c´est sur cette page.
http://www.ataricommunity.com/forums/showthread.php?s=c4e73d571a6a86900de649b6b92616aa&threadid=423120&perpage=30&pagenumber=1
fichier a télécharger ==> http://www.mavisxp.com/public/rct3-tunnel.rar
Comment les faire fonctionner:
Start with FLAT GROUND, no hills or mountains or anything. JUST FLAT.
Build your ride.
Next, use scenery objects ( walls, rooves, etc) to enclose the part of the coaster you want to be underground.
Use the " Save Custom Buildings" feature to save the enclosure. Once it´s saved, delete it from the map, so just the coaster remains.
Now, build your mountain.
The mountain will form around the coaster ( little trenches where the track is) so now you need to delete the coaster. Use the terrain smoothing tools to fill in the trenches.
Now, place your coaster again, using the SHIFT key to move it down, into the mountain.
Finally, place your enclosure over the coaster ( again, using the SHIFT key to move it into the mountain) . ..
désolè si c´est en anglais j´ai toujours pas compris comment on fait.