KNOW WHY I-SECTION BEAMS ARE USED FOR RAILWAY TRACKS !!

Generally rail tracks are made in I Section.We might wonder many times that why any other shape is not used.We might also wonder, why solid section is not used??We will discuss the reason behind selection of I beam for railway tracks in this article.

The usual, Flat Footed rails used for Broad Gauge lines is shown below with its components below.

This is typical shape of the cross-section of a track laid with Flat-footed Rails.

The Bull headed rails resemble the 'I' shape more correctly.

These are shaped so for following purposes:

> The top portion or the HEAD of the rail is thicker to take up the impact of the fast moving wheels, and carry the load of trains preventing abrasion of the tracks.

>The WEB of the rail is to uplift the train from the ground level; and as the inner flanges of wheels are of greater area than the outer flanges as shown below, so the web mainly provides clear cover (distance) between wheel base and the sleeper/ ballast layer.

>The FLAT FOOT provides two-fold purpose. Easy clamping i.e fixing to the sleeper beneath it because of wider area as well as greater surface area due to flat foot helps in load transfer to the sleeper more efficiently which further transfers the load to ballast and later sub-base.

WHY I-SHAPED ONLY USED,WHY NOT ANY OTHER SHAPE:

• A beam is more efficient when more material is AWAY from the center. It’s has more strength as compared to solid.

• Upper half should be wide enough to support the wheel and lower half should be wide & thick enough for clamping. Taking out extra materials saves significant amount of iron without compromising over strength thus giving it the shape of what you asked.
• Rail needs to be stiff in the vertical direction to take the load of the train.
• It needs to be relatively flexible in the horizontal direction so it can easily bend around curves.So material is reduced at the center to allow a bit of flexibility.