Elements Of Reverse Curve (semester 4 b-tech civil cusat 2012 scheme)

Spending time to study the previous day of exam is what make good engineers. Its a saying that I have been hearing since the day I joined the course. So this is what I did to appear for my internal examination on Survey  part 2 .

Elements of a reverse curve

This is a typical reverse curve

R1 is the radius of the first curve

R2 is the radius of the second curve

AV is the tangent to the first curve

VC is the tangent to the second curve

BD is the common tangent to both the curves

T1 is the point of curvature,i.e from where the curves start(P.C)

T2 is the point of tangency(P.T)

T1T2 is the line connecting P.C and P.T

Methods of locating sounding

Introduction

Sounding is the process by which depth of water bodies is measured.There are various methods adopted to employ the same.They are listed below.

1)Location by cross rope

It is very advantageous to use this method in the case of narrow rivers or water bodies. A wire with markings or a long rope with markings is stretched over the water body and the sounding is done with respect to the marked readings.

2)Location by range and time intervals

This method is adopted mainly in still water.Sounding is done from boat at regular time intervals keeping the speed of the boat constant.As the speed of the bat is constant the range at which sounding is done will also be constant.

3)Location by range and angle from the shore

For this a boat with sounding man is made to traverse along the ranging line and at angle of 90 degree from the ranging line a suitable station point is taken for setting up theodolite on the shore.

The transit man measures the horizontal angle at equal intervals and the sounding man measures the depth at same time intervals.Generally all the fifth readings are measured using the horizontal angles.The intermediate sounding points are noted with respect to time alone.        

4)Location by range and angle from the boat

In this unlike in the above mentioned method the angles are taken from the boat using a sextant.This is a better method compared to the earlier one

Curve surveying

Introduction

Though there are a variety of curve surveying here the discussion is mainly constrained to

1)Reverse curves

2)Transition curves and 

3)vertical curves

the source for the page is from  Surveying, volume 2 by Punmia and from global video library youtube

2.1)Reverse curves

2.1.1)What do you mean by a reverse curve?

A reverse curve consist of two simple curves of opposite directions that joint together at a common tangent point known as "Point of reverse curvature"(P.R.C). 

2.1.2)Speciality of reverse curve

Their change in direction at Point of reverse curvature is instantaneous. Reverse curves are pleasing to the eyes and are used in park roads, formal paths and waterway channels.

 D2.1.3)Disadvantages of reverse curves

The change of direction at point of reverse curvature is instantaneous as a result:

1) Sudden change of direction is required on either side of P.R.C.

2)No way to rise the outer bank of the curve.
3)From a passenger prospective sudden change in direction is objectionable and dangerous.
4)Steering is dangerous.

*elements of a reverse curve to be updated soon

Hydrographic surveying basics

what do you mean by an hydrographic surveying?

Hydrographic surveying is simply the branch of surveying that deals with surveying in water bodies. It is with this surveying that we create navigation channels.  

what do you mean by sounding in hydrographic surveying?

Consider a water body whose depth is to be determined. Sounding is that process which enables you to find the depth of the water bodies.

What do you mean by shoreline survey? 

A shoreline survey is a survey of all property that borders shellfish areas from the shore to 500ft. inland. The goal of the shoreline survey is to locate pollution sources. Surveyors go door-to-door and look for evidence of failing septic systems, straight pipes emptying untreated water, pet or wildlife waste, livestock, and uncontained livestock manure, that does or may adversely impact coastal water quality.

Why shoreline surveying?

Shoreline surveying is done in order to locate shorelines. It helps in locating prominent features that may effect sounding. It helps in determining low and high water lands.