SURCON QUESTION: YOUR FIRM HAS BEEN CONTRACTED ABOUT CARRYING OUT A ROUTE, LOCATION AND
RIGHT-OF-WAY SURVEY OF THE EXTENSION OF THE NIGERIA RAILWAY LINE FROM AJAOKUTA
IN KOGI STATE TO DELTA STEEL COMPANY IN ALADJA IN DELTA STATE. PREPARE A
DETAILED PROPOSAL FOR THE CLIENT, WHICH SHOULD INCLUDE FINANCIAL ASPECTS.
Introduction
The survey shall provide geospatial
data needed for design, setting-out and construction of the railway line. The
project shall be sub-divided into the following procedures.
1.
Reconnaissance
survey
2.
Connection
survey
3.
Establishment
of control points
4.
Marking
of centerline and cross-sections
5.
Detail
survey and corridor mapping
6.
Right-of-way
survey
7.
Processing
and plotting
NOTE: Here, we shall only describe
the works that shall be done. The financial aspect follows the direct cost for
scale of fees described @ PROPOSAL FOR PERIMETER AND TOPOGRAPHICAL SURVEYS. The reader should attempt to do the calculation.
Reconnaissance Survey
Reconnaissance survey shall consist
of two parts. Firstly, planning the project shall be carried out during which
existing topographic maps covering the project length would be studied.
Probable centerline of the proposed railway line would be identified.
Government control points would also be identified. Other features that shall
be identified in along the project corridor include towns, villages, rivers,
hills, bridges, farmlands and swamps.
Secondly, field reconnaissance shall
be carried out during which the survey control points shall be located on the
ground. Also, suitable and inter-visible locations for more control points
shall be identified and marked on the ground. Finally, the proposed centerline
shall be identified and adjusted and obstructions along the centerline shall be
noted.
Connection Survey
Global Positioning System (GPS)
equipment shall be deployed to carry out connection survey in order to connect
the project to national framework of government control points. This shall
serve as geodetic backbone for the entire project.
Further control points shall be
extended to the project area. The control points shall be cast in accordance
with the specifications given by Surveyors Council of Nigeria. The cast beacons
shall be allowed to settle for three days before survey can be carried out on
them.
Marking of Centerline and Cross-Sections
The final adjusted centerline shall
be pegged at 25m interval beginning from chainage 0+000 at the beginning of the
project. At each chainage along the centerline, cross-sections shall be taken
at 10m intervals up to 50m on both the left-hand-side and right-hand-side of
the centerline.
Corridor Mapping and Detail Survey
The railway corridor shall be mapped
50m on either side of the centerline. Every feature along the corridor shall be
identified and surveyed, such as road crossings, built-up areas, rivers,
bridges, farmlands, pipelines, plantations and swampy areas.
During the corridor mapping, the
right-of-way survey shall be carried out, during which features that fall
within the right-of-way shall be identified and surveyed.
Data processing and presentation
During data processing, the following
map products shall be generated:
·
Digital
terrain model (DTM)
·
Contour
map
·
Longitudinal
profile
·
Cross-sections
·
Plan
showing the centerline and all features along the corridor.
Accuracy
The project shall be of third-order
accuracy; that is, not less than 1:3000.
Conclusion
The survey shall be concluded within
a period of one month.
DISCLAIMER: This material
is only an attempt to answer an examination question, though written from a
background of solid knowledge and practical experience in Surveying and
Geoinformatics. It has not gone through peer review. Therefore, all views and
opinions expressed therein remain the responsibility of the author and do not
necessarily represent that of any institution. Feedback on corrections
and constructive criticisms are welcome. Thank you.
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