The 3 Materials Used to Make Rail Pads: EVA, HDPE and Rubber Compared

A rail pad (also called a rail rubber plate or sleeper pad) sits between the rail tie plate or baseplate and the rail foot. Its job is to protect the sleeper surface from wear and impact, add controlled elasticity to the track, distribute the wheel load, and damp vibration. The material of the pad decides how well it does each of these jobs, so the three materials used in rail pad production, EVA, HDPE, and rubber, deserve a close look before you specify.

1. EVA (Ethylene-Vinyl Acetate) Rail Pads

EVA pads are a copolymer of roughly 80% polyethylene and 20% vinyl acetate. They combine light weight with good electrical insulation and consistent damping, which makes them a common choice for concrete sleeper fastening systems, especially where track circuits require insulation between rail and sleeper.

Technical Parameter	Unit	Technical Requirement	Typical Value
Density	g/cm3	0.95-0.98	0.95
Tensile strength	MPa	min 15	16
Elongation	%	greater than 500	550
Melting point	degrees C	170-190	170
Insulation resistance	ohm	min 1 x 10^10	5.0 x 10^10
Hardness	Shore A	min 90	92

2. HDPE (High-Density Polyethylene) Rail Pads

HDPE pads are harder and stiffer than EVA, with very low water absorption and good wear resistance. They suit demanding industrial environments where the pad must resist crushing and abrasion while keeping its insulating properties.

Technical Parameter	Unit	Technical Requirement	Typical Value
Density	g/cm3	0.95-0.98	0.95
Tensile strength	MPa	min 19	19
Elongation	%	greater than 80	150
Melting point	degrees C	170-190	190
Insulation resistance	ohm	min 1 x 10^10	3.5 x 10^10
Hardness	Shore A	min 98	98

3. Rubber Rail Pads

Rubber pads deliver the elasticity and impact absorption that EVA and HDPE cannot fully match. They are the first choice where vibration, impact, and compression set resistance matter, such as heavy-haul lines, crane runways, and urban tracks near sensitive buildings.

Technical Parameter	Unit	Typical Range
Stiffness	kN	90-130
Hardness	Shore A	72-80
Electrical resistance	ohm	min 10^6
Tensile strength before aging	MPa	min 12.5
Elongation before aging	%	min 250

How to Choose Between the Three

Rubber where vibration and impact are the problem: heavy axle loads, crane runways, urban noise-sensitive sections.

EVA where electrical insulation and light weight are priorities, and loads are standard mainline or metro conditions.

HDPE where hardness, low water absorption, and abrasion resistance are needed in demanding industrial or outdoor environments.

Mixed systems exist: grooved, studded, or composite pads can combine layers to reach stiffness and insulation targets that one material alone cannot.

All three pad types are available for common rail sections including UIC54, UIC60, BS80A, and BS100A, and can be produced with or without grooves and in custom designs. The pad is then selected as part of the complete fastening system, because the clip toe load and the pad stiffness are designed together.

Frequently Asked Questions

Why is insulation resistance important in a rail pad?

On signalled track, the two rails must be electrically isolated from each other through the sleepers so track circuits can detect train positions. A pad with an insulation resistance in the range of 10^10 ohms keeps the rail-sleeper path highly resistive, which the signalling system depends on.

Is a harder pad always better?

No. Stiffness must match the fastening system design. A very hard pad reduces damping and increases impact on the sleeper; a very soft pad allows excessive rail movement and reduces gauge stability. The right stiffness is the one the fastening system was designed for.

Can rail pads be used on both concrete and wooden sleepers?

Yes, with different interfaces. On concrete sleepers the pad protects the sleeper seat from impact; on wooden sleepers it is often combined with a tie plate. The pad dimensions follow the rail foot and the sleeper seat geometry in both cases.

What does elongation of more than 500% mean for EVA?

It is a measure of ductility: the pad can stretch over five times its original length before breaking. High elongation helps the pad survive handling, installation, and the repeated deformation of the rail seat without cracking.

Which material lasts longest under heavy axle loads?

Rubber pads with compression set resistance generally hold their stiffness longest under heavy haul, which is why they are specified on many heavy-haul and crane runways. EVA and HDPE excel in insulation and hardness respectively, so the best material depends on which failure mode matters most on your line.

Are grooved rail pads available in all three materials?

Yes. Grooves, studs, and custom surface patterns can be moulded into EVA, HDPE, and rubber pads to suit the fastening system drawing. The pattern is part of the specification, not a cosmetic choice.