Garden railroading often defines track curve dimensions with four different radii, called R1, R2, R3 and R5. These sections form circles of the following diameters:

DIAMETER MEASURED CENTER OF TRACK-TO-CENTER OF TRACK

• R1 = 1200 mm = 48.0"
  
• R2 = 1560 mm = 61.5"
  
• R3 = 2390 mm = 94.0"
  
• R5 = 4640 mm = 182.7"

DIAMETER MEASURED OUTER EDGE-TO-OUTER EDGE

• R1 = 1286 mm = 50.62"
  
• R2 = 1646 mm = 64.8"
  
• R3 = 2476 mm = 97.5"
  
• R5 = 4726 mm = 186.0"