From OpenStreetMap Wiki
|barrier = spikes|
|Used on these elements|
|Tools for this tag|
on the ground that prevent unauthorized access. Can also be removeable e.g. after payment in a garage.
How to Map
Simply add the tag barrier=spikes to a node where the spikes are.
You should also add further tags to more fully specify what kinds of vehicle or foot traffic have reasonably unhindered access using access=*.