100-year floodplain
The area covered by a flood having a 1 percent chance of occurring in any given year, i.e., once in 100 years. The 100-year floodplain is an official designation as indicated by Flood Insurance Rate Maps.
Aesthetics
In the highway context, the considerations of landscaping, land use and structures to insure the proposed highway is pleasing to the eye of the viewer from the roadway and to the viewer looking at the roadway.
Alignment
The vertical and horizontal location of a roadway.
Alternative
An alternative includes various improvements designed to address transportation needs in the project area.
Average Daily Traffic or ADT
A measurement of the number of vehicles which use a highway over a period of a year divided by 365 to obtain the average for a 24-hour period.
Auxiliary lane
The portion of roadway adjoining the through traffic lanes used for speed change, turning, storage for turning, weaving, truck climbing and other purposes supplementary to through traffic movement.
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Borrow
An excavation used to provide soil, material or fill for construction activities.
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Categorical exclusion (CE)
An action that falls within a category that has been found not to have significant environmental impact and does not require an environmental assessment or environmental impact statement.
Cultural resource
A property or artifact that pertains to or identifies human activities. This is also a common term for the National Register of Historic Places “historic properties.” It can mean an archaeological site, historic structure, building, district and landscape.
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Design year
The future year used to estimate the probable traffic volume for which a highway is designed. A time (usually 20 years) from the start of construction is normally used.
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Environmental Assessment (EA)
A concise document that explains the decision of whether to prepare an environmental impact statement or a finding of no significant impact.
Environmental Impact Statement (EIS)
A document written to explain a proposed major federal project which significantly affects the human environment and illustrates the following: purpose and need of the proposed project, alternatives considered, the affected environment, environmental consequences, the relationship between short-term uses of the local environment and the results of its maintenance over the long-term, and finally, any commitment of resources that would be irretrievable if the project is implemented.
Environmental studies
The exploration of environmental resources in the project location and determination of what type of environmental document should be written.
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Finding of No Significant Impact (FONSI)
A document that supports the decision that there is no significant impact and thus, the preparation of an environmental impact statement is unnecessary. The FONSI must include either a summary of the environmental assessment or the environmental assessment must be attached and is referred to to within the FONSI document. Any environmental documentation that supports the finding must accompany the FONSI.
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Historic property
Any prehistoric or historic district, site, building, structure or object included in (or eligible for) the National Register of Historic Places(36 CFR Part Section 800.16 (1)(1).
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Level of Service (LOS)
An indicator tool that determines the functionality of the roadway in terms of capacity, volume and delays at intersections. It ranges from A to F, F indicating worst possible congestion and longest delay.
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Market value
The highest price for which property can be sold in the open market by a willing seller to a willing purchaser, neither acting with compulsion and both exercising reasonable judgment.
Mitigation
Compensation for an environmental impact, including in order of consideration: 1) avoiding the otherwise impacted area altogether; 2) minimizing impact by lessening its degree or magnitude; 3) repairing the affected area; 4) minimize impact over time by preservation or maintaining the quality of the area; and 5) mitigating for the resource lost by creating it elsewhere or protecting similar environmental resources located elsewhere.
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National Environmental Policy Act (NEPA)
Federal legislation that requires impacts to both the human and natural environments be considered when federal actions are undertaken.
National Register of Historic Places (NRHP or National Register)
The National Park Service (NPS) on behalf of the Secretary of the Interior administers the National Register. National Register listings include buildings, structures, sites objects and districts of historic architectural, engineering, archaeological or cultural significance. Properties listed are not limited to those of national significance; most listed properties are significant at the state or local level.
Noise sensitive receiver
Any property (owner occupied, rented or leased) where frequent exterior human use occurs and where a lowered noise level would be of benefit. In those situations where there are no exterior activities to be affected by the traffic noise, the interior of the building shall be used to identify a noise sensitive receiver.
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Peak hour
The one-hour period during which the maximum amount of travel occurs. Generally, there is a morning peak and an afternoon peak.
Public hearing
A meeting wherein Iowa DOT officials hear the public’s views and concerns about a proposed project. (A public hearing is always conducted for an Environmental Impact Statement and typically conducted for an Environmental Assessment.)
Public information meeting (PIM)
A forum to solicit input from or provide information to the public on a proposed action.
Purpose and need
A statement that describes what the purpose is for the project and what need(s) the proposed alternatives will rectify.
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Reconstruction
A project that entails the removal of existing surface and/or structure and replacing it with a new surface and/or structure.
Record of Decision (ROD)
A document prepared after the Final Environmental Impact Statement (EIS) is signed which explains what the preferred alternative is and why it was chosen, outlines mitigation measures that will be integrated into the project and describes what Section 4(f) approval was received.
Regulated substance
As defined in part by Iowa Code 567-135.2(455B), an element, compound, mixture, solution or substance that, when released into the environment, may present substantial danger to the public health or welfare or to the environment.
Right-of-way (ROW)
Generally refers to a longitudinal strip of land used for transportation purposes.
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Section 4(f)
A special provision in the United States Department of Transportation Act of 1966 (now codified at 49 USC 303, 23 USC 38) that states special effort should be made to preserve the natural beauty of the countryside and public park and recreation lands, wildlife and waterfowl refuges and historic sites. Section 4(f) applies only to federally funded transportation projects and only if the park, recreation area or waterfowl or wildlife refuge is significant and publicly owned.
Substantial noise increase
This is an increase of 10 or more decibels above the existing noise level as a direct result of the transportation improvement project in question.
Substantial noise reduction
This is an effort to reduce traffic noise impacts at benefited receivers by 8 to 10 decibels, if possible, with a minimal acceptable level of reduction at no less than 5 decibels.
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Tiering
A system of preparing multiple Environmental Impact Statements (EIS), one of which discusses the environmental impact on a broad scale while the others focus on more specific environmental impacts not now ready for decision.
Traffic count
A count of total vehicular traffic passing a given point on a highway during a specified time period. This might be a manual or machine count.
Traffic noise impacts
Impacts which occur when the predicted traffic noise levels approach or exceed the noise abatement criteria or when the predicted traffic noise levels substantially exceed existing noise levels.
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Vehicles Per Day (VPD)
Number of vehicles that pass a particular point on the road during a period of 24 consecutive hours
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Wetland
As defined in the Corps of Engineers Wetland Delineation Manual, “Those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas.“
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