Railway formation upgrading

Building a new rail formation on swampland. DCP test give CBR value of < 3. Propose lay woven Heavy Duty Geotextle then 100mm 30mm minus ballast then Tensile Geogrid layer then 300mm formation ballast. Trying to save costs over this section 500m. Any ideas- sensitive enviro. area.
Thanks TOOT TOOT>>>>

 

[ishvaaag]

If the bearing capacity is simply too low for the available area from thickness, ballast and geogrids system, use extended transverse slabs or beams to gain further surface.