Yes, visual look at it both tops of the U have caps that open. Pipes loook lie this... ----U---- where left dotted line is pipe from house then the U trap. The right dotted line is the pipe leaving the house to the sewer.
No I do not like winter much
House watcher did not notice as he was not looking. A water alarm I installed in the house alerted him to the backup and experience made him open the trap caps to see the frozen water right to the top of both sides of the U.
I would have to dig up the garage floor to wrap the pipes. Can you really wrap underground pipes?
Yes 4 inch pipes. I do not know what the difference is from my house to my neighbors. I wish I did.