Architecture Elements

ITS Infographic

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.


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.


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.


Express Lanes

A system of High Occupancy Vehicle (HOV) lanes has been an integral part of the California freeway system for the past 30 years and express lanes have been an innovation that have been implemented in the past 15 years. Currently, neither the Regional ITS Architecture nor most of the county architectures address HOV lane management and/or electronic toll collection – the foundation of express lane operations.

Express lanes have been regarded as a localized service with projects deployed within individual counties in Orange and upcoming in Los Angeles and Riverside. The success of the 91 Express Lanes is paving the way for more projects throughout the state and across the country. The movement toward more express lanes – both from the perspective of being interconnected and crossing county boundaries in the near future makes this a critical, multi-county issue

To learn more about express lane services in the region, view the information in the Express Lane Regional ITS Elements and Recommended Express Lane Subregional ITS Architecture Elements documents.


Active Transportation

Non-motorized transportation provides a sustainable alternative to the impacts associated with driving. Switching automobile trips to biking and walking improves mobility and air quality. In the SCAG region, the mode share for non-motorized work trips is 3% while the share of all trips is 12%. Non-motorized transportation in the region is supported by land use decisions that promote bike and pedestrian friendly development and facilities that provide pathways and trails for bicycle and pedestrian users. Cities and county transportation agencies in the SCAG region have planned and built a regional bicycle transportation network. The networks consist of off road (Class I) and on-road (Class II and Class III) facilities that interface with transit routes and pedestrian activity centers. Several counties in the SCAG region maintain a non-motorized transportation plan to designate locations for existing and planned bikeway, bike facility improvements and policies to accommodate the needs of cyclists and pedestrians.

Currently, the National ITS Architecture does not recognize any user service specific to non-motorized transportation and does not address individual technologies. In addition, most pedestrian and bicycle projects are locally deployed and are not generally addressed in a regional architecture. The 2011 update to the Regional ITS Architecture will make recommendations for updates to the sub-regional architectures.

To learn more about non-motorized services, view the information in the update document, Non-Motorized Transportation ITS Elements.


Traveler Information

In the SCAG region, the public can access a wide array of traveler information services by dialing 511 or going online. The two regional traveler information providers offer a one stop solution for anyone looking for real time traffic conditions, transit information or help planning their next trip.

The Southern California Go511 service provides multi-modal traveler information to through a 511 interactive voice response (IVR) system and the web portal. Go511 is operated by LA SAFE and provides traffic information for Los Angeles, Orange, Riverside, San Bernardino and Ventura counties. Traveler information services available include drive times and freeway speeds, road construction and incident notices, transit schedules, carpool/vanpool matching, trip planners, and real time transit departure times.

The Riverside County Transportation Commission (RCTC) and the San Bernardino Association of Governments (SANBAG) formed a partnership to develop a 511 system dedicated to the Inland Empire. The public can access the Inland Empire 511 traveler information service by dialing into the 511 IVR system or going online at Traffic coverage includes Los Angeles, Orange, Riverside, San Bernardino and San Diego County.

Callers in the region dial 511 to access either service; callers dial the same 511 number and are transferred according to the originating area code for landline users or the location of the receiving cell phone tower for mobile users.

Traveler information services integrate multiple sources of ITS data, supported by information flows and coordination between many agencies. In addition to the 511 phone and web site outlets, data feeds are available to third party information service providers. Sources for real-time data include RIITS (District 7), Caltrans Traffic Management Center (District 8 and District 12), the Caltrans Lane Closure System portal, California Highway Patrol CAD and numerous transit operators.

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



SCAG is home to an economic base that is among the world’s largest producers of goods and services. Regional economic activity depends on an extensive transportation system, highlighted by a sprawling network of seaports, airports, and thousands of miles of freeways, bridges and roads. The region is susceptible to natural disasters such as earthquakes and fires, in addition to potential targets for terrorist acts. In an emergency event or attack, the transportation system plays a critical role in evacuation and delivery of aid.

The Safe, Accountable, Flexible, Efficient Transportation Equity Act (SAFETEA-LU) requires metropolitan planning agencies (MPOs) to incorporate emergency preparedness and security in regional transportation planning.

SCAG works with federal, state and local stakeholders to facilitate coordination and increase situational awareness for regional emergency preparedness and security. SCAG actively promotes the Southern California Regional ITS infrastructure as an important tool in improving the capability of government agencies to protect vital infrastructure and respond effectively to emergencies and disasters. Agencies that plan and develop their projects in accordance with the regional ITS Architecture ensure that individual projects can work together, enhancing the ability for agencies to coordinate response and preparedness by sharing information seamlessly. ITS elements of the transportation system can be leveraged for emergency response and preparedness activities.

As part of the 2008 RTP process, SCAG updated the 2004 Regional ITS Architecture to incorporate security elements. The security update to the architecture establishes a framework for deploying ITS to support emergency preparedness and response and protecting critical infrastructure. Planning and developing ITS projects in accordance to the regional architecture will help ensure that the project enables coordinated operations and information sharing among the many different agencies that respond to incidents, emergencies and threats.

To learn how the Southern California Regional ITS Architecture addresses emergency management and security services, view the information in the 2008 Southern California Regional ITS Architecture Update for Transportation Security report and the Security Supplement Turbo Architecture file.


Positive Train Control

The Southern California Regional Railroad Agency (SCRRA) that operates the Metrolink regional commuter rail plans to implement a positive train control (PTC) system by 2012, ahead of the deadline set for the end of 2015. Implementation of the PTC system is required by the Rail Safety Improvement Act (RSIA) of 2008. The RSIA requires all Class I railroads, intercity passenger and commuter railroads to implement a PTC system on all main-line tracks where intercity passenger railroads and commuter railroads operate and where toxic-by-inhalation hazardous materials are transported.

The five county members of the SCRRA are jointly funding the development of an interoperable PTC system to improve safety for freight and commuter railroads in the region. PTC is designed to prevent train collisions using GPS tracking to remotely monitor train movements. In a typical PTC system, onboard equipment on the train uses GPS satellites to transmit speed and location data over wireless or hard line communications links to an operations center. A back office system at the operations center analyzes the data using software that determine the likelihood of a collision or derailment. An advance alert is sent by the dispatch center to the locomotive and brakes are automatically engaged if the warnings are not acted on by the train engineer. Federal regulations does not prescribe the type of technology a PTC system uses as long as it can accomplish the following functions: preventing train-to-train collisions, derailment from over speeding, incursions into designated work zone areas and train movements caused by switches left in the wrong position.

To learn more about the implementation of PTC services in the region, view the information in the following update documents: Positive Train Control History and Plans for Deployment; Positive Train Control Regional ITS Architecture Elements; and Recommended Positive Train Control Subregional ITS Elements.