What Are the Requirements of Rail in a Railway Track?

What the Track Demands From a Rail

A rail is not just a long steel bar. Its geometry, material and surface condition together define what the track can do: the maximum speed, the axle load, and how often maintenance is needed. Selecting the right rail reduces both immediate cost and long-term maintenance, while a mismatched rail shows up quickly as wear, cracking or geometry faults.

The Core Requirements

Strength and toughness. The rail must resist vertical wheel loads and lateral forces without bending permanently or cracking. Strength is set by the steel grade; toughness protects against brittle fracture, especially at low temperatures and at welds.

Wear resistance. The head must survive constant abrasion from wheels. Hardness is the controlling property: harder heads wear slower, which is why head-hardened grades are used on curves and heavy-haul lines.

Friction and contact behaviour. The running surface needs controlled roughness for traction without excessive resistance, and the head width must suit the wheel flange profile. The head profile radius affects both wheel wear and rolling contact fatigue.

Geometric precision. The rail must be straight, with tight tolerances on vertical and lateral straightness, cross-section and end squareness. Track gauge, level and superelevation all start from the rail itself. Dimensional tolerances are defined in the rail standard and verified during production.

Material quality. Controlled chemical composition and low inclusion content protect against fatigue and weld defects. Ultra-clean steels and microalloyed or bainitic grades are specified where fatigue drives the design.

Thermal management. Rails expand and contract with temperature. Continuous welded rail (CWR) is laid with a designed stress-free temperature, and jointed track uses expansion gaps. The rail must tolerate these movements without buckling or pulling apart.

Rail Families by Weight

Family	Weight Range	Typical Sections
Light rail	8-30 kg/m	GB 8, 9, 12, 15, 18, 22, 24, 30 kg/m; JIS 15, 22, 30A
Heavy rail	38-75 kg/m	GB 38, 43, 50, 60, 75 kg/m; UIC54, UIC60; 115RE, 136RE
Crane rail	about 50-120 kg/m	QU70, QU80, QU100, QU120; DIN 536 A-series

Typical Steel Grades by Standard

Grade	Standard / Region	Typical Use
U71Mn	GB/T 2585 (China)	50-60 kg/m mainline rail, crane rails
U75V	GB/T 2585 (China)	High-speed and heavy-haul lines
R260	EN 13674-1 (Europe)	Medium-traffic lines, good weldability
R350HT	EN 13674-1 (Europe)	High-speed and heavy-haul, sharp curves
Grade 260 / 350	AREMA (North America)	115RE and 136RE freight networks
900A / 1100	UIC 860 (International)	UIC54 and UIC60, standard and hardened

Selection Checklist for Buyers

Define the axle load, maximum speed, annual tonnage, curve radii, climate and sleeper/fastening system. From these, the rail standard, profile and grade follow. Confirm the delivery length, end finish, and any drilling or machining requirements, and require the mill certificate with chemical and mechanical results per heat.

Frequently Asked Questions

1. What determines the weight of rail a line needs?

Axle load and traffic density. Heavier rails carry more load and last longer under heavy traffic. As a rule of thumb, mainline freight and high-speed lines use 50-75 kg/m rails, while light industrial and mining tracks use 8-30 kg/m rails.

2. Why does rail geometry tolerance matter so much?

Because the rail is the reference for the whole track. Straightness errors of a few millimetres per metre cause dynamic forces, vibration and accelerated wear. Tolerances are written into the rail standard and checked during production and at delivery.

3. What is continuous welded rail and why is it used?

CWR is rail welded into long strings with no joints. It removes joint impact, reduces maintenance and allows higher speeds. The rails are laid at a designed stress-free temperature so that thermal expansion stays within acceptable compression and tension limits.

4. Can a rail be too hard for its traffic?

Yes. Very hard rails on light, slow traffic can develop brittle fractures at welds and details, and they wear wheels faster. Match hardness to traffic: hard head-hardened grades belong on curves and heavy tonnage, not on light industrial lines.

5. How are rails verified at delivery?

By comparing the mill certificate against the standard: chemical composition, tensile strength, hardness, straightness and surface quality. Sampling and ultrasonic testing are applied for critical projects, especially for rails destined for welding.

6. Do you supply rails with pre-drilled holes and machined ends?

Yes. Rails can be supplied with drilled fishplate holes, machined ends, cut-to-length and other processing per the project drawing, together with the matching fastening components.