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Noise Barrier Design Handbook

12. Maintenance Considerations

The expected maintenance-free life span of a noise barrier varies considerably based on many factors, including the barrier material type, surface texture, color, and component parts. Climatic conditions and the barrier's relationship to the roadway also play a role in the durability of most barriers. Many of these issues have been discussed elsewhere in this manual. Additional considerations are discussed below.

12.1 Repairs

Noise barriers will become damaged at some point in their life, either from handling mishaps during construction, installation defects that appear well after the barrier has been installed, vehicles or debris hitting the wall, or simply from old age and exposure to the elements over time (see Figures 242 to 245). The reasons to initiate a repair may vary depending on the severity and extent of the damage and the policies of the governing responsible organization. In all cases, the following factors should be considered in the decision to repair. The relative weight that each of these factors is assigned may vary locally. However, the order of importance should not deviate significantly from the order in which they are presented.

  1. Safety - Is the damage severe enough that the structural integrity of the barrier has been compromised; or have components been repositioned to create an obstacle/hazard to vehicles or pedestrians?
  2. Durability - Is the damage severe enough to diminish the durability or life expectancy of some or all the noise barrier components?
  3. Performance - Is the damage severe enough to significantly reduce the attenuation provided by the noise barrier system; or, in the case where the barrier also acts as a fence, is it possible for someone to have access through the wall?
  4. Aesthetics - Is the damage severe enough to create an unsightly appearance that is deemed unacceptable by the neighboring community?

Photo of damamged noise barrier

Figure 242. Repairs
photo #736a

Photo of damamged noise barrier

Figure 243. Repairs
photo #2488

Photo of damamged noise barrier

Figure 244. Repairs
photo #1052

Photo of damamged noise barrier

Figure 245. Repairs
photo #450

12.2 Availability of Replacement Parts

Since replacement of barrier elements may be required throughout the life of the noise barrier, the availability of replacement parts becomes a critical issue. If the components are standard products, such as steel "I" beams for posts, this issue will have very little importance. However, if the components are custom made for a specific project, then the issue becomes very critical (see Figure 246).

Photo illustrating a concern for availability of replacement parts

Figure 246. Availablility of replacement parts
photo #226

To address this concern, some agencies have instituted a stock piling policy where the contractor/ manufacturer, at the time of construction, supplies additional components to the organization responsible for maintenance. Typically, an additional 10 percent would by supplied to the responsible organization for stock piling purposes. The disadvantage to this type of practice is that the responsible organization, after several years of constructing noise barriers, may end up with an excessively large amount of varying stock on hand that has the potential of never being used.

The issue of future availability becomes even more critical when the components have to be custom fitted with either very few or none of the pieces the same. In this situation, stock piling may not be an option. This consequence should be seriously considered during the design stage and should be avoided if at all possible.

12.3 Access

Section 9.4 discussed a variety of means for providing access to both sides of noise barriers for general maintenance and emergency access purposes. These requirements exist for both ground-mounted and structure-mounted noise barriers. The placing of a noise barrier is usually dictated by the results of acoustical analyses which are aimed at determining the best location to block line-of-sight between the noise source and the receivers. This location may or may not be the most accessible from either a construction or maintenance standpoint. These accessibility issues should be considered in the design phase in conjunction with the acoustical, construction, maintenance, and barrier material selection issues. If the only location to place an effective noise barrier is relatively inaccessible, then the design should focus on developing a barrier and related surface treatment and landscaping which is relatively maintenance free.

12.4 Surface/Material Wear and Deterioration

All noise barrier materials will wear over time. The severity is dependent on the type of material, proximity to the roadway, exposure to deicing chemicals, climate, and component design. Typical damage associated with wear are:

12.5 Landscaping

Comprehensive discussion of landscaping, its relationship to other barrier elements, and its relationship to maintenance factors is contained in Section 6.2. The issue of consistency between the barrier's aesthetic treatment, including landscaping, and the maintenance philosophy of the owner of the barrier, as discussed in Section 6.2, is critical and bears repeating here. No matter how well designed and coordinated a landscape plan may be from the aesthetic standpoint, it is only as good as the ability of the responsible organization to adequately maintain it. It is a waste of time and money to design an aesthetic treatment for which there is neither the commitment (in terms of manpower) nor the funding (long term) to adequately maintain. No matter what the desire from an aesthetic standpoint, the landscape plan needs to be responsive to these financial and manpower constraints. Such constraints may appropriately lead to the selection of vegetation that is native "maintenance free" and to a plan that will foster growth of natural vegetation.

12.6 Graffiti

Section 5.9.3 discusses the various maintenance aspects of the varieties of coatings, stains, and anti-graffiti coatings available for application on noise barriers (see Figure 250).

Photo showing a noise barrier with graffiti problems

Figure 250. Graffiti
photo #757

12.7 Litter

Barrier design should consider the location of a noise barrier in terms of litter susceptibility (Is it a high litter area?), the barrier's ability to "trap" litter, and the philosophy of the responsible organization regarding cleanup of litter (see Figure 251). Often, leaves, grass clippings, and other litter tend to be dumped in the area between the barrier and the right-of-way fence ("no man's land" or "dead man's zone"). If possible, allow adjacent residents to extend their sideline fences to the barrier. Also, landscaping in a high litter area should consider what type of vegetation is best to use. A thorny type of bush may make litter cleanup more difficult than such litter removal from a grassy area. Special design features such as insert areas, planter boxes, etc., may "catch" litter or even become target areas for litterers.

Photo showing litter collected at the base of the noise barrier

Figure 251. Litter
photo #1642

12.8 Snow Storage

When noise barriers are installed too close to the roadway it becomes difficult to store snow on the side of the road (see Figure 252). If the snow is piled up on the shoulders, it is a potential safety issue in that vehicles cannot safely pull-off of the main travel lanes during emergencies. This condition usually warrants timely removal of the snow, typically with a front end loader and dump trucks. The removal operation creates serious safety problems with heavy equipment operating so close to the roadway.

Photo of snow stored at the base of a noise barrier adjacent to the highway

Figure 252. Snow storage
photo #5342

The close proximity of the noise barrier will also make it susceptible to damage from snow plowing operations due to the force of the snow being thrown against the barrier and the resultant pressure of the snow piled-up against the barrier.

12.9 Snow Drifting

Depending on the height, proximity to the roadway and orientation related to prevailing winds, snow drifting may occur across the road as a result of the construction of a barrier (see Figure 253). Drifting creates not only safety problems but also difficulties for snow removal operations compounding the problems associated with snow removal.

Photo of a noise barrier near the residences with snow drifted against the barrier

Figure 253. Snow drifting
photo #2540

Consideration should be given to this concern at the design stage so that, in critical areas, wider shoulders, relocation of the barrier, or possible reduction in barrier heights can be incorporated.

12.10 Issues Related to Specific Barrier Types

Special or unique barrier types may sometimes have unique maintenance related issues which should be considered in the design process. Barriers in a "zig-zag" configuration (see Sections 3.5.5.2 and 4.1.2.3.1) present opportunities for plantings within the barriers "pockets" or recesses, but may make mowing operations more difficult. Barriers with large caps (see Section 6.1.3) or special barrier tops (see Section 3.5.5.3) may shade the top portion of a barrier and prevent the natural cleansing of that area by rain water (see Figure 254). Planted noise barriers (see Section 4.1.2.3.2) and noise barriers constructed behind the top of a retaining wall (see Section 4.2.2) may require irrigation and protective fencing (to prevent unauthorized access and climbing). Barriers mounted on structures (see Section 4.2.1) may create special access conflicts if utilities such as electric, gas, fiber optic lines, water lines, or sewer lines are suspended from the bridge or contained in conduits within the bridge beams or parapets.

Photo illustrating issues with specific barrier types. This barrier has a wide cap that prevents natural cleaning by rainwater.

Figure 254. Issues related to specific barrier types
photo #3125

Section Summary

Maintenance considerations for all noise barriers.

Item# Main Topic Sub-Topic Consideration See Also Section
12-1 Availability of Replacement Parts . If barrier components are custom made for a specific project, then the issue of replacement parts becomes very critical. 12.2
12-2 Access . If the only location to place an effective noise barrier is relatively inaccessible, then the design should focus on developing a barrier and related surface treatment and landscaping which is relatively maintenance free. 12.3
12-3 Surface/ Material Wear and Deterioration Deterioration from Moisture If the design may result in moisture ponding on its surface, consideration should be given to redesign replacement parts. In some climatic conditions, consideration should be given in the design phase to selecting a barrier and surface treatment which can minimize mildew and mold growth and be capable of being cleaned on a regular basis. 12.4
Deterioration from Ultraviolet Light Exposure When using paints, stains, graffiti coatings, and stenciled designs, consideration should be given to the effects of ultraviolet light, especially in the design of transparent barriers. 12.4
Loss of Stains and Painted Coatings If the coating or stain is providing protection for the barrier material, then it becomes an issue of reduced life expectancy of the material. 12.4
12-4 Landscaping . The issue of consistency between the barrier's aesthetic treatment, including landscaping, and the maintenance philosophy of the owner of the barrier is critical. Manpower and financial constraints may appropriately lead to the selection of vegetation that is native "maintenance free" and to a plan that will foster growth of natural vegetation. 12.5
12-5 Litter . Barrier design should consider the location of a noise barrier in terms of litter susceptibility, the barrier's ability to "trap" litter, and the philosophy of the responsible organization regarding cleanup of litter. Landscaping in a high litter area should also consider what type of vegetation is best to use. A thorny type of bush may make litter cleanup more difficult than such litter removal from a grassy area. Special design features such as insert areas, planter boxes, etc. may "catch" litter or even become target areas for litterers. 12.7
12-6 Snow Storage Consideration must given to a barrier's susceptibility to damage from snow ploughing operations by both the force of the snow being thrown against the barrier and the resultant pressure of the snow piled-up against the barrier. 12.8
Drifting Consideration should be given to snow drifting in the design stage so that, in critical areas, the possibilities of wide shoulders and minimum necessary barrier heights can be incorporated. 12.9
Updated: 07/14/2011
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