First I clipped the guard rail off each side. Each side clips on in 4 places:
Next I removed the metal walkways by straightening out the metal tabs below
Then I made a bunch of cuts in from one side, some as far as the walkway on the far side, but mostly just to the middle
Then I screwed one end down to a plank, bent the ramp into a curve and inserted a piece of curved track and screwed down the other end too
This was to hold the curve in place whilst I glued the cuts shut again
I placed super glue on the guard rails and glued them in place with the aid of some clamps...
Then I snipped the metal walkways so that they too could be bend into a curve and super-glued them in place
Because of the new curve, not all the original tabs fit and they have to be snipped off.
The finished curved ramp with a Märklin 2374 track piece