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AMI - ODOT Approved Terms & Definitions

A - B

"A"

Term Defined as:
Add-Mileage All roadways that are not Non-add mileage. The term "add-mileage" generally applies when milepoints have increasing values in the direction of travel. The term originated from the fact that the direction of increasing milepoints is used for mileage summarization, whereas separate roadways mileposted in the opposite direction are not counted in totals. The Pacific Highway is the only exception in that the add-mileage is accumulated in the direction of decreasing milepoints.
Alignment The horizontal and vertical control of a section of roadway or other transportation facility (e.g. multi-use paths, railway, etc.)
Asphalt Concrete Pavement A mixture of mineral aggregate and bituminous materials used in a pavement structure.
At Grade Used to express that a feature and a roadway meet at the same elevation.

"B"

Term Defined as:
Base The portion of the pavement structure beneath the surface course, which can be placed directly on the subgrade soil or on the top of a subbase
material. The major function of the base is to provide structural support and it is usually an aggregate material and may be treated with asphalt,
cement or other stabilizing admixtures.
Beginning Milepoint The milepoint notation, to the nearest 0.01 mile, that describes the location of the beginning of a linear feature or attribute.
Bike Lane A portion of the roadway, which has been designated by striping and pavement markings for the preferential or exclusive use of bicyclists.
Bridge A structure spanning and providing passage over a river, chasm road or the like. A structure including supports erected over a depression or an obstruction, such as water, highway, or railway, and having a track or passageway for carrying traffic or other moving loads, and having an opening measured along the center of the roadway of 6 feet or more between undercopings of abutments or spring lines of arches, or extreme ends of openings for multiple boxes; it may also include multiple pipes, where the clear distance between openings is less than half of the smaller
contiguous opening.
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C - D

"C"

Term Defined as:
Cattle Guard Painted or fabricated device designed to discourage livestock from entering the roadway.
Certified Public Mileage Total road miles certified to FHWA which are public roads under the jurisdiction of and maintained by a public authority and open to travel by 2-
wheel drive passenger vehicles.
Channelized Intersection The separation or regulation of conflicting traffic movements into definite paths of travel by traffic islands or pavement markings to facilitate the safe
and orderly movements of both vehicles and pedestrians
Clear Zone The total roadside border area, starting at the edge of the traveled way, available for safe use by errant vehicles. This area may consist of a
shoulder, a recoverable slope, a non-recoverable slope, and/or a clear run-out area. The desired width is dependent upon the traffic volumes and
speeds and on the roadside geometry.
Common Alignment Any length of roadway upon which more than one state highway is designated.
Connection A street or road, open to vehicular travel, which joins a road from the State of Oregon Highway System to any other road, entity, or another state owned road. A connection is usually much shorter than a spur or frontage road.
Construction Location The location of a construction project as defined by its beginning and ending milepoint.
Construction Plan Detailed drawings and diagrams, usually drawn and plotted to scale, showing the structure or arrangement to accomplish the construction of a
project. Also referred to as a contract plan.
Contract A business arrangement for the supply of certain goods or services at a fixed price.
Couplet The two roadways of a divided highway, named differently, approximately parallel with traffic flow in opposite directions and separated by
accessible land uses. In ITIS, all couplets are divided highways.
Crosswalk Portion of a roadway designated for pedestrian crossing, marked or unmarked. At intersections, unmarked crosswalks are the natural extension of the shoulder, curb line or sidewalk.
Culvert A drainage structure that passes through a roadway embankment or past some other type of flow obstruction. In some cases these are also used
as grade separated cattle passes. (Culverts can be from 12" to greater than 20 feet in span.)

"D"

Term Defined as:
Diamond Lane See HOV lane
Ditch A ditch is an open channel, usually located parallel to the roadway that collects surface runoff from the highway right-of-way. A ditch conveys the accumulated runoff to acceptable outlet points.
Drainage Installation Includes drains, inlets, etc. under 6 ft in diameter and box culverts under 2 ft square
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E - F

"E"

Term Defined as:
Embankment Raised structure constructed of natural soil from excavation or borrow sources.
Ending Milepoint The milepoint notation, to the nearest 0.01 mile, that describes the location of the end of a linear feature or attribute.
Engineering Station Surveyed location on a defined alignment.
Engineering Station Equation A statement that specifies two different linear measurements that exist at a single point on an alignment. This is a method of accounting for changes in a linear measurement system without restationing the entire alignment. The changes in stationing can be the result of an error or revision of a curve or the joining of two separate surveys.
Engineering Stationing Sequential numbering of surveyed locations on an alignment.
Exit Number Identifier assigned to a location where a vehicle may leave the roadway via a ramp or connection. Denoted by the number associated with the
nearest milepoint. When there is a need for more than one exit number within one mile, a letter is added to keep the exit number unique.

"F"

Term Defined as:
Federal Aid Primary Historical system abolished in 1991 and no longer in active use. Federal Aid Primary was based on the functional classification system. It consisted
of rural principal and minor arterials and their extensions into and through the urban areas. This system included interstate routes. For Oregon, a
FAP route must be on a state highway. This system was regulated by the FHWA.
Federal Aid Secondary Historical system abolished in 1991 and no longer in active use. Federal Aid Secondary is based on the functional classification system. It consists
of rural major collector routes on state highways, county roads, and city streets not contained within urban areas (I.e. having less than 5000
population). They cannot be designated in urbanized or urban areas. The designation of these routes requires the concurrence of the state,
counties and cities. It was regulated by the FHWA.
Federal Aid System The Federal Aid System identifies road segments that are eligible for Federal funding. This system was implemented in 1991 with the passage of
ISTEA.
Federal Functional Classification Federal Functional Classification is the system by which roads are grouped into functional systems according to the type of service and amount of
traffic the facility carries. This system determines the level of federal funding available for maintenance and improvements. Federal Functional
Classification is determined using federal guidelines and is approved by FHWA.
Fill See the definition of embankment
Flume A wooden, steel or concrete open channel to carry water or other products.
Frontage Road A road secondary to and generally parallel to a highway, providing service to abutting property and adjacent areas and for control of access. A
frontage road may or may not be directly connected to the highway it services.
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G - H

"G"

Term Defined as:
Gate A hinged device used to control access.

"H"

Term Defined as:
Highway Every public way, road, street, thoroughfare and place, including bridges, viaducts and other structures within the boundaries of this state, open,
used or intended for use of the general public for vehicles or vehicular traffic as a matter of right. Some highways are designated by the Oregon
Transportation Commission as State Highways – see the definition of State Highway for more information.
Highway Name See State Highway Name.
Highway Number See State Highway Index Number.
Historical Alignment A travel way that no longer exists, or is no longer used for vehicular traffic.
Horizontal Curve A series of points of change in direction (in the form of circles of varying radius) that transitions between two intersecting tangent alignments. A
horizontal curve is used as a transition element between two tangent alignments that intersect. An angle point is called a point of intersection or PI Station; and the change in alignment is defined by a deflection angle.
High Occupancy Vehicle (HOV) Vehicles that can carry two or more persons. Examples of high occupancy vehicles are a bus, vanpool, and carpool. (American Public Transit
Association Transit Fact Book APTA1) HOV Lane High Occupancy Vehicle Lane. Exclusive road or traffic lane limited to buses, vanpools, carpools, and emergency vehicles. (American Public Transit Association Transit Fact Book APTA1)
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I - J

"I"

Term Defined as:
Interchange A system of interconnecting roadways and structures in conjunction with one or more grade separations that provides for the movement of traffic
between two or more roadways on different levels.
Intersection The area where two or more roadways join or cross at the same elevation.
Interstate Route A route system that consists of all presently designated freeway routes meeting the Interstate geometric and construction standards for future
traffic, except for portions in Alaska and Puerto Rico. The Interstate System is the highest classification of arterial roads and streets, and provides the highest level of mobility, at the highest speed, for a long uninterrupted distance. This system is intended for through traffic, has full access control, and has grade separations at major intersections. Interstate Routes are signed routes. All Interstate Routes are state highways.

"J"

Term Defined as:
Junction The intersection of two or more state highway roadways.
Jurisdiction The governmental “entity” that owns the road. A road is said to have Federal, State, County, City, Private or etc. jurisdiction.
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K - L

"K"

Term Defined as:

"L"

Term Defined as:
Lane A portion of a roadway, usually indicated by pavement markings, designated for travel by one line of vehicles.
Lanemile The product of distance (in miles) times the number of lanes for motorized vehicles.
Layer The roadway structure is made up of materials stacked on top of each other. The typical layers in a roadway are the subbase, base, intermediate
pavement layer(s), and the wearing surface. Each layer is of designed thickness and quality.
Lift Layer The maximum thickness that a given material can be placed and compacted for its intended use.
Located Line A surveyed alignment where a road is planned to be built. The location where highway construction plans have been developed, and the geographic location surveyed for construction, but no paved surface yet exists.
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M - N

"M"

Term Defined as:
Mainline Refers to all roadways for a highway, excluding connections and frontage roads.
Maintenance Yard The main maintenance facility for each ODOT crew.
Median A physical separation between lanes of highway traffic, excluding the shoulders.
Milepoint Equation A statement that specifies two different milepoints that exist at a single point on the same roadway. This is a method of accounting for changes in a
linear measurement system without remilepointing the entire roadway. The changes in milepoints are usually caused by new construction.
Mowable Brush Shoulder Linear shoulder mowed by maintenance crews, measured in kilometers
Mowing Area Area in the right-of-way mowed by maintenance crews, measured by hectares.
Multi-Use Path A Path physically separated from motor vehicle traffic by an open space or barrier and either within a highway right-of-way or within an independent
right-of-way, used by bicyclists, pedestrians, joggers, skaters, and other non-motorized vehicles

"N"

Term Defined as:
National Highway System (NHS) The National Highway System is the network of nationally significant roads approved by Congress as required by the Intermodal Surface
Transportation Efficiency Act (ISTEA) of 1991. It includes the Interstate system, the Strategic Highway Network (STRAHNET), and over 100,000
miles of arterial and other roads. Designation of the original system was completed on November 28, 1995, when President Clinton signed the
National Highway System Designation Act of 1995 (Public Law 104-59). Intermodal Connectors were added to the system in 1998 when Congress
approved the Transportation Equity Act for the 21st Century (TEA-21).
FHWA requires that ODOT report on the NHS system using the following numbers to differentiate between the different types of NHS.
NHS (original system approved in 1995)
NHS Intermodal Connector (Airport)
NHS Intermodal Connector (Port)
NHS Intermodal Connector (Amtrak)
NHS Intermodal Connector (Rail/Truck)
NHS Intermodal Connector (Intercity Bus)
NHS Intermodal Connector (Public Transit)
NHS Intermodal Connector (Pipeline)
NHS Intermodal Connector (Ferry)
National Highway System (NHS) Intermodal Connector NHS Intermodal Connectors are NHS roads that provide service to major intermodal terminals. Section 101 of the National Highway System
Designation Act of 1995 required the Secretary of Transportation to submit NHS Intermodal Connectors to Congress for approval. Congress
approved the Intermodal Connectors in 1998 with the passage of the Transportation Equity Act for the 21st Century (TEA-21).
NBI Structure A Structure including supports erected over a depression or an obstruction, such as water, highway, or railway and having a track or passageway
for carrying traffic or other moving loads, and having an opening measured along the center of the roadway of more than 20 feet between
undercopings of the abutments or spring lines of arches, or extreme ends of openings for multiple boxes; it may also include multiple pipes, where
the clear distance between openings is that has an opening measured along the centerline of the roadway of more than 20’ between undercopings
of abutments or spring lines of arches, or extreme ends of openings for multiple boxes; it also includes multiple pipes where the clear distance
between openings is less that half of the smaller contiguous opening. (Federal Code of Regulations Paragraph 650.301)
Non NBI Structure A structure which is 6' to under 20' in span. Maintenance Features Inventory staff uses the term minor structure instead of non NBI structure.
Non-Add Mileage Roadways with one direction of travel and milepoints that decrease in the direction of travel. The Pacific Highway is the only exception in that the
non-add mileage is accumulated in the direction of increasing milepoints.
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O - P

"O"

Term Defined as:
Overlapping Mileage See Z Mileage
OR Route A route system established by the Oregon Transportation Commission (OTC) in 1932 to facilitate travel on main highways over the shortest
distance and the best roads throughout the state. This route system is currently regulated by the OTC. OR Routes are signed routes. Not all OR
Routes are state highways. Not all state highways have an OR Route Number.

"P"

Term Defined as:
Portland Cement Concrete Pavement Mixture of Portland Cement Concrete, aggregate and water used in a pavement structure. There are two general types of PCC pavements,
Continuously reinforced, and jointed concrete pavement.
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Q - R

"Q"

Term Defined as:

"R"

Term Defined as:
Railroad Crossing At grade intersection of a railroad and a roadway
Rest Area A designated public facility with restrooms usually located along major highways.
Road Geometry The physical characteristics of a road, such as curvature, length, width, depth of pavement, etc.
Roadbed Completed excavations and embankments for the subgrade, including ditches, side slopes, and slope rounding, if any.
Roadway The portion of the highway, including shoulders, for vehicular use.
Route A designated path through a road network.
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S - T

"S"

Term Defined as:
Shoulder The portion of a roadway, whether paved or unpaved, contiguous to the traveled way that is for use by pedestrians and bicyclists, for the accommodation of stopped vehicles, for emergency use and for lateral support of base and surface courses.
Sidewalk A walkway separated from the roadway with a curb, constructed of a durable, hard and smooth surface, designed for preferential or exclusive use by pedestrians.
Signed Route Any designated route, which is, signed (e.g., US, Ore., Interstate, scenic byway, historic route, etc.)
Span The distance between the supports of a bridge, truss, arch, girder, floor beam, etc. (Dictionary of Civil Engineering)
Spur Any State Highway designated as such by the Oregon Transportation Commission, prevalently a branch or extension of an existing State Highway.
State Highway A land based public way designated by the Oregon Transportation Commission as a highway for the purpose of vehicular travel. The State of Oregon commonly has, but may not have all right, title, interest, jurisdiction, maintenance and control of the entire area within the highway right-of-way.
State Highway Index Number An Oregon Transportation Commission approved identifier assigned to a highway. The valid range of identifiers is from 1 to 499.
State Highway Name An Oregon Transportation Commission approved name used in conjunction with a State Highway Index Number to identify a state highway.
Stockpile Site Designated site where ODOT maintenance crews store materials.

"T"

Term Defined as:
T-Mileage Milepoints assigned to a temporary traveled route
Temporary Mileage See T-Mileage.
Temporary Traveled Route Temporary Traveled Routes are roads that are meant to temporarily function as state highways until a replacement state highway alignment is built or dedicated. These roads do not belong to ODOT, but ODOT has legally agreed to maintain them. TTR’s can occur because of a detour or
highway construction.
Travel Way A designated path used by a specific mode of the transportation system. Examples of Travel Ways are Roads, Railroads, Waterways, Pipelines, Air
Routes, Bike Trails.
Traveled Way The portion of the roadway for the movement of vehicles, exclusive of shoulders and median.
Tunnel An underground passage that allows water or vehicles to pass through, open to daylight at both ends.
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U - V

"U"

Term Defined as:
US Route A route system that was established by Congress in 1926 to facilitate travel on main highways over the shortest distance and best roads nationwide. This route system is currently regulated by an AASHTO committee. US Routes are signed routes. Not all US Routes are state highways. Not all state highways have a US Route Number.

"V"

Term Defined as:
Vertical Curve The measurement system used to describe a change in elevation. Transition curve, usually in the form of a parabola, of varying radius used to
provide a smooth transition between segments of differing grade in the vertical plane. An angle point is called a point of intersection or PI Station;
and the change in alignment is defined by a deflection angle.
Viaduct A series of spans carried on piers at short intervals. (Bridge Inspection Training Manual/90)
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W - X

"W"

Term Defined as:
Wearing Course The uppermost layer in a pavement structure. Its major functions include support of traffic loads and to provide a skid resistant surface. May consist of flexible materials such as asphalt concrete or rigid materials such as Portland Cement Concrete.

"X"

Term Defined as:
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Y - Z

"Y"

Term Defined as:

"Z"

Term Defined as:
Z-Mileage Milepoints assigned to a roadway when the roadway has been lengthened due to realignment.
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