Work on the multibillion-riyal Riyadh Metro project is progressing well and is about 10 per cent ahead of schedule, said a report, citing a top government official.

One of the world’s largest metro projects, this automatic driverless network will be more than 170 km long and have 87 stations on six lines, reported the Arab News.

It is scheduled for completion in 2018, said Riyadh Governor Prince Turki bin Abdullah bin Abdul Aziz after an inspection at the work site.

Prince Turki, who is also president of the High Commission for the Development of Riyadh (HCDR), and King Abdulaziz Public Transport supervisory committee, held the 11th meeting of the HCDR in a tunnel.

The tunnel is below what is expected become the Olaya station site, at a depth of 25 m. Project officials briefed Prince Turki on the drilling that has already extended 218 m east and west, said the report.

He also had a close look at various aspects of the work including geological tests, and the use of sensors to monitor the thickness of the soil on the surface above the tunnel.

At the meeting, the officials outlined the ventilation, lighting system and equipment to monitor the level of oxygen and gases inside the tunnel, to ensure that workers are safe underground.