Engineering & Consulting

Magnetic field studies (NIS)

On the 1st of February 2000, the regulations for the protection against non-ionised radiation (NISV) came into effect in Switzerland. This subject is a major concern for railway facilities, and ENOTRAC has experience in many of the relevant fields.

NIS evidence catenary line systems
NISV-evidence of electrical substations

We measure the magnitude of the magnetic fields emitted by the existing facilities, such as overhead wires or substations. The measurements are used by the facility owners as proof of compliance with the legal limits. The measurements are also used by builders to get a feeling of the actual magnetic field density when constructing near railways.


  • Canton of Solothurn: University of Applied Sciences of North-West Switzerland in Olten
  • BLS: Building at Flensburg
  • SBB: Durchmesserlinie in Zürich
  • SBB: New line Mattstetten-Rothrist (NBS)
  • BAFU: Long-term measurements at various locations between Thun and Spiez
Different aerial lines at a house in Felsenburg at the BLS Lötschberg linezoom
Magnetic flux density measurements along the SBB tracks in Oltenzoom

In accordance with article 11 of the NISV, details of the non ionising radiation must be provided for each overhead line system for approve of design by the government. It must be verified that the NISV limits are respected in all sensitive places (PSU).
The verification of the limits is based on simulations with our simulation tools SIMNET and EMFCALC. Thereby the magnetic fields are calculated based on the simulated models.

In order to create calculations, a detailed model of the traction power system (contact wires, rails, earth wires, transmission lines etc.) in the affected area is created. The current used in these models is based on simulations and/or measurements.

Simulation results from SIMNET and emfcalc for the 1 uT curve at a buildingzoom
Simulation results from SIMNET and emfcalc for the 1 uT curve in a tunnelzoom

Various validation measurements served as plausibility checks for the simulation model in SIMNET

ENOTRAC has verified compliance with NISV on a number of projects, including:

  • BLS line Bern - Neuenburg: Rosshäusern tunnel, Railway station Ins, Fanel-Wald, Marin - Neuchâtel
  • BLS Gürbetal line: Wabern – Kehrsatz, Toffen - Kaufdorf, modification of the railway stations Thurnen and Burgistein-Wattenwil
  • BLS modification of the railway station Frutigen
  •  BLS traction current line Gampel - Hohtenn
  • BLS Hasle Rüegsau - Ramsei, railway station Huttwil
  • CEVA, Liaison ferroviaire Cornavin — Eaux-Vives — Annemasse
  • CFF, various contact wire building projects
  • DB, Railway station Thayngen
  • MGBahn, UL Visp – Herbriggen, various contact wire sections
  • RhB, modification of various stations: Klosters, Samedan, Davos Platz, Landquart, St. Moritz etc.
  • RhB, adjustments to the electric traction supply: Chur Langwies, Davos – Glaris
  • SBB, changing electrification node Geneva
  • SBB, modification node Lausanne und 4. track Lausanne - Renens
  • SBB, the Brig area
  • SBB, tunnel-restoration in St-Maurice and Sieders
  • SBB, decartelization catenary wire installation Wylerfeld in Bern
  • TPF, various contact wire rebuild projects
  •  TransRUN, Neuchâtel - La Chaux-de-Fonds
  • Zb Zentralbahn, various contact wire rebuild projects

In accordance with NISV, details of the non ionising radiation must be provided for each electrical substation planning application. It must be proven that the NISV limits are respected in all sensitive places (PSU). We have used our simulation tools for following electrical substations:

  • SBB, substation Vernayaz
  • SBB, substation Le Day
  • SBB, substation Brig
  • SBB, substation Deitingen
  • SBB, substation Giubiasco (16.7 Hz and 50 Hz)
  • SBB, substation Massaboden
Simulation results from emfcalc3d for a SBB substation (15 kV / 16.7 Hz)zoom
Model of a substation for the calculation of the magnetic flux densityzoom
1uT-curve of a railway substation, ground view, based on simulationszoom
1uT-curve of a railway substation, 3D model view, based on simulationszoom

On behalf of the Federal office for the environment (FOEN), ENOTRAC undertook a cost benefit analysis of the potential methods of reducing the magnetic flux density of the overhead systems. This study is available for download (in German) on the website of the FOEN.
Additionally, ENOTRAC was heavily involved in the development of an implementation aid for non-ionised radiation (NISV) protection for the FOEN, and has also conducted some basic research, and developed numerical tools.

Simulation results from SIMNET and emfcalc for the 1 uT curve of a cantenary systemzoom

ENOTRAC AG, Seefeldstrasse 8, 3600 Thun, Switzerland, Tel: +41 33 346 66 11
ENOTRAC SA, Avenue de la Gare 1, 1003 Lausanne, Switzerland, Tel: +41 21 623 83 00
ENOTRAC UK Ltd, Chancery House St Nicholas Way Sutton, Surrey SM1 1JB England, Tel: +44 20 8770 3501

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