Archive for December, 2011

With less than one hundred days to go before the first tunnel drive on the Crossrail project, Crossrail has finally unveiled the first of its giant tunnel boring machines. The TBM is now fully assembled and is currently being put through some rigorous tests at the factory in Germany before it is dismantled once again and shipped to the UK in time to begin tunnelling.

Crossrail will be using a total of eight tunnel boring machines to complete the tunnelling section of the Crossrail project, all of which are being constructed by Herrenknecht AG. This is the same German company that was responsible for supplying tunnel boring machines to work on the Docklands Light Railway Extension project as well as the Jubilee Line extension.

The first stage of tunnelling is scheduled to begin in March next year and the first of the Crossrail TBMs will begin tunnelling at the Crossrail Royal Oak portal. Another tunnel boring machine will also be sent underground from the Royal Oak portal a few weeks after the first TBM. Further tunnelling launches will commence from Limmo Peninsula at the end of 2012, and thereafter there will be TBM launches in 2013 and 2014.

In total, there are ten separate tunnel drives planned for the Crossrail route and by the time the tunnel boring machines have completed their mammoth schedule of work, 21 kilometres of tunnel will have been bored beneath London. The completed tunnels will be 6.2 metres in diameter and as each TBM progresses slowly, pre-cast concrete rings will be put in place behind them. In order to ensure there is a ready supply of concrete for the Crossrail project, a concrete segment factory has been built at Old Oak Common. Once tunnelling is underway, the tunnel boring machines will be working 24/7 with no breaks expect for scheduled maintenance work.

Justine Greening, the government’s Transport Minister, is currently considering plans for a new 1.5 mile tunnel for the controversial HS2 high speed rail link between London and Birmingham. As such, there will now be a delay in the announcement of the government’s final decision on the HS2 scheme.

Should HS2 get the final go-ahead, the route will stretch 100 miles across the Midlands and dissect some areas of outstanding natural beauty. However, commuters will be able to travel between London and Birmingham in only 49 minutes, which will be a major boost top the economy.

Unfortunately, HS2 has thus far proved to be deeply divisive across all sections of the government and many ministers are deeply opposed to the project going ahead. Critics of the scheme believe that building HS2 will have a catastrophic effect on some of the most beautiful parts of the UK, specifically the Chiltern Hills, and if the project goes ahead without the extra tunnelling work, there is a danger that the government will be split down the middle with one half for and one half firmly against.

The planned new 1.5 tunnel is intended to reduce the environmental impact as it will connect with two existing planned tunnels and divert the rail line beneath the Chilterns. But in order for the tunnel to be built, an extra $500 million of funding is required. Hence the delay in the final decision on the project as the Transport Minister needs more time to see if the money can be made available. The extra delay will enable feasibility and environmental studies to be carried out.

Environmental campaign groups are fully in favour of extra tunnelling on HS2 as it will have a much lower environmental impact on the area. However, some concerns have been expressed that the extra funding could be pulled from cutting back on existing environmental mitigation elsewhere on the route.

The proposed Thames Water Super Sewer scheme has come under fire after a report commissioned by London borough council claims there are several cheaper alternatives to the planned £3.6 billion project.

The current Thames Water super sewer scheme will involve 20 miles of tunnel beneath the city of London. The new sections of tunnel will help to channel raw sewage to a pumping station and reduce the amount of effluent that is currently leaking into the River Thames each time the region experiences heavy rainfall. Unfortunately, the construction and tunnelling work taking place as part of the proposed scheme will affect many local residents during the next few years.

The authors of the report have now suggested that a large and very expensive tunnelling scheme is completely unnecessary and Thames Water can still meet new EU water quality objectives if they choose to embark on a cheaper and greener alternative. One such alternative scheme has been proposed by Jacobs Babtie Engineering. This involves a shorter tunnel and would cost half as much as the current Thames Water preferred option.

Critics of the Thames Water planned super sewer project are most concerned about the negative effect tunnelling infrastructure work will have on local residents living in the vicinity of proposed construction sites. They also believe that Thames Water is more driven by financial concerns than any real desire to choose a cheaper alternative.

The cheaper tunnelling schemes currently being put forward will considerably less than the super sewer scheme in favour with Thames Water. They will also be more environmentally friendly and probably a lot more popular with the local communities likely to be affected by the scheme, which is why Lord Selborne, chairman of the report commission, has called for further investigations to be made into the alternative schemes.