RITES Limited, a Public Sector Enterprise under the Ministry of Railways, floated online e-tender for Topographical survey using DGPS, total station, auto level and preparation of drawings using mapping software & utilities collection for Detailed Project Report for Mass Rapid Transit System (MRTS) in Prayagraj City, Uttar Pradesh.
- Tender Reference Number: RITES/CO/UE&S/DPR/MRTS/Prayagraj/2023/01
- Name of Work: Topographical survey using DGPS, total station, auto level and preparation of drawings using mapping software & utilities collection for Detailed Project Report for Mass Rapid Transit System (MRTS) in Prayagraj City, Uttar Pradesh.
- Estimated Cost of Work: INR 16,88,080/-
- EMD: INR 34,000/-
- Period of Completion: 60 Days
- Document Download / Sale Start Date: 26th Sep, 2023
- Document Download / Sale End Date: 09th Oct, 2023
- Bid Submission Start Date: 27th Sep, 2023
- Bid Submission End Date: 09th Oct, 2023
- Bid Opening Date: 10th Oct, 2023
Scope of Work:
Establishment of “Prime Traverse” through DGPS (As a Whole):
The proposed tentative alignment will be supplied to the contractor for getting an idea of alignment for the purpose of fixing Control Pillars as per specifications.
Strategic point locations/DGPS points for long hour observation at start, end & intermediately in the area of interest shall be selected and get approved from RITES on Google earth.
Minimum 24 hours observation using minimum 3 DGPS at vertices of a well-conditioned triangle having sufficient long baseline (Equivalent to end to end distance of survey area) should be done for common period.
Recorded data of long hour observation shall be downloaded and processed through software application to establish prime traverse as a whole.
Processed grid coordinates (Cartesian) will be further processed to arrive at ground coordinates. Values for northing & easting of grid coordinates should be considered as fixed for any DGPS sub-traverse/intermediate loops, initiating or passing through these points and the data shall be processed in accordance with fixed values of the grid coordinates.
Similarly, values for northing & easting of ground coordinates should be considered as fixed for any Total station sub-traverse, initiating or passing through these points and the data shall be processed in accordance with fixed values of the ground coordinates.
GPS and Total station instruments used for traversing purposes should possess software qualification to work in both grid and ground coordinate systems or else, it should be accompanied by manufacturer supplied software for conversion of data from grid coordinates to ground coordinates and vice versa.
Establishment of DGPS Controls (Whole to Part):
The pillars/points (henceforth designated as Control Points) for which coordinates in line with prime traverse are to be established shall be decided in advance in consultation with RITES.
The contractor shall plan closed loops consisting of a network of well-conditioned triangles, connecting these control points. He shall submit this network on Google earth for approval by RITES before proceeding to the site.
The triangles shall be well formed and preferably neither too acute (<30°) nor too obtuse (>120°), with sufficient redundancy so that a baseline could be confirmed by observations from multiple control points. There may be occasions where due to some specific site constraints, this network may require change. If a RITES representative is available, his concurrence may be taken for this change.
If a RITES representative is not available, necessary changes may be carried out by the Surveyor himself with reasons recorded by him which may be approved by the RITES representative later on.
Horizontal control grid in line with prime traverse will be established using DGPS at about 2 km along the alignment on a pair of control stations/control points fixed at a distance in the range of 100m to 200m apart from each other along the proposed alignment for clear inter visibility.
In addition, the contractor has to take GPS observations at existing pillars available en-route and also pillars exist at natural & man-made features like river/nallahs, road, tunnel, culvert, bridges etc. as desired by RITES representatives at site.
If such features are not available, pillars may be erected there specifically for this purpose. At least two adjacent control points (i.e. a pair of DGPS control points) shall be inter-visible with reference to each other and shall preferably be fixed on ridge lines, in sections where no field surveys have yet been done.
The DGPS sets used shall be with at least 12 channels having differential post processed accuracy of at least ±(5mm+1ppm x Baseline Length). The stations selected shall be obstruction free towards sky at an angle of 15 deg with horizontal plane.
The control point locations should be selected so as to be:
- Clear of HT/LT lines,
- Free from multipath problems associated with tall features in the vicinity,
- Free from foliage,
- Open to sky with a clear view of the horizon,
Close to the proposed alignment where features such as rock outcrop, culvert etc. is available; control points may be located there. If such features are not available, pillars may be erected there specifically for this purpose. At least two adjacent control points (i.e., a pair of DGPS control points) shall be inter-visible with reference to each other and shall preferably be fixed on ridge lines, in sections where no field surveys have yet been done.
GPS observations shall be taken at control points in differential mode for sufficient time (Minimum 2 hours) using at least 3 receivers forming 3 vertices of a well formed good triangle.
For carrying out network adjustment, one permanent control point may be fixed for both horizontal and vertical control. Horizontal control may be fixed with long hour GPS observation (24 Hours) continuous observation. Minimum common period of observation for other GPS points shall be not less than two hours.
The Surveyor shall also carry out comparative analysis of GPS coordinates obtained by observations from subsequent control points forming redundant triangles. The accuracy of these shall be at least 1 in 1,00,000 or better. Measurements taken with Geometric Dilution of Precision (GDOP) exceeding 5 should not be considered for post-processing.
The Surveyor shall download raw GPS data on a PC/laptop at site itself and thereafter apply suitable projection system so as to arrive at grid coordinates (Northing, Easting and Elevation with reference to Mean Sea Level) from geographical coordinates (Latitude, Longitude & Ellipsoidal Height) observed at site.
Horizontal control may be fixed selected from the points of the “prime traverse”. Vertical control (i.e. mean sea level height) will be established with reference to known available surveys of India GTS/GCP benchmark(s). Each day’s work shall be compiled and mapped/documented on the same day.
The parameters used for transformation shall be duly documented in the Report provided by the Contractor. The coordinates for the entire section shall be with reference to single grid in metric system and WGS datum on UTM projection system.
The GPS work will be followed by Total Station Survey Work. The Contractor will provide the grid and ground coordinates of all Control Points to RITES. Both the Raw Data (in RINEX as well as proprietary formats of GPS manufacturer) as well as the Transformed Data shall be supplied by the Contractor to RITES.
All teams shall ensure that details in required format are furnished promptly to RITES representatives working near the site, in softcopy and hardcopy forms, duly checked and verified, supported with “not to scale” neat sketches. The Surveyor shall also submit photographs of all control points surveyed by him. The photographs shall indicate the pillars/points and its surrounding areas clearly.
During survey, careful notes with dates should be made on the ground, from personal enquiry and observations regarding any information likely to be useful in working out details of the project. Necessary jungle clearance and construction of pathways for proper execution of the work, wherever required, shall have to be done by the contractor at no extra cost.
Deliverables in connection with Topographical survey shall broadly comprise of but not limited to the following:
- Topographical Survey Plans for the route alignments and other facilities like Station areas, Maintenance Depot as per project requirements.
- Photographs of every DGPS point/other important points with description.
- Baseline processing reports.
- Loop closure.
- All Raw dataset of Base and Rover in .dat format.
- Final processed data of GPS in desired format as per project requirement.
- Auto CAD drawing as per Clause-xxv of Scope of Work of Section-3.
- Layer specific Surveyed data in GIS supported format.
- Preparation and Submission of Survey Report.
- Utility Tables as per the format of RITES.
All the Plan and Drawings should be prepared shall be compatible with Auto CAD/Microstation Standards. The tentative route map of the proposed MRTS corridors to be surveyed are as under.
The Corridors shown are tentative for information only. Sub-consultant shall carry out the survey along any proposed corridor(s) in Prayagraj City as per instructions of Engineer-In-Charge.
Only empanelled shortlisted sub-consultant/agencies of UE&S sub-unit for the work of Topographical surveys are eligible to participate in this tender.
Source: RITES- Tender | Image Credit (representational): Central Railway