Architecture Elements

Image: ITS Architecture Elements



There have been several changes since the Southern California Regional ITS Architecture was first developed in 2005. The National ITS Architecture has been updated to reflect new user services, Southern California has continued as a national leader in ITS deployment with extensive ITS investments, and new technology applications have emerged. The 2011 update to the Southern California Regional ITS Architecture reflects changes since 2005 and positions the architecture to guide future ITS deployments as new technologies emerge.

Topics covered in the 2011 update include express lanes, positive train control, technologies in support of non-motorized transport, and goods movement in addition to the updates for other cross-county services such as to address traveler information, regional data exchange and archiving of regional data. Additionally, recommendations are made to subregional (county-level) ITS Architecture champions for their consideration in the event that changes are desired to be made at the county level for the associated topic. The Southern California Regional ITS Architecture leverages long standing investments in ITS by fostering coordination and cooperation among public agency stakeholders.

Data Exchange & Archive

Regional Traffic Management is an important cross-county service that involves the exchange of real-time traffic information. A significant number of vehicle trips in the SCAG region cross one or more county boundaries, highlighting the importance of coordinating network surveillance and information broadcast activities among the different traffic management centers in the region. Projects such as the LA County IEN, RIITS and PeMS highlight efforts to integrate regional traffic management control and information sharing. A brief overview of each project is provided below.

 
LA County IEN
The Los Angeles County Information Exchange Network (IEN) is a system developed by the Los Angeles County Department of Public Works (DPW) that shares information and control of traffic control systems (TCS) throughout the county. The system is interoperable with different TCS packages by using open architecture components such as a standard software interface to connect the TCS to the IEN. Agencies participating in the IEN can share and access real-time intersection data to support enhanced arterial traffic management, improve traffic operations along multi-jurisdictional corridors and coordinate emergency response. Through 2009, the TCS of eight cities are connected to the IEN backbone, with the IEN and the City of Los Angeles (LADOT) TCS exchanging data through a separate interface. An interface between the IEN and signals in the LA County DPW network is currently being planned.
 
RIITS
The Regional Integration of Intelligent Transportation System (RIITS) network is the core project within the LA County Regional ITS Architecture that integrates different sources of transportation data from multiple agencies. The RIITS network features interfaces with transit agencies, Caltrans districts, the California Highway Patrol (CHP) and LADOT provide a source of transit, freeway, and arterial-based travel information. The RIITS network distributes the data to users through a XML data feed. The RIITS network currently supplies data to the MATIS traveler information service, and other information services providers who distribute the data to the public through a variety of applications. Future plans include new data interfaces with Caltrans Districts in neighboring counties and the Los Angeles County IEN.
 
LA Metro is currently developing an Archived Data Management Service (ADMS) that that will capture real-time data transmitted through the RIITS network. Ths ADMS will store three years of historical data for all modes of transportation from the various participating agencies. The ADMS database could be will be used to monitor system performance, support regional and corridor-level planning efforts and provide input for project funding applications. The ADMS is expected to support the MATIS program and support performance evaluation for future Express Lanes operations.
 
PeMS
The Freeway Performance Measurement System PeMS is a program that was developed jointly by the University of California at Berkeley and the California Department of Transportation to collect historical and real-time freeway data from the various freeway management systems in Caltrans for performance measurement calculations. PeMS is the primary tool for collecting data from loop detectors embedded into the freeway pavement on facilities across the state. The loop detector data is transmitted from Caltrans district traffic management centers over the Caltrans WAN to the PeMS host server which aggregates the data and provides performance measurement tools to review the data on its website. Additional interfaces include information from the CHP computer aided dispatch system (CAD) on incidents and lane closures, Caltrans District CMS messages, and FasTrak readers that report travel time on Bay Area toll facilities.
 
Real-time and historical traffic data can be accessed from the PeMS web portal for roadways in the SCAG region. Freeway data is collected and distributed by the District 7, 8 and 12 traffic management centers. A limited amount of arterial traffic data is available for the City of Los Angeles and the County of Los Angeles.

To learn about data exchange and archiving services in the region, view the information in the Existing and Planned Cross-County Services document and associated Turbo Architecture file.