The key statistics are:
Overall Size: 18ft x 14ft
NG full circuit: ~ 80ft
NG mainline maximum grade: 1 in 28 (3.5%) - from lower tunnel exit to quarry loop
NG mainline minimum radius: 27in - the big spiral and a small section c. 22in between quarry and viaduct.
The quarry lines are much steeper and tighter.
SG end to end length: ~30ft
SG maximum grade: 1 in 25 (4%) - mainly in hidden track
Grid squares = 1ft
The plan below shows the section that was exhibited at ExpoNG 2014 with the additional boards that were built to allow operation: