How To Guide: Making Polygon Zones for Roads using StreetLight InSight
This tutorial will show you how to make Road Segment Zones for StreetLight InSight Travel Projects. This type of Zone is used for turning ratios, corridor studies, select links, and so much more. Think of a road segment Zone as a “gate” or digital sensor line that measures the volume of trips that pass through it.
This tutorial describes how to create Road Segment Zones by drawing polygons or uploading polygon shapefiles.
This tutorial contains supporting files. Click here to download them.
Step 1: Designate Road Zones using the “Draw” Tool
1a. First go to the Manage Travel Projects Tab in StreetLight InSight and click “Add Zone Set.”
1b. Create a name for your Zone Set, then click “Draw New Zone.”
1c. Designate your Road Segment Zones. This works best if you draw gates across the road, but be careful not to catch any neighboring roads in your gate. You can zoom the map using an address or latitude/longitude coordinates. For this tutorial, you can use (38.2323381, -85.7091183) to zoom in an intersection in Louisville.
Keep in mind that for all Road Segment Zones, you are capturing information about trips passing through the Zone, not trips that are originating or ending in the Zone. Thus it’s important to check the “Pass Through Zone” box.
Pro Tip: For turning ratios, draw your Zone close to the intersection (but not in the intersection) so that the vehicles can’t slip past the gate and the intersection on some other road.
If you want to analyze traffic going west AND east through the gate, you’re done. Simply click “Save.”
Step 2: Designate Interest in Trips Traveling in Just One Direction
If you want to analyze Eastbound traffic, click “draw direction” before you save your Zone. Click once to create a “start” pin, then click once to create an “end” pin. You will see an arrow that designates the direction of travel. Then click “Save” to save your Road Segment Zone with directionality.
Step 3: Ramps and Other Complex Road Segment Environments
Sometimes roads are in complex environments. To view a complex highway interchange, input the latitude and longitude: 38.190286, -85.729077. For off and on ramps, be sure that your gate only includes the exact ramp you want to analyze, and that it does not catch any other ones. However, drawing gates on curves is fine.
In the case shown below, the ramp is one way, so you do not need to designate directionality. Should you choose to use directionality of a curve, make sure to designate the direction of the road as it passes through the gate.
If you need to analyze a road segment as it crosses another road, you can use the directionality arrows to “filter out” traffic on the crossing road. In the example below, only traffic traveling South-West on Phillips Ln will be captured.
You also have the option to analyze bi-directional traffic. A bi-directional zone designation will allow you to analyze trips that Pass-Through Phillips Ln in either direction, but do not travel along the expressway. Bi-directional designations are particularly useful when analyzing intersecting road segments.
Pro-Tip: One way to confirm that your Zone will cover the intended traffic patterns is to turn on the OpenStreetMap layer when drawing your Zones. This layer is what our system currently uses to lock Navigation-GPS trips to the existing road network. On occasion, the OpenStreetMap road network might differ slightly from what is depicted my Google Maps or Satellite views. For this reason, it’s always a good idea to reference the layer by checking the box “Show OSM Layer.”
Step 4: Uploading Shapefiles for Road Segments
You can create a shapefile of “gates” using the techniques described here and upload them to StreetLight InSight. If you need to use directionality, you should designate the direction using as a degree from 0° to 360°, where 0 is true North, 90 is East, etc. Be sure to make a ZIP file of your shapefile with all the requisite files. You can follow our shapefile template to be sure that you include everything. To upload a shapefile, click the “Upload Shapefile” button.
Next, browse to your zipped shapefile and click upload. You will see the “Choose Data” fields dialogue box appear. Use this dialogue box to map the fields in your shapefile to the fields in our template. Each Zone must have a unique name. Zone IDs (a number assigned to each Zone) is optional. For road segments, the most important thing is that you select “Always Yes” on the “Zone is Pass Through” drop down. If you are using degrees to assign Direction values, you can also pick “Determine by the Direction.”
After mapping your fields, click continue. You’ll have one more chance to edit your Zones using the draw tool, duplicate Zones, or delete Zones from your Zone Set before saving. To do so, click on the edit pencil icon next to the Zone before you save the Zone Set.
If you have a road Zone set that is a shapefile of road as links, please email it to firstname.lastname@example.org, and ask that it be converted into gates and added to your account. We will respond within two business days.