Using ArcGIS and the Caltrans Postmile Toolbar to Manage Field ElementsCaltrans District 11 GIS and Traffic Operations

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GIS staff receives the source information provided by Traffic Operations and reformats the data fields as necessary. Fields must be defined as either text strings or numbers so that the data import cleanly into a File Geodatabase table. Once the source data are in the File Geodatabase, they are interoperable with ArcGIS and the Caltrans Postmile Toolbar.

The Caltrans District 11 GIS/Project Development Support Branch and the Traffic Operations Advanced Transportation System Engineering Branch are developing and maintaining a database of Traffic Operations field elements. The field elements include closed circuit TV cameras (CCTV), changeable message signs (CMS), ramp meters, fiber optic network, and vechicle detection system (VDS). These elements are used to collect and monitor information of traffic flow on San Diego's metropolitanarea freeways. The information collected from these elements,such as speeds and volumes, are used for real-time monitoring, planning, and project development purposes.The first step in developing a concise and up-to-date database of the field elements is for Traffic Operations staff to provide spreadsheets with locations and other information of the field elements to the GIS Branch.

The output from the Postmile Toolbar is imported into a master File Geodatabase for Traffic Operations field elements. The Geodatabase contains a Feature Class for each of the field element categories. The Feature Attribute Tables are exported and provided to Traffic Operations for project delivery and databasemaintenance.

Maps created from the data are symbolized by the attributes of the field element.Map A displays all locations of exisiting VDS elements. It was used to perform a gap analysis to identify where new elements were needed.Map B displays the VDS by type and status of element: radar, loop detectors, ramp meters, or elements that are under construction. Map C displays the communication type: DSL, leased data line, fiber optic, cellular, XML, as well as the communication type of future elements.

The Traffic Operations Field Elements Geodatabase is an iterative and on-going project. As new technologyand monitoring sensors are added to the system, and the obsolete and inactive elements are removed, the Geodatabase is edited accordingly and updated mapping is developed.The process described here is periodically reviewed to ensure that database and mapping needs are being met in an efficient and effective manner.

District 11 GIS BranchJuly 2008Poster created by Barbara Kent for the 2008 ESRI International User Conference

3The File Geodatabase tables are processed through the Postmile Toolbar. The Postmile Toolbar is a customized ArcGIS Desktopapplication. The Toolbar enables users to create georeferenced features aligned to Caltrans roadways from tabular data formats. The tool is a linear referencing system with a four-step wizard interface. At a minimum, input data must include the county, route, and postmile of events. Any other attributes included with the input data are preserved in the output shapefle.

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