Ethernet Communications to ITS Equipment

1. Ethernet Communications to ITS Equipment System Change Request for New Alternative May 11, 2004 Teresa Krenning, MoDOT Luis Porrello, HNTB Dan Gibbons, NET

2. Introduction • MoDOT would like to enhance the ITS communications system by incorporating technologies that have become recently available to the ITS arena.

3. Introduction • These new technologies provide an opportunity for the use of Ethernet communications to devices, an option that was not available to previously designed and constructed ITS deployment efforts in the State of Missouri.

4. Introduction • The requested alternative would provide enhancements to system: • Reliability • Flexibility • Maintainability • Cost-effectiveness

5. Introduction • To minimize the risk of oversights and incompatibilities, the optional communications approach was developed and tested in accordance with system deployment methodologies: • Concept • Requirements • Design • Implementation • Unit Testing • System Testing • Operations

6. Description of Requested Option • Current system: All field equipment except loop detectors uses EIA-232 serial communication • Proposed option: all field equipment except loop detectors will use Ethernet communication • Note: In both systems the central computers and the trunk communication system that carries the data to and from the field currently use an Ethernet interface

7. Description of Requested Option • Serial communications approach requires intermediary devices (e.g. FTCs) in the proximity of a cluster of devices that communicate with the central computers via an Ethernet interface, and communicate with the camera controllers, dynamic message signs, and out-of-pavement vehicle detectors via EIA-232 serial interfaces. • FTCs have contact closure interfaces for communication with loop detectors. • The proposed system will also use FTCs for interfacing with loop detectors that may be incorporated with arterial projects and with future devices that may require the FTC as an intermediate device.

8. Description of Requested Option

9. Items Affected • CCTV camera controllers that use the Cohu proprietary communication protocol • Radar-type vehicle detectors that have EIA-232 interfaces and use the Electronic Integrated Systems proprietary protocol • Dynamic message signs that use the National Transportation Communications for ITS Protocol (NTCIP)

10. Enhancements: Reliability • Less frequent use of intermediary devices eliminates a number of possible failure points • Use of Ethernet communications permits a backup communication path to each ITS device and the use of spanning tree protocols to route packets over the backup path when the primary path is severed

11. Enhancements: Flexibility • Install stand alone subsystems without the expense and delay of developing new software for intermediary devices or their associated central computer

12. Enhancements: Maintainability • Reduce the number of intermediary devices • Eliminating the need for excessive record keeping, research, and guesswork concerning fiber usage • Enable MoDOT to use the same network management tools for its metropolitan area network that it uses for its local and wide area networks

13. Enhancements: Cost Effectiveness • Reduction in the required number of intermediary devices • Reduction in expected maintenance over a longer period of time • Partially offsetting these savings is the cost of modifying those parts of the ATMS central software that provide communications to the front-end processor

14. Risk Assessment - Equipment • Cameras • Out-of-pavement detectors • DMS • Weather Stations • Traffic Controllers • GPS • Device Servers • Ethernet Switches

15. Risk Assessment - System

16. Risk Assessment - System • Concept: Alternative approach would be compatible with the changes MoDOT is initiating in the Gateway Guide communication backbone (ATM to IP over SONET) • Requirements: General agreement was reached by all parties on the conceptual design of the alternative approach • Design: All parties confirmed that the design was the appropriate to act on

17. Risk Assessment - System • Implementation: A prototype model was constructed that represented the nature of the designed system • Unit Testing: The testing did not reveal any type of equipment for which an acceptable device could not be found • System Testing: The model demonstrated the high reliability that had been expected

18. Risk Assessment - System • Operations: Moving into the operational phase awaits a decision by the Management and Operations Configuration Board to allow the Ethernet device communication option

19. Architectural Enhancements – Current System

20. Architectural Enhancements – Proposed System

21. Architectural Enhancements – Proposed System • Redundant path • In the point to point approach, a single point of failure is created and a great number of fibers is used • In the last mile Ethernet approach, daisy chaining allows the switches to speak with either hub. In the event of a hub failure, or fiber cut, the 2955s simply reverse the direction of data transmission to the active hub. In this fashion, the impact of single point failures is limited to the devices at the location of the failure.

22. Architectural Enhancements – Proposed System

23. Cost Comparison Gateway Guide Using Current Architecture – Scenario Cost Assessment

24. Cost Comparison Gateway Guide Using Proposed Enhanced Architecture – Scenario Cost Assessment

25. Conclusions • The requested alternative would enhance the reliability, flexibility, maintainability and cost-effectiveness of the ITS communications system

26. Conclusions • The requested alternative has endured unprecedented testing and analysis to insure system compatibility

27. Conclusions • The requested alternative represents consensus among a number of internal and external stakeholders as an enhancement to the current communications approach