In order to receive federal funds, TxDOT must abide by federal guidelines, including the Federal Highway Administration's Noise Standard 23 Code CFR Part 772.
This code is designed to bring proposed projects into compliance with the National Environmental Protection Act (NEPA) of 1969. All federal, federal-aid and state funded roadway projects authorized under Title 23 of United States Code are subject to the FHWA Noise Code.
As a recipient of federal transportation funds, Texas Department of Transportation (TxDoT) developed “Guidelines for the Analysis and Abatement of Highway Traffic Noise” as noise policy. Compliance with the TxDoT Guidelines is required for compliance with NEPA to obtain an environmental clearance with a Finding of No Significant Impact (FONSI) or a Categorical Exclusion (CE).
The City of Pearland utilizes the same state and federal guidelines for Major and Secondary Thoroughfare expansion when adjacent to residential neighborhoods to determine if a Soundwall is included in the project.
About Soundwalls. Soundwalls-- also called noise barriers-- are used as a noise abatement measure to reduce noise created from highway traffic. Sound walls are normally solid wall-like structures built between highways and residential or business areas to reduce noise levels.
Designing noise barriers is a complex process that includes determining reasonable cost of construction and maintenance, measuring the ability of the noise barrier to effectively reduce noise level, and accounting for the number and category of impacted activity areas, among many other factors.
Although the purpose of a noise barrier is to reduce noise levels for people nearby, no barrier of any design can eliminate all traffic noise.
How Does My Neighborhood Qualify for a Soundwall?
The City of Pearland utilizes state and federal guidelines to determine if a Soundwall is included in the project when widening or extending a Major or Secondary Thoroughfare adjacent to residential neighborhoods.
In order to qualify for a soundwall, the area in question must meet noise impact criteria, which is determined through field surveying.
According to the TxDoT Guidelines document, a noise impact occurs when either the Absolute or Relative criterion is met:
Absolute Criterion: predicted noise level at a receptor approaches, equals or exceeds the noise abatement criteria provided by the FHWA. For residential areas the Absolute Criterion is is 66 dB(A) (exterior).
Relative Criterion: the predicted noise level is expected to substantially exceed the existing noise level, specifically by 10dB(A). The predicted noise level is extrapolated from data based on 20 years from the date TxDOT's area study.
Primary factors influencing the requirement of a property to receive any form of noise abatement include:
- Is it is possible to construct an abatement measure (typically a wall) given site constraints and whether that measure provides a minimum reduction of at least 5dB(A) at greater than 50% of the first row on impacted receptors?
- Is the abatement measure (typically a wall), including cost effectiveness, OR noise reduction effectiveness meets the following:
Below is a flowchart illustration how determinations are made for the construction of a soundwall.