At the commencement of contract all the basic traverse points will be checked with engineer and if any are found to be missing or appear to have been disturbed, necessary arrangements will be made to re-establish
the points and traverse survey is carried out and if any adjustments would be found which would be done with the Engineer. Subsequently control point coordinates would be submitted to the Engineer for approval.
Initially the Engineer’s/Employer’s occurrence will be sought to obtain details of permanent bench marks tied with national grid. Temporary bench marks will be established at the rate of four per km and also at or near all structures and TBM list and levels would be submitted to the Engineer for the approval. Checks would be carried out on these bench marks once every month and adjustments, if any should be agreed with the Engineer. An up-to-date record of all bench marks including approved adjustments would be maintained with the Engineer.
Center Line Setting out and Marking
Using total stations and approved coordinates of control points, the road center line would be marking at every 10m interval on the road jointly with the Engineer. Chainage would be marked on the road center line in each 20m and 100m interval with meter and kilometer interval respectively.
With the aid of rope and road marking paint, the center point marked in every 10m intervals of the road would be extended as a center line and that established centerline would be maintained until the end of the project.
According to the Engineer’s instructions, corrections if any would be made and which would be followed for the remaining work.
Cross Section Survey
The cross section survey would be commenced as soon as center line is marked and approved by the Engineer. Levels of the cross section will be taken at every chainage point marked on the center line. Cross sections at 20m intervals and in special cases such as sharp curves; the cross section intervals reduced to 10 meters will be submitted to the Engineer’s approval. At the same time, for plotting of longitudinal section (LS) the center value of each cross section would be used.
Submission of Drawings
Initial cross section drawings plotted on A4 sheet on scale of 1:1000 both vertical-horizontal and longitudinal profiles of the road (both hard & soft copy) would be submitted to the Engineer along with back up data sheets for approval.
(a) Level Instrument
Calibration certificate for brand new level instrument is given by the manufacturer and two peg level tests on the leveling instrument would be carried out once in a month and if we would find any error in instrument during working, immediately we would be attending to the calibration of the instrument.
(b) Total Station
Calibration certificate for brand new total station is given by the manufacturer and once in an every six month period, the calibration would be carried out until the project end accordance with relevant standards and if we would find any defect in instrument during working, immediately we would be attending to the calibration of the instrument.