Thank you very much for your comments, this will keep me motivated.
@Audrey
I am very happy with the mat. It has the right mix of streets, a small railway track and other areas and everything is a little bit dirty, so ist perfect for walking dead. I bought the single piece mat, because my gaming table is a little bit too short to lay out all tiles and I was unsure if the single tiles will all lay flat on the table. You are right about the width of the streets. There is a hugh difference between the width of the Deep Cut Studio mat and the mat included in the Mantic starter set.
I made pics with a 1:50 truck, some 1:43 smaller cars and an old matchbox standard size car model (maybe 1:72 to 1:87). The width of the streets are a little bit underscaled and will better fitt to HO-scale I think.
The other map from the Mantic starter set