Joint resistance The normal rail joints are designed to allow the rail length variation due to temperature. To do this the joints have a well-defined maximum gap and a set of installation parameters to provide an optimum behaviour at temperature variation and a good maintenance regime. Any modern rail joint has a standard bolt tightening torque…
In the previous article, Jointed track breathing, was described for jointed track the complex activation phenomenon of the track resistance forces that oppose to rail thermal length variation. In the case of the jointed track this activation takes place on the entire length of the rail. As the rail length increases a greater temperature variation…
Rail breathing Normally on the railway track the rail is fixed through a set of superstructure elements (fastenings, sleepers, ballast) that opposes the rail tendency to expand or contract due to temperature variations. This fixation is achieved through friction forces and once the rail axial forces are above these friction forces, the rail will start…
Motto: Tolle lege! Perhaps the best and most complete technical book about track is “Modern Railway Track” written by Dr Coenraad Esveld, Professor of Railway Engineering at Delft University of Technology. A detailed Table of Contents of the second edition can be found here together with a brief selection of the book. The second edition, written…
When exposed to temperature variations, the rail tends to vary its length. If this tendency would be freely allowed, for a temperature variation Δt° the rail length L will vary by ΔL. This length variation is ΔL = αLΔt°. If, on the other hand, the expansion is not permitted in any way, and both ends of…
There are two types of railway track superstructure from the point of view of the response to rail temperature variation: free thermal expansion (FTE) track superstructure which allows the rail to freely vary its length due to temperature variation. This superstructure does not provide reliable constant and easy to control and maintain track longitudinal resistance…
Thermal expansion When exposed to temperature variations, the rail tends to vary its length. If this tendency is freely allowed, for a temperature variance Δt°, the rail length L will vary by ΔL. This length variance can be computed as: ΔL = αLΔt° In this formula, α is the steel expansion coefficient = 11.5·10−6 mm/mm°C. If…
General considerations The relative position of railway double or multiple adjacent lines is of critical importance for level crossings. On canted tracks, the road traffic is affected if the level crossing does not provide a good riding plane, especially for long vehicles or the (sometimes expensive) low profile ones. This is why the design of…
When it comes to Railway track engineering literature, there are a few books we can consider “classic”. Even old, some very old, these books still have significant railway engineering value and can be always a good reference both for young and inexperienced engineers as for the ones that already have robust railway track experience and…
A rail joint is a track component that connects two pieces of rail and it provides room for rail expansion and contraction due to the changes in temperature. The mechanical rail joint is designed to allow a gap variation and, as such, has two well defined limits of this gap. The minimum gap of a mechanical rail…
A railway track blog 