(a) Uniformity at any point along the track is established by averaging the measured mid-chord offset values for nine consecutive points that are centered around that point and spaced according to the following table: ------------------------------------------------------------------------
Chord length Spacing------------------------------------------------------------------------31...................................................... 79"62...................................................... 156"124..................................................... 310"------------------------------------------------------------------------
(b) Except as provided in paragraph (c) of this section, a single alinement deviation from uniformity may not be more than the amount prescribed in the following table: ----------------------------------------------------------------------------------------------------------------
The deviation The deviation The deviation
from uniformity from uniformity from uniformity
of the mid-chord of the mid-chord of the mid-chord
Class of track Tangent/ Curved track offset for a 31- offset for a 62- offset for a 124-
foot chord may foot chord may foot chord may
not be more not be more not be more
than--(inches) than--(inches) than--(inches)----------------------------------------------------------------------------------------------------------------Class 6 track...................... Tangent.............. \1/2\ \3/4\ 1\1/2\
Curved............... \1/2\ \5/8\ 1\1/2\Class 7 track...................... Tangent.............. \1/2\ \3/4\ 1\1/4\
Curved............... \1/2\ \1/2\ 1\1/4\Class 8 track...................... Tangent.............. \1/2\ \3/4\ 1
Curved............... \1/2\ \1/2\ \3/4\Class 9 track...................... Tangent.............. \1/2\ \1/2\ \3/4\
Curved............... \1/2\ \1/2\ \3/4\----------------------------------------------------------------------------------------------------------------
(c) For operations at a qualified cant deficiency, Eu, of more than 5 inches, a single alinement deviation from uniformity of the outside rail of the curve may not be more than the amount prescribed in the following table: ----------------------------------------------------------------------------------------------------------------
The deviation The deviation The deviation
from uniformity from uniformity from uniformity
of the mid-chord of the mid-chord of the mid-chord
Class of track Track type offset for a 31- offset for a 62- offset for a 124-
foot chord may foot chord may foot chord may
not be more not be more not be more
than--(inches) than--(inches) than--(inches)----------------------------------------------------------------------------------------------------------------Class 6 track...................... Curved............... \1/2\ \5/8\ 1\1/4\Class 7 track...................... Curved............... \1/2\ \1/2\ 1Class 8 track...................... Curved............... \1/2\ \1/2\ \3/4\Class 9 track...................... Curved............... \1/2\ \1/2\ \3/4\----------------------------------------------------------------------------------------------------------------
(d) For three or more non-overlapping deviations from uniformity in track alinement occurring within a distance equal to five times the specified chord length, each of which exceeds the limits in the following table, each track owner shall maintain the alinement of the track within the limits prescribed for each deviation: ----------------------------------------------------------------------------------------------------------------
The deviation The deviation The deviation
from uniformity from uniformity from uniformity
of the mid-chord of the mid-chord of the mid-chord
Class of track offset for a 31- offset for a 62- offset for a 124-
foot chord may foot chord may foot chord may
not be more not be more not be more
than--(inches) than--(inches) than-- (inches)----------------------------------------------------------------------------------------------------------------Class 6 track............................................. \3/8\ \1/2\ 1Class 7 track............................................. \3/8\ \3/8\ \7/8\Class 8 track............................................. \3/8\ \3/8\ \1/2\Class 9 track............................................. \3/8\ \3/8\ \1/2\----------------------------------------------------------------------------------------------------------------
(e) For purposes of complying with this section, the ends of the chord shall be at points on the gage side of the rail, five-eighths of an inch below the top of the railhead. On tangent track, either rail may be used as the line rail; however, the same rail shall be used for the full length of that tangential segment of the track. On curved track, the line rail is the outside rail of the curve. [78 FR 16104, Mar. 13, 2013]