CHAPTER ONE
1.0 INTRODUCTION
As-built survey has been an essential element in the development of the human environment since the beginning of recorded history. It is performed to verify that a particular improvement on a parcel of land has been built according to the proposed design plans, specifications and setback requirement. It shows how any field change made during construction fit the overall design of the development. If this As-built data are not obtained, engineers, architect, land planners, clients and other may be misled in assuming that the construction work performed conforms perfectly to the original drawing .It is used to document the size and / or location of an improvement used to aid in the design of addition of buildings, extention, sewer and parking lot expansion. It help landing institution to protect their interest, accurate decision making, updating of information and as a reference material for student ministry and individual.
Medium density layout, Ifuho, is a residential estate located in Ikot Ekpene Local Government Area, Akwa Ibom State. It is made up of twenty-five(25) existing building with internal access road, available space which is used for agricultural farming.
Due to increase in population, scarcity of houses, political and topographic effect, medium density layout needs As-built survey in order to determine the final location of existing features and the available space for proper planning ,redesigning and expansion.
The aim of As-built survey on medium density layout is to produced an As-built plan to ascertain the final location of available detail and available space for further development of the estate by way of expansion.
The processes involved in the achievement or the above aim is reported here forthwith.
STATEMENT OF PROBLEM.
Due to political reason, cost and topographic of the area, errors(instrument, atmospheric, human etc),buildings were not built according to the design. Medium density layout need As-built survey to determine the final location of existing feature, thus enhances proper use of available space for expansion.
AIM AND OBJECTIVES
The aim of this project was to produce an As-built plan of medium density layout, Ifuho, Ikot Ekpene Local Government Area for the purpose of ascertaining variations of detail as constructed from the design.
This was achieved through the following objectives:
- Establishing the perimeter using traverse.
- Measurement of relative position of the detail within the study area.
- Preparation of an overlay plan which facilitated the comparison.
- To explore the power of computer application software especially in the plan production.
SCOPE AND LIMITATION
The scope of this project, amongst other things is limited to the production of As-built plan of medium density layout using traverse method through the objective stated in 1.2 above.
However, height information was not considered.
SIGNIFICANCE OF STUDY.
Production of As-built survey plan of medium density layout will be significant in the following ways:
- For accurate decision making to the developer for physical planning and further development and/or expansion of the estate.
- For updating of information and quick retrieval of information for environmental management for the government.
- As a reference material for student, ministry and individual for further research work.
- Enhance the knowledge of the student in the area of As-built survey.
SPECIFICATIONS
Angular Observations:
Type of instrument-minimum of 20”graduation interval.
Number of observation- 2 zeros(face left/face right).
Accuracy of observation- the maximum spread of 2 zeros valves shall be 20 seconds.
Linear Observations:
Type of equipment: EDM
Method of measurements: on level smooth ground, surface taping may be employed. On rough terrain catenary tapping may be used, preferably EDM Accuracy of measurement: standard error of linear measurements should be one part in 20,000. Differences between two observations should exceed 1cm.
Instrumentation; Any instrument including electronic theodolites, total stations or GPS capable of achieving the above accuracies or better may be used.
Accuracy:
- Four set of observations (for doubtful latitude pair East/West observations).
- Angular spread -10” 0n 4 zeros.
- Bearing closure at Azimuth check points not to exceed 30”±N, where “N” is the number of instrument stations.
Plotting of plan:
- Plotting should be done by rectangular coordinates, details and irregular boundaries by offsets or bearing and distances.
- Plans shall show clearly defined plot boundaries, detail within and along the boundary.
Heading for a certified plan:
Should include:
- Title of survey.
- Locality- street–town/village, Local Government Area and state.
- Scale and with its linear representation
- North Arrow/origin ,AREA
Demarcation of Boundaries
Type of beacons:
- Property beacons shall be 18cm×18cm×75cm.
- Cemetry beacons shall be 10cm×10cm×60cm.
- Spikes shall be rod pin 40mm marked with the center punch mark at the top.
Marks on boundary walls, a cross ‘x’ with identification number shall be cut and painted on the outside wall where it intercept surveyline. Public survey shall carry double arrows.
Large concrete beacons/markers may be used for right of way survey (ROW).
Location of boundary beacons.
All corners of plot including point of changes in direction and on straight long lines at intervals of not more than 250m in layouts and 400m in farmland.
Requirements of boundary beacons.
Adjacent boundary beacons should be inter visible, but where for some reasons this is not possible, multiple observation from proven station or pair of stations to fix a beacon.
Survey of boundaries.
Available methods of survey
The boundaries will usually be surveyed by closed theodolite traverse. Other methods include staring the traverse on checked and proven boundary beacons and ending same on checked and proven boundary beacons insofar as the starting and closing beacons form part of the new boundary of the property surveyed .For any of the methods, the position closure (after Azimuth adjustment where applicable)shall be 1/5,000.
Field books
- All field observation must be entered in the field book clearly with neat booking.
- Clear diagrams: Diagrams of plot survey must be unambiguously represented in the field book. Such diagram will also show permanent features within and along area adjacent to the plot.
- Electronic field book may also be used.
Computations:
- Computation – manual or electronic shall include the following:
- Azimuth computation where necessary.
- Reduction of bearing showing angular closures.
- Distance, measured/corrected.
- Un-adjusted/final coordinate/linear closures.
- Area computation.
- The required computational accuracy are as follows:
- Deduced bearing to the nearest 10”
- Corrections to measured distance for slope, standard(standardization where applicable) to the nearest mm.
- Coordinates to the nearest mm.
- Area
Allowable drawing scales:
The following drawing scale shall be used for plotting:
- 1:250
- 1:500
- 1:1,000
- 1:2,000
- 1:2,500
- 1:5,000
- 1:10,000
- 1:20,000
- 1:25,000
Different scales may be used for the main survey and the connection where the latter is long. Any chosen scale should permit the clear representation of all measured detail, bearing, distances and area on plan.
Electronic copy maps must be prepared using base data with relevant location accuracy.
STUDY AREA
The study area is medium density layout, Ikot Offiong, Ifuho, Ikot Ekpene Local Government Area, Akwa Ibom State and it is located on latitude 58 46 longitude 135 00 UTM zone 32 north. The estate is situated along Ikot Offiong road on the south and on the west 500m away from Aba r
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