Bothar’s expertise was tasked with the installation of 19 x 102m (DN500) canopy tubes for the Boggo Road tunnel - launch site of Cross River Rail’s key infrastructure in Queensland.
Within the industry there was limited trenchless methods capable of the project specific requirements. As such, Bothar developed an innovative solution to install canopy tubes with pinpoint accuracy without the ability to install a retrieval shaft whilst ensuring the ground was fully supported at all times. Bothar designed a specialized bespoke bidirectional retractable cutting head which had never previously been utilized on this size installation.
The laser guided system was used to achieve the tight design tolerances at the significant length of 102m. The modified head was developed to ensure the 102m of bored tunnel was always supported by the installed steel casing in the unlikely but possible case of ground movement. There are very limited trenchless technologies capable of boring DN500 steel casing to within the design tolerance at 102m lengths whilst being able to retract the bidirectional cutting head at any stage throughout the process leaving the steel case in place to mitigate the risk of ground subsidence.
