Object: To collect data for cross-sectional leveling of a proposed road using Auto Level.
Theory:
In cross-section leveling, you determine the elevations of points on a succession of lines running at right angles to the lengthwise line of the road. The cross-section lines are established at regular stations, at any plus stations, and at intermediate breaks in the ground. Cross-sections run at a right angle to the longitudinal profile and on either side of it for the purpose of lateral outline of the ground surface.
Instruments required:
Auto Level, Tripod, Measuring Tape, Staff rod, Chalk.
Procedure:
- Start at the project benchmark/datum. Since the primary measurement being recorded by the Auto Level is elevation, you will want to make sure that your very first measurement is recorded in this datum. This will be the basis for all your subsequent measurements.
- Situate your Auto Level in a location where you can clearly see the project benchmark and your first cross-sectional location. This will allow you to establish the elevation at the start of your cross-section profile. If you do not have a clear line of sight from the benchmark to your cross-section location, you will need to traverse (set up a temporary turning point that you will survey in from the project benchmark to the cross-section location using a turning point.
- Once you have determined your Auto Level instrument setup location, set up the Affix the Auto Level and level the tripod and Auto Level by adjusting first the tripod legs to get the level bubble close to the ‘level circle’.
Fine leveling adjustments can be made using the leveling screws on the Auto Level.
- Once your instrument has been set up, you will want to determine the elevation at the horizontal line within the eye-piece. This will be the foundation from which you will make your future measurements. To establish your instrument elevation, set your staff rod on the project datum. Read the vertical distance from the rod, this distance when added to the project datum gives you the elevation at the instrument center. All future measurements will be subtracted from this number to yield the surveyed ground elevation.
- Once you have determined the elevation at the starting point of your cross-section, extend your measuring tape across the alignment of your cross-section.
- Point stations are marked. Stations are set at starting and ending points, at the center line and both sides of the center line, then intermediate stations.
- Setup level and take readings of all stations. Record the station number.
- Staff readings are then taken with Level and the distance of staff points is measured with the tape. Left and right of the center station are also entered in the field book.
Results:
| Station | Distances(m) | B.S(m) | I.S(m) | F.S(m) | H.I(m) | R.L(m) | Remarks | ||
| L | C | R | |||||||
| 1 | |||||||||
| 2 | |||||||||
| 3 | |||||||||
| 4 | |||||||||
| 5 | |||||||||
| 6 | |||||||||
| 7 | |||||||||
| 8 | |||||||||
| 9 | |||||||||
| 10 | |||||||||
| 11 | |||||||||
| 12 | |||||||||
| 13 | |||||||||
| 14 | |||||||||
| 15 | |||||||||
| 16 | |||||||||
| 17 | |||||||||
| 18 | |||||||||
| 19 | |||||||||
| 20 | |||||||||
| 21 | |||||||||
| 22 | |||||||||
| 23 | |||||||||
| 24 | |||||||||
| 25 | |||||||||
| 26 | |||||||||
| 27 | |||||||||
| 28 | |||||||||
| 29 | |||||||||
| 30 | |||||||||
| 31 | |||||||||
| 32 | |||||||||
| 33 | |||||||||
| SUM | |||||||||
ApplyingCheck: