Archive for the ‘Tunnelling’ Category

The first major tunnelling contract in the Washington DC Clean Rivers Project has just been awarded to a joint venture team comprised of Skanska, Jay-Dee, Traylor, and designer Halcrow. The team were one of three joint venture partnerships short-listed for the Blue Plains Tunnel contract. The evaluation process was based on a combination of technical expertise and price, and the Skanska JV scored highest overall. Final approval for the $350.5 million contract is expected on April 7.

There are four tunnels planned for the Washington DC Clean Rivers Project, of which the Blue Plains Tunnel is the longest. The tunnel will be 7,315 metres in length and once completed, it will pass beneath the Potomac and Anacostia Rivers. An EPBM will be used to excavate the tunnel through silt and clay and a precast liner will be used for reinforcement. Tunnelling work on the Blue Plains Tunnel will begin in 2013 and the planned completion date is the end of 2015.

The Anacostia Tunnel is the second major tunnel in the Washington DC Clean Rivers Project. Preliminary engineering and geotechnical work has already begun on the tunnel and this will have been completed at the end of 2011. The Anacostia Tunnel will be shorter than the Blue Plains Tunnel at 3,840 metres, but it will eventually connect with the longer Blue Plains tunnel at Poplar Point. Five shafts will be excavated and a pressurised TBM will be used to excavate the tunnel from clay and silt.

The Anacostia River Tunnel procurement process will begin at the end of 2011 and the short list of teams will be announced next April, with RFP documents released shortly after. If all goes well, the successful winner of the Anacostia River tunnelling contract will be announced in May 2013.

There are further black clouds looming on the horizon for the controversial Blanka Tunnel project in the Czech Republic as a recent report suggests costs are continuing to spiral out of control.

According to the latest figures announced by the new Prague Mayor, Bohuslav Svoboda, cost overruns on the beleaguered project have now hit the $561 million figure. This is a large increase and there is currently a great deal of debate as to who might be responsible for the massive hike in costs.

The main contractor on the tunnelling project is Metrostav and construction works are being carried out in accordance with the FIDIC Red Book contract. Mayor Bohuslav has stated that he intends to examine the original plans to try and ascertain where the cost spikes originate. There are also negotiations taking place between the contractor and the clients, plus the Prague Magistrate is studying the contractual agreement for verification purposes.

This is not the first time there have been problems with the Blanka Tunnel and cost issues have dogged the project since well before the latest administration came to power in Prague.

The original administration promised the local people that the Blanka Tunnel would be delivered on time and within its budget, but it was not long before delays were incurred and costs began to spiral. Unfortunately, members of the previous administration and the present administration have spent a great deal of time pointing the finger of blame at each other. Previous administrators at the City Hall claim to know nothing about the cost issues and are adamant that the cost problems with the Blanka Tunnel lay squarely at the door of the current administration.

However, despite the problems with costs and political bickering behind the scenes, construction work on the Blanka Tunnel project continues to move forward.

A Sino-Austrian JV is working on the Pinglu Tunnel in China and just before the New Year they announced a breakthrough had been achieved on the impressive tunnel section of the project. The Pinglu Tunnel is part of the Yellow River Water Diversion Project and has been designed to connect the North Main Line on the same project to allow water transfer to Pinglu, Datong, and Shuozhou. Alpine Bau are the Austrian contractor heading the JV team and they believe the single drive TBM tunnel will reach completion by October 2011.

A veteran Robbins TBM first used ten years ago on the same project is also being used on the Pinglu Tunnel. There are two world records in place from then the Robbins TBM worked on a different 12km section of the tunnel project and so far these records have yet to be broken by any other TBM. The records to beat are highest average monthly drive of 1352m and best monthly drive of 1855m.

The Robbins TBM has encountered some challenging geological conditions this time around, including abrasive sandstone with up to 70% quartzite, and coal seams. Despite this, the TBM has still managed 70m per day. In order to maximise efficiency on the Pinglu Tunnel drive, some operational changes were made to the TBM including extending the back-up frame of the TBM from one stroke to two strokes. This has helped the team achieve good advance rates even though the tunnel is exceptionally long and the muck trains take more than 70 minutes to travel from the tunnel face to the entrance.

An innovative tunnel lining has also been developed and a crew of more than 400 people have been working in a segment factory and on site to manufacture specific hexagonal segments designed to be placed in a honeycomb configuration.

Work on the tunnel between Niagara Falls and Queenston ground to a halt on December 3rd when the tunnel boring machine known as Big Becky broke down. A crack was discovered in the main supporting beam and the tunnel boring machine was taken out of service until engineers were able to fix it using welded supports. Fortunately, no time was lost on the project as the team had plenty of other maintenance work to continue with. Following the successful repairs, Big Becky finally returned to work last Wednesday and tunnel boring work continues.

The Niagara Falls tunnel is being constructed on behalf of Ontario Power Generation to help boost electricity in the area by a huge 1.6 terawatt hours a year. Once completed, it will carry water from Niagara Falls to an electricity generating station at Queenston, situated downstream from the famous waterfall at Niagara.

The completed tunnel will be 10.3 kilometres long and Big Becky has already bored 9.1 kilometres. Engineers expect the tunnel boring machine to break through the rock wall above Niagara Falls later on this month and a coffer dam has been constructed to prevent flooding of the tunnel. The tunnel will require further bracing and lining work and the team hope to have this completed so that the tunnel is fully operational by 2013.

The Niagara Falls tunnel should have been finished last year, but due to difficult rock conditions affecting tunnel boring progress, there have been substantial delays. Engineers were forced to re-route the tunnel and the project is well behind schedule as a result. The cost of the project has soared and although it was originally expected to cost $985 million, cost estimates are for the completed Niagara Falls tunnel are now in the region of $1.6 billion.

Cavico Bridge and Tunnel has just announced a tunnelling breakthrough as part of its work on the A Luoi hydropower plant in Vietnam. Cavico Bridge and Tunnel is a subsidiary of Cavico Corp., a major infrastructure company based in Vietnam, and the company is currently excavating two sub tunnels more than 1.8 miles underground for the hydropower plant.

The tunnelling work is part of a larger contract awarded to Cavico in 2007. The work on the hydropower plant includes the existing tunnel, four other sub tunnels, plus a vertical shaft and a service access road. A breakthrough on the first sub tunnel took place back in August. Once completed, the headrace tunnel will be 7 miles long and 3 miles wide, and it is widely considered to be the most complex tunnel engineering project ever before attempted in Vietnam.

Vice president of Cavico, Mr. Hai Thanh Tran, has commented that the tunnel engineering team are very happy with tunnelling progress to date and they are hoping to continue delivering “top quality work in the safest and most timely manner” as the project progresses.

The A Luoi hydroelectric plant is being built on the A Sap River in the Thua Thien Hue Province in central Vietnam. Once it is finished, the hydropower plant, owned by Central Hyrdopower Joint Stock Co., based in Vietnam, will have a total capacity of 170-megawatt and be capable of generating almost 700 million kilowatt-hours of energy for the people living in the area.

Cavico Corporation, parent company of Cavcico Bridge and Tunnel, was founded in 2000. The company is based in Vietnam and has a head office in Hanoi and a satellite office in Australia. It has been involved in major infrastructure projects all over the world, including bridges, tunnels, ports, dams, roads, highways, hydropower plants and facilities, mines, and urban buildings.

The remains of the Stalag Luft high-security prisoner of war camp is set to receive some new visitors soon as a British team of tunnelling engineers heads out to help excavate the remains of an escape tunnel named George.

The Stalag Luft III camp was featured in the famous film, The Great Escape starring Steve McQueen, and told the story of the Allied prisoners of war who dug tunnels beneath the camp in an attempt to escape. Each tunnel was given a name and it was after the first tunnel, Tom, was discovered, that a large group of men made their escape via a second tunnel, Harry.

Following the mass escape in 1944, another tunnel, George, was excavated, although this tunnel was only intended to be used as a last resort rather than as an escape tunnel. The entrance to the tunnel started in the camp theatre and it surfaced again by the main gate and adjacent armoury. The men planned to escape into the tunnel and arm themselves in the event the camp guards turned on them as the Soviet forces advanced.

The Allied prisoners of war never had the chance to test their tunnel as the camp was evacuated when the Soviet line pushed closer. The remaining men were forced to march 200 km to Spremburg and those who survived the atrocious conditions were dispersed between other camps.

The team of tunnelling engineers are hoping to find all kinds of memorabilia still stashed inside the remaining tunnels and they are also intending to excavate the remains of Harry as well as George. Veterans have said there is likely to be a great deal of equipment and personal effects hidden inside the tunnels.

An earlier team travelled to Stalag Luft III in 2007 and excavated another tunnel, Dick. They discovered milk cans once used as ventilation pipes and reported that more than one hundred tunnels were hidden beneath the remains of the camp.