Roadblock
From Halopedia, the Halo wiki
File:Roadblock.jpg
A Deployable Roadblock
The Covenant employ Roadblocks to block access to enemy troops and vehicles that might try to attack or bypass a fortified position. These roadblocks are small flat platforms that are placed on the ground, the top section is then pushed up on a hinge by an anti-gravity beam. The gravity beam can be disrupted by sustained weapons fire, or a small explosion, nullifying the roadblock's use by lowering the raised platform and allowing passage. Many Covenant troops will also use the roadblocks as a cover when being fired upon.
