The directionality settings used for your Zones will depend on your Project needs.
No direction: Pass-Through Zones without a direction setting will analyze any trip that passes through the Zone, regardless of the direction of travel. A Pass-Through Zone with no direction might be used when you’re analyzing traffic traveling in both directions on an isolated highway, where no other roads intersect your Zone. Another example for using a non-directional Zone is when capturing traffic on a one-way road, such as a freeway entrance ramp.
Uni-directional: Pass-Through Zones with a direction and an “Is Bi-directional” setting of “No” are considered uni-directional. This means that they capture trips traveling in a single direction, as indicated by an arrow drawn in the StreetLight InSight platform, or a direction setting between 0 and 359 in the download files, where 0 is due North, 180 is due South. A uni-directional Zone should be used when only care about one direction of trips passing through the Zone, for example, only North-bound traffic.
Bi-directional: Pass-Through Zones with a direction and an “Is Bi-directional” setting of “Yes” are considered bi-directional. Bi-directional Zones capture traffic in two opposite directions in a single set of Metric values. Use this setting when you’re interested in traffic flowing in two directions, but not in any other direction, in a single Metric, for example combining North-bound and South-bound traffic through an intersection. Alternatively, if you want to analyze traffic going both directions through the Zone separately, duplicate the Zone with a directional arrow in the opposite direction.
Learn more in our directionality guide.