Recently almost every coaster that I download is failing the tunnel test. To see if your coaster passes the tunnel test you put a tunnel on a piece of track that you think might be a little close to another one and check it out in the simulator. If there is another part of the track coming through the tunnel it has failed the tunnel test and you need to fix the track. The only thing that is acceptable to be in the tunnel is the track and the supports under it (for a regular coaster), or the supports above it( for an inverted or suspended coaster). This is something that is really easy to do and takes all of a couple minutes. Supports from another part of the coaster should not be in the tunnel. The reason why we use this test is to see if the coaster would be safe for people to ride. I hope that some people will find this helpful because it can make a difference of a few points in your technique rating, and usually with a good technique rating the other things fall into line with it. Good luck.