I've just finished a curved garden bridge so thought i'd put a few pics up, in it their are two main parts of the bridge are 80X80X8 angle. The two bits are back to back to check the curve is the same...which it wasn't so needed a bit more "adjustment".
To get the curve i cut slots with a 9" grinder and 3mm thick cutting disc then bent it and welded it all up. The cuts were 13" apart so 6" boards with a 1/2" gap should look ok.
The frame with 50X50 box to make it about 5' wide. Sticking it all together with the lorch m-pro in the background. Some more angle to run down the centre. The offcuts used were a bit short so had to weld on a handle to bend it. Then main frame (nearly finished.) had to be moved outside before fixing on a handrail or it wouldn't fit out of the door.
The hand rail is 50X25 flat sided oval which i was able to curve in this roller i had made for another job. Fixed the boards down with tek screws. Shifted it into position with a Matbro telehandler and fixed it down to the slabs.
There is no lower handrail at the mo ...will see how it goes.It should be wide enough for a ride on mower but the lower side is a bit steep because i made it 14" lower so will have to see how that pans out.