To permanently ease road traffic and create a public means of transport for the growing population of Thailand's capital city, the Bangkok Metro (MRT) was opened in 2004 under the supervision of the Mass Rapid Transit Authority of Thailand (MRTA).

The existing metro lines, which are marked with the colours blue (Blue Line) and purple (Purple Line), cover 35 stops over a distance of approx. 28 miles (45km). In addition to the current expansion of existing lines, another line is now under construction: the MRT Orange Line. In the future, this will complement the existing MRT network and provide a link between the eastern suburbs of Bangkok and the city centre.

Thai Bauer Company, the Thai subsidiary of Bauer Spezialtiefbau, had in the past carried out foundation engineering work for the MRT Blue Line and Purple Line as well as for the extension of the Green Line of the BTS Skytrain. Now it was once again being commissioned by the client, the Joint venture Ch. Karnchang - Sino Thai, with the execution of various specialist foundation engineering works for the construction of the newest Metro line.

More than 370 bored piles with diameters between 800 and 2,000mm are being drilled to a depth of between 40 and 65m, and approximately 58,600m² of diaphragm wall with a width of 800 to 1,000mm are being produced down to a depth of 27m.

"The challenges of this project are diverse," said Mike Sinkinson, managing director of Thai Bauer. "First of all, extremely strict tolerances for the production of the bored piles have to be adhered to and the work is carried out above existing tunnels - great care and accuracy are crucial for the success of the project."

In addition, during the rainy season, the stability of the subsoil and the access to the construction site need to be guaranteed. "The logistics between the steel processing sites and the respective application areas must be regulated and the access to the construction site via the main road permanently made possible," continued Sinkinson.

The work on the Metro extension began in March 2018 and the completion of the special foundation works of Thai Bauer is scheduled for spring 2019. Completion of the new Orange Line is expected to be in 2022.