Engineers and procurement specialists must understand exact train rail sizes to ensure the structural integrity and safety of railway tracks and crane runway systems. The specific profile of a rail section—defined by its height, head width, base width, and web thickness—determines its load-bearing capacity and compatibility with rolling stock. Whether you are sourcing materials for a light industrial spur, a heavy-haul mainline, or an overhead crane system, identifying the correct rail section is the critical first step in track design and maintenance.
Train Rail Sizes for Industrial Applications
When discussing train rail sizes, the terminology often refers to the weight of the rail per unit length. In the United States, this is typically expressed as pounds per yard (lb/yd), while metric standards use kilograms per meter (kg/m). For example, an “85 lb rail” weighs approximately 85 pounds for every yard of length. However, weight is just one identifier. Two rails can share the same weight but have drastically different cross-sectional dimensions, known as the rail “section.”
The section designation typically includes the weight followed by the governing standard, such as ASCE (American Society of Civil Engineers), AREA (American Railway Engineering Association), or ARA (American Railway Association). For instance, an 85 lb ASCE rail has different geometric properties than an 85 lb ARA-A rail.
Selecting the wrong profile can lead to disastrous consequences, including derailments, premature wear, or the inability to properly secure the rail to the ties using standard rail clips. Therefore, verifying the dimensional data against the mill marks found on the rail web is standard practice in the industry.
Standard Train Rail Sizes and Profile Dimensions
To accurately identify train rail sizes, one must measure four key dimensions. These measurements provide the unique fingerprint for each rail section.
- Rail Height: The vertical distance from the flat bottom of the base to the top of the rail head.
- Base Width: The horizontal measurement across the bottom flange. This dimension dictates the type of tie plate or rail clip required.
- Head Width: The measurement across the top running surface. This impacts the wheel-rail interface and wear patterns.
- Web Thickness: The width of the vertical section connecting the head and base.
Below, we categorize these specifications by the standard engineering associations that defined them.
ASCE Rail Section Dimensions
The American Society of Civil Engineers (ASCE) established some of the most common rail sections used in North America, particularly for light rail and industrial applications. These rails typically range from light mining tracks (12 lb) to standard mainlines (100 lb).
Light Rail Specifications (12 lb – 45 lb)
Light rails are frequently used in mining, temporary construction tracks, and amusement devices. The train rail sizes in this category are compact, with narrower bases and shorter heights.
|
Nominal Weight (lb/yd) |
Section Designation |
Height (inches) |
Base Width (inches) |
Head Width (inches) |
Web Thickness (inches) |
|
12 |
12 AS |
2 |
2 |
1 |
3/16 |
|
16 |
16 AS |
2 3/8 |
2 3/8 |
1 11/64 |
7/32 |
|
20 |
20 AS |
2 5/8 |
2 5/8 |
1 11/32 |
1/4 |
|
25 |
25 AS |
2 3/4 |
2 3/4 |
1 1/2 |
19/64 |
|
30 |
30 AS |
3 1/8 |
3 1/8 |
1 11/16 |
21/64 |
|
35 |
35 AS |
3 5/16 |
3 5/16 |
1 3/4 |
23/64 |
|
40 |
40 AS |
3 1/2 |
3 1/2 |
1 7/8 |
25/64 |
|
45 |
45 AS |
3 11/16 |
3 11/16 |
2 |
27/64 |
Heavy Rail Specifications (60 lb – 100 lb)
As loads increase, the web must become thicker to resist shear forces, and the head must become wider to distribute wheel loads. These train rail sizes are common in older sidings, industrial yards, and some short-line railroads.
|
Nominal Weight (lb/yd) |
Section Designation |
Height (inches) |
Base Width (inches) |
Head Width (inches) |
Web Thickness (inches) |
|
60 |
60 AS |
4 1/4 |
4 1/4 |
2 3/8 |
31/64 |
|
65 |
65 AS |
4 7/16 |
4 7/16 |
2 13/32 |
1/2 |
|
70 |
70 AS |
4 5/8 |
4 5/8 |
2 7/16 |
33/64 |
|
75 |
75 AS |
4 13/16 |
4 13/16 |
2 15/32 |
17/32 |
|
80 |
80 AS |
5 |
5 |
2 1/2 |
35/64 |
|
85 |
85 AS |
5 3/16 |
5 3/16 |
2 9/16 |
9/16 |
|
90 |
90 AS |
5 3/8 |
5 3/8 |
2 5/8 |
9/16 |
|
100 |
100 AS |
5 3/4 |
5 3/4 |
2 3/4 |
9/16 |
AREA and ARA Rail Specifications
For modern freight and heavy-haul lines, the American Railway Engineering Association (AREA) sections are the standard. These designs prioritize stability and longevity under massive loads. You will notice that for similar weights, AREA rails often differ slightly in height or head width compared to ASCE rails, which is why precise measurement of train rail sizes is non-negotiable when replacing track segments.
|
Nominal Weight (lb/yd) |
Section Designation |
Height (inches) |
Base Width (inches) |
Head Width (inches) |
Web Thickness (inches) |
|
90 |
90 RA (ARA-A) |
5 5/8 |
5 1/8 |
2 9/16 |
9/16 |
|
100 |
100 RE (AREA) |
6 |
5 3/8 |
2 11/16 |
9/16 |
|
115 |
115 RE (AREA) |
6 5/8 |
5 1/2 |
2 23/32 |
5/8 |
|
132 |
132 RE (AREA) |
7 1/8 |
6 |
3 |
21/32 |
|
136 |
136 RE (AREA) |
7 5/16 |
6 |
2 15/16 |
11/16 |
|
140 |
140 RE (AREA) |
7 5/16 |
6 |
3 |
3/4 |
Crane Rail Dimensions (DIN and QU Standards)
Crane rails are distinct from standard railway rails. They feature a wider web and a lower center of gravity to handle the immense vertical loads of overhead cranes and gantries. While they are generally not referred to as standard train rail sizes, they are integral to rail logistics and industrial handling. The DIN (German standard) and QU (Chinese standard) are widely used globally.
|
Rail Type |
Height (mm) |
Head Width (mm) |
Base Width (mm) |
Web Thickness (mm) |
Nominal Weight (kg/m) |
|
A45 (DIN) |
55 |
45 |
125 |
24 |
22.1 |
|
A55 (DIN) |
65 |
55 |
150 |
31 |
31.8 |
|
A75 (DIN) |
85 |
75 |
200 |
45 |
56.2 |
|
A100 (DIN) |
95 |
100 |
200 |
60 |
74.3 |
|
QU70 |
120 |
70 |
120 |
28 |
52.8 |
|
QU80 |
130 |
80 |
130 |
32 |
63.69 |
|
QU100 |
150 |
100 |
150 |
38 |
88.96 |
|
QU120 |
170 |
120 |
170 |
44 |
118.1 |
Technical Specifications for Rail Clips
Once the correct train rail sizes are identified, the next engineering challenge is fastening the rail to the sleeper or support beam. This is the function of the rail clip. Rail clips must be matched precisely to the base width and web mechanics of the rail section. Using an incompatible clip can lead to rail slippage, gauge widening, and eventual system failure.
Rail clips are generally categorized by their fastening method (bolted vs. welded) and their adjustability. In industrial settings, clips are often designated by a model number that corresponds to specific rail ranges.
Clip Compatibility Table
The following table outlines common industry rail clips and the corresponding train rail sizes they are designed to secure. This data ensures that the fastening system provides adequate clamping force without interfering with the rail web or rolling stock wheels.
|
Clip Model |
Compatible Rail Sections |
Clip Weight |
Bolt Diameter |
Description |
|
Clip 114 |
12 lb – 40 lb ASCE |
0.24 lb |
5/8″ |
Designed for light rail applications. Single-hole clip for securing Tee rails to supports. |
|
Clip 120 |
25 lb – 50 lb ASCE |
N/A |
N/A |
Intermediate clip for light-to-medium industrial tracks. |
|
Clip 103 |
55 lb – 100 lb ASCE & ARA-A |
0.58 lb |
3/4″ |
Standard industrial clip featuring an oval hole (1-1/16″ x 25/32″) for adjustment tolerance. |
|
Clip 106 |
60 lb – 100 lb ASCE & ARA-A |
1.15 lb |
3/4″ |
Heavier duty version for standard rail sections, providing greater hold-down force. |
|
Clip 128 |
80 lb – 100 lb ARA-B |
0.89 lb |
3/4″ |
Specifically designed for the slightly different base geometries of ARA-B sections. |
|
Clip 62 |
115 RE, 132 RE, 136 RE |
1.3 lb |
1″ |
Heavy-duty clip for modern freight rail sections. Also compatible with 104-105 lb crane rail. |
|
Clip 175 |
175 lb Crane Rail |
2.1 lb |
1″ |
Specialized clip for massive crane rails, designed to handle extreme vertical loads. |
Selecting the Right Clip for Your Rail Size
The interaction between train rail sizes and clips is governed by the “toe load” and the geometric fit. The “toe” of the clip must sit flat on the rail base. If the rail base is too wide for the clip, the bolt hole will not align with the support structure. Conversely, if the rail base is too narrow, the clip may not exert enough pressure to prevent lateral movement.
For example, a Model 62 clip is robust enough for a 132 lb RE rail, which has a base width of 6 inches. Attempting to use a Model 103 clip on this rail would be impossible, as the Model 103 is optimized for rails with base widths around 5 inches (like the 85 lb ASCE).
Furthermore, crane rail clips often feature a weldable base lower component and a bolted upper component. This allows for significant lateral adjustment during installation to ensure perfect track gauge, a feature less common in standard fixed railway clips like the 114 or 103 series.
Material Specifications and Engineering Data
Beyond physical dimensions, train rail sizes imply specific mechanical properties. Heavier rails like the 136 RE are not just larger; they are often rolled from premium steel alloys to resist contact fatigue and plastic deformation.
Section Modulus and Moment of Inertia
When engineers select train rail sizes, they calculate the Section Modulus and Moment of Inertia.
- Moment of Inertia (I): This measures the rail’s resistance to bending. A higher Moment of Inertia means the rail deflects less under a passing wheel load. For example, a 132 RE rail has a much higher Moment of Inertia than an 85 lb ASCE rail, allowing it to span wider tie spacing or support heavier axle loads without excessive bending.
- Section Modulus (S): This helps determine the flexural strength of the rail. It is crucial for calculating the maximum stress in the rail head and base under load.
Hole Drilling Patterns
The “drilling” refers to the bolt holes at the end of the rail, used for joining rails with splice bars (joint bars). As train rail sizes vary, so do the drilling patterns.
- Hole Diameter: Larger rails utilize larger bolts (e.g., 1-inch or 1-1/8-inch) compared to light rails (e.g., 3/4-inch).
- Elevation: The height of the hole from the base must be precise. If the hole is drilled too high or too low, the splice bar will not seat correctly between the head and base fillets, compromising the joint.
Common standard drillings (End-to-Center of first hole x Center-to-Center of holes):
- Light Rail: Often 2″ x 4″ or 2-1/2″ x 5″.
- Heavy Rail: Often 3-1/2″ x 6″ x 6″.
Frequently Asked Questions About Train Rail Sizes
Q: How do I identify the size of my train rail?
A: Measure the height, base width, and head width. Compare these dimensions to a standard specification table (like ASCE or AREA). Also, look for embossed mill marks on the rail web, which typically state the weight and section (e.g., “85 AS”).
Q: What does the “lb” or “kg” number mean in rail sizing?
A: It represents the weight of the rail per unit of length. In the US, “85 lb” means 85 pounds per yard. In metric systems, “60kg” means 60 kilograms per meter. Heavier rails generally support heavier loads.
Q: Can I use different rail sizes on the same track?
A: Yes, but you must use a “compromise joint bar” or a transition rail to connect them securely. You cannot simply butt two different rail sections together, as the height and running surface will not align, causing immediate derailment risks.
Q: What is the difference between Tee Rail and Crane Rail?
A: Tee rails (like ASCE or AREA) are taller with thinner webs, designed for train wheels. Crane rails (like DIN or QU) are shorter, squat, and have very thick webs to support massive vertical loads from slow-moving overhead cranes.
Q: Why are rail clips specific to rail sizes?
A: Clips are designed to fit the specific slope and width of the rail base. Using an incorrect clip can lead to loose rails or clips snapping under tension. The bolt location relative to the rail edge is critical for proper clamping force.
