45 Questions
What is the formula for H in terms of S and α?
H = S ×Sin α
What is the name of the instrument used in spirit leveling?
Level
Who invented the Dumpy level?
William Gravatt
What is the main advantage of using a Digital level?
It eliminates staff-reading errors
What is the material used to make a leveling staff in a Digital level?
Synthetic material
What is the characteristic of the automatic level?
It has a clean, uncluttered appearance
What is the advantage of the automatic level over the tilting level?
It is much easier to use and rapid in operation
What is the method of leveling that uses an instrument known as level with a leveling staff?
Direct method
What is the equation that relates ∆H, hi, ht, and H?
∆H + hi = ht + H
What is contouring in surveying?
The determination of elevation of various points on the ground and fixing these points of the same horizontal positions in the contour map
What is the purpose of levelling in engineering surveying?
To determine the elevation of points on the ground
What is represented by the vertical column on the contour map?
Elevation of points on the ground
What is the relation between the contour lines on the contour map?
They are of the same elevation
What is the purpose of creating a contour map?
To visualize the elevation of points on the ground
What is the unit of measurement for elevation in the given contour map?
Metres
What is the value of the elevation at Station R.L. in the given contour map?
98.41
What is the purpose of profile leveling?
To produce ground profiles in the design of roads, railways, and pipelines
What is the purpose of the C.L. in the given contour map?
To indicate the crossing point of the design line
What is the value of the design line at Station 2+040 in the given contour map?
98.52
What is the term for the points along the profile and cross-section where elevations are taken?
Stations
What is the purpose of drawing a datum line in a profile?
To provide a reference point for the profile
What is the purpose of cross-section leveling?
To estimate the earthwork volumes and create a detailed design of the route
What is the typical interval for setting out the route center-line using pegs?
10 m, 20 m, or 30 m
What is the term for a point located between full stations?
Plus station
What is the purpose of plotting the profile on an x-y graph?
To supply details along the section of the amount of cut/fill
What is the typical vertical scale used in profile plotting?
10:1
What is the purpose of establishing TBMs throughout the route?
To provide a basis for further surveying and engineering design
What is the purpose of the two peg test in levelling?
To check that the line of sight through a level is horizontal
What is the recommended distance between the two points in the two peg test?
60m - 90m
What type of levelling circuit starts from a known point and ends at an unknown point?
Uncontrolled levelling
What is the cause of personal errors in levelling?
Booking errors
What is the effect of earth curvature and atmospheric refraction in levelling?
Natural error
What is the recommended distance for taking data in levelling?
25m - 30m
What is the cause of sluggish bubbles in levelling?
Instrument error
What is the effect of settlement of the tripod in levelling?
Instrument error
What type of levelling circuit starts from a known point and ends at the same point?
Closed loop circuit
What is the main disadvantage of the direct contouring method?
It is slow and tedious
What is the advantage of the direct contouring method?
It is the most accurate
What is the purpose of establishing a grid of intersecting evenly spaced lines in indirect contouring?
To establish a grid spacing that depends on the roughness of the ground
What is the assumption made in the interpolation method?
A uniform ground slope between each pair of points
What is the purpose of the interpolation method?
To estimate the contours by using linear interpolation
Which method of contouring is suitable for small areas and where great accuracy is required?
Direct contouring
What is the purpose of determining the elevation of each grid point in indirect contouring?
To estimate the contours by using linear interpolation
What is the formula used in the interpolation method?
𝒀𝟐 − 𝒀𝟏 𝒀 − 𝒀𝟏 = 𝑨𝑩 𝑿
What is the result of the indirect contouring method?
A contour map with labels
Study Notes
Levelling
- Levelling is the process of determining the elevation of various points on the ground and fixing these points of the same horizontal positions in the contour map.
Types of Level Instruments
- Dumpy level: invented by William Gravatt in 1832
- Tilting level
- Automatic level
- Digital level: uses electronic image processing to evaluate the staff reading, replacing the observer and eliminating staff-reading errors
Digital Level
- The leveling staff is usually made from a synthetic material with a small coefficient of expansion
- The staff has a binary bar code for electronic measurement and conventional graduations in meters
- Each manufacturer uses a different code on their staff, so an instrument will only work with a staff from the same manufacturer
Automatic Level
- Recognized by its clean and uncluttered appearance
- Advantages: easier to use, rapid operation, and no need for adjustments
Two Peg Tests
- Purpose: to check that the line of sight through a level is horizontal
- Procedure: fix two points at a distance (60m-90m) apart, set up the level at midway and take readings at both points, change the location of the instrument and read both points again
Levelling Errors and Adjustments
- Quality of leveling: controlled leveling circuit (closed loop and between controlled points) and uncontrolled leveling
- Leveling errors: instrument errors, natural errors, and personal errors
Leveling Errors
- Instrument errors: due to poor correction, distance of taking data, errors due to sluggish bubbles, and staff graduation errors
- Natural errors: due to earth curvature and atmospheric refraction, variation in temperature, wind, and vibration
- Personal errors: due to the staff not being vertical, booking errors, and settlement of the tripod
Profile Levelling
- Used to produce ground profiles in the design of roads, railways, and pipelines
- Route center-line is set out using pegs at 10m, 20m, or 30m intervals, and levels are taken at these peg positions and at critical points
- Plotting on x-y graph with a vertical scale exaggerated compared to the horizontal scale
Profile Uses
- To decide the most suitable economic levels and gradients to which the ground should be worked
- To supply details along the section of the amount of cut/fill
Cross-Section (X-Section) Levelling
- The term cross-section refers to a relatively short view of the ground that is drawn perpendicular to the project centerline on each side for (10-30m)
- Cross-section drawings are particularly important for estimating the earthwork volumes
Contouring Methods
- Direct contouring: tracing out contours directly in the ground by locating and surveying points on each contour
- Indirect contouring: establishing a grid of intersecting evenly spaced lines, determining the elevation of each grid point by leveling, and estimating the contours by linear interpolation
Interpolation Method
- Refers to the process of determining intermediate values between observed data points by assuming a uniform rate of change of ground elevation (grade) between two adjacent points
Test your knowledge of railway station operations and management with this quiz. Questions cover various aspects of station operations, including schedules and timings.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
