What the GB Light Rail Range Covers
GB/T 11264 is the Chinese national standard for hot-rolled light rails. It defines an asymmetric flat-bottom profile family from 8 kg/m up to 30 kg/m, including the intermediate 9, 12, 15, 18, 22 and 24 kg/m sizes. The 8 kg/m and 30 kg/m sections mark the practical limits of that range. Both are hot rolled from carbon structural steel, both are supplied with plain or drilled ends according to the joint design, and both are normally bolted to timber, concrete or steel sleepers through fishplates and baseplates instead of being welded into continuous track.
Because the two sections differ by a factor of roughly 3.6 in unit mass, they are rarely interchangeable. Choosing between them is a question of axle load, traffic frequency, formation quality and expected service life rather than purchase price alone.
Dimensional and Mass Comparison
The table below sets out the principal dimensions of the two profiles as published for the GB light rail series.
| Parameter | 8 kg/m light rail | 30 kg/m light rail |
|---|---|---|
| Rail height | 65 mm | 107.95 mm |
| Bottom width | 54 mm | 107.95 mm |
| Head width | 25 mm | 60.33 mm |
| Web thickness | 7.0 mm | 12.3 mm |
| Section area (from unit mass at 7.85 g/cm3) | about 10.7 cm2 | about 38.3 cm2 |
| Theoretical mass | 8.42 kg/m | 30.1 kg/m |
Two practical conclusions follow. First, the 30 kg/m rail is more than 50 mm taller and carries a head almost 2.5 times wider, which greatly increases the second moment of area and therefore bending stiffness. Second, the bottom width of the 30 kg/m section is 107.95 mm; catalogue entries quoting 109.95 mm are transcription errors and must not be used when dimensioning baseplates, clips or sleeper spacing.
Material Options: Q235B and 55Q
Both sections are commonly rolled from Q235B ordinary carbon structural steel to GB/T 700. Where the 30 kg/m profile runs on curves, on high-frequency hauls or under abrasive loads, a rail-specific carbon steel such as 55Q is selected instead, because its higher carbon and manganese content raises hardness and wear resistance.
| Property | Q235B | 55Q rail steel |
|---|---|---|
| Yield strength | min. 235 MPa | not quoted as a design value |
| Tensile strength | 375-460 MPa | min. 685 MPa |
| Elongation | min. 26% | lower than Q235B, controlled by rolling practice |
| Hardness | reported in HB | min. 197 HBW |
| Carbon | 0.12-0.22% | 0.50-0.60% |
| Silicon | max. 0.35% | 0.15-0.35% |
| Manganese | 0.30-0.70% | 0.60-0.90% |
| Phosphorus and sulphur | max. 0.045% each | max. 0.04% each |
The higher carbon level of 55Q also lowers weldability and ductility, so it is normally bolted rather than welded and is specified for wear-limited tracks rather than deflection-limited tracks.
Strength, Cost and Service Life Trade-offs
Stiffness: a unit mass about 3.6 times higher, combined with a deeper web and a wider head, gives the 30 kg/m rail far greater resistance to bending under a moving wheel load, so sleeper spacing can be wider for the same deflection target.
Steel consumption: the 8 kg/m rail uses roughly one quarter of the steel per metre of track, which keeps both the material cost and the foundation cost low.
Wear life: the thicker head of the 30 kg/m section offers more material for head wear before the profile must be replaced or re-profiled.
Handling: 8 kg/m rail can be carried and laid by hand on short temporary lines, while 30 kg/m rail needs mechanical lifting and heavier fishplates and baseplates.
Maintenance: light tracks tolerate uneven ground better, but heavier loads on an 8 kg/m section quickly cause permanent deformation, so the cheap option becomes expensive if duty grows.
Typical Applications
| Section | Typical duty |
|---|---|
| 8 kg/m | Temporary haul roads in forest and mining areas, small construction sites, internal workshop transfer lines, narrow-gauge amusement and resort tracks, light trolley and cart systems |
| 30 kg/m | Urban light rail and tram depot tracks, mine ore haulage, heavy production-line transfer, yard tracks worked by locomotives, tracks carrying repeated wheel loads |
Where a track starts as temporary but is expected to serve for years, the 30 kg/m section usually repays its extra cost through lower maintenance and fewer interruptions.
Ordering and Inspection Points
Specify the section by nominal mass and by the GB light rail standard, plus the steel grade, so that the mill rolls the correct profile and chemistry.
Confirm the drilling pattern at both ends and the matching fishplate profile before the first bundle is rolled, because joint hardware is not interchangeable between the two sizes.
Check that the delivered mass per metre matches the theoretical value within the normal rolling tolerance and that section dimensions are within the standard range.
Ask for mill test certificates covering heat analysis and mechanical properties for each cast.
Verify straightness, end squareness and freedom from surface defects such as laps, seams and roll marks before installation.
Frequently Asked Questions
Q: Can 8 kg/m and 30 kg/m light rails use the same fastening system?
No. The bottom width, web thickness and height differ so much that baseplates, clips and fishplates are size specific and cannot be shared between the two profiles.
Q: What is the actual bottom width of the 30 kg light rail?
It is 107.95 mm. Dimensions of 109.95 mm seen in some online tables are transcription errors and should not be used for design work.
Q: Which grade should be used for a curved or abrasive application?
A rail-specific carbon steel such as 55Q is preferred because its higher carbon and manganese content gives min. 197 HBW hardness and better wear resistance than Q235B.
Q: Can the two sections be welded together to form a transition?
Transition welds between such different sections are difficult and are rarely economical; a bolted junction with a matched transition plate is normally used for light rail.
Q: How much does a 30 kg/m rail weigh per 6 m length?
At a theoretical mass of 30.1 kg/m, a 6 m length weighs about 180.6 kg, which requires lifting equipment and a two-person minimum handling team.
Q: Is the theoretical mass the same as the delivered mass?
The theoretical mass follows from the nominal section and the steel density of 7.85 g/cm3, so delivered bundles can differ slightly within the standard dimensional tolerance.