NDRC 132 KV Electrical Cable
The project work comprised installation of electrical cables underneath existing King Salman Bin Abdulaziz Al Saud Street and tram lines by Horizontal Directional Drilling (HDD) for the establishment of SEYAHIST - MCLB 132 kV Circuit, in accordance with the requirements of the Authorities.
The cable installation works were carried out using the directional drilling technique with launching and receiving shafts at both ends. The maximum depth of gradient tunneling was about 6.5 m below ground level. The tunnel was at a depth of 6.5 m below tram line and at depths of 3 m and 2 m below the existing roads.
As the HDD tunnel crossed under existing busy road and tram lines, instrumentation was planned for safety monitoring of infrastructure, as well as for the risk management of construction works, even though the shafts were excavated only up to 2.5 m depths.
Encardio-rite’s sister concern Encardio-rite Geosystems LLC in UAE was instructed by the Road and Transport Authority (RTA-Owner of Road and Tram) and Emirates Electrical Engineering L.L.C to provide instrumentation and monitoring solution during NDRC to assess the impact on existing infrastructure.
Scope of works included:
- Pre-construction survey of the tram line
- Supply of geotechnical instruments, precise survey instruments
- Installation of geotechnical instruments including subsurface instruments
- Manual and automatic monitoring
- Optical survey and Precise leveling
- Setting up an online web-based data management system (WDMS) and maintenance during the contract period
- Daily & weekly reporting with evaluation & interpretation
Instrument used for surface/sub-surface monitoring for Road and Tram safety included:
- Automatic Vibration sensor Installed near tram tracks to monitor any vibration caused by nearby and underneath construction works
- Cat-eye Prisms Installed near tram track to monitor any settlement caused by nearby and underneath construction works
- Borehole extensometer Installed in soil to monitor settlement in the ground along the tram alignment
- Surface settlement points Installed in the soil to monitor surface settlement along the tram alignment
The NDRC/HDD works started after the installation of the above instruments and recording their base readings. Installation and monitoring of the above-mentioned instruments were executed successfully by experienced and proficient I&M team of Encardio-rite. The real-time data from the vibration sensor was continuously accessible to the consultant/contractor at their desk, during NDRC works. Monitoring reports for the manual data was also provided to the contractor daily.