Civil Engineering All Engineering Career

In route surveys, the most suitable method of contouring is:

By cross-sections

Reasoning:

• Efficiency: Cross-sections provide a direct and efficient way to determine ground profiles, especially for linear projects like roads and railways.

• Accuracy: By taking cross-sections at regular intervals, it's possible to accurately capture the ground's undulations and elevations.

• Design: The data from cross-sections is directly used for designing the route, including earthwork calculations and determining the optimal alignment.

While tacheometry can also be used for contouring, cross-sections are specifically tailored to the linear nature of route surveys and provide more detailed information for design purposes.

A line normal to the plumb line at all points is known as:

Level line

• A level line is a curved line perpendicular to the direction of gravity (plumb line) at every point.  

• It follows the curvature of the earth.

While in practical surveying, over short distances, a level line is often considered to be a horizontal line, it's essential to understand the theoretical difference.

Departure of the line

• Departure is the horizontal distance between the meridians passing through the two ends of a survey line.

• It's essentially the east-west component of a traverse line.

Therefore, the correct answer is departure of the line.

The correct answer is deflection angle.

The angle by which the forward tangent deflects from the back tangent of a curve is called the deflection angle. This angle measures how much the direction changes at the curve.

The correct answer is sub chord.

When the length of a chord is less than the peg interval, it is known as a sub chord. This term is used to describe a chord that is shorter than the interval between the pegs used in surveying.

The correct answer is contour interval.

The vertical distance between any two consecutive contours is called the contour interval. This interval represents the difference in elevation between adjacent contour lines on a map.

It is more convenient and gives better results when measuring horizontal distance down the hill by stepping.

Explanation:

• Downhill: While measuring downhill, the chain or tape pulls down due to gravity and thus there is less sag and tension error, hence giving more accurate measurements.
• Going uphill: More difficult. Chain or tape sags and gives increased error.
• Plane areas: Stepping can be used in plane areas, but it is normally less effective than direct chaining.

one-fourth 

The shift of a curve is four times the perpendicular offset from a tangent to the junction of the transition curve and circular curve.

Explanation:

• Shift (S): This is the distance between the tangent to the circular curve and the tangent to the transition curve, measured along the tangent to the circular curve.

• Perpendicular offset (O): This is the distance from the tangent to the junction point of the transition curve and circular curve.

The relationship between the shift and the perpendicular offset is:

• S = 4O

Therefore, the perpendicular offset is one-fourth of the shift.

Would you like to know more about the shift and its role in curve design?

The correct answer is clothoid spiral.

The ideal transition curve used in road and railway design is a clothoid spiral. This type of curve smoothly transitions from a straight path to a circular curve, allowing for gradual changes in curvature and providing a safer and more comfortable experience for vehicles.

The correct answer is 30°.

In a well-conditioned triangle, no angle should be less than 30°. This condition helps ensure that the triangle is well-proportioned and that the measurements and calculations are more reliable and accurate.