your portal to more fun in scale model railroading

S-3.2 Standard Scale Trackwork

S-3.2 Standard Scale Trackwork

S-3.2

 
 

  G C S F H P
Name of Scale Track Gage (Min./Max.) Check Gage
(Min.)		 Span
(Max.)		 Flangeway
(Max.)		 Flange
Clearance
(Min.)		 Switchpoint Spread (Max)
(Elec/Mech)
1" 4.750* (120.7 mm) 4.581 4.429 .220 .156 -
4.910 (124.7 mm) (116.4 mm) (112.5 mm) (5.59 mm) (3.96 mm) 4.536 (115.2mm)
3/4" 3.500* (88.9 mm) 3.349 3.212 .181 .125 -
3.605 (91.6 mm) (85.1 mm) (81.6 mm) (4.60 mm) (3.18 mm) 3.312 (84.1mm)
F With the exception of the minimum Flange Clearance, F uses the same track geometry as Proto 20.3 Gauge track (see S-3.1) (see Note 2)
.090		  
(2.29 mm)

 

Fn3

 Fn3 uses the same track geometry as #1 Gauge track)    
 

 
No.# I 1.766* (44.85 mm) 1.660 1.563 .106 (see Note 2)
.064		 1.634 (41.5mm)
1.793 (45.5 mm) (42.16 mm) (39.69 mm) (2.68 mm) (1.63 mm) 1.639 (41.63mm)
No.# In3 1.125* (28.6 mm) 1.058 .997 .079 .047 1.037 (26.4mm)
1.167 (29.6 mm) (26.9 mm) (25.3 mm) (2.00 mm) (1.19 mm) 1.042 (26.5mm)
O 1.250* (31.8 mm) 1.179 1.115 .079 .047 1.159 (29.4mm)
1.285 (32.6 mm) (29.9 mm) (28.3 mm) (2.01 mm) (1.19 mm) 1.164 (29.6mm)
On3 .750* (19.1 mm) .705 .664 .053 .030 .690 (17.5mm)
.778 (19.8 mm) (17.9 mm) (16.9 mm) (1.35 mm) (0.76 mm) .695 (17.7mm)
On30 On30 uses the same track geometry as HO Gauge track        

 

 

 

 
On2 .500* (12.7 mm) .455 .414 .050 .028 .440 (11.2mm)
.522 (13.3 mm) (11.6 mm) (10.5 mm) (1.27 mm) (0.71 mm) .445 (11.3mm)
S .883* (22.42 mm) .839 .798 .050 .030 .814 (20.68mm)
.905 (22.99 mm) (21.32 mm) (20.27 mm) (1.27 mm) (0.76 mm) .819 (20.80mm)
Sn3 .563* (14.3 mm) .519 .478 .050 .030 .494 (12.55mm)
.585 (14.9 mm) (13.2 mm) (12.1 mm) (1.27 mm) (0.76 mm) .499 (12.68mm)
OO .750* (19.1 mm) .705 .664 .050 .028 .690 (17.5mm)
.772 (19.6 mm) (17.9 mm) (16.9 mm) (1.27 mm) (0.71 mm) .695 (17.7mm)

 

 

  G C S F H P
Name of Scale Track Gage (Min./Max.) Check Gage
(Min.)		 Span
(Max.)		 Flangeway
(Max.)		 Flange
Clearance
(Min.)		 Switchpoint Spread (Max)
(Elec/Mech)
HO .649* (16.5 mm) .605 .564 .050 028 .590 (15.0mm)
.672 (17.1 mm) (15.4 mm) (14.3 mm) (1.27 mm) (0.71mm) .595 (15.1mm)
HOn2 .276* (7.01 mm) .246 .219 .033 .022 .235 (5.97mm)
.290 (7.37 mm) (6.25 mm) (5.56 mm) (0.84 mm) (0.56 mm) .240 (6.10mm)
TT .471* (12 mm) .437 .406 .036 .026 .425 (10.8mm)
.483 (12.3 mm) (11.1 mm) (10.3 mm) (0.91 mm) (0.66 mm) .430 (10.9mm)
N .353* (8.97 mm) .323 .296 .0303 .022 .312 (7.92mm)
.367 (9.32 mm) (8.20 mm) (7.52 mm) (0.7684 mm) (0.56 mm) .317 (8.05mm)
Nn3 .250* (6.35 mm) .228 .207 .025 .020 .218 (5.53mm)
.260 (6.61 mm) (5.78 mm) (5.26 mm) (0.63 mm) (0.51 mm) .224 (5.66mm)
Nn2 .177* (4.50 mm) .147 0.117 .030 .020 .219 (5.56mm)
.189 (4.80 mm) (3.74 mm) (2.97 mm) (0.76 mm) (0.51 mm) .224 (5.69mm)
Z .257* (6.53 mm) .236 .217 .025 .020 .226 (5.74mm)
.270 (6.86 mm) (5.99 mm) (5.51 mm) (0.64 mm) (0.51 mm) .231 (5.87mm)

* Denotes Preferred Dimension for Tangent Track (see Note 44)

NOTES:

  1. For information on both minimum and maximum manufacturing limits please see
    NMRA Tech Note: TN-1.2.1
  2. For maximum interchange the minimum flange clearance (H) should be increased to 3mm. This allows all models that operate on 45 mm track to operate with no problems. It is also much easier to fill in a deep flange ais needed rather then making a small flange depth deeper.
  3. HO (fine), TT (fine), and N (fine) were specifically designed to work well in dual gauge trackage with their n3 counterpart.
  4. The F limit applies only to the wing rail, and the C limit applies only to the guard rail. Both apply to the same rail only in special work such as a crossing.
  5. For Gauge widening in curves for long wheelbase equipment see RP-8.
  6. For a full discussion of minimum radius, minimum turnout and radius equivalents of degrees of curvature. etc., see S-8 and RP-11.
  7. Guard and wing rails shall be flared to a minimum dimension across the flared flangeway end of 1.5 x Fmax. Flare angle shall not exceed 10 degrees, and the Flare must disappear before reaching the working area of its rail.
  8. P electrical is only needed if the points are electrically connected together. If the points are electrically connected to their corresponding stock rail and are thus electrically isolated from each other (the preferred approach) then P electrical does not apply.