An Eye Toward the Traffic of Tomorrow

Every day, the city of Irvine experiences a population explosion. The city's population of 160,000 nearly doubles as people commute into this California city to work. The city is committed to reduce traffic congestion by using the latest in traffic management control technology.

"We have certain goals, and one key goal is to achieve and maintain an advanced traffic management system to reduce traffic congestion and make traffic flow at peak performance," said Richard Nelson, the city's senior transportation analyst.

The city's goal for its traffic management system: transmission of TCP/IP over a data network that uses Ethernet technologies to transfer data in real- time. The key is that all transmissions are over the same city-owned data network, allowing for real-time communications.

This is a long way from the original system where half a dozen different types of systems--all using different pathways or links--communicated back to the operation center.

"This was a cumbersome system with two sets of communication--one set brought back the signal; the other set returned the control," Nelson explained.

Because one data network takes care of all the transmissions to and from the traffic signals it is actually easier, less complex and less expensive to maintain.

The city's traffic management system began as a basic video surveillance system and has evolved to a comprehensive architecture designed to incorporate all forms of ITS communication on a common, fault-tolerant, open standards platform. As part of the planned evolution of the system hardware, the city selected Optelecom's modular system 9000 to provide the fiber-optic video communication function.

"Optelecom has been willing to work with us to develop new technology for our traffic management system," Nelson said.

Nelson said that the hardware has virtually no delay in camera function and movement. In addition, a lot of video compression equipment requires a computer. The manufacturer offers a stand-alone system so the city does not need an actual PC for each video stream it compresses, explained Nelson.

"Our commitment is to work with the city of Irvine officials to support their efforts to continually improve the city's traffic management system," said Optelecom President and CEO Edmund Ludwig. "Our products offer significant advantages that are ideal for traffic management systems," he added. For example, the equipment is modular, meaning that users can plug in the cards to a standard chassis. The cards are rugged to withstand the demanding environments of traffic control. In addition, the equipment allows the city to monitor the health of the network equipment. 

Traffic management system

The core of the traffic management system is a network capable of dissemination of comprehensive information, including real-time video, from multiple sites to multiple clients to report on citywide road conditions and allow remote actions which will reroute traffic to maintain maximum flow.

"We are incorporating the technologies that are available today into our traffic management system," said Nelson.

The ultimate system will include up to 200 cameras providing MPEG 2 and MPEG 4 multicast digital video over a fiber-optic gigabit Ethernet network using an IP format. The system includes a PC application-based camera selection and control system accessing individual camera sites by IP address. Incorporating the traffic control signal system into the Ethernet IP network will achieve the ultimate goal of a unified system concept. This concept will operate with open standard communications protocol for an "anywhere, anytime" capability.

The city's traffic management system is in three phases, or generations of development, explained Nelson. The city is in what Nelson calls Phase II of the plan. This phase calls for installing switches in traffic cabinets and using an Ethernet mesh to connect all the switches together. This connects all the components in the city's traffic control system.

Part of an $11 million project is to update the city's traffic management system. The project includes updating controllers, cabinets, switches in cabinets and converting the system to a data network. The city will eventually use hub points to connect cameras, signal control, CCTV and changeable message signs.

Last year the city updated its 10-year-old Traffic Management Operational Study. The 500-page update outlines the city's future goals for its traffic control system. "Technology and how to implement technology in our traffic management system are key goals in our plan," explained Nelson, who has 22 years of experience in the city's traffic management area.

Where it started

Irvine is a relatively new city, incorporating in 1971 from mainly farmland. The city had little existing infrastructure. With its rapidly expanding population, most public services were created from a small base. Today, the city covers 46 square miles, with an extensive road system, including several highways which bisect the area.

The city's commitment to traffic management started in 1978 with traffic controllers communicating over twisted-pair copper. At first the system grew slowly as the city would gradually add controllers at key intersections as the city infrastructure expanded. For more than 10 years, the city relied mainly on inductance loop detectors installed at intersections to control traffic flow.

In 1991 the city undertook an ambitious program to construct a leading-edge traffic management system beginning with the installation of two CCTV cameras transmitting analog video over six miles of optical fiber cable.

The following year, the city built the Irvine Traffic Research and Control (ITRAC) center. It serves as the traffic control center and as a lab for future system research. ITRAC also displays live video from CCTV cameras at monitored intersections on a video monitor wall. The city gradually enhanced and updated the video system, adding analog video multimode fiber links, feeding point-to-point video into hub sites.

With this system, a central video matrix switch located at the ITRAC center provided a method to select and display specific video information on individual monitors. Where fiber optic cable was not yet available, video feeds were transmitted over twisted-pair copper cable.

As the city expanded its traffic control system, adding video, CCTV control, changeable message signs and traffic control signals, all were configured to operate over separate communication paths.

Although the limitations of this system became apparent over time, it served the city until 1998. At that time, a more "network centric" concept was necessary to provide the flexibility to expand and reconfigure the system as more advanced traffic control concepts evolved.

Since 1998, the city has implemented a more advanced and partially network-based system. This system overcomes some of the limitations of the first system and also provides higher quality video content, better system availability through the use of fault-tolerant links and the ability to place cameras anywhere in the city. The current system incorporates over 95 miles of multimode and single-mode fiber.

These cables connect over 66 CCTV cameras to a central video matrix switch. Multimode video links and new Optelecom uncompressed digital video units have been installed around the city. The city kept its legacy microwave link and added new wireless links. The wireless equipment provides a similar function as the microwave, with the added benefits of lower cost, easier installation and greatly simplified licensing that is not tied to a site or pathway.

With this system, CCTV, camera control and other communications are combined on the same fiber, a capability provided by the new digital equipment, increasing the capacity of the existing fiber-optic cables.

The city also has installed, in addition to inductance loop detectors, video detection at selected intersections. The city has five changeable message signs at various locations in the city. Ethernet conversion technology links the signs to ITRAC.

The future of traffic control

The future system includes merging all communications streams--video, camera control, traffic control signals, along with other ITS functions--onto a common network as a pure digital data stream. One requirement is that all legacy analog functions be converted to a compatible digital format. The network must be fault tolerant and provide the capability of accessing, monitoring and controlling from any nodal point. The system requires a significant increase in traffic capacity or bandwidth to accommodate the greatly expanded use of CCTV cameras.

This system is operating in parts of the city. The test configuration is digital, switched Ethernet system architecture with Optelecom pluggable MPEG 2 compressed digital video encoders, decoders and IP Network Interface Cards using standards transmitted with IP protocol for system-wide compatibility with all network elements.

In the new system, every traffic signal cabinet has an Ethernet switch. The entire camera control and traffic signaling system will be integrated into the Ethernet data stream using IP protocol, so all traffic management functions are converged into a common switched network. In its ultimate form, fiber cable will be installed to every traffic signal cabinet which is more than 170 miles of cable. From each traffic signal location, a real-time MPEG 2 or MPEG 4 multicast video stream will be transmitted using IP protocol to the ITRAC center or any networked station. Up to 200 CCTV cameras will be connected to the network, and no central video matrix switcher will be necessary since each signal source can be accessed through its IP address.

The city will accomplish CCTV control by using a PC application program, using once again the IP address. Gigabit Ethernet links will be established between data node sites to replace the ATM backbone, 100 Base-FX links will connect each traffic signal cabinet, traffic signal controllers will be Ethernet capable. PCs will be used to access and control the entire system.

Digital video compression is essential to any practical network video distribution concept, explained Ludwig. When the city's system is complete, it will require over 1.3 GBps bandwidth capability. Future growth may require a 10 GBps bandwidth level. At this level, the city also will need to improve its switching and data node equipment.

With any network implementation, the city did experience difficult integration problems. The city has found the ITRAC environment useful to allow real-time comparison of different scenarios using a live traffic environment in an off-line laboratory setting.

"This approach will greatly enhance the chance of success in introducing this new network concept into the traffic management community," said Ludwig.

Nelson continually looks to what the future will bring to the city's traffic management system. "A traffic management system is never complete," he said.

"We have set our goals, but with traffic management, it is always a moving target," explained Nelson. "We will continue to research the best possible options that are available in traffic control.

"Our goal is to have an even more intelligent traffic control system, eventually adding true adaptive control," he said. Over the next three years, the city will transfer 84 signals a year to the new traffic control system. In five years, the city's new traffic control system will be in place, all working over the city's network.

As the city continues to grow, so will its traffic control. Currently the city has 264 intersections. Over the next 15 years, this is expected to increase to 460.

Although it's a challenging environment to keep pace with technology and the city's growth, according to Nelson, the key to success is simple: Have a good plan and focus on your goals.             TME