Calculation of Expansion Gaps at Rail Joints
Apr 21, 2026| Rails are connected to one another on the track using rail clips and bolts; this connection is known as a rail joint. Due to the high dynamic forces at the joint and the significant maintenance requirements, rail joints are considered one of the weakest links in the track structure.
To accommodate thermal expansion and contraction of the rails, a rail gap must be provided at the rail joint. The size of the rail gap is subject to specific limits; for standard track joints, the reserved rail gap must be calculated in accordance with regulations. The rail gap for insulated joints must not be less than 6 mm, and the maximum rail gap must not exceed the design rail gap.
If the rail gap is too small, a blind gap will form as the rail temperature rises. If the rail temperature continues to rise, significant internal pressure will build up in the rail, potentially causing the rail to expand and derail.
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