What is the WZDx Specification?
The Work Zone Data Exchange (WZDx) Specification enables infrastructure owners and operators (IOOs) to make harmonized work zone data available for third party use. The intent is to make travel on public roads safer and more efficient through ubiquitous access to data on work zone activity. Specifically, the project aims to get data on work zones in to vehicles to help automated driving systems (ADS) and human drivers navigate more safely.
Why is WZDx being developed?
Improving access to work zone data is one of the top needs identified through the US Department of Transportation (USDOT) Data for Automated Vehicle Integration (DAVI) effort.
Up-to-date information about dynamic conditions occurring on roads – such as construction events – can help ADS and humans navigate safely and efficiently. Many IOOs maintain data on work zone activity. However, a lack of common data standards and convening mechanisms makes it difficult and costly for third parties – including original equipment manufacturers (OEMs) and navigation applications – to access and use these data across various jurisdictions.
Inspired by the General Transit Feed Specification (GTFS), USDOT launched WZDx to jumpstart the voluntary adoption of a basic work zone data specification through collaboration with data producers and data users. Longer term, the goal is to enable collaborative maintenance and expansion of the specification to meet the emerging needs of ADS.
More broadly, through this project, USDOT aims to identify a repeatable approach to accelerate harmonization of local data sources that can improve roadway safety and efficiency.
A USDOT webinar on the WZDx project from February 26, 2019, is available here with associated slides.
A USDOT and American Association of State Highway and Transportation Officials (AASHTO) co-sponsored virtual event on Increasing Worker and Driver Safety through Access to Work Zone Data from May 19, 2020 is available here with associated slides.
Who is involved in developing WZDx?
The Federal Highway Administration (FHWA) and Intelligent Transportation Systems Joint Program Office (ITS JPO) co-led the early stages of the WZDx project and remain actively involved along with the Bureau of Transportation Statistics (BTS), Federal Motor Carrier Safety Administration (FMCSA), and others in the USDOT. Several data producers and data users voluntarily developed version 1.1 of the specification in collaboration with USDOT and have started to set up data feeds based on it.
In 2019, the Work Zone Data Working Group (WZDWG) was established under the Federal Geographic Data Committee (FGDC) Transportation Subcommittee with the primary goal of developing version 2.0 of the WZDx Specification based on lessons learned from version 1.1 and new insights from the user community. Version 2 of the Work Zone Data Exchange (WZDx) Specification was released in early 2020. Several data producers have already established WZDx feeds based on version 2:
The Texas Department of Transportation data feed based on WZDx Specification v2.0 can be found here.
The Massachusetts Department of Transportation data feed based on WZDx Specification v2.0 can be found here.
The Maricopa County Department of Transportation data feed based on WZDx Specification v1.1 can be found here and v2.0 can be found here.
The Iowa Department of Transportation data feed based on WZDx Specification v1.1 can be found here.
In September 2020, the WZDWG published version 3.0 of the WZDx Specification based on the prioritized issues and new industry insights from the data producer and data consumer community. This past development cycle demarcated several WZDWG milestones including the launch of two new additional WZDx Subgroups – the Technical Assistance and Worker Presence Subgroups – who worked in tandem with the Specification Update Subgroup to advance WZDx goals for its v3.0 release.
All the proposed changes passed by a supermajority agreement of the WZDWG in late August of 2020 and were merged into the specification to form WZDx version 3.0. Visit the WZDx project site for more information, to set up or ingest a feed, and/or to provide feedback on the specification.
What changed in version 3.0?
The following new features and fixes were made to the WZDx Specification:
Restrict version format to major.minor and enforce via v3.0 JSON schema.
Add order property to lane entity to indicate a lane's position in sequence on the roadway
Remove lane_edge_reference and standardize on counting lanes from the left side of the roadway
Add event_type property to the road event entity and new Event Type Enumerated Type with the values work-zone and detour, to support adding detour information (and more in the future)
Add relationship entity (one per road event entity) to enable describing relationships (hierarchical and sequential) between road events and other non-WZDx entities (such as a work zone phase or project)
Add road_event_data_source entity to allow specifying multiple data sources within a single feed
Streamline metadata (previously given in an external file, by URL) and add relevant fields to the road_event_feed_info and road_event_data_source entities
Require restriction_type if providing a lane-level restriction
Change Spatial Verification Enumerated Type and Time Verification Enumerated Type values to be all lowercase
Remove all plural or nonsensical lane types from the Lane Type Enumerated Type and clarify that each WZDx lane should represent a single lane on the roadway
Version 3.0 of the WZDx Specification and release notes can be found on the WZDx release page.
Download the WZDx postcard.