We offer curved tracks with various radii. The bigger the radius, the smoother the curve. The R40 is the original Lego curve. Having different curves allows to run perfectly parallel tracks on the curve as shown in the picture below.
R120 Curved Track Set, 32 Sections, Full Circle - old version with 4 full sleepers
R120 Curved Track Set, 16 Sections, Half Circle - old version with 4 full sleepers