If you're going to use Atlas O track, it's best to get Ross Roadbed from Ross Switches.
The roadbed has grooves that match the ties and the track fits right in without moving. No nails needed!!! Makes the Atlas track which is already low noise, even more quieter. It is very affordable and is on Page 6 of the price list. No, I'm not the PR firm for Ross Switches, they just make very good product. I may plan on buying some for my Christmas layout when it is built (which has to be very soon now that the calendar has turned).
OGR user Putnam Division has used a lot of Ross Roadbed (which he has painted) on his layout and it looks awesome. Look up some of his posts that show his layout and you will see.