# Linear asset terminology

A linear asset is an asset whose length plays a critical role in its maintenance.

## Purpose

The following terms are associated
with linear assets:

- Attribute
- A property of a linear asset or of a feature. For example, speed limit is an attribute of a highway (a linear asset) with multiple possible values (40 miles per hour, 50 miles per hour, and so on). A guardrail (a feature) comes in different types. You can specify "Type" to be an attribute of a guardrail, and specify a value for each type of guardrail.

- Dynamic segmentation
- The ability to analyze a linear asset multiple ways without affecting its underlying geometry. For example, you define a road as a linear asset. The road starts at mile zero and ends at mile 60. You assign a speed limit of 55 miles per hour to miles 0 - 20, and a speed limit of 65 miles per hour to miles 20 - 60. At the same time, the number of lanes might be three lanes from miles 0 - 40, and four lanes from miles 40 - 60.

- Feature
- A physical object that you associate with a linear asset, but which itself is not an asset. Use features, such as, mile posts, to locate where work takes place. Create feature records using the application.

- Feature instance
- A feature that you have associated with a linear asset. For example, you create a feature called Mile Post. When you associate Mile Post with a linear asset in a location, it is a feature instance.

- Linear referencing
- Define the location of a point along a linear asset. Linear referencing uses distance measures from known points along the X, Y, and Z axes. The X axis is the length of the linear asset. The Y axis is the distance to the right or to the left of the linear asset. The Z axis is the distance above the linear asset or below the linear asset.

- Linear referencing method
- A method of determining a position by using a known starting point, a measure, a direction, and offset values. To define a linear referencing method, specify units of measure for the length of the linear asset, and for three offset measures (see offset). You can define multiple linear referencing methods.

- Linear segment
- A span of a linear asset defined by a starting measure and by an ending measure. The span can be the entire length of the linear asset or it can be any continuous part of it. The starting measure and ending measure for the linear segment must be within the starting measure and ending measure of the linear asset. A linear segment cannot overlap two linear assets.

- Measure
- The absolute distance from the start of a linear asset. You can specify a measure manually. The measure is calculated for you if you enter a reference point and a reference point offset.

- Offset
- A measure from a previously defined reference point. The three
kinds of offsets are as follows:
- Reference Point Offset
- A distance along the length of the asset measured from a previously defined reference point. For example, a speed sign is 0.2 miles from Mile Post 10.

- Y-Offset
- A distance perpendicular to the direction of the linear asset. For example, a speed limit sign is located 10 feet from the right edge of the road. Right is positive and left is negative. Therefore, the Y offset is 10.

- Z-Offset
- A distance above a linear asset or below a linear asset. For example, an exit sign is located 18 feet above the surface of the road, and a culvert is 4 feet below the surface of the road. The Z offset for the sign is 18, and the Z Offset for the culvert is -4.

- Point asset
- An asset whose length does not play a critical role in its maintenance. For example, a pump, a railway switch, or a camera. With a point asset, you do not assign work to a particular length of the asset, but rather to the entire asset or to its parts.

- Reference point
- A feature instance that you can use as a starting point or as an ending point for a linear segment. A reference point is a means of communicating a work location. For example, it can be more useful to workers to say that roadside plowing on Route 96 begins at the intersection of Routes 96 and 75, and ends at Exit 34, rather than to say that the work begins at mile 27.85 and ends at mile 33.8.

- Relationship
- A defined interdependency between two linear assets: a linear and a point asset, or a linear asset and a location. Define relationships using the application. Relationships can be physical. For example, intersects with or is parallel to. Relationships can also be abstract. For example, belongs to or is owned by.