UK Motorway verges - what are the areas enclosed by short posts and plastic sheeting?

Areas enclosed are on the grass verges, vary in size and I have occassionsly seen long, low 'walls' of short posts and plastic sheeting. Anyone know what these are for?UK Motorway verges - what are the areas enclosed by short posts and plastic sheeting?
I have never observed such areas, but it sounds like some kind of temporary structure.UK Motorway verges - what are the areas enclosed by short posts and plastic sheeting?
newly planted shrubs and trees
There are loads of them along a new road by me. They are baby trees. Have a closer look.





You can't see the baby tree's because they are still so small just yet.
ok i work for the highway agencey and i know what you are talking about ok these enclosed areas are called culverts what it is that when it rains like a down poor on the motorway all the water goes down the drains and the drains run in to these little areas and then runs down the sream every year as mataince the culverts get a good triming like trees cut down and the grass aroun them get cut but if you cant see a river it might be the other drainage system , the other drainage system well how can i explain this ok underneith the motorway there are 2 big drums i mean these are masive drums and what happens is that when a car/lorry spills its load like oil or petrol the substance will drain off in to these drums and stops it going in to the rivers near by and yearly they get drain and in most places we mark them tops with a small fence or a post ith a number on it but i think what you a discibeing is the culverts i hope this helps
Its reptile fencing. The areas are fenced off where lizards are and work is going to happen. The lizards are then removed from the site (usually just over the fence). Once work has finished the fencing is removed and the lizards can go back.
I've sen these in the states only near construction areas. They are called silt fence and it is to keep the debris from the construction site from blowing onto the roadway. Not sure if this is the case in your area.





Regards!!