Hard to get a sense of scale from the picture, but it looks like about 5-7 kg. Most flat-bottom rail is between 40 and 70 kg per metre, so you would only need a short piece - somewhat more than 10 cm by the time you narrowed the flat bottom and added a handle on top. (I'm talking about serious railway line, not tram rail or crane rail.) It would be very helpful if Bob could weigh his - pity to spend hours cutting a piece of rail only to find the weight is wrong. Rail line is structural steel, not mild steel, which makes cutting it a bit slower. My power hacksaw would take a number of minutes to cut it to length, and milling or sawing the bottom flange would take a while.
