A recent horizontal directional drilling (HDD) project in southern France successfully completed a 196.38m crossing beneath two active railway tracks using an intersect method.
The works in Castelsarrasin were completed by Dutch company Prime Horizontal, a specialist company that relies on the ParaTrack HDD system to complete its works with precision.
The bore was executed at a depth of 16m with a straight alignment and 15° entry and exit angles. Clay ground conditions dominated the area, but the presence of a gravel layer near the surface required additional support measures.
Casings of 30m on the entry side and 24m on the exit side were installed to bypass the unstable zone.
The intersect took place within a limited 35m straight section directly under the tracks, making it the shortest intersect completed on this project to date.
This constrained window left no room for deviation, requiring precise coordination and execution from both ends of the bore.
A 250mm high-density polyethylene (HDPE) sleeve was installed to house a 160mm HDPE product pipe, intended for gas transport.
The use of an intersect method was dictated by site conditions and proved critical in achieving a successful outcome under tight technical constraints.
The project is an example of the practical use of HDD intersect techniques in complex subsurface environments with minimal tolerances.
Do you have news for the international trenchless industry? Contact journalist Gerald Lynch at gerald.lynch@primecreative.com.au
