years (2007–2009 and 2014). Air quality measurements were conducted in the street canyon for two years, 2009 and 2014. Two road dust emission models, NORTRIP (NOn-exhaust Road TRaffic Induced Particle emissions) and FORE (Forecasting Of Road dust Emissions), were applied in combination with the Operational Street Pollution Model (OSPM), a street canyon dispersion model, to compute the street increments of PM10 (i.e. the fraction of PM10 concentration originating from traffic emissions at the street level) within the street canyon. The predicted concentrations were compared with the air quality measurements. Both road dust emission models reproduced the seasonal variability of the PM10 concentrations fairly well but under-predicted the annual mean values. It was found that the largest reductions of concentrations could potentially be achieved by reducing the fraction of vehicles that use studded tyres. For instance, a 30 % decrease in the number of vehicles using studded tyres would result in an average decrease in the non-exhaust street increment of PM10 from 10 % to 22 %, depending on the model used and the year considered. Modelled contributions of traction sand and salt to the annual mean non-exhaust street increment of PM10 ranged from 4 % to 20 % for the traction sand and from 0.1 % to 4 % for the traction salt. The results presented here can be used to support the development of optimal strategies for reducing high springtime particulate matter concentrations originating from road dust. Short summary Nordic countries experience the deterioration of air quality in springtime due to high PM10 concentrations. Non-exhaust emissions from vehicular traffic are regarded as the most significant source of particulate air pollution during this time of year. The results from this study demonstrate the fact that changes in winter tyre types and adjustments to road maintenance could substantially reduce non-exhaust emissions.
  • Ilveskorpi, Liisa; Päivänen, Jani; Murole, Pentti; Vanhanen, Tero; Airas, Päivi (Ympäristöministeriö, 2007)
    Suomen ympäristö 17/2007
    Eri puolilla Suomea on käynnistynyt tiiviiden ja matalien asuinalueiden rakentaminen. Tämä julkaisu käsittelee tiiviin ja matalan asuinalueen eri suunnittelukysymyksiä. Erityisesti paneudutaan laadukkaan katutilan muodostamiseen. Esimerkkikohteena on Lahden Karisto ja sen ensimmäiset kaava-alueet Järvenpää ja Rantakylä. Karistossa pääosa rakennuksista toteutetaan omatoimisina pientaloina, mikä tuo erityisiä haasteita myös katusuunnittelulle. Kariston rakentaminen on raporttia kirjoitettaessa kesken. Karistosta on opittu, että katujen luonne ja katutilan eri toiminnot olisi selvitettävä kunnolla jo kaavoitusvaiheessa ja tehtävä selväksi, tarvitaanko tavanomaisesta poikkeavia suunnitteluperiaatteita. Toiseksi on keskityttävä rakennusten luontevaan sovittamiseen monimuotoiseen maastoon ja katutilaan. Kolmas kysymys on omatoiminen rakentaminen, joka toisaalta luo mahdollisuuden monimuotoiselle ja rikkaalle kaupunkikuvalle, mutta edellyttää vahvaa koordinoivaa otetta, jotta kokonaiskuvasta muodostuu hallittu. Neljänneksi, asuinalueen yhteisöllisyyden tukeminen katujen ja aukioiden taitavalla suunnittelulla on mahdollista, mutta tällöin on määriteltävä, millaista yhteistoimintaa toisaalta asukkaiden välille, toisaalta kaupungin ja asukkaiden välille toivotaan. Julkaisussa käsitellään myös useita matalien ja tiiviiden alueiden suunnittelun erityiskysymyksiä, joita liittyy mm. maankäyttöön, kaupunkikuvaan, viherrakentamiseen, katurakentamiseen ja infrastruktuurin. Tiivis pientalorakentaminen edellyttää, että uskalletaan tarvittaessa kyseenalaistaa totutut, paljon tilaa vievät tekniset normit. Toisaalta on arvostettava eri asiantuntijoiden osaamisalueita ja pyrittävä löytämään uusia ratkaisuja yhteistyössä.
  • Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka (Helsingin yliopisto, kulttuurien tutkimuksen laitos, folkloristiikka, 1981)