How high is the sound insulation effect of highway sound barriers?

When we are driving on the road, we will see that road sound barriers are set up on both sides of the road to reduce the noise pollution caused by cars. How high is the sound insulation effect of the road sound barrier? Let me introduce you to the following highway sound barriers:

The construction form of highway sound barrier foundation and the environment on site determine everything!

The screen body of highway sound barrier is composed of perforated panel, back plate, keel support, sound insulation cotton, waterproof cloth and other components. The production process of sound barriers on expressways is cumbersome. The sections explain the following: The panels are flat: The metal coils must be leveled and cut first: The leveled metal plates are cut and punched according to the required size. Requires the operation of CNC punching machine for punching and bending: the punched metal sheet is bent according to actual requirements, and the process of pressing the tile to process the backing plate removes the punching process. The rest is consistent with the above keel bracket: according to the actual size Cut the required keel and weld the welding frame: Weld the processed panel, back plate, and keel into a box shape according to the required size, and reserve a side to put the filler in the assembly: Put the required soundproof cotton into the box frame. It should be wrapped with tarpaulin, and then assembled with plastic sprayed with rivets: the assembled screen is treated with anticorrosive plastic.

Highway sound barriers have ordinary heights of about 3 meters and up to more than 9 meters; some are installed on elevated and light rails, and also are installed along railways and high-speed road shoulders; there are fully enclosed barriers on light rails, and there are nearly 20 spans Meters of elevated pavement are fully enclosed, etc .; there are ordinary metal structures and brick-concrete structures; each sound barrier has different heights and different installation locations, and its structure and basic settings are still very different, especially in Steel structure and foundation design section.