Understanding Zones

Zones are enclosed areas on the map used to categorize a landmark or area of interest.

Zones often include neighborhoods, freeway corridors, city blocks, or any other areas that may be of interest in traffic-related analysis. By default, Altitude offers standard zones such as states, counties, cities, FSA, and TAZ. However, custom zones can help you analyze traffic around a specific geographic area, such as a port or urban core location.

Within Altitude, there are three broad categories of zones:

Standard
A standardized breakdown of geography, broadly accepted and utilized in classifying geography (state, provinces, counties, cities, FSA/ZIP, CTR and TAZ).
Custom
A user-defined area of coverage; represented as a geospatial polygon.
Segment
A road segment (segment); represented as a geospatial line string.

Within the ERROR - unresolved reference (VARS) platform, zones are input via standard parameter input structures.

Overlapping zones

If zones in an analysis overlap, a trip is defined for every applicable zone pair. This means a single physical trip may be counted multiple times in the final output.

See how it works

Custom Zones for Truck Stop Demand Analysis – Site-Level Setup

Create Custom Zones for truck stops. Define zones around formal rest areas and informal parking locations to prepare for site-level stop behavior analysis.

Zone types

Zone types help you organize the zones in your database.

All zones added to your database should include at least one zone type that helps you organize your zones. You can use the built-in types or add your own.

By default, Altitude includes the following zone types:

  • Port

  • Commercial Center

  • Highway

  • Custom

State, county and city zone types

These types of zones are identified through tags built into our road segments themselves. Road segments are exclusive to state, county and cities, meaning no segments belong to more than one state, county or city. If one would cross the boundary, it should be cut into two different segments for each of the geographies in which it resides. When using these geographies as zones, segments are pulled based on the tags that associate it to whichever state, county and city to which it belongs.

Other zone types

For all other zone types, we calculate which road segments belong to a zone by determining if any point in the segment resides within the zone. If any point of the segment is within the zone boundaries, then that segment is considered part of that zone. This process is more complex, as it requires looking at all points in a segment to determine if any of them are within the zone boundaries.

Metrics impact

Due to efficiency optimization for both our scenarios, the results can be slightly different when pulling segments from states, counties, and cities compared to other zone types. When pulling segments and comparing between the smaller and larger zones, the sum of the segments may be different than a collection of different zones that make the same geography as the larger zone, such as pulling for all CTRs in a county instead of using the county zone itself.