Heavy Rails vs Light Rails: Key Differences and How to Choose
Sep 29, 2025
How Heavy and Light Rails Are Defined
In rail terminology the boundary is drawn by mass per unit length. Light rails are sections up to 30 kg/m, defined by GB 11264, while heavy rails start at 38 kg/m and run to 75 kg/m, defined by GB/T 2585 (also known as GB 2585 series). A common misunderstanding is that 30 kg/m belongs to both groups; in the Chinese standard system 30 kg/m is the top of the light rail family, and heavy rail classification begins with 38 kg/m. In European practice the same idea is expressed by EN 13674-1 rail profiles from 46E1 upwards, and in North America by AREMA sections such as 115RE and 136RE.
Section Dimensions Compared
The table below lists the principal GB light and heavy rail sections with their typical dimensions. The heavier the rail, the greater the height, head width, base width and web thickness, and the higher the bending stiffness of the section.
| Classification | Section | Height (mm) | Head (mm) | Base (mm) | Web (mm) | Weight (kg/m) |
|---|---|---|---|---|---|---|
| Light rail | 8 kg/m | 65 | 25 | 54 | 7 | 8.42 |
| Light rail | 9 kg/m | 63.5 | 32.1 | 63.5 | 5.9 | 8.94 |
| Light rail | 12 kg/m | 69.85 | 38.1 | 69.85 | 7.54 | 12.2 |
| Light rail | 15 kg/m | 79.37 | 42.86 | 79.37 | 8.33 | 15.2 |
| Light rail | 18 kg/m | 80 | 40 | 80 | 10 | 18.06 |
| Light rail | 22 kg/m | 93.66 | 50.8 | 93.66 | 10.72 | 22.3 |
| Light rail | 24 kg/m | 107 | 51 | 90 | 10.9 | 24.46 |
| Light rail | 30 kg/m | 107.95 | 60.33 | 107.95 | 12.3 | 30.1 |
| Heavy rail | 38 kg/m | 134 | 68 | 114 | 13 | 38.733 |
| Heavy rail | 43 kg/m | 140 | 70 | 114 | 14.5 | 44.653 |
| Heavy rail | 45 kg/m | 145 | 67 | 126 | 14.5 | 45.546 |
| Heavy rail | 50 kg/m | 152 | 70 | 132 | 15.5 | 51.514 |
| Heavy rail | 60 kg/m | 176 | 73 | 150 | 16.5 | 60.64 |
Load Capacity and Service Life
The larger section of a heavy rail gives higher sectional rigidity and bending strength, which is exactly what high-speed trains and heavy-haul wagons demand. Heavy rails distribute wheel loads over a wider base, reduce localised stress on sleepers and ballast, and cope with the longitudinal and lateral forces generated at speed. On main lines, a 50 kg/m or 60 kg/m rail in a wear-resistant grade such as U71Mn or U75V can serve 20 to 30 years or longer before renewal. Light rails have a much smaller section, so bending and fatigue resistance are limited; they suit low-speed operation and light axle loads, with a correspondingly shorter service life.
Where Each Type Is Used
Heavy rails (38-75 kg/m): high-speed passenger lines, main line mixed traffic, heavy-haul freight corridors, and industrial dedicated lines with high annual tonnage.
Light rails (8-30 kg/m): branch lines, mining and quarry tracks, industrial sidings, temporary construction lines, and light tram or internal plant railways.
How to Choose the Right Section
Selection starts with the axle load, operating speed, and annual tonnage of the line. A 15 kg/m or 22 kg/m rail is adequate for a workshop siding carrying small wagons at walking speed, while a port or steel plant line handling 30 t axle loads will need 50 kg/m or 60 kg/m rail in a hardened grade. Welding and fastening compatibility also matter: heavier sections normally require heavier baseplates, clips, and fishplates, so the rail and the fastening system should be specified together.
Processing and Supply
Whatever the section, rails are delivered in fixed lengths and are usually processed before installation. Cutting, drilling of fishbolt holes, end grinding, and surface treatment can all be carried out to match the track design. Suppliers such as GNEE RAILWAY RAILWAY routinely provide both heavy and light rails to GB, EN, AREMA, UIC, and JIS profiles, together with the corresponding fishplates and fastening parts, so the rail section and its accessories come from one source.
Frequently Asked Questions
1. At what weight is a rail considered "heavy"?
Under the GB system, heavy rails start at 38 kg/m, and the standard family runs 38, 43, 45, 50, 60 and 75 kg/m. Light rails are 30 kg/m and below. The 30 kg/m section is the largest light rail, not the smallest heavy rail.
2. Can a light rail be used on a main line?
No. Main lines carry high speeds and heavy axle loads, and light rail sections lack the bending strength and fatigue resistance needed. Using an undersized rail leads to rapid wear, rail bending, and premature sleeper and ballast failure.
3. What is the difference between 50 kg/m and 60 kg/m rail?
The 60 kg/m section is taller (176 mm vs 152 mm), wider at the head and base, and heavier, giving higher stiffness and longer fatigue life. 60 kg/m is the standard for high-density main lines; 50 kg/m remains common for secondary main lines and industrial tracks.
4. Do heavy rails need special fasteners?
Yes. Heavier sections produce higher forces at the rail seat, so they are paired with heavier baseplates, elastic clips with higher toe load, and rail pads matched to the track stiffness. The fastening system must be designed for the rail mass and the axle load.
5. Which steel grades are used for heavy rails?
Common grades include U71Mn and U75V under GB/T 2585, and R260, R350HT and R350LHT under EN 13674-1. Hardened grades such as R350HT are chosen for curves and heavy-haul lines to resist wear and rolling contact fatigue.
6. Are light rails welded or jointed?
Light rails on industrial tracks are usually jointed with fishplates because traffic is slow and the cost of flash-butt welding is hard to justify. Heavy rails on main lines are normally welded into continuous welded rail and jointed only at turnouts and insulated joints.
