Table of Contents
Introduction
These are the clearances for bridges, structures and tangent tracks for Old Time (pre-1920), Classic I (1920–1969), Classic II (1969–1983), and Modern (post-1983) eras.
The numbers here are for N scale (1:160). The prototype (1:1) dimensions are given for conversion to other scales or you can check the NMRA standard to get information for other scales. The numbers in the following tables were taken from NMRA Standard S-7 Clearances (February 2012), except for dimensions C and D in Classic II (1969–1983) Clearances, which were calculated. All fractional inches are rounded off to the nearest 1/32 inch.
Old Time (pre-1920) Clearances

NMRA Clearances: Old Time (pre-1920)
Scale | N (1:160) | Prototype (1:1) | |||
---|---|---|---|---|---|
inch | inch | mm | inch | mm | |
A | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
B | 7/32 inch | 0.219 inch | 6 mm | 3 feet | 914.4 mm |
C | 10/32 inch | 0.313 inch | 8 mm | 4 feet | 1219.2 mm |
D | 24/32 inch | 0.750 inch | 19 mm | 10 feet | 3048 mm |
E | 7/32 inch | 0.219 inch | 6 mm | 3 feet | 914.4 mm |
F | 5/32 inch | 0.156 inch | 4 mm | 2 feet | 609.6 mm |
G | 13/32 inch | 0.406 inch | 10 mm | 5 feet 6 inch | 1676.4 mm |
H | 1 9/32 inch | 1.281 inch | 32 mm | 17 feet | 5181.6 mm |
P | 13/32 inch | 0.406 inch | 10 mm | 5 feet 6 inch | 1676.4 mm |
Classic I (1920–1969) Clearances

NMRA Clearances: Classic I (1920–1969)
Scale | N (1:160) | Prototype (1:1) | |||
---|---|---|---|---|---|
inch | inch | mm | inch | mm | |
A | 18/32 inch | 0.563 inch | 14 mm | 7 feet 6 inch | 2286 mm |
B | 10/32 inch | 0.313 inch | 8 mm | 4 feet | 1219.2 mm |
C | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
D | 29/32 inch | 0.906 inch | 23 mm | 12 feet | 3657.6 mm |
E | 10/32 inch | 0.313 inch | 8 mm | 4 feet | 1219.2 mm |
F | 6/32 inch | 0.188 inch | 5 mm | 2 feet 6 inch | 762 mm |
G | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
H | 1 21/32 inch | 1.656 inch | 42 mm | 22 feet | 6705.6 mm |
P | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
Classic II (1969–1983) Clearances

NMRA Clearances: Classic II (1969–1983)
Scale | N (1:160) | Prototype (1:1) | |||
---|---|---|---|---|---|
inch | inch | mm | inch | mm | |
A | 18/32 inch | 0.563 inch | 14 mm | 7 feet 6 inch | 2286 mm |
B | 10/32 inch | 0.313 inch | 8 mm | 4 feet | 1219.2 mm |
C | 10/32 inch | 0.313 inch | 8 mm | 4 feet | 1219.2 mm |
D | 1 2/32 inch | 1.050 inch | 27 mm | 14 feet | 4267.2 mm |
E | 10/32 inch | 0.313 inch | 8 mm | 4 feet | 1219.2 mm |
F | 6/32 inch | 0.188 inch | 5 mm | 2 feet 6 inch | 762 mm |
G | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
H | 1 21/32 inch | 1.656 inch | 42 mm | 22 feet | 6705.6 mm |
P | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
Modern (post-1983) Clearances

NMRA Clearances: Modern (post-1983)
Scale | N (1:160) | Prototype (1:1) | |||
---|---|---|---|---|---|
inch | inch | mm | inch | mm | |
A | 22/32 inch | 0.688 inch | 17 mm | 9 feet | 2743.2 mm |
B | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
C | 7/32 inch | 0.219 inch | 6 mm | 3 feet | 914.4 mm |
D | 1 6/32 inch | 1.188 inch | 30 mm | 16 feet | 4876.8 mm |
E | 10/32 inch | 0.313 inch | 8 mm | 4 feet | 1219.2 mm |
G | 14/32 inch | 0.438 inch | 11 mm | 6 feet | 1828.8 mm |
H | 1 23/32 inch | 1.719 inch | 44 mm | 23 feet | 7010.4 mm |
P | 13/32 inch | 0.406 inch | 11 mm | 5 feet 7 inch | 1701.8 mm |