Lesson Note On Leveling Survey (Longitudinal and Cross-section)

Leveling Survey (Longitudinal and Cross-section)

Learning Outcome

By the end of this practical work students should be able to:

1.           Setup level equipment

2.           Take back sight, intermediate sight and fore sight reading

3.           Make correct booking

4.           Calculate reduced level of all the point taken

5.           Perform correction to the reduced level

6.           Plot a longitudinal profile and cross section with a suitable scale

Theory

Leveling is the art of determining relative height or elevations of different points on the earth surface. The elevation of a point has been defined as its vertical distance above and below a given reference level surface and usually a mean sea level. The leveling work can be carried out by using direct method or indirect method. The main equipment needed to carry out leveling works is level and staffs. The elevation of the point is calculated using Height of Collimation Method or by using Rise and Fall Method. The final works of the leveling is to transform the numerical data into graphic form either in map or drawing.

Equipment

1. level
Automatic level is used to compare points on the surface of the earth and series of heights observed must be relative to a plane called datum. Automatic level is a device that gives a truly horizontal line. The telescope of this instrument need only be approximately level and the compensating device, usually a pendulum system inside the telescope corrects for the residual mislevelment. This instrument has no bubble tube; therefore preliminary leveling is carried out using the conventional three-screw leveling head and a small target bubble mounted on the tribach which brings the collimation to within 10’ of the horizontal. A prismatic compensator fitted between the eyepiece and the objective lens make correction of slight tilt automatically.

2. Leveling staff

The staff used for ordinary leveling work is sectional and assemble either telescopically or by slotting one another vertically. Most modern designs are manufactured in an aluminum alloy BS4484:Part1:1969 requires length of 3 m, 4m or 5m extension. The graduations are in the form of an E or F shape and the graduations in the 100mm interval.

3. Staff bubble

An instrument to ensure the staff is erected vertically. It is place at the side of the staff.

4. Tapes

Tape is made of synthetic material, glass fiber or linen. The length of the tape is 10m, 20, 30m and 50m are generally available. The tape is graduated at every 5mm and figures every 100mm. the first and the last meter lengths are graduated in millimeters. Whole meter figures are shown in red at every meter.

Procedures

·                     Longitudinal leveling (60m length)

1.           The suitable position for the level to be set up is selected

2.           The level is set up. The temporary adjustment is made

3.           The staff is placed at the bench mark and the reading is taken

4.           The reading is noted in the form provided

5.           Another staff is placed at the distance of 7.5m from the first staff

6.           The reading of second staff is taken and is noted as the intermediate sight

7.           A distance of 7.5m is measured and the third staff position is placed. The reading is noted in the field sheet as an intermediate sight

8.           Step 5 to 7 is repeated until the staff cannot be read. The last reading of the staff before the level is moved is noted in the column foresight. The staff at the foresight position must not move until the back sight reading is taken

9.           The level is moved to new suitable position and the temporary adjustment is made

10.        The back sight reading is taken

11.        A cross section reading is taken at every 15m

12.        Steps 5 to 10 are repeated until the work is completed

13.        A fly level is performed back to the benchmark

14.        The HOC and the reduced level of all the staff positions is calculate

15.        The longitudinal and cross section profile of the road is plotted

·                     Cross section leveling (0m, 40m, 80m, 120m, 160m and 200m)

1.           Five staff positions is selected perpendicular to the longitudinal line at position A, B, C, D and E

2.           The staff is placed at point A and the reading is taken

3.           The reading is entered as intermediate sight if the level is still not being moved from the previous position

4.           Taking reading for points B, C, D and E is continued

5.           After completed cross section leveling, taking the longitudinal leveling is continued until completed

Conclusion

From this practical, we were able to setup the compass survey stations and their equipment correctly. We have taken the reading of three points of static things that have at our location from station A. There are 3.25m, 1.80m and 3.35m from station A

We have calculated the misclosure as mentioned in the local attraction method table. The corrected bearing and the final bearing is determined by followed the correct steps

Discussion and Recommendations

1.           Avoid taking measurement near magnetic sources such as hand phone, watch, electric cable and etc

2.           Make sure the bubbles are properly level

3.           Triple check with the work and reading

4.           Make sure the plum bob properly centered over the peg

Lesson Note On How to establish controls in Hydrographic Surveying

How to establish controls in Hydrographic Surveying
	The first step in making a hydrographic survey is to control both horizontal and vertical. Horizontal Controls: In an extensive survey, the primary horizontal control is established primarily by running theodolite and tape traverse before the triangulation station. Tthe traverse lines being run to following the shore lines approximately. In survey of less extent the primary horizontal control only is required and is established by running a theodolite and tape traverse sufficiently close to shore line. For rough work, the control may be established by running a theodolite and staid traverse or plane table trader. Stadia Surveying: The distances are determined by angles there are stadia hairs from which angles and all calculations are determined without change. Vertical Controls: These are based upon a series of bench marks established near the shore line by spirit leveling and these serve for setting and checking tide gages etc to which the sounding are referred.
Shore Line Surveying: Purpose: To determine the shore lines. To locate the shore details, promise topographical feature, light house, pointt of reference etc. To determine the high and lower water lines for average spring. Both in please and elevations in the case of tidal waters. All irregularities in the shore line as well as the shore details are located by means of offsets measured with a tape form the traverse lines, by staid or plane table. The points of reference should be dearly risible form the water and should be near enough such wing mills, flag poles etc. buoys anchored off the shore and light houses are used reference points. The position of the high water line may be judged roughly form deposits an marks on rocks however to locate it accurately the elev of mean high water is determined and point are located on the shore at that elevation. The line connecting these points represent high water level.

Lesson Note On Field procedure for setting out the curve with Theodolite

Field procedure for setting out the curve

1. A theodolite is set up at the point of curvature T1, and get it temporary adjusted. 2. The vernier A is set to zero, and get the upper plate clamped. After opening the lower plate main screw, sight the point of intersection, V. Then the lower plate main screw gets tightened and get the point V bisected exactly using the lower plate tangent screw. Now the line of sight is in the direction of the rear tangent T1 V and the vernier A reads zero. 3. Open the upper plate main screw, and set the vernier A to the deflection angle Da. The line of sight is now directed along the chord T1 a. Clamp the upper plate. 4. Hold the zero end of the tape of a steel tape at T1. Note a mark equal to the first chord length C1 on the tape and swing an arrow pointed at the mark around ‘a' till it is bisected along the line of sight. The arrow point then indicates the position of the first peg ‘a'. Fix the first peg at ‘a'. 5. Unclamp the upper plate, and set the vernier A to the deflection angle Db. The line of sight is now directed along T1 b. 6. With the zero end of the tape at a, and an arrow at a mark on the tape equal to the normal chord length C, swing the tape around b until the arrow is bisected along the line of sight. Fix the second peg at the point b at the arrow point. It may be noted that the deflection angles are measured from the tangent point T1 but the chord lengths are measured from the preceding point. thus, deflection angles observed are cumulative in nature but chord lengths swung are individual in nature. 7. Repeat steps (5) and (6) till the last point is reached. The last point so located must coincide with the tangent point T2 already fixed from the point of intersection.

Lesson Note On Setting out of Foundations

Setting out of Foundations

Before Commencement, of the excavation of trenches for foundation, a setting out plan is prepared on paper. The setting out plan is a dimensioned ground floor plan, usually drawn to scale of 1:50. The plan is fully dimensioned at all breaks and openings. One of the methods of setting out of foundations is to first mark the centre line of the longest outer wall of building by stretching a string between wooden pegs driven at its ends. This serves as the reference line for marking the centre line of all the walls of the building. The centre line of the wall, which is perpendicular to the long wall, is marked by setting up a right angle. Right angle is set up by forming triangles with sides 3,4and5units long. If we fix the two sides of the right angles triangle to be 3 m, and 4 m, then the third side i.e. the hypotenuse should be taken a 5 m. The dimensions should be set out with a steel tape. The alternative method of setting out right angle is by the use of theodolite. This instrument is also helpful in setting out acute or obtuse angles. Small right-angled Projections are usually set out with mason’s square.

The method of  Setting out of Foundations described above is not so reliable for important works as there is likelihood of the wooden pegs being pulled up or displaced. In an accurate method, the centre lines of the building walls arc carefully laid by means of small nails fixed into the head of the wooden pegs driven at the quoins. In case of rectangular buildings, the diagonal from the opposite corners are checked for their equality. Small brick walls, pillars or platforms are constructed 9ocm clear of the proposed foundation trench. The platforms are about 15 cm wider than the trench width and are plastered at top. The tops of all platforms or pillars should be at the same level preferably at plinth or floor level of building. The strings are then strenched over the nails in the pegs and the corresponding lines are marked on the wet plastered platforms top by pressing the stretched string on the plastered surface by a trowel. The outside lines of thefoundation trench and the plinth lines are marked on the wet plastered platform top in the similar manner.

Before starting excavation, the strings are stretched between the outside lines of thefoundation trench marked over the platform top and the cutting lines are marked on the ground by lime powder. If necessary, the lines may be marked by a daghbel or pick-axe.

LESSON NOTE ON TWO THEODOLITE METHOD FOR SETTING OUT A CURVE

TWO THEODOLITE METHOD FOR SETTING OUT A CURVE

RANKINE'S METHOD In this method, curves are staked out by use of deflection angles turned at the point of curvature from the tangent to points along the curve.

This method is based on the following geometry:

 Let AB & BC be two tangent intersecting

at B, the deflection angle be (shown infig.)

 the tangent length is calculated &

tangent pt. are marked.

 Let,

= first pt. on the curve.

= length of cord.

= deflection angle for first chord.

R = radius of curve

= total deflection for the chord.

 Procedure:-

i. Set the instrument up at the tangent point, sight along the tangent and turn off the first deflection angle ( Φ =Ө/2 ).

ii. Fix one end of tape at A, measure off 'c' meters, and swing tape until it aligns with the line of sight. Put in peg B.

iii. Turn theodolite a further Φ°. Fix one end of tape at B, measure off 'c' meters, and swing tape until that point on the tape crosses the line of sight. Put in peg C. iv. Repeat step (iii) until you peg the curve. If the line of sight becomes obstructed, then simply set up on any peg on the curve, sight back along the chord to the previous peg and continue to establish the deflection angles.

 Precautions to take:

Calculate the angle Φ to seconds, or errors will be considerable if many pegs must beplaced.

The final reading, to the other tangent point, should equal L.

Aim: To set out the simple curve by two theodolite method.

Instruments Required : Two Theodolites and Ranging rods.

Principle: The angle between the target and the chord is equal to the angle which that chord subtends in opposite segment.

Given : Chainage of the curve , angle of intersection and Radius of curve (R).

Procedure :

1. Prepare a table of deflection angle for the first sub chord, Normal chord and last sub chord .

2. Set up one theodolite over T1 and another over T2 .

3. Direct the instrument at T1 to the ranging rod at the point of intersection B and bisect it.

4. Direct the instrument at T2 to the first target point T1 and bisect it.

5. Set the verniers of both the theodolites to read zero.

6. Set the first deflection angle (D1) on both theodolites so that the telescopes are in the direction of T1D and T2D respectively.

7. Move the ranging rod until it is bisected by the cross hairs of both the theodolites to locate the point D on the curve .

8. Set the second value of deflection angle on both the theodolites and repeat the step 7 above to get the location of E.

9. Continue the process for obtaining the locations of other points in a similar manner.

Lesson Note On Site Setting Out / Field Setting Out

Site Setting Out / Field Setting Out
	The method of setting out is the reverse of surveying process. The process involves the positions and levels of building lines and road alignments shown on the construction plans to be established on the ground by various techniques and instruments. See Also: Setting Out Circular Curves Methods of Setting Out Setting out buildings by coordinates Setting out with theodolite and level Checking verticality Setting out and alignment in steel framed buildings Alignment and verticality in form work Control and calculation for route surveying
1. Setting Out Building by Coordinates A building can be set out by taking referencing from an already established baseline. An irregular building or a building having a complex geometry can be also be located using the same method. For each corner of the building, a grid line can be established from the baseline. 3. Checking Verticality: To check verticality of points in a building, the following surveying instruments can be used: Plumb Bob (For buildings less than 20m in height) Optical Plummet (A transparent plastic sheet is used as a target for checking verticality of tall buildings) Theodolite Setting out works also include Computations and setting out Methods for: Simple Circular Curves Compound Curves Reverse curves Transition curves Vertical curves

Lesson Note on Types of Surveying

Types of Surveying
	Surveying has a broader scope of application. Its importance is felt in the following areas and/ or services: Agricultural surveying services Building control regulations Building defects Building maintenance and repairs Building refurbishment Building surveying Commercial property agency Commercial property management Commercial property valuation Commercial property dispute resolution Commercial rent review (and lease renewals) Dilapidations General practice Home buyers’ survey and valuation Insolvency advice Industrial property agency Industrial property valuation Hotel and licensed property Property investment advice Rating advice and appeals Residential property valuation Rural practice Annual developmental study Economic growth review Production and consumption statistics Transportation Communication Mapping Definition of legal boundaries for land ownership
Classification Of Surveying Surveying is indispensable to a number of human endeavour, which use surveying principles and practice to their required areas of application. The types of surveying and application are identified and explained below: ALTA / ACSM survey Archaeological survey Agricultural development survey As-built survey Bathymetric survey Construction survey Deformation survey Engineering survey Erosion and Sediment control plan Foundation survey Geological survey Hydrographic survey Mortgage survey or physical survey Plot plan or site plan Soil survey Sub division plan Tape survey Topographic survey Wet lands Delineation and Location survey. 1. ALTA, ACSM Survey: This a surveying standard jointly proposed by the American Land Title Association and the American Congress on surveying and mapping that incorporates elements of the boundary survey, mortgage survey, and topographic survey. ALTA/ACSM Surveys, frequently shortened to ALTA surveys, are often required for real estate transactions. 2. Archaeological survey: Used to accurately assess the relationship of archaeological sites in a landscape or to accurately record findings on an archaeological site. 3. Agricultural Development Survey: It is a survey carried out to assess the production, yield studies, growth, and the development of agricultural sector taken over a specified period of time saying 2001-2008. 4. As–build survey: Is a survey conducted several times during a construction project to verify, for local state and federal boards, that the work authorized was completed to be specifications set on the plot plan or site plan. This usually entails a complete survey of the site to confirm that the structures, utilities, and roadways proposed were built in the proper locations authorized in the plot plan or site plan. As – built survey is usually done 2-3 times during the building of a house, once the foundation has been poured, one after the walls are put up, and at the completion of construction. 5. Bathymetric survey: This is a survey carried out to map the seabed profile. 6. Boundary survey: A boundary survey to establish the boundary of a parcel using its legal description which typically involves the corners or restoration of monuments or markers at the corners or along the lines of the parcel, often in the ground, or nails set in concrete or asphalt in the past, wooden posts, blazes in trees, piled stone corners or other types of monuments have also been used. A map or plat is then drafted from the field data to provide a representation of the parcel surveyed. 7. Construction Survey: This is otherwise described as “Lay-out” or “setting out”. It is the process of establishing or marking the position and detailed layout of new structures such as roads, or buildings for subsequent construction. Surveying is regarded as a sub-discipline of civil engineering all over the world. All degree and diploma level engineering institutes world wide have detailed items of surveying in the curriculum for undergraduate courses in the discipline of civil engineering. 8. Deformation Survey: This is a survey carried out to determine if a structure or object is changing shape or moving. The three dimensional positions of specific points on an object are determined. A period of time is allowed to pass and these positions are then re- measured and calculated, and a comparison between the two sets of positions is made. 9. Erosion and sediment control plan: This is a plan that is drawn in conjunction with a sub division plan that denotes how up coming construction activities will affect the movement of storm water and sediments across the construction site and into abutting properties and how developers will adjust grading activities to limit the depositing of more storm water and sediment into abutting properties than was done prior to construction 10. Foundation survey: A survey done to collect the positional data on the foundation that has been poured and is curved. This is done to ensure that the foundation was constructed in the location authorized in the plot plan, site plan, or sub division plan. When the location of the finished foundation is checked and approved, the building of the remainder of the structure can commence. This should not be confused with an As-built survey which is not to be done until a particular lend of work is completed on the required stage. 11. Geological Survey: It is a generic term for a survey conducted for the purpose of recording the geologically significant features of the area under investigation. In the past in the remote areas, there was often no base topographic map available, so, the geologist also needed to be a competent survey or to produce a map to the terrain, on which the geological information could then be draped. More recently, satellite imagery or aerial photograph is used as a base, where no published map exists. Such a survey may also be highly specialist for instance focusing primarily on hydro-geological, geochemical or geomagnetic themes. 12. Hydrographic Survey: Hydrographic survey is a survey conducted with the purpose of mapping the coast line and seabed for navigation, engineering, or resource management purposes. Products of such surveys are nautical charts. 13. Mortgage survey or physical survey: It is a simple survey that generally determines land boundaries and building locations. Mortgage surveys are required by title companies and lending institutions when they provide financing to show that there are no structure encroaching on the property and that the position of structures is generally within zoning and building code requirements. Some jurisdictions allow mortgage surveys to be done to a lesser standard, however most modern Nigerian minimum standards require the same standard of care for mortgage surveys as any other survey. The resulting high price of mortgage surveys has led some lending institutions to accept mortgage inspections not signed or sealed by the surveyor. 14. Plot plan or site plan: It is a proposal plan for a construction site that include all existing and proposed conditions on a given site. The existing and propose conditions always, include hydrology, drainage flows, endangered species habitat, among others. 15. Soil survey: This is also called soil mapping. It is the process of determining the soil types or other properties of the soil covered over a landscape, and mapping them for others to understand and use. 16. Subdivision Plan: It is a plot or map based on a survey of a parcel of land. Boundaries lines are drawn inside the larger parcel to indicate the creation of new boundary lines and roads. The number and location of plats, or the newly created parcels, are usually discussed back and forth between the developer and the surveyor until they are agreed upon. At this point, monuments, usually in the form of square concrete blocks or iron rods or pins are driven in to the ground to mark the lot corners and curve ends, and the plat is recorded in the cadastre or land registry. In some jurisdictions, the recording or filling of a subdivision plat becomes, in effect a contract between the developer and the city or country, determining what can be built on the property and under what conditions. Always upon finally completion of a subdivision, an As-built plan is required by the local government. This is done so that the roadway constructed therein will pass ownership from the developer to say local government by way of a contract called a covenant. When this stage is completed, the roadways will now be maintained, repaved, swept, and plowed (if necessary) by the local government. 17. Tape survey: This type of survey is the most basic and inexpensive type of land survey. Popular in middle part of the 20th century, tape surveys while being accurate for distance, lack substantially in their accuracy of measuring angle and bearing. Considering that a survey is the documentation of half (1/2) distance and half (1/2) bearing, this type of survey is no longer accepted among local, state or federal regulatory committees for any substantial construction work. 18. Topographic survey: This is surveys that measures the elevation of point on a particular piece of land, and present them as contour lines on a paper. 19. Wetland Delineation and location survey: This is a survey that is completed when construction is to be done on or near a site containing defined wetlands. Depending on the local state, and federal regulations, wetlands are usually classified as areas that are completely inundated with water more than two weeks during growing season. The boundary of the wetlands is determined by observing the soil color, vegetation, erosion patterns, scour marks, hydrology and morphology. Typically blue or pink coloured flags are then placed in key locations to denote the boundary of the wetland. A survey is done to collect data on location of the placed flags and a plan is drawn to reference the boundary of the surrounding plots or parcels of land and the construction work proposed within. BUILDING SURVEYING Building surveying emerged in the 1970s as a profession in the United Kingdom by a group of technically minded general practice surveyors. Building surveying is a recognized profession within Britain and Australia. In Nigeria in particular, due to risk mitigation/ limitation factors, the employment of surveyors undertaken in Nigeria are broad but include: Construction design and building works Project management and monitoring Property Legislation Adviser Insurance assessment and claims assistance Defect investigation and maintenance adviser Building surveys and measured surveys Handling planning applications Building inspection to ensure compliance with building regulations. Undertaking pre-requisition surveys Negotiating dilapidations claims Design Maintenance Repair Refurbishment Restoration of constructed works.