ROAD PROFILING, CROSS SECTION & SETTING OUT SEWER LINE
- 1. JJOOMMOO KKEENNYYAATTTTAA UUNNIIVVEERRSSIITTYY OOFF AAGGRRIICCUULLTTUURREE AANNDD TTEECCHHNNOOLLOOGGYY Setting Trends in Higher Education, Research and Innovation School of Civil Engineering and Geospatial Engineering Bachelor of Geomatics Engineering and Geospatial Systems Bachelor of Geospatial Information Science INTERNAL ATTACHMENT Group 4 Fieldwork 4 Report ROAD PROFILING, CROSS SECTION & SETTING OUT SEWER LINE Student Name Registration Nº Gavin Kendo ENC221-0330/2016 Stildon Kimani ENC222-0337/2016 Tarri Halakhe ENC221-0159/2016 Calvin Kiplimo ENC222-0168/2016 Ivy Njeri ENC221-0157/2016 Raymond Rawlings ENC222-0362/2016 Sharon Mwanza ENC221-0098/2016 Barasa Samuel ENC222-0351/2016 Faith Mwende ENC221-0311/2016 Kosgei Antoney ENC222-0354/2016 Paul Akelo ENC222-0331/2016
- 2. Group 4 ǀ Fieldwork 4 2 Introduction In profile leveling, you determine the elevations of a series of points lengthwise along a road. Profile are plotted such that the vertical scale is exaggerated in relation to the horizontal scale so that the difference in the elevation are accentuated. The line along which the profile is to be taken may be marked prior to the survey. This is normally done in 100-foot stations. A rod reading is taken at each full station and at each major break in the ground slope. This procedure differs from the running of a circuit level in that more foresights are taken from each set-up. The stations of the breaks in slope are taped and referenced from the full stations established along the profile line 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 highway. Cross sections are necessary for measurement of earthwork volumes in roadway construction. They are profile views of the ground, perpendicular to the centerline or base line, and indicate ground elevations at points of change in the ground slope. Original cross sections indicate the profile of the original ground before the ground is disturbed. These measurements may be used for primary design, estimating volumes, etc. Borrow pit original cross sections are taken after stripping has occurred. Cross sectioning is a method of leveling to know the nature of ground on either side of the centerline of the proposed route and leveling is carried out along this cross section. During location and construction of highways, Rail tracks sewers and canals mark are placed at various aligned points. Cross sections are the sections run at right angles to the centerline and on the either side of it they are taken at each 5,10m station on the centerline. The length of cross section depends upon the nature of the work. Manhole is a small covered opening in a paved area allowing access beneath, especially one leading to a sewer. Drainage set-out surveys generally provide the set-out required for the designed horizontal and vertical alignment of a road
- 3. Group 4 ǀ Fieldwork 4 3 or drain. Survey can consist of a peg or mark placed indicating an offset and level at incremental distances along the designed alignment. This information will determine the required cut/fill required, to meet the design criteria. Both road and drainage set-out generally will require as-built surveys to be carried out. This information can be used to calculate how close the road has been built to design, and if it meets the design tolerances and standards. Volumes of material used and required can also be determined from these surveys and are useful in accounting for materials used and also forecast what cut or fill volumes remains. Objectives: To determine the elevations of the ground surface. To set out sewer line and Manholes. Carry out accurate setting out. Carry out all the necessary calculations to establish the setting-out points. Work as a team in order to execute a large-scale surveying work. Produce and present an engineering report on an engineering survey work. To find elevation of longitudinal and transverse stations for making profile and cross sections. Instruments to be used: 1. Level. 2. Staff. 3. Tripod. 4. Measuring Tape. 5. Ranging Rod.
- 4. Group 4 ǀ Fieldwork 4 4 Fig1.0 Area of work Procedure 1. Fix the stations for the centerline 20m each from 0+00 to 0+400 by measuring tape. 2. Then for each station mark 5R, 10R, 5L and 10L perpendicular to the longitudinal line. 3. Instrument level is setup at convenient positions near bench mark. 4. First sight of B.M (point of known elevation) is taken and reading is entered in back Sight column. 5. If distance is large instrument is shifted, the instrument becomes turning point (or) changing point. 6. After setting up instrument at new position, performing temporary adjustment and Take back sight as turning point. 7. Thus, turning point will have both back sight and fore sight readings. 8. Take readings for near stations and enter the readings in intermediate column. 9. Then take another turning point and shift to new location for other stations.
- 5. Group 4 ǀ Fieldwork 4 5 10. Lock the leveling operation by returning to the first point (BM). 11. Readings are entered in a tabular form given below and Reduced levels are calculated by height of instrument method. Sources of Error They are staff readings and tilt of the pole or staff. Observer tends to make wrong observation when observing the staff reading, they might misread the staff marking scales and this brought to the crucial error along the booking process. Besides, the tilting of the staff rod can influence the accuracy of the height readings taken from the staff. When the staff is not truly vertical (90º) or almost to it, the reading taken is incorrect and lead to the failure of tachometry process. Errors in conducting tachometry survey also caused by natural causes. These include errors due to high winds. During high winds, it is difficult to keep the staff vertical and read it accurately. Works should be undertaken during hot mid-day period. In very hot conditions, the instrument should be protected with an umbrella to avoid errors due to the unequal expansion of different parts of instruments. Work may also be hampered by bad visibility due to strong sunlight and glare. Error due to manipulation and sighting are inaccurate leveling of the instrument, inaccurate reading of horizontal line and vertical angles, poor focusing errors, inaccurate bisection of the target, inaccurate reading of the staff intercept and lastly due to errors in holding the staff. Instrumental errors. They are those caused by the adjustment of the instruments used or faults in them. Any errors in these measurements have serious implications in the heights and distances measured with the instruments. To avoid such errors, the following points should be taken care of:
- 6. Group 4 ǀ Fieldwork 4 6 a) The level should be in perfect adjustment for taking observation. b) The altitude bubble should be at the centre of its run while reading the vertical circle for angles. Any index error should be detected and eliminated or accounted for. c) The multiplying and additive constants of the instrument should be periodically checked to see that they indeed have the values that are being used. d) The stadia rod (staff) should be accurately divided into parts. The graduations should be uniform and free of errors. They should be marked bold for greater visibility from a large distance. Conclusion In this experiment we worked in field and we obtained desired data. From the profile run, we know the center-line elevation at each station. And we take cross-section elevations at (0+20 m) for center line and both sides of the center line. On the plot of the profile we note that the road line is slope, it decreases when we move from left to right. From the field sheet we see the cross-section of the road and we note that the center line is higher than both sides (right and left).