The reduction of sound produced by the layout track base itself has been a prime objective and the process outlined in the Track Base article worked when reviewed by others at the state shown in the article and below.
When the foam blocks used in the scenery were glued on both sides it was a different case. The noise of a piece of rolling stock was overpowering and something had changed. The open area under the road base was sealed by the scenery foam on two sides and the urethane foam base - a drum had been created.
As sound requires air movement the best way to stop unwanted sound is to stop the movement but with what?
|Cut using a fine wood saw|
|Stuffing the gap|
The solution was found in using foam as it easily compressed to fill the cavity. Clarke Rubber stocks a 100 mm [4''] foam mattress and for a extra $10 it was cut into 150 mm [6''] strips. These are pushed into the cavity before the last scenery foam block is installed - problem solved. In any future construction this foam would be installed as part of the road base installation. The off-cuts have been used to seal the smoke ducts, gaps in the scenery and as a signal base.