StreetLight InSight® Central Glossary

StreetLight InSight Glossary of Terms

Do you need the definition of a term we use in StreetLight InSight? Find the answers you need right here in our Glossary - it's your guide to our vocabulary. This information is also available as an illustrated PDF, which you can download below.

Zone and Zone Sets


A place you want to analyze, such as a geospatial shape, or polygon, that represents an area. It can be something standardized, such as a TAZ or road segment, or it can be any other shape created manually by a user.

Zone Sets:

A group of Zones. Create these in the Manage Zone Sets tab. This tab contains a “bank” or “library” of Zone Sets for your entire organization.

Pass-Through Zone:

A type of Zone (usually a road) where you want to measure trips that are passing through, not trips that are starting or stopping in that Zone.


For Zones marked with "Is Pass-Through" values of "Yes", a user may indicate a direction for the Zone. Only trips that travel through the Zone in that direction will be included in the analysis. In the download files, this is represented as a direction between 0 and 359, where 0 is due North, 180 is due South, etc.

Origin Zone:

A Zone in which trips start or initially pass through. Often abbreviated to OZ. Any Zone Set can be designated as an Origin Zone.

Destination Zone:

A Zone in which trips end (or later pass through) after beginning (or passing through) an Origin Zone, and, if applicable, a Middle Filter Zone. Often abbreviated to DZ. Any Zone Set can be designated as a Destination Zone.

Middle Filter:

A Zone that trips must pass through between an Origin and Destination Zone. Abbreviated to MF. This could be something like a bridge, neighborhood or road segment.

Trip Filter Zone:

A Zone that trips must pass through to be included in the analysis. Typically, these Zones are bridges, neighborhoods, or road segments.

Calibration Zones:

Use this type of Zone to add your local traffic count data to individual Road Segment Zones or to use StreetLight AADT for calibration. When you use Calibration Zones in a Project, StreetLight InSight will use traffic counts for those Road Segments to normalize the StreetLight Index values for your Project's Metrics.

Projects and Project Types


An analysis of one or more Zone Sets in a configuration of options. Create Projects to run Metrics.

Origin-Destination Analysis:

This is a Project Type. It can be a “complete” O-D Analysis that shows true trip origins and destinations, or a “partial” O-D (e.g.: ramp to ramp). Origins and Destinations can be Regular Zones or Pass-Through Zones.

O-D to Preset Geography:

Analyze travel patterns from your Zone Sets with a standard geography: ZIPs, TAZs, or census block groups.

Zone Activity Analysis:

Analyze all travel patterns in a Zone Set, regardless of Origins or Destinations. A Zone Activity Analysis is for All Trips, regardless of Origin or Destination.

Visitor Home and Work Analysis:

Analyze the home and work locations of visitors to a Zone or Zone Set by grid or census block group. Demographics are also available.

StreetLight Volume 2017 AADT:

Estimated average annual daily traffic (AADT) at the Zone, for travel in any direction. The Project must have at least one Zone Set. Each Zone in the Zone Set must be pass-through with directionality and tagged as bidirectional. (Blended Navigation-GPS and LBS Data)

Segment Analysis:

The Segment Analysis provides three Metrics that describe trips through corridors: the speed and duration of trips, and "Free Flow Factor," which measures congestion. Free Flow Factor is a ratio of the average trip speed for the Day Part to the maximum average trip speed for the segment in any hour during the entire Data Period. This means that when the Free Flow Factor is close to 1, there is little congestion on the corridor. The lower the Free Flow Factor, the greater the congestion.

Traffic Diagnostics:

Traffic Diagnostics combines several StreetLight InSight Projects: Segment Analysis, 2016 AADT, O-D by Preset Geography (by TAZ), and Zone Activity Analysis with Premium Trip and Traveler Attributes. It requires using a Line Segment Zone Set that overlays the existing road or network of roads that you want to analyze. The results of these different Projects are combined and into Traffic Diagnostics that can be visualized through StreetLight InSight's "Interactive Visualizations" tool.

The Interactive Visualizations tool allows you to manipulate and combine the Metrics provided by the Projects listed above. It enables you to scan for congestion on road segments, explore causes of congestion, and review potential mitigation solutions - all within the StreetLight InSight platform.

Metrics and visualizations can be downloaded directly from the Interactive Visualizations tool. Metrics can also be downloaded in the standard StreetLight InSight format for each sub-project included in Traffic Diagnostics.

Data Types

Location-Based Services Data:

Created by smart phone apps that use location-based services. Offers the same benefits of cellular data but with greater spatial precision and fewer coverage gaps.

Navigation-GPS Data:

Originates from connected cars, smart phones using GPS navigation and connected commercial trucks. Data is very spatially precise and hews tightly to roadways.

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