Fig. 2

Absolute values of the magnetic field due to a south-north dc-electrified railway. The thicker upper (black) curve and the thinner lower (blue) curve refer to a linearly changing and to a constant leakage current density, respectively. The horizontal axis gives the distance along a line towards the east from the substation. Additional details of the calculations are given in the text. The small (red) circles show measured data in Calgary, Canada, in March 2006 (cf. Pirjola et al., 2007).