The National High Speed Rail Corporation Limited (NHSRCL) has issued a Letter of Acceptance (LOA) to M/s Aarvee-GSL Consortium for Final Alignment design including Aerial LiDAR survey and other related works for Chennai-Mysore High Speed Rail Corridor (about 435 kms. long).
- Contract Package No.: NHSRCL/CO/CA/LIDAR/2020/48
- Name of work: Final Alignment design including Aerial LiDAR survey and other related works for Chennai-Mysore High Speed Rail Corridor (about 435 kms. long)
In January this year, the NHSRCL had invited online tender for the Contract Package No.: NHSRCL/CO/CA/LIDAR/2020/48.
About the project:
With an objective to meet growing passenger demand and optimise high speed rail connectivity between major cities/commercial and economic activity centres, a HSR corridor is being planned between Chennai-Mysore covering desired obligatory points and major public hubs among other considerations. For this purpose, it is now proposed to undertake Detailed Project Report of this corridor:
| S. No. | Corridor | Corridor Length (Approx.) |
| 1 | Chennai-Mysore | 435 km |
Scope of works:
- The Contractor shall submit relevant documents for approval wherever required and will interact with the concerned authorities/State Government/other Govt. departments as required.
- The work shall be executed in a phased manner unless otherwise directed by NHSRCL so that succeeding tasks can also be initiated as per Schedule for timely completion of the Project.
- The scope of work shall be carried out as per NHSRCL’s Schedule of Dimension for High Speed Rail, Relevant Design manual, IS codes and as per International accepted norms. The document submissions shall be in formats as per HSR Codes and manuals, soft copies and hard copies as laid down. The latest modern techniques and software shall be used for this work.
Scope for Final Alignment Report: Detailed Final Location Survey and Studies with final alignment design:
The contractor shall further refine the alignment in the selected alignment corridor by undertaking a detailed Final Location Survey using Aerial LiDAR technology along with establishment of Ground Control Network, Pillar fixing, Hydrological Survey (wherever required) and final alignment design (horizontal as well as vertical). For doing this, the contractor shall undertake the following:
- Aerial LiDAR & Imagery Survey: The contractor will undertake Aerial LiDAR Survey complemented by Aerial Imagery in a corridor width of 300 m (150 m on either side) around the proposed alignment. Detailed Specifications are provided in TOR and Broadly the work will involve the following:
- Collection & paper study of existing alignment reports, data, drawing, documents, ground control points etc.
- Ground Control Survey to be undertaken as follows:
- Carrying out reconnaissance survey of the project area for identifying the Control Points locations for carrying out DGPS survey and preparing a plan of a grid network of Control Points on SOI topo-sheets/satellite imagery.
- Survey of India Benchmarks to be located during the above reconnaissance survey. These benchmarks shall be tested for stability and the same shall be reported to the client. The entire horizontal and vertical control shall be linked to the approved stable Benchmarks for conversion of LiDAR data to MSL.
- Master Control Network comprising interconnected triangles (with baseline of about 25km) to be established for overall horizontal control with approx. 25 km baseline length throughout the alignment. Secondary Control Network comprising of interconnected triangles weaved with the Master control network to be established with a baseline length of approx. 3-5 km throughout the alignment.
- Target LiDAR points to be established at an interval of approx. 5 km within the final alignment. To densify Horizontal Control Network, the GNSS triangulation method should be adopted and processing of data for network adjustment should be done to achieve an accuracy of at least 1:100,000 in horizontal.
- Establishment of vertical control referenced to SoI MSL Permanent Benchmarks to be undertaken by double tertiary leveling along the entire route by connecting target points. The threshold limit for levelling loop closure accuracy should be 12√K mm, where K is circuit length in km.
- Monumentation of Master and Secondary Control Points shall be undertaken if required in consultation with client as per Section 3.3.2.
- Applying to DGCA/Ministry of Defence for flying permissions as per DGCA guidelines and procedures along with adherence to all security stipulations issued by Ministry of Defence in the issue of the permit. NHSRCL will provide the necessary support.
- The contractor will mobilize an aircraft/helicopter to site fitted with state of art Aerial LiDAR and Imagery sensors (equipment as per minimum specification mentioned in Annexure 3) after due security inspection as per MoD stipulations.
- Preparation of flight plan for the Area of Interest.
- Acquiring and pre-processing LiDAR data and digital imagery with LiDAR collected at a point density of 10 points per sq m with FHA (Fundamental Horizontal Accuracy) of 10 cm and FVA (Fundamental Vertical Accuracy) of 10 cm both at 95% confidence interval level. Imagery is to be taken at a resolution of 10 cm GSD.
- Pre-processing data to be referenced to MSL with SoI permanent benchmarks.
- Ground survey/Hydrological survey using traditional methods such as Echo Sounders etc along areas such as river crossings etc where Aerial LiDAR data needs to be complemented, including the following:
- 4 km (2 km on each side of centerline) along all river crossings with river cross-sections soundings (or alternate acceptable method) taken at centerline and then at every 500 m distance along upstream and downstream of the river and upto 50 m beyond high bank
- The DEM generated from this data shall be suitably merged with the LiDAR DEM in consultation with the client.
- Post-processing of LiDAR data to produce the following:
- Classified Point Cloud in LAS (las) format (Soft Copy format)
- Three-Dimensional Topographical map of 50 m corridor on either side of the finalised alignment on a scale of 1:2500.
- Contours of 50 cm interval for the 50 m corridor.
- Digital Orthophotos of 10 cm GSD resolution (in tiles and seamlessly mosaicked over the survey area).
- DSM of 1 m grid.
- DEM/DTM of 1 m grid g. 3 sets of all deliverables to be provided in Hard Copy.
- Soft copy of all deliverables to be provided.
What is LiDAR technology?
NHSRCL is adopting Light Detection and Ranging Survey (LiDAR) technology which provides all the ground details and data in 3-4 months wherein this process normally takes 10-12 months.
- The ground survey is a crucial activity for any linear infrastructure project as the survey provides accurate details of areas around the alignment.
- This technique uses a combination of Laser data, GPS data, flight parameters and actual photographs to give accurate survey data.
- During the Aerial LiDAR survey, 150 mtrs of area around the proposed alignment is being captured for the survey purpose.
- After the collection of data, Three Dimensional (3D) Topographical map of corridor of the proposed alignment on a scale of 1:2500 will be available for designing of the vertical & horizontal alignment, structures, location of the stations and depots, Land requirement for the corridor, identification of project affected plots/structures, Right of Way etc
- To provide clear pictures of the structures, trees and other minute ground details,100 megapixel cameras are being used for the LiDAR survey.
- NHSRCL has been entrusted to prepare the Detailed Project Reports for seven (7) High Speed Rail Corridors and LiDAR survey technique will be used for ground survey in all the corridors.
Recent Updates:
The NHSRCL has already started the LiDAR survey for preparation of Detailed Project Reports (DPRs) for Mumbai-Nagpur High Speed Rail Corridor (approx. 736 km) and Delhi-Varanasi High Speed Rail Corridor.
- The proposed plan for Mumbai Nagpur HSR Corridor (approx 736 km) will connect Mumbai city with cities/towns like Nagpur, Khapri Deport, Wardha, Pulgoan, KaranjaLad, Malegaon Jahangir , Mehkar, Jalna, Aurangabad, Shirdi, Nashik, Igatpuri, Shahapur.
- The proposed plan for Delhi-Varanasi High Speed Rail Corridor will connect the National Capital Territory (NCT) of Delhi with major cities like Mathura, Agra, Etawah, Lucknow, Raebareli, Prayagraj, Bhadohi, Varanasi and Ayodhya.
- The main corridor from Delhi to Varanasi (Approx. 800 km) will also be connected to Ayodhya.
- The High Speed Rail (HSR) route will also connect the upcoming international airport at Jewar in Gautam Buddha Nagar District of Uttar Pradesh
Source: NHSRCL-Tender update | Image Credit (representational): NHSRCL
