Another thing...
If you will look carefully at the drawings of the tunnel you will see that the material it is built from is wide (looks like a wood or w/e...), and the INNER dimensions of the tunnel is 36" wide (According to the manual) which means the outer width has to be larger, which is also the platform width.
so lets say the width of the material the tunnel is built from (Or the total width) is 4" then it is 36"(Inner width) + (4"(Material width) * 2) with comes to the total of 44" which is the platform width as written in the manual.
Hope it helps
