The BR HTA Bulk Hopper has an axle load of 26t and can't use rail tunnels (max. axle load 23t).
Are you using the 11.32 release version, or the latest development version of the code? I ask because, in the latest development version, the track in the tunnel is separate to the tunnel, so you can lay the heavyweight concrete track in the tunnel to allow these wagons to be used in it.
OK, thanks!