When Games Workshop released Cities of Death, they released a set of resin Urban Barricades and Walls. You got six barricades and they blended in nicely with the plastic ruins which were also released with Cities of Death.
They are very well detailed.
First was a black undercoat.
I gave the barricades a Codex Grey drybrush, this was quite a heavy drybrush.
I painted the inside walls a dark blue.
The earth sections were drybrushed with Scorched Brown.