(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:

Open 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:

Open Table
Class of track Tangent/
Curved track
The deviation from uniformity of the mid-chord offset for a 31-foot chord may not be more than—(inches) The deviation from uniformity of the mid-chord offset for a 62-foot chord may not be more than—(inches) The deviation from uniformity of the mid-chord offset for a 124-foot chord may not be more than—(inches)
Class 6 track Tangent 12 34 112
    Curved 12 58 112
Class 7 track Tangent 12 34 114
    Curved 12 12 114
Class 8 track Tangent 12 34 1
    Curved 12 12 34
Class 9 track Tangent 12 12 34
    Curved 12 12 34

(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:

Open Table
Class of track Track type The deviation from uniformity of the mid-chord offset for a 31-foot chord may not be more than—(inches) The deviation from uniformity of the mid-chord offset for a 62-foot chord may not be more than—(inches) The deviation from uniformity of the mid-chord offset for a 124-foot chord may not be more than—(inches)
Class 6 track Curved 12 58 114
Class 7 track Curved 12 12 1
Class 8 track Curved 12 12 34
Class 9 track Curved 12 12 34

(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:

Open Table
Class of track The deviation from uniformity of the mid-chord offset for a
31-foot chord may not be more than—(inches)
The deviation from uniformity of the mid-chord offset for a 62-foot chord may not be more than—(inches) The deviation from uniformity of the mid-chord offset for a 124-foot chord may not be more than— (inches)
Class 6 track 38 12 1
Class 7 track 38 38 78
Class 8 track 38 38 12
Class 9 track 38 38 12

(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]


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