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Tu, M., Cha, Y., Wahlström, J. & Olofsson, U. (2019). Towards a two-part train traffic emissions factor model for airborne wear particles. Transportation Research Part D: Transport and Environment, 67, 67-76
Open this publication in new window or tab >>Towards a two-part train traffic emissions factor model for airborne wear particles
2019 (English)In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 67, p. 67-76Article in journal (Refereed) Published
Abstract [en]

In 2017 a new railway tunnel containing two stations opened in Stockholm, Sweden. A series of field measurements were carried out on the platforms in this tunnel before and after it was opened for normal traffic. These measurements were used to investigate the contribution of airborne particle emissions from wear processes to total train emissions. This field data was used to develop a two-part train traffic emission factor model for PM10. The two parts are the accumulative effect term (relating to operating distance such as wheel-rail contact and overhead electric line sliding contact) and a brake effect term (relating to the number of braking operations such as brake disc and brake pad contact). The results show that operating a single trial train at a higher than normal frequency on an otherwise empty platform increases the platform particulate concentration until the concentration reaches a steady value. The model suggests that brake emissions account for about 50% of the total emissions measured in the tunnels.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Airborne particle, Emission factor, Railway tunnel, Wear particle emission, Brakes, Electric lines, Railroads, Rails, Wear of materials, Emission factors, Field measurement, Overhead electric lines, Railway tunnels, Stockholm, Sweden, Wear particles, Wheel-rail contacts, Railroad tunnels, atmospheric pollution, concentration (composition), emission inventory, particulate matter, quantitative analysis, railway transport, traffic emission, wear, Stockholm [Stockholm (CNT)], Stockholm [Sweden], Sweden
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-248230 (URN)10.1016/j.trd.2018.11.006 (DOI)000464890900005 ()2-s2.0-85056898654 (Scopus ID)
Note

QC 20190411

Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2019-05-13Bibliographically approved
Cha, Y., Tu, M., Elmgren, M., Silvergren, S. & Olofsson, U. (2019). Variation in Airborne Particulate Levels at a Newly Opened Underground Railway Station. Aerosol and Air Quality Research, 19(4), 737-748
Open this publication in new window or tab >>Variation in Airborne Particulate Levels at a Newly Opened Underground Railway Station
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2019 (English)In: Aerosol and Air Quality Research, ISSN 1680-8584, E-ISSN 2071-1409, Vol. 19, no 4, p. 737-748Article in journal (Refereed) Published
Abstract [en]

The construction of a new railway tunnel for commuter trains in Stockholm was completed in 2017. It included two modern stations (Odenplan and Stockholm City) with platform screen doors (PSD) and one old station (Stockholm Sodra) without PSDs. This study evaluates the concentrations of airborne particulates at the new Odenplan station, focusing on the effects of traffic operation, system age and train movement. For comparison, the other two stations in the tunnel and an above-ground railway station (Solna) were also investigated. The new platform was clean prior to opening for traffic (the average concentration of PM10 and PM2.5 was 12 and 2 mu g m(-3), respectively). Substantial increases in the PM10 and PM2.5 levels were observed after it came into service, with the average concentrations increasing to 120 and 30 mu g m(-3) after 1 week and then to 175 and 35 mu g m(-3) after 3 months of operation. The train movement factor (traffic frequency and train stopping period) was found to have a strong effect on the coarse-sized particle concentrations (0.3-10 mu m). Comparable levels of PM10 and PM2.5 were measured at both the new Odenplan station and the old station, where the amount of traffic was similar. For the other new station, Stockholm City, where traffic was only half as frequent, the PM10 and PM2.5 levels were substantially lower.

Place, publisher, year, edition, pages
TAIWAN ASSOC AEROSOL RES-TAAR, 2019
Keywords
Platform air quality, Railway tunnel, New railway station, Particulate matter, Platform screen door
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-248315 (URN)10.4209/aaqr.2018.06.0225 (DOI)000462169700006 ()
Note

QC 20190409

Available from: 2019-04-09 Created: 2019-04-09 Last updated: 2019-04-09Bibliographically approved
Cha, Y. & Olofsson, U. (2018). Effective density of airborne particles in a railway tunnel from field measurements of mobility and aerodynamic size distributions. Aerosol Science and Technology, 52(8), 886-899
Open this publication in new window or tab >>Effective density of airborne particles in a railway tunnel from field measurements of mobility and aerodynamic size distributions
2018 (English)In: Aerosol Science and Technology, ISSN 0278-6826, E-ISSN 1521-7388, Vol. 52, no 8, p. 886-899Article in journal (Refereed) Published
Abstract [en]

The objective of this study is to investigate the particle effective density of aerosol measurements in a railway tunnel environment. Effective density can serve as a parameter when comparing and calibrating different aerosol measurements. It can also be used as a proxy parameter reflecting the source of particles. Effective density was determined using two different methods. Method one defined it by the ratio of mass concentration to apparent volume size distribution. Method two relied on a comparison of aerodynamic and mobility diameter size distribution measurements. The aerodynamic size range for method one was 0.006–10 µm, and for method two, it was 10–660 nm. Using the first method, a diurnal average value of about 1.87 g/cm3 was observed for the measurements with tapered element oscillating microbalance (TEOM) in tandem with aerodynamic particle sizer + scanning mobility particle sizer (SMPS), and 1.2 g/cm3 for the combination of TEOM with electrical low pressure impactor plus (ELPI+) in the presence of traffic. With method two, the effective density was 1.45 g/cm3 estimated from the size distribution measurements with ELPI + and fast mobility particle sizer (FMPS), and 1.35 g/cm3 from ELPI + in tandem with SMPS. With both calculation methods, the effective density varied for conditions with and without traffic, indicating different sources of particles. The proportion of particles with small sizes (10–660 nm) had a significant effect on the value of the effective density when no traffic was operating. The responses of different instruments to the railway particle measurements were also compared.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-234236 (URN)10.1080/02786826.2018.1476750 (DOI)000442403500007 ()2-s2.0-85051125932 (Scopus ID)
Note

QC 20180906

Available from: 2018-09-04 Created: 2018-09-04 Last updated: 2019-05-21Bibliographically approved
Cha, Y., Tu, M., Elmgren, M., Silvergren, S. & Olofsson, U. (2018). Factors affecting the exposure of passengers, service staff and train drivers inside trains to airborne particles. Environmental Research, 166, 16-24
Open this publication in new window or tab >>Factors affecting the exposure of passengers, service staff and train drivers inside trains to airborne particles
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2018 (English)In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 166, p. 16-24Article in journal (Refereed) Published
Abstract [en]

This study investigated train air conditioning filters, interior ventilation systems, tunnel environments and platform air quality as factors affecting the concentrations of airborne particles inside trains and provides information on the exposure of passengers, train drivers and service staff to particles. Particle sampling was done inside the passenger cabin, the driver cabin and the service staff cabin during on-board measurement campaigns in 2016 and 2017. The results show that interior ventilation plays a key role in maintaining cleaner in-train air. Noticeable increases in PM10 and PM2.5 levels were observed for all of the measured cabins when the train was running in the newly opened tunnel. The increases occurred when the doors of the passenger cabin and the service staff cabin were open at underground stations. The door to the driver cabin, which remained closed for the entire measurement period, acted as a filter for coarse particles (PM2.5–10). The highest particle exposure occurred in the passenger cabin, followed by the service staff cabin, while the driver had the lowest exposure. The highest deposition dose occurs for the service staff and the lowest for commuters.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:kth:diva-234244 (URN)10.1016/j.envres.2018.05.026 (DOI)000445318200003 ()29859369 (PubMedID)2-s2.0-85047643832 (Scopus ID)
Note

QC 20180906

Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2019-05-21Bibliographically approved
Cha, Y., Abbasi, S. & Olofsson, U. (2018). Indoor and outdoor measurement of airborne particulates on a commuter train running partly in tunnels. Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, 232(1), 3-13
Open this publication in new window or tab >>Indoor and outdoor measurement of airborne particulates on a commuter train running partly in tunnels
2018 (English)In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 232, no 1, p. 3-13Article in journal (Refereed) Published
Abstract [en]

Wear processes from mechanical braking, rail/wheel contact, the railway electrification system and re-suspended materials due to the turbulence of passing trains in tunnels and stations have been suggested to be the main contributors to particulate matter levels inside trains. In this study, onboard monitoring was performed on a commuter train stopping at underground and aboveground stations. The concentration and size distribution of particulates were monitored for both indoor and outdoor levels. The results show that the levels of PM10 and PM2.5 inside the train were about one-fifth of the outdoor levels. Significant increases in indoor particulate number concentrations were observed in tunnel environments and there was a slight increase when the doors were open. Differences in the size distributions of micro- and nano-sized particulates could be identified for different tunnels.

Place, publisher, year, edition, pages
Sage Publications, 2018
Keywords
Train, underground, indoor aerosol, airborne particulates, railway tunnel
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-185505 (URN)10.1177/0954409716642492 (DOI)000419833100001 ()2-s2.0-85040337944 (Scopus ID)
Note

QC 20180122

Available from: 2016-04-20 Created: 2016-04-20 Last updated: 2019-05-21Bibliographically approved
Cha, Y., Tu, M., Bergstedt, E., Carlsson, P., Lyu, Y., Olofsson, U., . . . Norman, M. (2018). Ombordmätningar av luftburna partiklar i X60 samt på citybanans plattformar. Kungliga Tekniska högskolan
Open this publication in new window or tab >>Ombordmätningar av luftburna partiklar i X60 samt på citybanans plattformar
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2018 (Swedish)Report (Other (popular science, discussion, etc.))
Place, publisher, year, edition, pages
Kungliga Tekniska högskolan, 2018
Series
TRITA-MMK, ISSN 1400-1179 ; 2018:02
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
The KTH Railway Group - Tribology
Identifiers
urn:nbn:se:kth:diva-221674 (URN)
Note

QC 20180122

Available from: 2018-01-19 Created: 2018-01-19 Last updated: 2018-03-13Bibliographically approved
Cha, Y., Olofsson, U., Gustafsson, M. & Johansson, C. (2018). On particulate emissions from moving trains in a tunnel environment. Transportation Research Part D: Transport and Environment, 59, 35-45
Open this publication in new window or tab >>On particulate emissions from moving trains in a tunnel environment
2018 (English)In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 59, p. 35-45Article in journal (Refereed) Published
Abstract [en]

Increasing attention is being paid to airborne particles in railway environments because of their potential to adversely affect health. In this study, we investigate the contribution of moving trains to both the concentration and size distribution of particles in tunnel environments. Real-time measurements were taken with high time-resolution instruments at a railway station platform in a tunnel in Stockholm in January 2013. The results show that individual trains stopping and starting at the platform substantially elevate the particulate concentrations with a mobility diameter greater than 100 nm. Two size modes of the particulate number concentrations were obtained. A mode of around 170 nm occurs when a train moves, while the other mode peaks at about 30 nm when there is no train in the station. By using principal component analysis (PCA), three contributing sources were identified on the basis of the classification of the sizes of the particles, namely railway-related mechanical wear, suspension due to the movement of trains and sparking of electric-powered components. It is concluded that the particulate matter released by individual moving trains is a key contributor to fine particles (100–500 nm) on the railway platform in a tunnel.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Airborne particulates, Individual train, Particle number concentration, Particulate size distribution, Railway tunnel
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-221145 (URN)10.1016/j.trd.2017.12.016 (DOI)000428100700004 ()2-s2.0-85040002421 (Scopus ID)
Note

QC 20180115

Available from: 2018-01-15 Created: 2018-01-15 Last updated: 2019-05-21Bibliographically approved
Cha, Y., Tu, M., Elmgren, M., Silvergren, S. & Olofsson, U. (2018). Variation of airborne particulate levels in a newly built railway tunnel. Aerosol and Air Quality Research
Open this publication in new window or tab >>Variation of airborne particulate levels in a newly built railway tunnel
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2018 (English)In: Aerosol and Air Quality Research, ISSN 1680-8584, E-ISSN 2071-1409Article in journal (Other academic) Submitted
Abstract [en]

The construction of a new railway tunnel for commuter trains in Stockholm was completed in 2017. It included two modern stations (Odenplan and Stockholm City) with platform screen doors (PSD) and one old station (Stockholm Södra) without PSDs. This study evaluates the concentrations of airborne particulates for the new stations, focussing on the effects of traffic operation, system age and train movement. For comparison, the other old station in the tunnel and an above-ground railway station (Solna) were also investigated. The new Odenplan platform was clean before its opening for traffic (12 and 2 μg/m3 for average PM10 and PM2.5, respectively). Substantial increases in the PM10 and PM2.5 concentrations were observed after it came into service. The average levels of PM10 and PM2.5 increased to 120 and 30 μg/m3 after one week of operation, and increased again to 175 and 35 μg/m3 after 3 months. The train movement factor (traffic frequency and train stop period) was found to have a strong effect on the particle concentrations of coarse sizes (0.3–10 μm). Comparable levels of PM10 and PM2.5 were measured at both the new station and the old station where the traffic frequency was similar. For the other new station, which had half the traffic frequency due to the station design with two separate platforms, the PM10 and PM2.5 levels were substantially lower.

National Category
Other Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-234246 (URN)
Note

QC 20180906

Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2019-05-21Bibliographically approved
Cha, Y., Olofsson, U., Gustafsson, M. & Johansson, C. (2016). On Particulate Emissions from Individual Trains in Tunnel Environments. In: Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance: . Paper presented at Third International Conference on Railway Technology, Sardinia, Italy 5-8 April 2016. Dun Eaglais, Kippen Stirlingshire, FK8 3DY, UK: Civil-Comp Press
Open this publication in new window or tab >>On Particulate Emissions from Individual Trains in Tunnel Environments
2016 (English)In: Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance, Dun Eaglais, Kippen Stirlingshire, FK8 3DY, UK: Civil-Comp Press , 2016Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Dun Eaglais, Kippen Stirlingshire, FK8 3DY, UK: Civil-Comp Press, 2016
Keywords
airborne particulates, individual train, particulate concentration, size distribution
National Category
Vehicle Engineering Other Environmental Engineering
Research subject
The KTH Railway Group - Tribology
Identifiers
urn:nbn:se:kth:diva-185507 (URN)978-1-905088-65-2 (ISBN)
Conference
Third International Conference on Railway Technology, Sardinia, Italy 5-8 April 2016
Note

QC 20160512

Available from: 2016-04-20 Created: 2016-04-20 Last updated: 2016-05-12Bibliographically approved
Tu, M., Cha, Y., Wahlström, J. & Olofsson, U.Towards a two-part train traffic emission factors model for airborne wear particles.
Open this publication in new window or tab >>Towards a two-part train traffic emission factors model for airborne wear particles
(English)Manuscript (preprint) (Other academic)
National Category
Other Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-234238 (URN)
Note

QC 20180905

Available from: 2018-09-04 Created: 2018-09-04 Last updated: 2018-09-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1291-8778

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