There is a popular saying give me a lever long enough and I will move the world. To be successful in construction industry, the basic knowledge of Physics as learned in secondary school must not be forgotten so quick. And as easy as some of the simplest structures look if you don’t apply that basic knowledge you will fail.
Constructing a barrier as shown in picture above involves three basic things at the back of your mind.
You must consider the weight behind the metal pole that will pull the pole up when you leave the anchor at the other end, the distance between the fulcrum and the load , then the length of the pole that lies as the barrier.
The barrier should naturally be able to pull up when is left freestanding, but this will only be achieved if the momentum or force generated by the load behind the fulcrum is more than the self weight of the barrier pole.
You can measure the weight of the metal pole and check with the weight of the load to ascertain if the load can carry the self weight of the metal pole. The load can be massof concrete, metals or any weighty object.
However the laboratory equipments to do this measurement are not available in most cases.
So you can do a test run, have the fulcrum constructed with iron in place, oryou can use a stone with pointed edge as a pivot, place the fulcrum in between the load and the rest part of the metal pole until you discover the distance that is okay for the weight of the metal pole which can be carried by the load behind the fulcrum. The momentum or force generated by the load depends on the length between fulcrum and the load and the weight of the load itself, in otherwords, the longer the distance, the higher the momentum or force, just test before the final placement.
Also you must place the barrier with a mixture of conspicuous and contrasting colours like black and white, black and red e.t.c
To reduce the weight of the metal pole so that the load can easily carry it, you can also reduce the thickness and size of the pole as it tapers to the end where is expected to be tied to.