California Road Sharing (CaRS)

California’s road system is managed by various roads data management government agencies. These include the California Department of Transportation (Caltrans), 58 counties and 482 municipalities using multiple data systems. Development of a common statewide road network dataset is needed so that the dataset can be used by multiple government agencies in California. The statewide roads dataset would also be used to report the roads data to Federal Highway Administration’s (FHWA) All Roads Network of Linear Referenced Dataset (ARNOLD) program and may potentially be even used for development of the National Road Network (NRN), which is currently being piloted by the FHWA and certain select State Departments of Transportation (DOT). Based on a technical feasibility investigation, a plan for development and deployment of the California Roads Dataset has been developed.

The California Road Sharing (CaRS) Program will establish a statewide roads dataset that will be available for use by stakeholders in the state using a web-based geospatial roads data management platform. The statewide roads dataset will be administered and governed by a California Road Sharing (CaRS) working group. The CaRS working group will comprise members of various roads data management agencies, particularly, Caltrans, Local agencies (counties and cities) and, California Office of Emergency Operations (CalOES).

• Create a governed statewide roads dataset to meet roads data use cases of multiple agencies in California.

• Provide mutual benefits to State and Local jurisdictions, especially the business users involved in highway project planning, survey, design, construction, safety, and traffic and asset management operations.

• Coordinate roadway cartographic and data model recommendations.

• Support Transportation for the Nation (TFTN), which promotes a publicly available, high quality road centerline that is coordinated across all levels of government.

• Building Information Modeling (BIM) for Roads and Assets using Standards for supporting AI/ML Applications, CV/AV and UAS.

During Phase 1, representatives from multiple agencies in California developed a statewide work group and a work group charter. The work group charter established the California Road Sharing (CaRS) program vision, objectives, and roles and responsibilities of work group members.

The data flow would involve the following steps:

1. Local agencies will create roads data and submit to CalOES as required by NG911 program
2. CalOES will conduct NG911 data checks and will integrate data from all local agencies into NG911 database
3. Caltrans will pull the local roads data from the NG911 database and conduct data quality checks
4. Caltrans will share data errors with local agencies based on agreed data quality validation rules
5. Caltrans will use the roads data that does not have errors to detect differences with its All Roads database
6. Caltrans will prepare NG911 road segments data for integration with its All Roads LRS Routes
7. Caltrans will use the NG911 roads data from local agencies to create demarcation points
8. Caltrans will integrate the NG911 road segments and demarcation points data into its LRS and publish

In Phase 4 of the project, the focus will be on expanding the Proof of Concept (POC) pilots, case studies, and investigations initiated in Phases 2 and 3.

Unlike the earlier phases limited to Merced County, Phase 4 aims to include additional local agencies in California. The extension involves integrating road centerlines data from various local agencies with Caltrans' All Roads data.

The review will include NG911 road centerline datasets and explore the feasibility of unifying county datasets with the Caltrans Linear Referencing System (LRS) dataset. The CaRS work group will identify 5-7 volunteer local agencies who would like to investigate the results of integrating their NG911 roads datasets into the Caltrans LRS. The group would also like to evaluate the use of the integrated roads dataset at their agency (for supporting various business processes).

Transportation agencies in states such as Arizona, Georgia, and Ohio implemented various iterations of the data supply chain between local agencies and state DOTs for exchange of roadway geometry and attribute data for integration into a statewide roads dataset.

The statewide roads dataset integration efforts in these states involve coordination across multiple agencies sharing road data. Across all the data supply chains between local agencies and state DOTs, an intermediate agency/group is in place who either facilitates or leads the governance of the data supply chain program in the state.

For example, in Arizona and Ohio, the state GIS offices play the role of intermediatory agency/group facilitating the data exchange between local agencies and state DOTs.

The states of Pennsylvania and California investigated the deployment of a data supply chain and worked with the emergency management agencies, Pennsylvania Emergency Management Agency (PEMA) and CalOES, to investigate how emergency management and local agencies compiled the NG911 roads database to be leveraged and integrated with the state DOT LRS routes.

Both states conducted this investigation as part of the AEGIST program and developed the data and application architectures associated with the NG911 road centerline data integration into the state DOTs LRS as NG911 road segments (referred to as LRS events).

In California, local agencies model all of the roads in their counties, including higher functional class roads, for submission to NG911. The local roads dataset can be imported and merged into the Caltrans All Roads LRS, allowing Caltrans to add missing local roads. Information such as road names, functional class, and direction from the local dataset can enhance the Caltrans All Roads LRS. Technical feasibility, confirmed in CaRS Phases 2 and 3, demonstrated tools like 1Integrate and ArcGIS Pro can identify differences in road datasets. Despite minor modeling rule differences, a unified road network database is feasible for statewide stakeholder distribution. The CaRS program proposes expanding the work group in Phase 4 for governance across agencies in California.