213.327—Alinement.
(a)
Uniformity at any point along the track is established by averaging the measured mid-chord offset values for nine consecutive points centered around that point and which are spaced according to the following table:
| Chord length | Spacing |
|---|---|
| 31′ | 7′9″ |
| 62′ | 15′6″ |
| 124′ | 31′0″ |
(b)
For a single deviation, alinement may not deviate from uniformity more than the amount prescribed in the following 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) |
|---|---|---|---|
| 6 | 1/2 | 3/4 | 11/2 |
| 7 | 1/2 | 1/2 | 11/4 |
| 8 | 1/2 | 1/2 | 3/4 |
| 9 | 1/2 | 1/2 | 3/4 |
(c)
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 owner of the track to which this subpart applies shall maintain the alinement of the track within the limits prescribed for each deviation:
| 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) |
|---|---|---|---|
| 6 | 3/8 | 1/2 | 1 |
| 7 | 3/8 | 3/8 | 7/8 |
| 8 | 3/8 | 3/8 | 1/2 |
| 9 | 3/8 | 3/8 | 1/2 |