Enclosed Traffic Area

The Enclosed Traffic Area (ETA) / Parking Lot usage attribute is used exclusively for designating segments inside parking lots. Parking lot segments can be described as Thoroughfares and Aisles, depending on the type of the parking lot and the way the segment is used.


Thoroughfares are the main paths through parking lots - these are the paths you would want to drive if you need to drive through the parking lot. Thoroughfares should be given Local priority to ensure they are prioritized for routing to destinations inside the parking lot.


Aisles are rows in parking lots that are used primarily for parking and should be given Terminal priority. Aisles are frequently more narrow than thoroughfares, and have parking stalls on both sides.

In the image below, the thoroughfares of the parking lot have been highlighted in blue. The highlighted segments should be marked as Local priority, with Enclosed Traffic Area usage. The other segments in the parking lot should be marked as Terminal priority with Enclosed Traffic Area usage.

Identifying a parking lot

There are two main ways to identify parking lots:

  • Dedicated parking area: A parking lot won’t typically have sidewalks or other features within it. Although some parking lots include paved walkways, these are to facilitate pedestrian travel outside or along the parking lot.
  • Parking stalls: Most parking lots have painted parking stalls arranged in rows. Although some parking lots may be unpaved with unmarked stalls, there is usually a clear organization to parking within the lot.

There are other locations that may seem like parking lots but that don’t qualify. For example, the roadside parking stalls with no dedicated parking areas don’t count as parking lots. Additionally, while some residential neighborhoods have roadside parking, these are not parking lots since their primary purpose is to travel through the neighborhood to access a residential destination. This doesn’t mean that ETAs cannot exist within residential areas. Sometimes apartment complexes or other residential areas will have small lots off of the main road that are specifically meant for parking.

Best Practices

  • All segments inside parking lots should have segment usage assigned as Enclosed Traffic Area.
  • Parking lots should only be assigned private usage if there is specific signage that limits its usage. Gated lots without signs should not be marked as private.
  • A named road should not be given ETA attribute. A road can either have ETA as segment usage or a name.
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