Nairobi County Draft Design Review Presentation_11.04.23-Working2.pdf

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1. Slide No. 39
KISIP II - Design Review & Construction Supervision – Nairobi (4 No. Settlements)
Nairobi County Draft Design Review Report Presentation | Tuesday, 11
th
– Wednesday, 12
th
April 2023
The primary aim of the detailed survey for the selected infrastructure within
the settlement was to providespatial data for review of the existing
infrastructure designs, review of theexisting topographical survey data
andmapsaswellasthe temporary benchmarks; review of thesetting out
datafor the previous design outputs.
The mapping exercise captured the following details in the survey:
(a) Summary of Topographical Surveys (1)3C
9Temporary structures
9Spot heights
9Road alignment center and edge
9Existing road, including carriageway,
shoulders, toe of embankment
9Drainage systems
9Culverts
9Manholes
9Power lines
9Water meter, meter box, power cables
9Building lines, hedges, walls
9Roads intersecting the project road, their
junction details

2. Slide No. 40
KISIP II - Design Review & Construction Supervision – Nairobi (4 No. Settlements)
Nairobi County Draft Design Review Report Presentation | Tuesday, 11
th
– Wednesday, 12
th
April 2023
The control points were set to the National Grid (Kenyan)
9Coordinate System:Arc1960
9Projection: Universal Transverse Mercator (UTM)
9Reference Ellipsoid:Clarke 1880
9UTM Zone: 37 South
The surveying was conducted according to topographical surveying accuracy
standards as per surveyingAct 299 and surveying regulations.
9Horizontal measurements accuracy = + /- 0.05m
9Vertical measurements accuracy = +/- 0.03m
Contours were generated by direct linear interpolation and smoothing of the
contours were done using cubic splines fitted though strings of interpolated
points.
(a) Summary of Topographical Surveys (2)3C