Urban areas and rural environments are dominated by noise sources that cause pollution. The most common source is highway traffic noise from vehicle engines, tires, and aerodynamics. Exterior structures have been designed to protect property users from unwanted sounds. The structures are referred to as sound barriers and they reduce the amount of sound pollution from sources. The type of sound barriers required in a place depends on the type of property. Highway traffic noise requires the use of highway sound barrier that insulate, absorb, and protect users from noise pollution.
The rise in environmental protection and concern has led to the innovation of environmentally friendly materials to use as sound barriers. Such types of material allow being used as a growing medium for plants that also reduce the impact of the noise from the roads. Plants act as barriers by confining the sounds in one area and also make the roads look more appealing. Most manufacturers prefer green sound barriers for their beneficial properties to both noise obstruction and plant growth medium. Road sound barriers are made of different types of material with varied properties that help to protect people from unwanted sound. Examples include.
- Metal road sound barriers
- Wooden road sound barriers
- Sound barrier systems that require core element
- Rock mineral wool sound barriers
There are various systems used to control noise pollution on highways. They include ground-mounted structures and structure mounted systems.
This type of noise barrier system is either installed into or put on top of the ground surface. There are three types of ground-mounted barriers. First Noise berms involve the construction of the barriers using normal natural materials such as stones, soil, rocks, and rubble. Such materials occur naturally and are mostly used from the waste and remainders from a construction job. They however need surplus material since the berms use a lot of materials and purchasing them can have a cost effect. The berms require a lot of material because of their sloping sides and the need to ensure that they stay stable. The berms can also have a plateau-like surface in which additional features like paintings, a noise wall, or a right of way fence can be included.
Noise walls are also ground-mounted but are constructed of the site of the road. The noise walls barriers are fabricated at a manufacturing plant site then carried to the site and assembled. On-site assembled noise wall types are concrete walls. However, there exist other types of noise walls such as brick and masonry, burial panels, posts, and panels, among others. Finally, road noise barriers can include both noise berm and noise walls systems. Since berms require a lot of material to build to a higher height, noise barriers can be made of both the berms and a mounted noise wall to cover the rest of its height.
Structure mounted noise walls
There are two types of structure mounted road noise barriers. Noise walls on the bridge include a wall attached to a bridge as part of the highway. There are several types of barriers with such combinations. Examples include post and panel, post fewer panels, masonry block noise barriers, and cast in place with a parapet wall, among others. The other structurally mounted noise barriers are noise walls on retaining walls. This type of noise barrier is suitable for locations where the highway is raised or higher than the adjacent ground level and therefore fills the highway section or retains an adjusted land in cases where the highway is built depending on the level of the adjacent wall. Such noise walls are either installed as part of the retaining wall or in its vicinity.
Most contractors focus on standards and designs of the noise barrier walls but it is key to have safety considerations while protecting road users from noise pollution. Noise pollution prevention barriers should ensure that vehicles are prevented from impact against each other and also protected from impact with a noise barrier structure. Best engineers and designers understand and know how to determine the degree of protection of a barrier during construction.
Below are some of the safety considerations.
- Evaluation of the need to make special considerations on road-related safety. Check to determine if the highway requires any modifications to the recommended noise barrier design. Things considered to determine this factor include.
- -Probability of the barrier being impacted.
- -consequences that result from the barrier impact.
- In case the first considerations check out on the possibility of impacts occurring, make decisions on what special modifications can be made. Examples of modifications that can be made on highway barriers include.
- Changing the barrier location to a location where it has less probability of being hit by vehicles.
- Adding barrier reinforcements details that help to retain the cables and panels holding the barrier in case of an impact.
- Changing the barrier type and design to a more favourable eg placing or remove barrier posts.
- Installing barrier protective devices in between the barrier and the highway traffic
Noise barrier installation procedure includes.
- Grading and preparation of the site
- Foundation requirements
- Noise barrier manufacturing
- Quality assurance
- Handling and storage of materials
- Barrier assembly and construction
- Construction noise barriers
Lastly, it is important to consider other natural factors when selecting barrier designs and installing them such as the effect of wind loads on the barrier components like posts, foundations, and panels. Manufacturers and contractors should provide specifications on the fabrication of noise barrier components. An analysis is also required that shows the soil parameters since they may affect the wall centre line. Quality control and quality assessment of various parameters in the samples also provide additional useful information.