Details about Combined Road Curve in Surveying

A curve stands for an arc that attaches two straight lines which are divided with some angle known as deflection angle.

This situation happens where the alignment of a road way or rail way alters its direction due to inescapable objects or conditions like a hill or a lake or a temple etc.

Therefore, in order to make smooth movement of vehicle at this point, a curve should be set.

This exclusive civil engineering video tutorial is about setting out a combined curve in road construction based on essential data.

Combined curves are created by integrating simple circular curves and transition curves. When transition curves are provided at both ends of a circular curve, the curve that is produced called as combined curve.

To set out a combined curve, the following data are essential :-

Deflection angle (∆)
Radius of curve (R)
Length of transition curve (L)
Chainage of point of intersection B

Also Read: How to measure different types of curves in roads

Normally, 10m for the transition curve and 20m for the circular curve are utilized.

Length of sub chords is measured after determining the chainages of relevant points.

The length of combined curve is calculated with the following formula :-
πR(Δ ¬– 2Ø1) / 180 + 2L

To get more details, go through the following video tutorial, presented by the renowned engineer S.L.Khan.

Video Source: Engineer Boy