Nice work there, Giles - even I could make those. I like your roads as well although your technique had me very close to manly tears. Why? Because a few years ago I thought I could do with some tarmac roads and I also used hardboard
BUT I thought it would be a great idea to glue emery paper to it to give, an admittedly quite convincing, tarmac look.
Unfortunately when the glue dried (PVA as I recall) it warped the hardboard so they don't lie flat. Whereas, if I'd just used your technique and not bothered with the emery paper, all would have been well.
Damn - now you tell me....!

Once again, loving the telephone/telegraph poles....
Doug