FREE NCEES Civil Surveying Questions and Answers
Grid lines are perpendicular to
Explanation:
The correct answer is B. Line representing the central true meridian of the grid. Here is an explanation. Grid lines are the lines that divide a map into squares or rectangles to form a grid system, which helps to locate any point on the map using coordinates. Grid lines are usually parallel to the meridians and parallels of the map projection, which are the lines of longitude and latitude respectively.
A plane table's "fix" from three known locations is good if
Explanation:
In plane table surveying, the process of fixing a position involves setting up the plane table over a point on the ground for which the coordinates are known. To fix the position of the plane table, it must be oriented in such a way that it accurately represents the area being surveyed. One common method of fixing a plane table is known as the "three-point problem." This method requires identifying and accurately measuring the distances from the plane table to three known points on the ground. These known points are typically marked with pegs or other markers. The three-point problem can be approached in various ways, but one of the key considerations is the location of the middle station (the point on the ground directly beneath the instrument). The fix will be accurate when the middle station is the nearest of the three known points. This is because it minimizes potential errors in distance measurements.
Included angles in a precise traverse are determined by setting the vernier
Explanation:
The correct answer is Somewhere near zero and reading both verniers on back station. A precision traverse is a method of surveying in which the lengths and directions of the traverse lines are measured with high accuracy using instruments such as a theodolite or a total station. An included angle is the angle between two line segments or rays that share a common vertex. For any triangle, its three interior angles are each included between two sides.
A dumpy level was placed halfway between the 50-meter-distance pegs A and B, and the staff readings at "A" and "B" were 1.22 and 1.06, respectively. The readings at "A" and "B" with the level set to "A" were 1.55 and 1.37, respectively. The collimation error for a sight line of 100 meters is
Explanation:
For the first setup, when the level is at the midpoint, the collimation error at A is 1.22 - 1.55 = -0.33 and the collimation error at B is 1.06 - 1.37 = -0.31. The average collimation error for this setup is (-0.33 + -0.31) / 2 = -0.32. For the second setup, when the level is at A, the collimation error at A is zero and the collimation error at B is 1.37 - 1.06 = 0.31. The average collimation error for this setup is (0 + 0.31) / 2 = 0.155. The difference between the average collimation errors of the two setups is 0.155 - (-0.32) = 0.475. This is the total collimation error for a sight length of 50 m + 50 m = 100 m. To find the collimation error per 100 m length of sight, we divide the total collimation error by the sight length and multiply by 100. This gives us (0.475 / 100) x 100 = 0.475 m per 100 m length of sight. Since the staff readings are higher when the level is closer to the point and lower when the level is farther from the point, this means that the line of sight is inclined upward from the horizontal axis. Therefore, the collimation error is positive and inclined upward. The final answer is rounded to two decimal places, which gives us 0.04 m inclined upward.
The horizontal distances measured by tacheometer are adjusted for
Explanation:
When horizontal distances are obtained tacheometerically (using a tacheometer, which is an instrument used in surveying), they need to be corrected for several factors:
Slope Correction: This correction is necessary when the line of sight is inclined. It accounts for the vertical component of the distance measured.
Temperature Correction: Changes in temperature can affect the measurements. Temperature corrections account for the expansion or contraction of the instrument and other components. Refraction and Curvature Correction: Refraction of light in the atmosphere can lead to inaccuracies in measurements, especially over long distances. Additionally, the curvature of the Earth must be taken into consideration for precise measurements over significant distances.Therefore, to obtain accurate horizontal distances, corrections for slope, temperature, refraction, and curvature are essential. This is why option"All the above" is the correct statement.
A prismatic compass's graded circle's zero is situated at
Explanation:
The correct answer is South end. A prismatic compass is a type of magnetic compass that uses a prism to read the graduations on a circular ring that is attached to the magnetic needle. The graduations on the ring are marked from 0° to 360° in a clockwise direction, starting from the south end of the needle. This is because the ring is read at the observer’s end instead of the target’s end, and the prism inverts the image of the ring. Therefore, the zero of the graduated circle of a prismatic compass is located at the south end of the needle, where the needle points to the magnetic north.
Correction for a chain of 100 links with a rise of 1 unit every n horizontal units is
Explanation:
The correct answer is 100/n2. This is because the correction for slope in chain surveying is given by the formula:
Cs = - [h^2 / 2L]
where Cs is the correction for slope, h is the vertical difference in elevation between the two points, and L is the measured distance along the slope. The correction for slope is always negative, as the horizontal distance is shorter than the measured slope distance.
Using a chain line, you may create a 45° angle with
Explanation:
A French cross staff is a surveying instrument used for setting out right angles and measuring angles. It consists of two cross pieces, one sliding along the other. By adjusting the position of the sliding piece, various angles can be measured, including a 45° angle with a chain line. This makes it a suitable tool for this specific task.
Which of the following errors/mistakes may add up to + or -?
Explanation:
The correct answer is Erroneous length of chain. This is because the length of the chain or tape used for measuring distances can be either shorter or longer than the standard length due to various factors, such as bending of links, removal or insertion of links, knots, clogging, temperature, shrinkage, etc.
Differences between the projected contour gradient uphill side and the actual road gradient include
Explanation:
The correct answer is Excavation on the centre line. Deviation of the actual road gradient from the proposed contour gradient uphill side means that the road is steeper than the contour line, which is a line of constant elevation.
Number of subdivisions per metre length of a levelling staff is
Explanation:
The correct answer is 200. A levelling staff is a graduated rod that is used with a levelling instrument to measure the difference in height between points or heights of points above a vertical datum.