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Title: Extremely low frequency magnetic field exposure in British railway environments
Author: Lazenby, Andrea Natalie
ISNI:       0000 0004 2718 3740
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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Exposure to extremely low frequency magnetic fields has been investigated in relation to various health effects. In the past, epidemiological studies have focused on residential and occupational exposures. The time spent commuting to work may not be insignificant, therefore any exposures acquired during those periods may have an effect on the strength of association. Given that millions of train journeys are made in Britain every year, extremely low frequency and static magnetic field measurements were made on six types of British trains and on five station platforms in order to characterise passenger exposure. Trains investigated included four elec- trical multiple units, one diesel-electrical multiple unit and one diesel locomotive. Power to the electric trains was supplied by either overhead cables (25 kV 50 Hz a.c.), the third rail (750 V d.c.) or from a four-rail system (630 V d.c.). The highest resultant a.c. magnetic field was measured on-board a diesel-electric multiple unit. The a.c. magnetic field was shown to vary with height above the carriage floor. The majority of resultant a.c. magnetic fields were higher closer to the floor, attributable to traction equipment mounted beneath the carriage. Average resultant a.c. magnetic fields at waist height across all train types were in the range 0.03-1.82 /-LT. The frequency component of the resultant a.c. magnetic field was shown to vary with increasing and decreasing speed on-board two different train types. The a.c. and d.c. magnetic field waveforms measured at different stations were dependent on the railway electrification and the types of train travelling on the line. Frequency spectra calculated from magnetic field waveforms taken on two station platforms showed component frequencies which were not multiples of the 50 Hz fundamental. Metrics such as the polarisation, total harmonic distortion and rate of change metric are considered, together with standard statistical measures of magnetic field.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available