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      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
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You are here: Home / Sources / Transport / EMFs from electric trains (UK)

EMFs from electric trains (UK)

On platforms etc, the electric fields come from the overhead catenary wire (in systems with overhead electrification), and the magnetic field comes from the current loop formed by the supply (the overhead catenary or the third rail) and the return (the running rails or a dedicated conductor).

On board trains themselves, there is still a magnetic field from the loop formed by the supply currents.  There may also be magnetic fields from conductors carrying currents through the train.  There can also be a magnetic field associated with the motors.  This is not usually from the motor itself but from inductors or solenoids in the control circuitry.  In electric multiple units, there are motors in at least some of the carriages and the supply circuitry, under the floor, can provide remarkably high fields close to the floor.  With locomotive-hauled trains, the circuitry tends to be in the locomotive and passengers are not exposed to the fields from it.

The WHO Environmental Health Criteria summarises the data as follows (reproduced from table 10, page 45 but with typos corrected):

Table 10. Alternating magnetic fields from UK electrified rail systems
System and SourceAC magnetic
flux density
FrequencyComments
London Underground
 Up to 20 μT100 HzIn the driver’s cab; arising from traction components and on board smoothing inductors
Suburban trains
750 DC Electric Motor UnitsUp to 1 mT100 HzFloor level
16-64 μT100 HzIn passenger car at table height
16-48 μT100 HzOutside train on platform
Mainline trains
Electric Motor UnitsUp to 15 mT100 HzFloor level above inductor
LocomotivesUp to 2.5 mT100 Hz0.5 m above floor in equipment car
5-50 μT50 HzIn passenger coaches

 

Sources of information

Much of the information comes from a paper by Chadwick and Lowes, see below.  There is also a Report:

Allen SG et al. Review of occupational exposure to optical radiation and electric and magnetic fields with regard to the proposed CEC physical agents directive. Chilton, National Radiation Protection Board, 1994 (NRPB-R265).

More recently, the Rail Safety and Standards Board have published research on EMFs.  This is focussed on compliance with the European Directive but contains quite a bit of general information on fields:

Investigation into the effect of the Physical Agents (Electromagnetic Fields) Directive on railway operations (T515)

 

Ann Occup Hyg. 1998 Jul;42(5):331-5.
Magnetic fields on British trains

Chadwick P, Lowes F.

National Radiological Protection Board, Chilton, Didcot, Oxon, U.K.

People on trains can be exposed to static and alternating magnetic fields which are higher than background levels in most homes and many workplaces. Quantification of such exposure may be of interest for epidemiological purposes but it is also important to ensure that exposure guidelines are complied with. This article describes the types of electric trains and trams in use in the UK and the results of measurements of static and alternating magnetic flux density. Many of the data have been supplied by the operators of the systems described. The measurements summarised in this article are indicative of the magnitudes of magnetic field exposures to be encountered on British trains, but without concomitant frequency information, they are not sufficient to allow demonstration of compliance with exposure standards.

 

 

See also:

  • EMFs from cars
  • Other sources of EMFs

Latest news

  • New publication on cancer incidence from the UK electricity industry Cohort Study August 27, 2019
  • How has the reported risk for childhood leukaemia changed over time? February 11, 2019
  • Media stories about microshocks in children’s playground September 10, 2018
  • New studies on leukaemia and distance from power lines June 1, 2018
older news

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Navigation
  • What are EMFs
    • Terminology – an introduction
    • Electric fields
    • Magnetic fields
    • Units for measuring EMFs
    • Measuring and calculating EMFs
      • “EMF Commercial”
    • Adding fields together
    • Radiofrequencies
    • Screening EMFs
  • Sources
    • Overhead power lines
      • Fields from specific power lines
        • 400 kV
        • 400 kV – specific cases
        • 275 kV
        • 132 kV
        • 66 kV
        • 33 kV
        • 11 kV
        • 400 V/230 V
        • Replacing a 132 kV line with a 400 kV line
      • Summaries of fields from all power lines
      • Factors affecting the field from a power line
        • Voltage
        • Current
        • Clearance
        • Height above ground
        • Conductor bundle
        • Phasing
        • Balance between circuits
        • Balance within circuit
        • Ground resistivity
        • Two parallel lines
      • Calculating and measuring fields from power lines
        • Geometries of power lines
        • Raw data
        • On-line calculator
      • Fields from power lines – more detail on the physics
        • Field lines from a power line
        • The direction of the field from a power line
        • Power law variations in the field from a power line
      • Statistics of power line fields
    • Underground power cables
      • Different types of underground cable
      • Fields from cables in tunnels
      • Gas Insulated Lines (GIL)
      • Underground cables with multiple conductors
      • Effect of height on fields from underground cables
      • Screening fields from underground cables
    • Low-voltage distribution
      • UK distribution wiring
      • USA distribution wiring
    • House wiring
    • Substations
      • National Grid substations
        • Static Var Compensators
      • Sealing-end compounds
      • Distribution substations
      • Final distribution substations
        • Indoor substations
    • Transport
      • EMFs from electric trains (UK)
      • EMFs from cars
    • Appliances
    • Electricity meters
      • Smart meters
      • Traditional meters
    • Occupational exposures
      • Live-line work
      • Static Var Compensators
      • Occupational exposures on pylons
    • Field levels and exposures
      • Personal exposure
      • Other factors that vary with magnetic fields
      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
      • Screening fields from underground cables
      • EMF Reduction Devices
  • Known effects
    • Induced currents and fields
    • Microshocks
      • Control of microshocks in the UK
      • Microshocks from bicycles
      • Bees and microshocks
    • EMFs and medical devices
      • Standards relating to pacemakers and other AIMDs
    • Effects of EMFs on equipment
  • Research
    • Types of research
    • Epidemiology
    • Animal and laboratory experiments
    • Mechanisms
    • Specific studies
      • UKCCS
      • CCRG
      • French Geocap study
      • CEGB cohort
      • Imperial College study
  • Current evidence on health
    • Childhood leukaemia
      • Survival from childhood leukaemia
      • Childhood leukaemia and Downs
      • Childhood leukaemia and night-time exposure
      • The “contact current” hypothesis
    • Other health effects
    • Scientific review bodies
      • WHO
      • IARC
    • Electric fields and ions
    • Comparing EMFs to other issues
  • Exposure limits for people
    • Limits in the UK
    • Limits in the EU
    • Limits in the USA
    • Limits in the rest of the world
    • Limits from specific organisations
      • ICNIRP 1998
      • ICNIRP 2010
      • NRPB 1993
      • NRPB 2004
      • EU 2004
      • EU 2013
  • Policy
    • UK policy
      • Power lines and property – UK
    • Compliance with exposure limits
    • European EMF policy
    • Precaution
    • SAGE
      • SAGE First Interim Assessment
        • Government response to SAGE First Interim Assessment
      • SAGE Second Interim Assessment
        • Government response to SAGE Second Interim Assessment
        • SAGE Second Interim Assessment – the full list of recommendations
  • Finding out more
    • EMF measurement and commercial services
    • Links
    • Literature
    • Contact us
  • Static fields
    • Static fields – the expert view