Subpart C - Track Geometry

1. Scope

This subpart prescribes minimum requirements for the gauge, alignment, and surface of track and the elevation of the outer rails and speed limitations for curved track. 

2. Gauge

2.1 Gauge is measured between the heads of the rails at right angles to the rails in a plane 5/8 inch below the top of the rail head.

2.2 Standard gauge is 56 ½ inches.

2.3 Gauge must be within the limits prescribed in the following table:

Class of track The gauge must be at least But not more than
Excepted track N/A 58 1/4"
1 55 3/4" 58"
2 55 3/4" 57 ¾"
3 56" 57 ¾"
4 and 5 56" 57 ½"
Yard Track Category 1 & Category 2 56" 57 ¾"
Yard Track Category 3 & Category 4 55 3/4" 58"

2.4 Variation in Gauge

When the gauge is less than 56 inches and the change in gauge over a distance of 20 feet (6.096 m) or less on either side of the defective location exceeds 1 ½ inches, train speed must be reduced according to Class 1 track speed.

3. Track Alignment

Alignment may not deviate from uniformity more than the amount prescribed in the following table:

Class of Track Tangent Track Curved Track
The deviation of the mid-offset from a 62-foot line[1] may not be more than - The deviation of the mid-ordinate from a 31-foot chord[2] may not be more than - The deviation of the mid-ordinate from a 62-foot chord[2] may not be more than -
1 5" N/A[3] 5"
2 3" N/A[3] 3"
3 1 3/4" 1 1/4" 1 3/4"
4 1 1/2" 1" 1 1/2"
5 3/4" 1/2" 5/8"

[1] The ends of the line must be at points on the gauge side of the line rail, 5/8 inch below the top of the railhead. Either rail may be used as the line rail; however, the same rail must be used for the full length of that tangential segment of track.

[2] The ends of the chord must be at points on the gauge side of the outer rail, 5/8 inch below the top of the railhead.

[3] N/A – Not Applicable

4. Curves: Elevation and Speed Limitations

4.1 The maximum cross level on the outside rail of a curve may not be more than 7 inches on any track. Curves exceeding 6 inches cross level must be monitored and have a remedial action plan to bring it back to 6 inches or less cross level. The outside rail of a curve may not be lower than the inside rail, except as per table in Part II, Subpart C section 6 Track Surface.

4.2 The maximum allowable operating speed for each curve is determined by the following formula:

V max is equal to the square root of the sum of Ea plus 3 divided by the product of 0.0007 multiplied by d

where:

Vmax = Maximum allowable operating speed (miles per hour)

Ea = Actual elevation of the outside rail (inches)1

d = Degree of curvature (degrees)2

1 For the purpose of calculating Vmax only, actual elevation for each 155 foot track segment in the body of the curve is determined by averaging the elevation for 10 points through the segment at 15.5-foot spacing. If the curve length is less than 155 ft, average the points through the full length of the body of the curve.

2 Degree of curvature is determined by averaging the degree of curvature over the same track segment as the elevation.

Below is a table of maximum allowable operating speed computed in accordance with this formula for various elevations and degrees of curvature.

Degree of Curvature Three-Inch Unbalance
Elevation in Inches
0 1/2 1 1 ½ 2 2 ½ 3 3 ½ 4 4 ½ 5 5 ½ 6
Maximum allowable operating speed (m.p.h.)
0° 30' 93 100 107 113 120 125 131 136 141 146 151 156 160
1° 00' 66 71 76 80 85 89 93 96 100 104 107 110 113
1° 15' 59 63 68 72 76 79 83 86 89 93 96 99 101
1° 30' 54 58 62 66 69 72 76 79 82 85 87 90 93
1° 45' 50 54 57 61 64 67 70 73 76 78 81 83 86
2° 00' 46 50 54 57 60 63 66 68 71 73 76 78 80
2° 15' 44 47 50 54 56 59 62 64 67 69 71 74 76
2° 30' 41 45 48 51 54 56 59 61 63 66 68 70 72
2° 45' 40 43 46 48 51 54 56 58 60 62 65 66 68
3° 00' 38 41 44 46 49 51 54 56 58 60 62 64 66
3° 15' 36 39 42 45 47 49 51 54 56 57 59 61 63
3° 30' 35 38 40 43 45 47 50 52 54 55 57 59 61
3° 45' 34 37 39 41 44 46 48 50 52 54 55 57 59
4° 00' 33 35 38 40 42 44 46 48 50 52 54 55 57
4° 30' 31 33 36 38 40 42 44 45 47 49 50 52 54
5° 00' 29 32 34 36 38 40 41 43 45 46 48 49 51
5° 30' 28 30 32 34 36 38 40 41 43 44 46 47 48
6° 00' 27 29 31 33 35 36 38 39 41 42 44 45 46
6° 30' 26 28 30 31 33 35 36 38 39 41 42 43 45
7° 00' 25 27 29 30 32 34 35 36 38 39 40 42 43
8° 00' 23 25 27 28 30 31 33 34 35 37 38 39 40
9° 00' 22 24 25 27 28 30 31 32 33 35 36 37 38
10° 00' 21 22 24 25 27 28 29 31 32 33 34 35 36
11° 00' 20 21 23 24 26 27 28 29 30 31 32 33 34
12° 00' 19 20 22 23 24 26 27 28 29 30 31 32 33

4.3 A track owner or a railway company may request approval from Transport Canada to operate specified railway equipment at a level of cant deficiency greater than 3 inches.

5. Elevation of Curved Track: Runoff

5.1 If a curve is elevated, the full elevation must be provided throughout the curve, unless physical conditions do not permit. If elevation runoff occurs in a curve, the actual minimum elevation must be used in computing the maximum allowable operating speed for that curve under 4.2.

5.2 Elevation runoff must be at a uniform rate, within the limits of track surface deviation prescribed in Part II, Subpart C section 6 and it must extend at least the full length of the spirals. If physical conditions do not permit a spiral long enough to accommodate the minimum length of runoff, part of the runoff may be on tangent track.

6. Track Surface

6.1 Each owner of the track to which this part applies shall maintain the surface of its track within the limits prescribed in the following table:

Track Surface Class of Track
1 2 3 4 5
The runoff in any 31 ft of rail at the end of the raise may not be more than 3 ½" 3" 2" 1 ½" 1"
The deviation from uniform profile on either rail at the mid-ordinate of a 62 foot chord may not be more than 3" 2 ¾" 2 ¼" 2" 1 ¼"
The difference in cross level between any two points less than 31 ft apart on spirals may not be more than 2" 1 ¾" 1 ¼" 1" ¾"
The deviation from zero cross level at any point on tangent track or reverse cross level elevation on non tangent track may not be more than 3" 2" 1 ¾" 1 ¼" 1"
The difference in cross level between any two points less than 62 ft apart may not be more than 3" 2 ¼" 2" 1 ¾ 1 ½"

6.2 To control harmonics on Class 2 through 5 jointed track with staggered joints, the cross level differences shall not exceed 1 ¼ inches in all of six consecutive pairs of joints, as created by 7 low joints. Track with joints staggered less than 10 feet (3.048 m) shall not be considered as having staggered joints. Joints within the 7 low joints outside of the regular joint spacing shall not be considered as joints for purposes of this subsection. For 79 or 80 foot long rails, this subsection is not applicable.

7. Interpolation of Speeds between Track Classes

In the event that a track geometry-related defect is detected during a track geometry car inspection, the railways may, for a period of seventy-two (72) hours after the inspection, use linear interpolation to determine the speed of the temporary slow order initiated to protect the defect. Records of slow orders imposed or reason for not imposing one must be maintained. Upon the expiration of the seventy-two (72) hours period, if the track defect has not been repaired, the slow order speed(s) must be revised to those of the next lower track Class.

8. Combined Alignment and Track Surface Deviations

A railway company must have defined measures to address the combination of track defects. Although the current TSR prescribe limits on geometry variations existing in isolation, it is recognized that a combination of alignment, and surface variations, none of which individually amounts to a deviation from the requirements of TSR may pose a higher risk when these defects are located at or near the vicinity of each other.

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