Dandenong gains additional lines in major upgrade
Due to low bearing capacity subgrades that can potentially cause deformations to the line, Westrail’s decision to upgrade the Dandenong Rail Line included construction of additional lines and new siding tracks.
The low bearing capacity of the weak and variable subgrade meant that areas of the subgrade would have to be excavated by as much as one metre to achieve the current rail standards as per the RTS 3430 - Track Reconditioning Guidelines and targeted bearing capacity.
GHD engineers proposed the use of bidim® A24 separation geotextile combined with Tensar® TX160 geogrid to reduce the large quantities of subgrade soils that would have to be removed and replaced with imported fill material.
Tensar® geogrids enabled the client to achieve the targeted bearing capacity for both the new track and siding tracks. Project costs were reduced as use of the Tensar® TX160 geogrids minimised the quantities of materials required and ensured rapid installation within tight timelines.
Installation periods were short and critical, generally works were conducted either overnight or on weekends.
The use of bidim® geotextile and Tensar® TX160 geogrids provided the Engineers with the capability of reducing subgrade excavation and disposal, the importation of less sub-base capping layer whilst at the same time achieving the targeted stiffness values required to support the ballast layer. All this results in less possession time of the track. The simple installation ensured the contractor could continue work during bad weather and complete the required works quickly and efficiently, with minimal effect on the adjacent operating rail lines.