rho_pond 10[ohm*m] "Resistivity of fresh water pond"
rho_clay 50[ohm*m] "Resistivity of clay"
rho_sand 400[ohm*m] "Resistivity of sandy clay"
rho_gravel 500[ohm*m] "Resistivity of gravel"
rho_tie 250[ohm*m] "Resistivity of concrete railway tie"
r_rail 0.05[m] "Rail radius, cylindrical cross-sectional approximation"
t_train 0[s] "Train traveling time"
r_pipe 0.2[m] "Pipe radius"
L_rail 1240[m] "Rail length or distance between traction substations"
sigma_steel 1e7[S/m] "Electric conductivity of steel pipe wall"
rho_tiex rho_tie*1/3+rho_gravel*2/3 "Resistivity of tie in x-direction, assuming 1/3 tie and 2/3 tie"
ro_pipe 7850[kg/m^3] "Density of pipe material"
M_pipe 55.85[g/mol] "Molar mass of pipe material"
L_rePos 0[m] "Repositioning distance pipe"
R_railins 1e-3[ohm*m^2] "Insulation resistance of rail"
z_pipe -2.5[m] "Depth in soil at which the pipe is located"