Route Survey

The first thing you should know about route survey is the construction of curves. There are two types of curves, circular or horizontal curves and vertical parabolic curves.

Circular or Horizontal curves
a.Simple curve- a circular arc extending from one tangent to the next.




b. Compound curve- consist of two or more simple curves having different radius but whose centers lie on the same side of the two curves must have a common tangent at their meeting point .






c. Reversed Curve- is formed by two circular simple curves having a common tangent but centers lying on opposite sides.

Deflection Angles and Chords
The deflection angle and chord method is frequently used for curve layout. A DEFLECTION ANGLE, in the sense, applied to a simple curve, is the angle measured at the PC from the back tangent to a desired point on the curve. A CHORD is a straight line between two parts on the curve. The method involves setting up a theodolite or total station at the PC, and orienting the circle by aiming at the PI with scale set as zero. Points on the curve, usually at half-station or 10m in intervals, are then staked out by measuring the computed chord length from each previous point set and by taking line from the total station or thedolite when it is set at the proper deflection.

Vertical Parabolic Curve
Instead of circular arcs to join tangents, parabolic arcs have been proposed and used in order to do away with the sudden changes in direction which occurs.
There are two types of vertical parabolic curve and these are:
1. Sag


2. Summit

Hi Maria, Good work

I would like to add few things to keep in mind before starting survey

1. As far as possible try to keep the alignment straight.
2. The route should be the shortest possible.
3. Avoid unstable ground, Crossing over major public utility services (gas pipe line, high transmission lines, water lines etc.) if possible, Area's proposed for future development, Area falling under forest reserve.
4. Ease of construction

Above mentioned points are general things, further considerations would be made depending on the nature of the Project.

Route Survey helps in minimizing the Project cost to a greater extent (the main agenda) and potential problems can be foresee much before execution.

@ raj: thanks for adding some points.
I just want to ask you something, for how many hours do you think to survey a 1km road???

maria florI just want to ask you something, for how many hours do you think to survey a 1km road???

It all depends on the nature of the site, skill level of the surveyor and the instrument used.

It would take 1 day for a normal site to collect data like existing utility, services, spot levels etc. depending on the complication time would very.

rajcivil2k6It all depends on the nature of the site, skill level of the surveyor and the instrument used.

It would take 1 day for a normal site to collect data like existing utility, services, spot levels etc. depending on the complication time would very.

Thank you so much. We're going to survey in the mountain.

The below link can be of use, HIGHWAY ENGINEERING FIELD FORMULAS

<a href="https://www.wsdot.wa.gov/publications/manuals/fulltext/M22-24/FieldFormulas.pdf" target="_blank" rel="nofollow noopener noreferrer">PDF</a>

There are two types of Parabolic curve and they are:
1.Symmetrical Parabolic curve- the length of curve to the right of the vertex is equal to the length of curve to the left vertex




2.Unsymmetrical Parabolic Curve-the length of curve to the right of the vertex is not equal to the left of vertex.

Sight distance

1. Passing Sight Distance. It is the distance required to overtake safely moving vehicle in the same traffic lane.




2.Non-passing Sight Distance. It is the safe stopping distance of a vehicle running of design speed.

In order to know what type of horizontal curves must be constructed on the road, route survey is necessary. See this:

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for the sight distance i had a comment if the before vehicle is slower than us before overtake when we started overtaking
if it raises fast what will the situation

narayana murthyfor the sight distance i had a comment if the before vehicle is slower than us before overtake when we started overtaking
if it raises fast what will the situation

Maybe an accident may occur....