A Look at Road Network Management in Baton Rouge, Louisiana (LA)
This edition’s Q&A is with Warren Kron, GISP, GIS Coordinator, and Justin Priola, GISP, Senior GIS Analyst, of the City of Baton Rouge and Parish of East Baton Rouge (City-Parish), LA. They discuss the conversion of the City-Parish’s GIS road network to a linear referencing system (LRS).
Obtaining accurate data and information for your local roadway network is crucial for departments such as planning, public works, public safety, and 911 communication districts. It is not uncommon to have street name duplications, several address reference system baselines, and multiple jurisdictions to work with. Often times, there is not one single ‘source of truth’, and departments have to deal with incomplete unique identifiers, un-named private roads, and non-calibrated road networks.
The City of Baton Rouge and Parish of East Baton Rouge, Louisiana (City-Parish) like many local governments, stores and maintains street centerline data for all roadways located within its jurisdiction and is responsible for management and update of these data. This data exists within an Enterprise GIS framework and is accessible to all City-Parish GIS users. One of the primary data maintenance responsibilities of the City-Parish Planning Commission is the geometric aspects of the street segments and the associated attributes. Other City-Parish departments maintain related datasets that are specific to their needs. The geometric data is periodically updated when new development occurs, or when roads are realigned or reconstructed.
The centerline data is the geometric basis for various datasets pertinent to the road network. These data are used by municipal departments in the process of carrying out their functions. Emergency Medical Services, for example, relies on dependable centerline data in order to locate a caller in a time of emergency. This information is used to direct first responders to the location via the shortest route. The Department of Public Works uses centerline data to manage roadway characteristics such as right-of-way width, pavement type, and locations of manholes. Also, while the City-Parish maintains the majority of the streets, there are quite a few roads in East Baton Rouge Parish that are maintained by the State of Louisiana, one of the three incorporated cities, and private landowners. Regardless of the jurisdiction, data and characteristics of these roadways must be stored for reference purposes and for use by City-Parish departments.
Street data in the City-Parish Enterprise GIS data warehouse are stored as line segment geometry, where each centerline is a discrete roadway, and roads are broken where other roads meet or intersect. While most of the attribute data pertinent to streets can be stored on an intersection to intersection geometric format, a number of attributes cannot be efficiently stored in this manner. For instance, the beginning and ending of school zones can occur either at an intersection or midblock. The same can be true for changes in pavement type, speed zones, etc.
The original street data model did not meet the needs of various City-Parish users due to the shortcomings described above. This problem led to the development of duplicate sets of street data and geometries by various City-Parish departments to meet internal needs. These separate records were not synchronized with other departmental street records, nor were the street names consistent with the Planning Commission “Official Street Name List”.
To resolve this problem, a committee was formed in 2009 comprised of representatives from all pertinent local government agencies to review street attribute data collection practices, and to decide what data should be stored as an integral part of the street centerline geometry. During this process, it was explained that certain types of data required a more dynamic type of storage method which could be provided using the intersection to intersection geometries. To improve the way in which these data were stored, a recommendation was made to pursue the development of a Linear Referencing System (LRS) for the street centerline data.
In 2011, the City-Parish obtained funding through its partnership with the U.S. Army Corps of Engineers to initiate development of the LRS. In coordination with the contractor, extensive preparatory work was performed on the centerline data to ensure its geometric validity. The linear reference system allows Baton Rouge to put standards into place to create an official repository for both buildings and street names. As a result, analysts are able to validate street name and building permit databases. Also, during the quality assurance phase, the Planning Commission digitized all un-named private and public streets and assigned unique street name identification numbers to these segments.
To manage the LRS, the Planning Commission acquired a license of the Intergraph® Corporation desktop software product GeoMedia® Transportation Manager. GeoMedia® Transportation Manager is a data management tool optimized for maintenance and update of linear reference system centerline data. The finished product provides a powerful tool to effectively and efficiently manage accurate street data that meets the requirements of all end users.
One of the immediate benefits of the LRS includes better collaboration between the City and State departments of transportation. With the new system, the City-Parish can now collect and populate additional event tables such as traffic counts, pavement type, sidewalks, and signage. Also, it is very easy to perform periodic recalibrations to support asset and incident locations.
The LRS was originally developed as single level, as it was believed that ‘starting simple’ would minimize any issues that might arise during the data development process. In 2013, the Planning Commission decided that it was ready to ascend to the next level by establishing a multi-level linear reference system (MLRS) which will build on the success of the existing LRS.
Because the City-Parish spent significant time during the quality assurance phase, a single user can maintain the dataset. Previously, the only way to view much of the event data was in tabular format. With the LRS in place, this information can now be presented on a map using dynamic segmentation tools. This system has dissolved redundant datasets by creating one repository to store all street related attributes. As a result, there is improved inter-governmental collaboration, and an easier, faster, and most of all, accurate way to access street data. Today, the City of Baton Rouge is positioned to provide data to the Louisiana Department of Transportation and Development in a format that will meet the upcoming MAP-21 mandates.