The protective shields of the look-out turrets can be lowered via the manipulation menu. Sadly the "manipulatorplace" is placed really bad - such as that you open the shield next to which you are standing or that you cannot even lwower the shield.
These are the look-outs I am talking about.
http://www.arma2base.de/content/images/Arma3_screenshot_stratis_1204_02.jpg
Also you can fall through the geometry on them but I will open another report for that one;)
Greetz