Section 3: Specific Environmental Compliance RequirementsAnchor: #i1004426
This section includes information regarding archeological, biological, water and historic resources, as well as information related to social issues and other legal requirements. Additional resources for environmental requirements during the project development process may be found at TxDOT’s Environmental Compliance Toolkits website.Anchor: #i1004442
Local governments (LGs) must comply with the Clean Air Act (CAA), the National Environmental Policy Act (NEPA) and the Federal-Aid Highways Code ( 23 U.S.C. 101-190) for potential project effects on air quality. The CAA prohibits federal agencies from providing funding or approving any activity not conforming to an applicable state implementation plan (SIP). A project environmental decision cannot be made for any project in a nonattainment and maintenance area subject to transportation conformity, until project level transportation conformity is demonstrated. Incorporating the LG project into the Statewide Transportation Improvement Program, Transportation Improvement Program or Metropolitan Transportation Plan and/or early in project development will help prevent project delays.
- Anchor: #LHDVFEIT
- 40 CFR Part 93 – Provides Environmental Protection Agency regulations implementing transportation conformity that require non-exempt projects in certain nonattainment or maintenance areas to be consistent with the SIP. Anchor: #UXRDLRRE
- 23 CFR 450.320 – Provides FHWA regulations implementing 23 U.S.C. §134 for the congestion management process. In order for federal funds to be programmed for projects adding single occupant vehicle capacity in certain nonattainment areas, the project must be addressed in a congestion management process. Anchor: #GVDWMMQD
- FHWA uses guidance rather than rule to establish requirements for air quality analyses, and these are disclosed in the TxDOT Environmental Handbook for Air Quality and are subject to periodic revision.
- Anchor: #PTJWVJTY
- 43 TAC Part 1, Chapter 2, Subchapter I – Requires documentation of compliance with air quality provisions under the memorandum of understanding (MOU) with the Texas Commission on Environmental Quality (TCEQ). Anchor: #WGJAPQKI
- 30 TAC 114.260 – Implements state requirements for transportation conformity.
Compliance responsibilities vary depending on the scope of the project and the potential social, economic and environmental impacts. The LGPM Guide provides details on the process used to achieve compliance for air quality regulations.Anchor: #i1004533
A series of laws and regulations requires the LG to identify and, if necessary, mitigate impacts to biological resources, including but not limited to endangered and threatened species, critical habitat and farmland. Violations of the Endangered Species Act and Migratory Bird Treaty Act are especially serious and can result in work stoppages and large fines. Because of the complexity of biological issues and the range of regulatory requirements, early coordination between the LG and the TxDOT district is essential.
- Anchor: #QPUPVRNH
- Endangered Species Act as amended 16 U.S.C. §§1531-1544 – Regulates impacts on endangered or threatened species, or critical habitat, and in some circumstances requires consultation with the U.S. Fish and Wildlife Service. Anchor: #XUDVQYKT
- Migratory Bird Treaty Act 16 U.S.C. §§703-712 – Prohibits taking, disturbing or harassing a wide range of migratory birds and their nests during nesting season. Anchor: #NQVWQXRP
- Fish and Wildlife Coordination Act of 1968 16 U.S.C. §§661-667d – Requires coordination with the U.S. Fish and Wildlife Service under circumstances where a U.S. Army Corps of Engineers individual permit is required. Anchor: #LJLELJGY
- Magnuson Stevens Fishery Conservation Management Act 16 U.S.C. §§1801-1891d – For projects in coastal counties, requires coordination with the National Marine Fisheries Service if the project area contains essential fish habitat in tidally influenced water. Anchor: #SIYBHLHA
- Farmland Protection Policy 7 U.S.C. §§4201-4209 – Requires evaluation of impacts to new right of way not developed, not urbanized and not zoned for urban use. Coordination with the Natural Resource Conservation Service may be necessary. Anchor: #FKWVEKJH
- Invasive Species Executive Order 13112 – Requires re-vegetation according to TxDOT’s standard practices for urban or rural areas if the project includes landscaping plans. Anchor: #DCFKUGYI
- Presidential Executive Memorandum on Environmentally and Economically Beneficial Landscaping Practices 4/26/1994 – Requires consideration of incorporating elements consistent with the executive memorandum if the project includes landscaping plans. Anchor: #OEWWJSOT
- Marine Mammal Protection Act 16 U.S.C. §§1361- 1423h – Requires coordination with the National Marine Fisheries Service if the project adversely affects tidally influenced waters. Anchor: #EYQISOOH
- Coastal Barrier Resources Act 16 U.S.C. §§3501-3510 – For projects within a coastal county and located, in whole or in part, within a system unit of the Coastal Barrier Resources System (CBRS), documentation of compliance with the Coastal Barrier Resources Act is required and may include consultation with the U.S. Fish and Wildlife Service. Anchor: #KQKYMAPC
- Bald and Golden Eagle Protection Act 16 U.S.C. §§668-668d – Requires coordination with the U.S. Fish and Wildlife Service if the project would result in unavoidable impacts to bald or golden eagles.
Guidance for these subjects and others can be found at the FHWA Environmental Review Toolkit website.
- Anchor: #LMTTORCI
- Texas Parks and Wildlife Code §68.015 – Prohibits capturing, trapping, taking or killing, or attempting to capture, trap, take or kill, endangered fish or wildlife. No exception is provided for construction or other projects. Anchor: #EDQDLKNN
- Texas Transportation Code §201.607 – Requires TxDOT to establish MOUs with resource agencies. Anchor: #DTPGQXHH
- 43 TAC §2.201-2.214 – MOU with the Texas Parks and Wildlife Department – MOU implementing Texas Transportation Code §201.607.
The LGPM Guide provides the required practices and procedures and LG and TxDOT responsibilities associated with biological resources. In general, the LG must coordinate with the TxDOT district early in the project to identify the applicable requirements.Anchor: #i1004688
Roadway construction projects typically transect or abut a number of waterbodies (streams, rivers, lakes, bays, wetlands) and, therefore, typically involve a number of related water quality issues. Water quality related permits and authorizations for construction activities are usually required. Some authorizations may be general permits or nationwide permits that can be obtained in a very short period of time. An example is the Texas Pollutant Discharge Elimination System (TPDES) stormwater permit for construction activities, an authorization that can be obtained in as little as 24 hours. Other authorizations, such as an individual U.S. Army Corp of Engineers permit or an individual TPDES wastewater discharge permit, may require a year or more to obtain. Therefore, it is important for the LG to identify water resource issues very early in the planning phase of a project and to allow ample time to obtain water resource authorizations. Violations of permit and other requirements are serious and can result in work stoppages and large fines.
- Anchor: #NPUVHJTA
- 33 U.S.C. §403 (relating to Protection of Navigable Waters and of Harbor and River Improvements Generally) – Requires a U.S. Army Corps of Engineers permit for a project obstructing navigable waters by fill, construction of a bridge, bulkhead or other structure. Anchor: #TWUOBSOK
- 33 U.S.C. §§525 et seq. (relating to the Construction and Operation of Bridges) – Requires a permit from the U.S. Coast Guard for the construction and operation of bridges over navigable waters (see also the General Bridge Act of 1946). Anchor: #HWFQABIB
- 33 U.S.C. §1342 [relating to National Pollutant Discharge Elimination System (NPDES)] – Prohibits discharge of pollutants (including stormwater associated with construction and industrial activities) into waters of the United States without first obtaining an NPDES permit (see related regulation 40 CFR Part 122). Anchor: #ASYBVRCF
- 33 U.S.C. §1344 (relating to Permits for Dredged or Fill Material) – Prohibits dredge and discharge of fill material in waters of the United States without first obtaining a permit from the U.S. Army Corps of Engineers. Anchor: #CDSBHPVE
- Executive Order 11990 – Protection of Wetlands – Prohibits construction located in wetlands unless there is no practicable alternative and the proposed action includes all practicable measures to minimize harm to wetlands. Anchor: #AHHXICCG
- Executive Order 11988 – Floodplain Management – Requires the beneficial values of floodplains be preserved. Anchor: #BWALYWCE
- 22 U.S.C. §277 – 1944 Water Treaty of the U.S. International Boundary and Water Commission (USIBWC) – Requires a license or permit from the USIBWC for any proposed activities crossing or encroaching upon the floodplains of USIBWC flood control projects and right of way (related regulation: U.S. Section Directive, Vol. IV, Chapter 315 dated July 27, 2000). Anchor: #YXUMLIUR
- 16 U.S.C. Chapter 28 (relating to Wild and Scenic Rivers) – Requires selected rivers shall be preserved in free-flowing condition and they and their immediate environments shall be protected. Applies only to projects along the designated portion of the Rio Grande at Big Bend National Park.
Guidance for these subjects and others can be found at the FHWA Environmental Review Toolkit website.
- Anchor: #CRUNFSMK
- Texas Natural Resources Code §33.205 (relating to Coastal Coordination Act) – Requires a project to meet the policies and goals of the Coastal Management Program. Anchor: #BIYTXFQV
- Texas Natural Resources Code, Chapter 61 (relating to Use and Maintenance of Public Beaches) – Requires projects in the vicinity of public beaches must not affect public access and use, and must comply with local beach access and use plans. Anchor: #IMPEOVOJ
- Texas Natural Resources Code, Chapter 63 (relating to Dunes) – Requires projects in the vicinity of dunes with public access must conform to local dune permit programs, ordinances and other protections established within the dune protection line. Anchor: #GTBODOQJ
- 31 TAC Part 16 (relating to Coastal Coordination Council) – Requires projects within Coastal Management Plan (CMP) boundaries must comply with the CMP. Anchor: #HRNBCOQP
- 30 TAC Chapter 213 (relating to Edwards Aquifer) – Requires projects within the Edwards Aquifer contributing or recharge zones must develop and implement an approved Edwards Aquifer protection plan. The regulated contributing and recharge zones occur only within TxDOT’s Austin, San Antonio and Laredo districts. Anchor: #ANSYCNHX
- 43 TAC Part 1, Chapter 2, Subchapter I (relating to MOU with the TCEQ) – Requires coordination of NEPA documents with TCEQ to address water quality issues under certain circumstances. Anchor: #JGYYICCL
- Texas Water Code §26.121 (relating to Unauthorized Discharges Prohibited) – Prohibits discharge of waste, wastewater and regulated stormwater runoff without a TPDES permit (see related regulations 30 TAC Chapters 205 and 216 and §281.25 regarding Storm Water Pollution Prevention Plan). Anchor: #OWLIHDKF
- Texas Water Code Chapter 11, Subchapter D (relating to Permits to Use State Water) – Requires a permit to appropriate state water for use.
More information including a description of the responsibilities of the LG and TxDOT district with respect to water resources issues that may impact the project is available in the LGPM Guide. In general, the compliance responsibilities vary depending on issues of funding, land ownership, geographic location, operational project control and the involvement of one or more federal agencies.Anchor: #i1004846
An archeological resource is a site characterized by the remains of past human occupation. Although it may be associated with a building, structure, object or district, an archeological resource is treated differently than historic resources. For the purposes of this discussion, “archeological resource” does not include historic resources, which are covered in another section. Protected archeological resources are called “historic properties.” An archeological historic property is an archeological resource listed in or eligible for inclusion in the National Register of Historic Places (NRHP) or eligible for designation as a state archeological landmark. Except under unusual circumstances, the archeological resource must be at least 50 years old at the time construction begins. A cemetery with graves more than 50 years old must be treated as an archeological resource. State and federal laws regulate the impacts of transportation projects on archeological resources, so the LG must coordinate with the TxDOT district during the scoping of project which may impact these sites.
- Anchor: #VAFTJULU
- Section 106, National Historic Preservation Act of 1966, 16 U.S.C. §470f (Section 106) – Requires federal agencies to consider the effects of their projects on archeological sites listed in or eligible for inclusion in the NRHP. The First Amended Programmatic Agreement among the Federal Highway Administration, the Texas Department of Transportation, the Texas State Historic Preservation Officer, and the Advisory Council on Historic Preservation Regarding the Implementation of Transportation Undertakings (PA-TU) identifies TxDOT as responsible for all consultation in compliance with Section 106 on FHWA projects and prescribes standard procedures for compliance. Anchor: #IOAJFWYR
- Section 110(k), National Historic Preservation Act of 1966, 16 U.S.C. §470h-2(k) (Section 110) – Section 110 prohibits demolition of an archeological historic property prior to conclusion of Section 106 consultation (“anticipatory demolition”). Anticipatory demolition may result in loss of FHWA funding or approval. Destruction of a site that has not been evaluated also may result in loss of funding or approval. Anchor: #FTBDBTDQ
- 36 CFR Part 800 – Prescribes procedures for complying with Section 106 for FHWA projects removed from the PA-TU and for undertakings where an agency other than FHWA has jurisdiction. Anchor: #MNETWSMT
- Native American Graves Protection and Repatriation Act, 25 U.S.C. Chapter 32 – Governs planning for Native American graves for projects on federal or tribal land, and disposition of human remains and funerary objects controlled by an entity receiving federal funds.
Guidance for these subjects and others can be found at the FHWA Environmental Review Toolkit website.
- Anchor: #VKYMMRBQ
- Texas Natural Resource Code, Chapter 191, Antiquities Code of Texas – Requires the Texas Historical Commission (THC) to be notified of proposed construction projects and prohibits unpermitted destruction of archeological sites eligible for designation as state antiquities landmarks. Anchor: #MMNWORDB
- 13 TAC Part 2, Chapter 26, Practice and Procedure – Rules implementing the Antiquities Code for projects on land. Anchor: #YPPSOFXT
- 13 TAC Part 2, Chapter 28, Shipwrecks – Rules implementing the Antiquities Code for projects crossing water bodies. Typically restricted to projects under U.S. Coast Guard or U.S. Army Corps of Engineers permits. Anchor: #XHTVLFWT
- 43 TAC Chapter 2, Subchapter H, MOU with THC (also adopted as 13 TAC §26.25) – Identifies whether TxDOT or the LG coordinates with THC for Antiquities Code compliance and prescribes standard procedures for complying with the Antiquities Code on projects for which TxDOT is responsible. Anchor: #BDWOQWGJ
- Texas Health and Safety Code, Chapter 711 – Specifies legal processes for removal of human graves and for converting cemetery land to a non-cemetery purpose. Cemeteries with graves more than 50 years old are additionally subject to the Antiquities Code and Section 106.
In general, archeological compliance responsibilities of the LG and TxDOT vary depending on project sponsorship, issues of funding, land ownership and the involvement of one or more federal agencies. The LGPM Guide provides a detailed discussion of these responsibilities.Anchor: #i1004951
A historic resource is a building, structure, object or district that, except under unusual circumstances, must be at least 50 years old at the time construction begins. Historic resources are treated differently than archeological resources. For the purposes of this discussion, “historic resource” does not include archeological resources, which are covered in another section. Protected historic resources are called “non-archeological historic properties.” A non-archeological historic property is listed or eligible for inclusion in the NRHP or eligible for designation as a state archeological landmark. State and federal laws regulate the impacts of transportation projects on historical resources, so the LG must coordinate with the TxDOT district during the scoping of project, which may impact these properties.
- Anchor: #FORDAFQN
- Section 106, National Historic Preservation Act of 1966, 16 U.S.C. §470f (Section 106) – Requires federal agencies to consider the effects of their projects on historic resources listed or eligible for inclusion in the NRHP. PA-TU prescribes standard procedures for complying with Section 106 on FHWA projects. Anchor: #AFWJWYCT
- Section 110(k), National Historic Preservation Act of 1966, 16 U.S.C. §470h-2(k) (Section 110) – Section 110 prohibits demolition of an archeological historic property prior to conclusion of Section 106 consultation (“anticipatory demolition”). Anticipatory demolition may result in loss of FHWA funding or approval. Destruction of a site that has not been evaluated also may result in loss of funding or approval. Anchor: #BKSURFQM
- 36 CFR Part 800 – Prescribes procedures for complying with Section 106 for FHWA projects removed from the PA-TU and for undertakings where an agency other than FHWA has jurisdiction.
- Anchor: #RTLATPMJ
- Texas Natural Resource Code, Chapter 191, Antiquities Code of Texas – Requires THC to be notified of proposed construction projects and prohibits unpermitted destruction of properties listed or eligible as a state antiquities landmark, listed on the NRHP or listed as a national historic landmark. Anchor: #SSKJFUEG
- 13 TAC 26, Practice and Procedure – Provides rules implementing the Antiquities Code. Anchor: #WBKORWUF
- 43 TAC Chapter 2, Subchapter H, MOU with THC (also adopted as 13 TAC §26.25) – Prescribes standard procedures for complying with the Antiquities Code on TxDOT projects, including projects requiring TxDOT approval. Anchor: #BPYCPQKR
- Texas Health and Safety Code, Chapter 711 – Specifies legal processes for removal of human graves and for converting cemetery land to a non-cemetery purpose. Cemeteries with graves more than 50 years old are subject to the Antiquities Code and Section 106.
Similar to “Archeological Resources” discussed above, the compliance responsibilities for historical resources vary depending on certain issues. The LGPM Guide provides guidance to the LG and TxDOT for their respective responsibilities for compliance related to historic resources.Anchor: #i1005041
Environmental Justice and Community Impact Analysis
Federal actions are required to comply with an array of laws pertaining generally to issues of civil rights, equity and community impacts. An environmental document must disclose effects related to these issues. The general methods for analyzing and disclosing these effects fall under what is generally referred to as environmental justice (EJ) and community impact analyses (CIA). Violations of the statutes below can have serious consequences. EJ and CIA issues are a major source of environmental litigation.
EJ and CIA analyses are among the most difficult analyses to perform because they resist standardization. The variables related to and affecting the analyses are complex, and their importance may vary as a result of the scale of project and the context within which the project occurs. In addition, guidance changes rapidly. The publication “ Community Impact Assessment, A Quick Reference for Transportation,” FHWA publication number FHWA-PD-96-036 (FHWA-CI), is especially useful for an LG to use during scoping of a transportation project. Many others are available from FHWA.
The statutes and executive orders listed below generally provide that a project must equitably distribute project benefits among members of covered groups or classes of people.
- Anchor: #MLQMEPBJ
- Title VI of the Civil Rights Act of 1964, 42 U.S.C. §§2000d-2000d-7 Anchor: #UNANOKXQ
- Civil Rights Restoration Act of 1987, 20 U.S.C. Chapter 38 Anchor: #QFRGJKQY
- Federal-Aid Highway Act of 1956, 23 U.S.C. Chapter 1, as amended Anchor: #XCCFTALP
- The Uniform Relocation Assistance and Real Property Acquisition Policies Act of 1970, 42 U.S.C. Chapter 61 Anchor: #RJMEOFKY
- Section 504 of the Rehabilitation Act of 1973, 29 U.S.C. §794 Anchor: #NCJENXUE
- Americans with Disabilities Act of 1990, 42 U.S.C. Chapter 126 Anchor: #VSFOTIIX
- Age Discrimination Act of 1975, 42 U.S.C. §§6101-6107 Anchor: #ECGJHIGJ
- Executive Order 12898, Environmental Justice – Specifies a project cannot have disproportionate effects on a minority or low-income population. Anchor: #FLGTOAQX
- Executive Order 13166, Improving Access to Services for Persons with Limited English Proficiency (LEP) – Specifies public involvement must give LEP populations meaningful opportunities for participation in public involvement. Access to public services and facilities is also covered by this requirement.
- Anchor: #XWJDNVRR
- No specific state statute applies to EJ or CIA. Federal statutes other than the executive orders apply independently of funding or other considerations
In general, the responsibilities for the EJ and CIA analyses vary and coordination between the LG and TxDOT is strongly encouraged. The LGPM Guide provides information related to these analyses and to the responsibilities of the LG and TxDOT for a project.Anchor: #i1005160
Taking or Use of Public Land Interests (Section 4(f) Property)
The USDOT defines a “Section 4(f) property” as any publicly owned land of a public park, recreation area or wildlife and waterfowl refuge of national, state or local significance, or land of an historic site of national, state or local significance ( 23 CFR 774.17). To be protected under Section 4(f), a historic site must warrant preservation in place and must be included in or eligible for inclusion in the NRHP. A historic site does not need to be publicly owned to be subject to Section 4(f).
Section 4(f) of the Department of Transportation Act of 1966 prohibits the USDOT from using land from a Section 4(f) property unless FHWA (or another USDOT agency with jurisdiction) determines there is no feasible and prudent alternative to the use of land from the property and that project planning includes all possible planning to minimize harm to the property resulting from such use. “Use” occurs when land is permanently incorporated into a transportation facility, when there is a temporary occupancy of land that is adverse in terms of the statute’s preservation purpose or when there is a proximity impact so severe the protected activities, features or attributes qualifying the property for protection under Section 4(f) are substantially impaired (constructive use). A use of a protected property can be processed with a de minimis Section 4(f) finding if the use is minor and does not adversely affect the property. For a historic resource, the THC must concur in writing that the project does not have an adverse effect. For parks, recreation areas or wildlife and waterfowl refuges, the Official with Jurisdiction over the property must concur in writing that the project will not have an adverse effect to the protected activities, feature or attributes and that he or she agrees with any proposed mitigation.
Similar state laws apply to publicly owned properties designated and used as parks, recreation areas, scientific areas, wildlife refuges and historic sites and to private land encumbered by an agricultural conservation easement purchased under Texas Natural Resources Code, Chapter 183. Before land on a protected property can be taken or used, state law requires the LG must demonstrate there is no feasible and prudent alternative to the taking and must hold a public hearing. For protected properties subject to Section 4(f) and Texas Parks and Wildlife Code, Chapter 26, the LG must document compliance with both statutes.
- Anchor: #AHEFVHAL
- 23 U.S.C. §138 and 49 U.S.C. §303 (Section 4(f)) – Requires there must be no feasible and prudent alternative to a project using publicly owned parks, recreation areas, wildlife and waterfowl refuges, or historic sites for a transportation purpose (see related regulation 23 CFR Part 774).
Guidance for Section 4(f) and other subjects can be found at the FHWA Environmental Review Toolkit website.
- Anchor: #TFREEMPJ
- Texas Parks and Wildlife Code, Chapter 26 – Requires there must be no feasible and prudent alternative to a project using publicly owned parks, recreation areas, wildlife refuges, scientific areas or historic sites for a transportation purpose. Anchor: #EJWJQLFI
- Natural Resources Code, Chapter 183 – Requires there must be no feasible and prudent alternative to the use or taking of private land encumbered by an agricultural conservation easement.
In general, the LG must determine if a project impacts property subject to Section 4(f) and must coordinate with TxDOT accordingly. The LGPM Guide provides guidance related to this determination and the responsibilities of both the LG and TxDOT.Anchor: #i1005240
Hazardous Materials Management and Pollution Prevention and Abatement
Under state and federal laws, a landowner is responsible for abating hazardous wastes. Purchasing contaminated land places the burden of abatement on the new owner. Known hazardous materials must be abated prior to construction, and construction must stop when hazardous materials are encountered during construction. Therefore, the LG must determine whether hazardous wastes occur in existing and new right of way. Contaminated right of way cannot be purchased in TxDOT’s name.
A variety of federal laws and regulations govern generation and abatement of pollutants.
- Anchor: #RTUFOSJK
- Comprehensive Environmental Response, Compensation and Liability Act, 42 U.S.C. Chapter 103 Anchor: #HTLCDCBT
- Resource Conservation and Recovery Act of 1976, 42 U.S.C. Chapter 82 Anchor: #JGMRDCCP
- 40 CFR Part 61 National Emission Standards for Hazardous Air Pollutants
A variety of state regulations govern generation and abatement of pollutants.
- Anchor: #BVWSAGCD
- 25 TAC Chapter 295 Subchapter C Texas Asbestos Health Protection Anchor: #BPDLQHRR
- 30 TAC Chapter 327 Spill Prevention and Control Anchor: #MGECTYEC
- 30 TAC Chapter 330 Municipal Solid Waste Anchor: #WXUHMVKN
- 30 TAC Chapter 333 Brownfields Initiatives Anchor: #GLKKLDXP
- 30 TAC Chapter 334 Underground and Above Ground Storage Tanks Anchor: #SXTXTOOQ
- 30 TAC Chapter 335 Industrial Solid Waste and Municipal Hazardous Waste Anchor: #PAQIMVGQ
- 30 TAC Chapter 350 Texas Risk Reduction Program
The LGPM Guide provides information related to the required practices and responsibilities of the LG and TxDOT for dealing with hazardous materials.Anchor: #i1005360
The LG must evaluate highway projects for their potential to cause noise impacts that must be abated.
- Anchor: #GAFDDTWP
- 23 CFR Part 772 – Provides standards, procedures for noise studies and noise abatement measures to be followed on federally funded projects.
- Anchor: #NXHPJTDI
- No specific state statute for noise abatement.
The LGPM Guide provides guidance related to the requirements for noise studies and noise abatement measures. Further guidance regarding traffic noise and noise abatement can be found at TxDOT’s Traffic Noise Toolkit website.