Riyadh Metro poses technical challenges to contractors
The Kingdom is set to construct the Riyadh Metro at a cost of $22 billion to provide a safe, efficient and fast means of public transport.
However, the project poses stiff technical challenges, according to a Saudi civil engineer teaching project management at the King Saudi University (KSU).
“This kind of engineering project is being undertaken in the Saudi capital for the first time. There will be trials and misses,” Ibrahim A. Al Hammad, also a member of the board of directors of the Saudi Council of Engineers (SCE), told Arab News on Thursday.
He said the contractors will dig a deep manhole of 30 meters or more with a diameter of 10 meters or so.
“Equipment has to be brought in and the tunnel has to be dug horizontally under the ground. Although this is a common procedure, the workers could be exposed to risk in the manhole due to failures during construction,” he said.
He noted that there are always risks in projects like these. He cited China where accidents had taken place in similar projects. So extra precaution has to be taken for the safety of the workers in the manhole.
“Most of the accidents in engineering projects I have seen took place underground and not above ground where high-rise buildings have been constructed,” Al Hammad said.
Moreover, engineers could estimate the costs more accurately for high-rise buildings, than for underground projects, he added.
“For the latter, engineers sometimes change their assessment. They stop work and the machines break down which may take a few months to fix. This would mean project delay,” he said.
“A few months’ delay also costs money and the question about whether the client or contractor should bear the cost is often a source of conflict,” said Al-Hammad who received his Ph.D. in civil engineering (Major in Project Management) from University of British Columbia in Vancouver, Canada, in 1991.
He also said that digging a manhole and construction of a tunnel for the subway could affect the stability of the foundations of the buildings nearby.
“Take Olaya Street, for instance. Most of the buildings along the road are low-rise, except for Al-Faisalia and the Kingdom Tower whose stability will be affected.”
He noted, though, that sensors will be available to signal if these buildings have strong foundations.
“If the engineers discover that the foundations of these buildings are not strong enough, work will have to be paused in order to find a solution,” he said, adding that there are many empty holes underground in the Saudi capital and these have to be filled with concrete mixed with other chemicals if they are in the way of the tunnel.
Work will only resume when the concrete is dry as this is one of the methods of going about the project, he said.
Despite the challenges the Riyadh Metro poses, Al-Hammad said that it was a move in the right direction, adding that it is a common trend globally.
“In fact, it has come a bit late probably because the Saudi capital is not as large as other cities which have constructed subways such as London, Paris and Shanghai,” he said. The estimated population of Riyadh is 5.7 million and expected to reach 8.3 million in 2030.
He added that generally, the metro minimizes environmental pollution, is more convenient as it’s cheaper for commuters but there are instances when it’s better to take a taxi.
“When I was in London, I had to take a taxi instead of the metro. The taxi only took me 20 minutes to reach my destination whereas the metro would have taken me 30 minutes or more,” he said.
The Riyadh Metro is scheduled to be completed in 48 months.