NDRC 132 KV Electrical Cable

The project work comprised installing electrical cables underneath existing King Salman Bin Abdulaziz Al Saud Street and tram lines by Horizontal Directional Drilling (HDD) to establish the SEYAHIST—MCLB 132 kV Circuit, in accordance with the authorities' requirements.

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 6.5 m below the tram line and 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 monitoring infrastructure safety and risk management during 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 solutions 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

Instruments 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 the tram track to monitor any settlement caused by nearby and underneath construction works
• A borehole extensometer was Installed in the soil to monitor settlement in the ground along the tram alignment.
• Surface settlement points are 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 the recording of their base readings. The experienced and proficient Encardio-rite I&M team executed the installation and monitoring of the above-mentioned instruments successfully. During the NDRC works, the consultant/contractor could continuously access the real-time data from the vibration sensor at their desk. Monitoring reports for the manual data were also provided to the contractor daily.