Metro Crosses The Creek

It looked like any other day on the Creek as abras and cargo ships plied the tributary laden with passengers and goods.

But deep beneath the fishes and sand-rock Creek bottom, one of Dubai’s crowning moments in history unfolded quietly with no public fanfare, XPRESS has learnt.

Thirty metres below the creek bottom, in a damp, enclosed manmade concrete tube, toiling workers watched as the final underwater stretch of Dubai’s first subterranean train tunnel was scoured out, linking Deira and Bur Dubai as part of the proposed Dh25.5-billion Dubai Metro system.

Dubai now joins the ranks of other major world cities with an underground train tube to ease growing traffic congestion.

My wife is very proud of what we have done. I phoned her to tell her. I am very proud of our guys. We have worked hard to make this happen. A construction worker

Seven months after a monster tunnel boring machine named Al Bugeisha set out from a deep shaft behind Dubai Municipality in Deira, it has broken through to firm ground on the Bur Dubai side of the creek, confirmed officials and workers with the Roads and Traffic Authority.

"Yes, we have crossed the Creek," said a senior manager with the RTA. "The machine reached the other shore less than a week ago.

"When we do tunnelling, we have GPS coordinates. The GPS indicated the moment we hit dry land on the other side of the creek."

The tunnel follows a line from Omar Bin Al Khattab Road in Deira westward to Trade Centre Road near the British Embassy in Bur Dubai and will provide a link for the Red Line of the Dubai Metro network.

It may be only a matter of weeks until the tunnel reaches BurJuman Metro station location where workers are preparing for the underground tunnel to emerge above ground.

The five-carriage Metro trains will travel above ground from the BurJuman area westward on concrete viaducts towards Shaikh Zayed Road.

The importance of the major milestone was lost on the public because news of the history-making achievement was not released by the RTA.

However, word that the tunnel-boring machine has crossed the creek was shared between employees through an internal electronic employee newsletter that contained a brief story and picture of the moment.

On site at Union Square in Deira where the digging began in late January, workers said they were proud of their achievement given there were no serious injuries or fatalities.

"We’re across, finally. We worked day and night and are now on the other side without any injury to anyone," said one Indian worker entering Gate 1 at Union Square worksite for an early morning shift. "I am glad that we made it, it’s been a lot of hard work."

Another worker was all smiles at mention of the underground crossing.

"My wife is very proud of what we have done. I phoned her to tell her. I am very proud of our guys. We have worked hard to make this happen," he said.

Despite the RTA’s silence on the milestone achieved, the Authority did say in a recent statement that it was making progress across the creek.

Adnan Al Hammadi, Director of Rail Projects Construction for the RTA, said late last month that the tunnel boring machine "is to tunnel a distance of 1,479 metres towards BurJuman Station, which is currently under construction, and should break through the BurJuman reinforced concrete wall some time around mid-August".

Al Hammadi said that the boring machine "has completed over 1,203 metres of tunnelling with 802 out of 986 rings being placed".

The total length of the journey from Union Square to BurJuman is 1,479 metres, he said.

The curved concrete rings lock together forming the interior wall of the underground tunnel that will allow the new Metro five-carriage train sets to pass through.

He confirmed progress is also being made in the second tunnel now under construction.

The second boring machine "is to tunnel a distance of 2,261 metres to City Centre via Al Rigga. Currently, TBM 2 is over 50 per cent on the way to Al Rigga", Al Hammadi said.

Giant Mouse Burrows Under Creek

The Al Bugeisha tunnelling machine weighs as much as 450 male Asian elephants.

And it eats rocks.

But Japanese builders have modestly dubbed their monster mechanical creation in honour of a tiny burrowing African desert rat.

The so-called "Al Bugeisha" — a 1,000-tonne tunnelling machine assembled in Japan to dig the Dh25.5-billion Dubai Metro is burrowing its way underground as part of the largest infrastructure project ever attempted by city authorities.

Officials with the RTA commissioned the 9.56-metre tall engineering marvel to bore out a 1.5-kilometre tunnel underneath Dubai Creek to link the city’s proposed rapid light rail transit system between Union Square and BurJuman.

A second underground tunnel is being dug between Union Square and Deira City Centre.

The 10-metre wide underpass lies 30 metres below the Creek’s bottom.

Sporting more teeth than a great white shark, the boring machine cuts through rock and sand using a cutter head that boasts a "revolution speed of 0.1 to 1.82 revolutions per minute", said Adnan Al Hammadi, Director of Rail Projects Construction for the RTA.

A Japanese-built boring machine makes complete sense, say authorities.

The construction consortium comprises mostly Japanese companies, including Mitsubishi Heavy Industries, Mitsubishi Corporation, Obayashi Corporation and Kajima Corporation.

While the RTA has not released the cost of the tunnel machine, expert data on similar machines say they are extremely expensive.

As far as size goes, at roughly 10 metres in diameter the RTA’s monster digger is only two-thirds as big as the largest of the 15-metre wide varieties that have been used in tunnel projects the world over.

Officials with RTA said: "Once a certain distance has been excavated [roughly 1.5 to two metres], a new tunnel ring is built using the erector. The erector is a rotating system that picks up pre-cast concrete segments and places them in the desired position."

As the tunnel machine cuts its way underneath the Creek, a concrete-lined tube will be formed with an extended ring of concrete absorbing the pressure from above.

Going Underground

The oldest recorded tunnel to carry irrigational water – a qanat – was built about 2,700 years ago and still brings drinking water to up to 40,000 people in Gonabad, Iran

Ionian engineer Eupalinos’s aqueduct was built in 520 BC in Samos and was dug by two groups of men who entered a solid limestone mountain from opposite sides. They took 15 years to complete the tunnel

The first underwater tunnel is The Thames Tunnel, opened in 1843. Originally used as a foot tunnel it is now part of the London Underground

The longest rail tunnel in the world currently is the Seikan Tunnel of Japan with a length of 53.9km, two thirds of which is under the water

The Channel Tunnel is actually two railway tunnels as well as a third smaller emergency tunnel with a total length of 50km. As much as 39km of the facility runs under the English Channel

The longest road tunnel in the world is the Laerdal Tunnel in Norway at 24.5km