Eugene Master Traffic Communications Plan

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4. COMMUNICATIONS NETWORK ARCHITECTURE & TECHNOLOGY OPTIONS A number of technology options are available to support the traffic communications network architecture for the City of Eugene. Chapter 5 of the Regional ITS Plan includes detailed descriptions of the various network components (e.g. backbone, distribution, local), network physical topologies (e.g. star, ring, mesh, hybrid), and technology options for each network component. This section includes a summary of the communications recommendations from the Regional ITS Plan, communications practices in the western U.S., and a description of the technology options most feasible for use in Eugene. 4.1 Summary of Regional ITS Plan Recommendations Chapter 5 of the Regional ITS Plan includes a summary of the communications requirements, alternatives, and high -level recommendations for the entire Eugene - Springfield metropolitan area. Recommendations of this plan include the following: • Use a two- tiered communications network that includes a robust backbone that allows data to travel in more than one direction and that is supported by a local distribution network. • Install a high -speed GigE backbone that includes a node in each TOC or main traffic system server location. Use a mesh configuration of communications corridors from the City of Eugene, the City of Springfield, ODOT, and Lane County to create data path reliability as shown in Figure 5 -16 of the Regional ITS Plan. • Install a local distribution network that connects field devices in a star or multidrop star configuration using RS -232 or Ethernet. Migrate RS -232 communications channels to 10/100 Mbps Ethernet as feasible. • Single mode fiber optic cable is the preferred technology at the plant level. Other communications alternatives to consider when installing new fiber optic cable is not cost effective: existing twisted pair copper plant, leased fiber optic plant from private providers or public entities (e.g. PAN), new wireless links, and leased wireless links. • Transmit video signals as IP video and use the MPEG -2 standard. 4.2 Communications Practices in the Western U.S. Other transportation agencies in Oregon, Washington, and California have been expanding and upgrading their traffic communications networks in recent years. The following is a brief description of common agency practices: • ODOT: ODOT uses a variety of hardwire, leased and wireless solutions to communicate with their traffic signals and ITS devices. In the Portland metropolitan area, ODOT has installed a significant amount of fiber optic cable on freeways to support communications to cameras, dynamic message signs and ramp meters. Where ODOT traffic signals are interconnected the most common medium used is twisted pair copper cable. However, some 900 MHz radio modems are used to provide interconnect. For rural ITS devices, such as weather stations, DMS, and count stations, ODOT is migrating from analog cell or dial -up modems to a leased wireless broadband service. Now that the ODOT freeways in the Portland metropolitan area have almost complete coverage, ODOT plans to upgrade communications infrastructure on arterial roadways and will likely use fiber optic cable for traffic signal interconnect. • Clackamas County (Oregon): Clackamas County has installed fiber optic cable and Ethernet communications on a major arterial roadway to support new CCTV cameras and video detection. The fiber optic cable connects directly to their TOC through a DKS Associates Eugene Master Traffic Communications Plan March 2008 ' Page 19