Roadblocks would be made with whatever materials are at hand and with whatever time and the situation permits. If a streetcar was available, it might be included. Rubble depends on the amount of damage beforehand. Wire, mines, dragons teeth, hedgehogs and other more traditional obstacles would be found in a more prepared killing zone type position.
Just do an image search, vary the search criteria, and you'll get some good results.
F is for FIRE, That burns down the whole town!
U is for URANIUM... BOMBS!
N is for NO SURVIVORS...
- Plankton
LSM