The induction heaters you're linking are designed to be permanently installed. They're perfect for switch heating, but probably not a cost-effective option for

The induction heaters you're linking are designed to be permanently installed. They're perfect for switch heating, but probably not a cost-effective option for maintenance work. You'd need to have the heaters installed very close together over the entire length of the track, and the likelihood that any one of them actually needs to be used to heat the track for repairs would be very small. A portable option might be possible, but then you'd have to mess with batteries or generators or something to provide the power. Ropes soaked in kerosene sounds to me like the "the cosmonauts used a pencil"† option. † (Yes, I know that this is an urban legend.)