Roads minister Stephen Hammond has confirmed the Crossrail project is now "over 40 per cent complete".
The massive development is aimed at making London more accessible to commuters and will prove to be vital as the capital's population grows in the coming years.
A number of completion targets have been set and the entire project is expected to be up and running by 2019.
Mr Hammond said that as of July 3rd 2013, 14 km of tunnelling had been finished, which is around 33 per cent of the final total. It is hoped the first tunnels will be bored out by the end of 2013.
Crucially, the new rail network is still likely to be completed within the agreed budget, with Mr Hammond revealing that no more than £14.5 billion will be spent, although this does not include rolling stock costs.
"UK businesses have benefitted from the award of 97 per cent of the contracts in the Crossrail supply chain, with 58 per cent of contracts awarded to small and medium-sized enterprises," he commented.