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usdot-jpo-ode / wzdx

The Work Zone Data Exchange (WZDx) Specification aims to make harmonized work zone data provided by infrastructure owners and operators (IOOs) available for third party use, making travel on public roads safer and more efficient through ubiquitous access to data on work zone activity.
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Allow "Point" for RoadEventFeatures #297

Closed j-d-b closed 2 years ago

j-d-b commented 2 years ago

Background

WZDx has always implied that a road event must include least a start and end coordinate, though it hasn't been technically required by the specification.

Currently, the documentation for the RoadEventFeature geometry property states:

The Geometry object's type property MUST be LineString or MultiPoint. LineString allows specifying the entire road event path and should be preferred. MultiPoint should be used when only the start and end coordinates are known.

The GeoJSON Point geometry is explicitly not allowed. However, there is nothing in the JSON schema limiting the number of positions (coordinate pairs) included for a LineString or MultiPoint, so technically including only one position is valid and has been used in practice.

Proposed Change Options

  1. Update the JSON schema to require at minimum that two positions are provided for LineString and MultiPoint. In addition, the description of the RoadEventFeature geometry should clearly state this. For cases where only a point location is known, producers can use the same lat/lon for both points in the coordinates array; OR
  2. Remove the language about road events needing at least a start and end point and allow "Point" as a geometry type option for the RoadEventFeature.
Dunge commented 2 years ago

Is there a specific reason triggering this request? We see some validity in having an event reported with just a single point in case of very short road work or when the ending position is yet unknown (currently deploying equipment).

rdsheckler commented 2 years ago

The vast majority of road events will only be a single point for many years into the future. It is just a reality that 85% of the work will be represented by an automated report from a truck with its flashers on or a smart arrow board.

j-d-b commented 2 years ago

Given the above comments, this issue can shift to discussion about adding Point geometry as an option for a RoadEventFeature.

Edit: updated the title and initial comment.

j-d-b commented 2 years ago

Note that Option 1. is a breaking change as any RoadEventFeatures including only one position would no longer be valid.

j-d-b commented 2 years ago

Co-chairs discussion 2022-09-23 led to supporting the current implementation which emphasizes that road events should have at least a start and an end point. It is valid to include an event with a single lat/lon pair, but is not recommended.