Pictures below show how I'm leveling the welded RSJ grid structure but demonstrates the jack it up and kick ballast under railway sleepers post earth quake irritations (!)
Here I'm using ratchet straps to raise the sleepers into position under the RSJs.
M12 wood bolts used to fix sleeper to RSJ
A technical triumph => booting the ballast into place under the sleeper (steel toe caps recommended)
The next stage is to weld the upper structure onto the RSJ grid base. I hope this doesn't cause the newly leveled parts to settle too far but after I've loaded the structure with about 5 tons of OSB sheet material I'm guessing some levleing adjustments might be necessary (!)