University of Idaho National Institute for Advanced Transportation Technology

Transcription

1 ADVANCED ACCESSIBLE PEDESTRIAN SYSTEM KLK266 Final Report University of Idaho National Institute for Advanced Transportation Technology Dr. Richard W. Wall June 2014

2 1. Report No. 2. Government Accession No. 4. Title and Subtitle Advance Accessible Pedestrian Systems 3. Recipient s Catalog No. 5. Report Date June Author(s) Wall, Richard W. 6. Performing Organization Code KLK Performing Organization Report No. N Performing Organization Name and Address 10. Work Unit No. (TRAIS) National Institute for Advanced Transportation Technology University of Idaho 875 Perimeter Dr. MS0901 Moscow, ID Sponsoring Agency Name and Address Mr. Phil Tate Campbell Company 450 W. McGregor Dr. Boise, ID Supplementary Notes: 11. Contract or Grant No Type of Report and Period Covered Final Report: September 2008 June Sponsoring Agency Campbell Company 16. Abstract: A networked based Accessible Pedestrian Systems (APS) was developed over a period of 10 years in conjunction with $1.2M funding through Federal, Idaho State, and private industry grants and contracts. The system is based on the Smart Signals enabling technology that uses modern distributed processing concepts to form a spatially dispersed information and control system. The development process followed the spiral design methodology typically used for innovative and new designs where complexity and functionality is added in iterative cycles of propose, assess, design, and evaluate phases. A complete system was designed that is currently being manufactured and distributed by Campbell Company of Boise, Idaho. The engineering designs for a second generation of Smart Signals APS have been completed that enhance the capabilities of the first generation while reducing manufacturing and installation costs. Nine graduate students worked on this project of whom three are currently working in the traffic control industry. Technical descriptions of the two systems are provided in report appendices. 17. Key Words: Pedestrian, Accessible, Traffic Controls, Distributed Systems, 18. Distribution Statement: Unrestricted; Document is available to the public through the National Institute for Advanced Transportation Technology; Moscow, ID. 19. Security Classif. (of this report) Unclassified 20. Security Classif. (of this page) Unclassified 21. No. of Pages Price Form DOT F (8-72) Reproduction of completed page authorized

3 TABLE OF CONTENTS FIGURES... ii TABLES... iii EXECUTIVE SUMMARY... 1 ACKNOWLEDGMENTS... 3 DESCRIPTION OF PROBLEM... 4 APPROACH AND METHODOLOGY... 6 FINDINGS... 9 PHASE I: ADVANCED ACCESSIBLE PEDESTRIAN SYSTEM DESIGN... 9 PHASE II: TECHNOLOGY TRANSFER PHASE III: ADVANCED ACCESSIBLE PEDESTRIAN SYSTEM REDESIGN CONCLUSIONS RECOMENDATIONS APPENDIX APPENDIX A - Record of AAPS Funding APPENDIX B AAPSI System Specifications APPENDIX C AAPS I Hardware and Software Reference Manual General Information AAPS I - A Networked Based APS System - Theory of Operation AAPS I System Architecture The Advanced Pedestrian Controller The Advanced Pedestrian Button AAPS I Communications Network Communications AAPS I Hardware Documentation APPENDIX D - Review of Initial Test Field Installation APPENDIX E - AAPS II Technical Description AAPS II Advance Pedestrian Coordinator AAPS II Advanced Pedestrian Button (APB) REFERENCES ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS i

4 FIGURES Figure 1. Spiral Design Model... 7 Figure 2. AAPS I System Block Diagram Figure 3. AAPS II Block Diagram Figure 4. Advanced Accessible Pedestrian System Block Diagram Showing Direct Wire Interface with NEMA TS1 and TS2 Type 1 Traffic Controllers Figure 5. AAPS Block Diagram Showing Direct Wire Interface with NEMA TS2 Traffic Controllers Figure 6. AAPS I System Block Diagram Figure 7: Block Diagram of Advanced Pedestrian Coordinator Figure 8: Block Diagram of Advanced Pedestrian Button Figure 9. Partial NTCIP Standards Framework Figure 10. Installation of the AAPS I at 6th and Deakin Streets in Moscow, ID Figure 11. ATMEL NGW100 with AVR32 Processor and Linux Operating System Figure 12. Picture of APC I PCB Side A Figure 13. Picture of APB I PCB Side A Figure 14. Picture of APB PCB Side B Figure 15. Climate Conditions during the Initial Minnesota Field Installation Figure 16. Minnesota Installation Activity Figure 17. AAPS II APC Block Diagram Figure 18. APC II Communications and Power Supply Module Block Diagram Figure 19. AAPS II Communication Unit Printed Circuit Board Figure 20. AAPS II Cabinet Interface Module Block Diagram Figure 21. AAPS II Cabinet Interface Unit Parts Layout Side A Photo Figure 22. AAPS II Cabinet Interface Unit Parts Layout Side B Photo Figure 23. Front Panel Display Used for AAPS I and AAPS II Figure 24. AAPS II Accessible Pedestrian Button Block Diagram Figure 25. AAPS II ABP Printed Circuit Board - Side A Photo Figure 26. AAPS II ABP Printed Circuit Board - Side B Photo ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS ii

5 TABLES Table 1: Intersection OID Definitions Table 2: Station Trap OID Definitions Table 3: Configuration OID Definitions ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS iii

6 EXECUTIVE SUMMARY Even though there is no age, physical capability, or degree of cognitive ability limitations, the pedestrian represents the user of signalized intersections who is the most at risk. The Americans with Disabilities Act (ADA) of 1990 recognizes that people with physical limitations that require a social infrastructure that allows for independent and low cost travel. Not until the 2000 edition of the Federal Highways Manual for Uniform Traffic Devices were the needs of handicapped pedestrian addressed. Traffic industry manufacturers began to manufacture systems known as Accessible Pedestrian Systems or APS. The first systems required special interfaces with the pedestrian signals to determine the state of the WALK and WAIT signals. In 2004, research at the University of Idaho began that looked at new ways of operating traffic signals. The new approach is comparable to the way in which we used to use computers one large centralized office computer versus many smaller computers distributed over many desks. The new approach is known as Smart Signals where the traffic control logic is distributed around to the signals themselves. The pilot demonstration targeted the APS controls initially because of the perceived low risk of the research. In 2008, a UI researcher contacted a pedestrian manufacture, Campbell Company of Boise, Idaho, and they formed a research association to develop a Smart Signals based APS system. In 2010, the first system was field tested in St. Paul, Minnesota. Subsequently, over 400 intersections have been equipped with Smart Signal based APS. The research project is the culmination of ten years research activity and over $1.2M funding from Federal, State, and private industry. This report discusses the iterative spiral design method used to develop the innovative APS. The research was completed in three phases in which two systems were produced. The second system is an enhanced version of the first. In the process, nine students received their Masters degrees and over 20 undergraduates participated in the research project. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 1

7 Information in the appendix of this report documents some of the design details to provide a sense of the scope of engineering required. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 2

8 ACKNOWLEDGMENTS We wish to thank the employees and management of Campbell Company for their funding support, technical advice, and hosting many of the pedestrian workshops. We are also thankful for the technical guidance we received from Gary Duncan of Econolite Controls, Inc. and Scott Evans of Eberle Design, Inc. We also acknowledge the assistance and office support by the staff with the University of Idaho NIATT center. We wish to also thank the University of Idaho Department of Electrical and Computer Engineering for the technical support in the construction of the electronic circuit boards developed under this research grant. Finally, the principle investigators wish to thank the graduate and undergraduate students who spent many hours bringing the designs to fruition. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 3

9 DESCRIPTION OF PROBLEM Traffic signals are society s solution to allocation of a shared scarce resource. At most urban and intercity signalized intersections, vehicles and pedestrians must use a common surface area known as the traffic intersection. The conflict that results has been long recognized as demonstrated in this statement in the Federal Highway Signal Timing Manual: The amount of time in an hour is fixed, as is the fact that two vehicles (or a vehicle and a pedestrian) cannot safely occupy the same space at the same time [1]. It is well acknowledged that the pedestrian is the party at greatest risk in a vehicle-pedestrian crash. The Center for Disease Control (CDC) reports: In 2010, 4,280 pedestrians were killed in traffic crashes in the United States, and another 70,000 pedestrians were injured. This averages to one crash-related pedestrian death every 2 hours, and a pedestrian injury every 8 minutes. Pedestrians are 1.5 times more likely than passenger vehicle occupants to be killed in a car crash on each trip [2]. One needs to consider the fact the CDC webpage reports that the state of Montana reported a higher death rate per 100,000 population higher than Illinois. If the pedestrian has vision impairment, the crash statics indicate a much higher risk. A National Cooperative Highway Research Program (NCHRP) report states In the ACB survey (of vision impaired pedestrians), 12 of 158 (8%) of respondents had been struck by a car at an intersection, and 45 (28%) had had their long canes run over [3]. Why is pedestrian travel so inherently dangerous? One explanation could lie in the difference in energy possessed by the pedestrian and the vehicle as well as their ability (or inability) to absorb that energy should they collide. The only viable solution is to avoid pedestrian-vehicle crashes altogether. Regardless of liability or right-of-way, the pedestrian who is at the greater risk of injury, is obligated to assume the higher degree of awareness to avoid crashes. The purpose of accessible pedestrian signals is, in part, to provide information to the pedestrian in making safe decisions before entering the danger zone known as the crosswalk. Accessible Pedestrian Systems (APS) are designed to address the legal requirements of Americans with Disabilities Act of 1990 [4]. The 2009 Manual for Uniform Traffic Control Devices (MUTCD) Section 1A.13 [5] defines an accessible pedestrian signal as being a device that communicates information about pedestrian signal timing in non-visual ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 4

10 formats such as audible tones, speech messages, and/or vibrating surfaces. An APS detector is defined as a device designated to assist the pedestrian who has visual or physical disabilities in activating the pedestrian phase. The research provided by this contract resulted in an advanced APS designed to provide all pedestrians regardless of ability or disability with a safer crossing at signalized intersections. From the initial concept, the Advanced Accessible Pedestrian System (AAPS) was focused on producing hardware that would be installed at signalized intersections in conjunction with traffic controllers. This system has both a customer and a user. The customer is responsible for purchasing, installing and maintaining the system. The user is the person who operates the system. The design objectives embraced by this research project addressed the needs and wishes of both groups: the customer wants a system that is affordable and easy to maintain while the user wants a system that provides safe access to the intersection crosswalk. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 5

11 APPROACH AND METHODOLOGY The overall goal of this research project was to develop an APS based upon Smart Signal technology. During the course of this project, numerous technological solutions were investigated and evaluated on the basis of performance, cost, reliability, and sustainability. This research project spanned a period of ten years using both government and private sources to provide the $1.2M funding as detailed in Appendix A. The ten years of development is divided into three phases: the initial system development, technology transfer, and system refinement through redesign. Appendix B contains the initial statement of work that was granted by Campbell Company through June 30, Smart Signals is a term used to describe the application of network based distributed control technology to the control of traffic signals at signalized intersections. Presently, signalized intersections use a centralized control approach where all of the control actions are initiated by a single computer-based device located in a traffic equipment cabinet. Dedicated wires are used to turn signal lights on and off. The Smart Signals paradigm uses microprocessors located in the signals to distribute the control intelligence. This approach has the advantage of local control with performance enhancement due to information obtained through communications with a distributed sensor system. As applied to accessible pedestrian systems, each pedestrian button is responsible for providing the safest operations for the pedestrian regardless of connectivity with other elements of the intersection control. In this paradigm, each pedestrian station is an autonomous master controller with other pedestrian stations and the coordinator that monitors the status of the traffic signals serving as smart sensors. Each device performs an element of the pedestrian interface with the traffic signal controller as well that of a smart sensor hence the nomenclature of smart signals. It will be shown that the resulting design descriptions of the AAPS follow this distributed control philosophy. The design approach for the development of the AAPS followed the spiral design process first proposed by Boehm [6] that is applicable for the development of new products ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 6

12 and systems. This design approach uses an iterative cycle of four activity phases as illustrated in Figure 1. Figure 1. Spiral Design Model This design approach uses risk assessment to guide product capability which is in contrast to the waterfall design approach that is a single pass development cycle that often results in time and cost overrun [7]. The spiral design methodology uses the six following underlying assumptions that were followed in the design of the AAPS: 1. The requirements are known in advance of implementation. 2. The requirements have no unresolved, high-risk implications, such as risks due to cost, schedule, performance, safety, security, user interfaces, organizational impacts, etc. 3. The nature of the requirements will not change very much during development or evolution. 4. The requirements are compatible with all the key system stakeholders expectations, including users, customers, developers, maintainers, and investors. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 7

13 5. The right architecture for implementing the requirements is well understood. 6. There is enough calendar time to proceed sequentially. Functional requirements were established with the aid of manufacturing experience of Campbell Company using the basic requirements of an APS as set forth in the Chapter 4E of the 2009 MUTCD. Five workshops were conducted over the course of this project to inform and solicit input from public users, equipment manufacturers, traffic agency professionals, and researchers. The feedback from these workshops as well as frequent discussions with Campbell Company employees, traffic agency engineers, and pedestrian advocate groups through Transportation Research Board (TRB) meetings resulted in additional requirements for performance and capability. The United States Department of Transportation (US DOT) University Transportation Centers (UTC) research projects, that were the major source of funding for the development of the AAPS, required annually establishing goals and assessing results. The UTC project funding cycle fit well into the spiral design model. Because of previous design experience, the faculty who worked on this project was responsible for a majority of the system architecture and hardware design. Staff provided most of the hardware fabrication and assembly. Students were responsible for developing a majority of the system computer code. The mission of the University of Idaho is stated as The University of Idaho is the state s land-grant research university. From this distinctive origin and identity comes our commitment to enhance the scientific, economic, social, legal, and cultural assets of our state, and to develop solutions for complex problems facing society. Our teaching and learning includes undergraduate, graduate, professional, and continuing education offered through both resident instruction and extended delivery. Our educational programs are enriched by the knowledge, collaboration, diversity, and creativity of our faculty, students, and staff [8]. The research funding was used to provide financial assistance to the undergraduate and graduate students who provided technical services relating to the engineering design of the AAPS. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 8

14 FINDINGS The AAPS designs resulted in proprietary custom hardware and many tens of thousands of lines of computer code. The system is a true distributed computing platform that provides processing capability as physically close to the actuators and sensors as possible. The result being improved service reliability and reduced infrastructure cost for implementing APS capability at new and existing signalized intersections. The softwarebased system is extensible allowing the system capability to be adapted and expanded to suit future requirements as well as incorporate future pedestrian interfaces. Appendix C and E provide a more detailed description of the hardware that was developed, fabricated, and tested as part of this project. Because this is a software based system, the program code is not reported except in abstraction that describes the system functionality. Proprietary engineering documentation is also excluded from this document to protect the licensee of this technology. PHASE I: ADVANCED ACCESSIBLE PEDESTRIAN SYSTEM DESIGN A block diagram of the AAPS I system is shown in Figure 2. The AAPS I hardware represented by the yellow rectangles consists of an Advanced Pedestrian Coordinator (APC) that is installed in the traffic controller cabinet and multiple Advanced Pedestrian Buttons (APB) installed at each crosswalk entry as specified by the MUTCD. The APC monitors the 120 VAC outputs to the pedestrian signals to determine their status. The signal status is communicated to all of the pedestrian stations where the APBs are located using the communications provided by the low voltage Ethernet over Power line (EoP) network. Each APB operates independently to determine the outputs to the local LED, the vibrotactile actuator, and the audible message that is played. When a pedestrian presses a button at the intersection crosswalk, a message is immediately sent to the APC that in turn activates one of the PED CALL inputs to the traffic controller. A more detailed description of the operation is provided in Appendix C. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 9

15 TS1/TS2 170/270/2070 Traffic Controller Signal Load Switches Existing Pedestrian Call Inputs Advanced Pedestrian Coordinator Low Voltage Power Distribution and Communications Network APB 1 APB 2 APB n Existing Traffic and Pedestrian Signals Cabinet Power APC Maintenance Interface Figure 2. AAPS I System Block Diagram The AAPS I system development phase was capped with a pilot installation in St. Paul, Minnesota as described in Appendix D. PHASE II: TECHNOLOGY TRANSFER After the test installation in Minnesota, the APB hardware design underwent three hardware redesigns and the APC underwent two hardware redesigns. University of Idaho Researchers assisted in the initial production of the AAPS I by providing a circuit board engineering files, computer software for the APC and APB units, and detailed parts and supplier list. Tate Engineering of Spokane, Washington was responsible for the initial hardware production. Graduate students at the University of Idaho worked closely with Campbell Company engineers to validate the hardware and software components of the design. Numerous modifications were made to the hardware (see Appendix C) and as well almost continuous modifications to the software of the APC and ABP computer code. This phase concluded when two of the research assistants who contributed significantly to the development were hired as full-time Campbell Company employees. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 10

16 An element of the technical transfer is the dissemination of information regarding engineering advances. The University of Idaho Mission Statement clearly identifies the educational component of research as an essential element of technology transfer. Over the course of the Smart Signals research, nine Electrical or Computer Engineering students have completed their Master of Science or Master of Engineering degrees. In addition over 20 undergraduate students worked as graduate assistants some of whom proceeded on to complete advanced degrees. Contributing to the technical transfer effort, two scientific journal papers and technical conference papers have been published. In addition to the technical papers, there were nine conference presentations, five pedestrian workshops, and two patent awards in the area of pedestrian signals. PHASE III: ADVANCED ACCESSIBLE PEDESTRIAN SYSTEM REDESIGN The hardware was specifically designed to be easily adapted to changing functional requirements. For example, portioning the pedestrian controller into three modules allows upgrading one hardware module and reusing the remaining modules. The three custom circuit boards were thoroughly tested in the course of this phase of the project. The significant design enhancements are: 1. Enhanced EoP communications allows for a tenfold increase in the number of pedestrian stations and information exchange. 2. Modular design allows for better packaging and partial hardware upgrading. 3. No-cost software development tools reduce development costs. 4. Using advance semiconductor technologies reduces both system equipment and installation costs. The additional hardware capability provides a system platform for investigating pedestrian assistance through tracking and guidance. The improvements relating to the three hardware units are discussed in Appendix E. These circuit boards were designed such that technicians employed at the University of Idaho were able to populate the circuit board in phases to allow thorough testing. As such, the fabrication capability at the University of Idaho limit the trace spacing of the circuits and size of components used on the circuit board. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 11

17 The spiral design methodology used to achieve objectives of the redesign allowed the examination of new technologies, review of user and customer requirements, and anticipation of future needs. Much of the work was an iterative process to test and redesign the hardware and software and insure the interface circuitry did not fail. Assessment of customization and recommended practices is an on-going process that involves interactions and feedback from traffic engineers and technicians. The overall objective of the research was to establish a hardware platform that is extensible and useable in a wide range of environments and applications by defining the system operations, to the extent possible, in software. Figure 3 provides a block diagram of the AAPS II system. The key element in this design is the Synchronous Data Link Control (SDLC) interface between the pedestrian controller and the traffic controller. Although the bus type network is comparable in structure to the first generation AAPS, the hardware that uses the network is a new design with much higher capability. In this design, the pedestrian button station can now serve as a communication hub for higher-level functions such as pedestrian guidance assistance. A detailed description of the hardware associated with the AAPS II is described in Appendix E. Traffic Controller Signal Load Switches Existing Signals PED CALLS Pedestrian Controller Power Detectors SDLC BUS PC MMU EoP VAC EoP EoP EoP EoP APB APS APB APS APB APS APB APS Figure 3. AAPS II Block Diagram ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 12

18 All software and hardware engineering design files associated with both AAPS I and AAPS II system have been delivered to Campbell Company as of June 1, AAPS II has been laboratory tested but there have been no field trials to date. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 13

19 CONCLUSIONS The level of funding and the diversity of groups who funded this research indicate that the devices and products produced as a result of the ten years of research have value to society. A completed system was produced that is being manufactured and sold by Campbell Company of Boise, Idaho and is in use at over 400 intersections in the United States. In light of this success, we are allowed to proclaim as did an ancient Italian circa 46 B.C. Vene vidi vici. Three graduate students who worked on this project are now employed in traffic equipment manufacturing industries two of whom are employed by Campbell Company and are responsible for carrying this research forward. The success of the Smart Signals application to pedestrian controls indicated that this technology can be expanded to all traffic control signals to enhance capability and reduce the expense of signalized intersections. This is my last year of teaching and research before retiring from academic life. The Smart Signals research has been my crowning engineering achievement. It is my hope that I have passed on my enthusiasm for transportation research and the love of the discipline of engineering. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 14

20 RECOMENDATIONS 1. Pedestrian tracking is currently receiving a significant amount of interest. The obvious benefactor is the low vision pedestrian. The interest is mostly due to the sensor suite provided with the ambitious smart phone. Now that Smart Signals places capable infrastructure at traffic intersections, research is needed to determine how best to complete the connection between pedestrian and traffic controller. 2. The transportation industry has become accustomed to having a monitor to verify that the traffic controller does not put vehicle operators and pedestrians at risk due to an equipment failure. In the transition from NEMA TS1 controllers to TS2, the conflict monitor (CM) has evolved into the malfunction management unit (MMU). Both are based on the concept the monitoring device can observe all of the outputs that the intersection uses are seen. This is possible only because all of the traffic control equipment is constrained to the physical space of the traffic controller equipment cabinet. In the Smart Signals environment, the problem of equipment malfunction still exists but the solution is quite different since the logic that produces the outputs are spatially distributed. Before the Smart Signals technology can be reliably extended to all traffic signals, an inexpensive and reliable monitoring system must be developed to replace the CM and MMU. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 15

21 APPENDIX APPENDIX A - Record of AAPS Funding Date Source Project Title Amount June 2004 USDOT Plug and Play (PnP) Smart Sensor Traffic Signals System August 2005 USDOT Full Scale Implementation of Plug and Play Smart Traffic Signal and Pedestrian Wait/Walk Display with PED button August 2006 USDOT Conflict Monitor for Plug and Play Distributed Smart Signals and Sensors for Traffic Controllers August 2007 USDOT Street Deployment of Pedestrian Control Smart Traffic Signals August 2008 Idaho SBOE Advanced Interactive Signals for Able-bodied and Disabled Pedestrians August 2008 USDOT Commercialization and Field Distribution of Smart Pedestrian Call Signal September 2008 Campbell Co. $99,556 $90,000 $100,000 $97,303 $75,000 $117,357 Networked Accessible Pedestrian Signals $60,520 August 2009 USDOT Closed Loop Operation of Network Based Accessible Pedestrian Signals $111,723 August 2010 USDOT Smart Signals Countdown Pedestrian Signal $124,633 September 2010 Campbell Co. Networked Accessible Pedestrian Signals - extended August 2011 USDOT Improving Pedestrian Safety at Signalized Intersections June 2011 Idaho SBOE Development of an Independent Fault Monitoring to Increase Safety and Marketability of the Advanced Accessible Pedestrian System, August 2012 USDOT Second Generation Accessible Pedestrian Systems August 2013 USDOT A Framework for Improved Safety and Accessibility through Pedestrian Guidance and Navigation $61,667 $120,281 $39,400 $59,978 $60,000 Total Project Funding $1,217,418 ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 16

22 APPENDIX B AAPSI System Specifications 1. The primary purpose of Smart Signals Pedestrian Call System is to provide safe and reliable access for able bodied and disabled pedestrians using an architecture for information exchanged that is scalable in both scope of control and range of devices used to register a request for service to signal traffic controllers. 2. Assure that all human interfaces comply with the Manual for Uniform Traffic Controller Devices (MUTCD) regarding Accessible Pedestrian Stations (APS) and the American with Disabilities Act (ADA). 3. The system described in Figures 1 through 4 capable of implementing the following features: a. System operations for placing pedestrian requests for service that are compatible with existing TS1 and TS2 type traffic controllers. b. A system that consists of one Pedestrian Management Unit (PMU) and one or more Pedestrian Activation Unit (PAU). c. The AAPS will interface with NEMA TS1 and TS2 type 2 traffic controllers as shown in Figure 4. d. The AAPS will interface with NEMA TS2 type 1 and type 2 traffic controllers as shown in Figure 5. e. A system that uses two wires of gauge and insulation rating consistent with current traffic system installation practices. f. A system that meets or exceeds the National Electric Code requirements regarding power distribution. g. A system that meets or exceeds ADA and MUTCD requirements for APS pedestrian stations. h. A system capable of performing system wide diagnostics, recording events regarding failures as well as normal operations. i. A system capable of identifying unique calls, both type and location, for special service that can change normal traffic controller timing operations. j. A system capable of providing estimated wait time before the pedestrian Walk sign is on. 4. One each fully functional prototype unit of the APC and the APB devices 5. All engineering electrical and mechanical drawings, microprocessor source code, code libraries, compliance and performance test data, and instructions for construction, installation and maintenance. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 17

23 Traffic Controller Cabinet Existing Traffic controller load switches TS1/TS2 170/270/ 2070 Traffic Controller #3 Switched 120 VAC Pedestrian Signal Outputs Existing pedestrian inputs to traffic controller cabinet #4 Inputs to Traffic controller #2. Pedestrian Management Processor Cabinet Power #5 AAPS Power supply #1 PMU #7 EoP #6 Ethernet interface to Ethernet over Powerline modem #9 Pedestrian Activation Unit (PAU) #10 #12 EoP Pedestrian Button Controller #11 PAU Power supply Station 1 of N #8 12VAC Power Distribution and Ethernet Communications Network #9 Pedestrian Activation Unit (PAU) #10 Pedestrian #12 EoP Button Controller #11 PAU Power supply Station N of N Existing 120 VAC vehicle and pedestrian traffic signals #13 Ethernet interface for installation and maintenance computer Figure 4. Advanced Accessible Pedestrian System Block Diagram Showing Direct Wire Interface with NEMA TS1 and TS2 Type 1 Traffic Controllers ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 18

24 Traffic Controller Cabinet Existing Traffic controller load switches TS2 Traffic Controller Existing pedestrian inputs to traffic controller cabinet #15 Ethernet interface to TS2 Traffic Controller Cabinet Power #5 AAPS Power supply #9 Pedestrian Activation Unit (PAU) #10 #12 EoP Pedestrian Button Controller #8 12VAC Power Distribution and Ethernet Communications Network #11 PAU Power supply Station 1 of N Existing 120 VAC vehicle and pedestrian traffic signals #14 Ethernet switch or hub #2. Pedestrian Management Unit (PMU) #7 EoP #1 PMU #6 Ethernet interface to Ethernet over Powerline modem #9 Pedestrian Activation Unit (PAU) #10 #12 EoP Pedestrian Button Controller #11 PAU Power supply Station N of N #13 Ethernet interface for installation and maintenance computer Figure 5. AAPS Block Diagram Showing Direct Wire Interface with NEMA TS2 Traffic Controllers ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 19

25 APPENDIX C AAPS I Hardware and Software Reference Manual This appendix contains the engineering technical details for the fabrication, assembly, and programming of the AAPS I System. There are two major components to the AAPS: The Advanced Pedestrian Coordinator (APC) and from 1 to 16 Advanced Pedestrian Buttons (APB). The APC communicates with all APBs using Ethernet over Power line (EoP) technology. General Information This appendix contains instructions for installation and operations of the advanced accessible pedestrian signals (AAPS) system. The AAPS I is designed to facilitate the latest ADA requirements for Accessible Pedestrian Signals (APS) using low voltage EoP technology. 1. Pedestrian station configuration and diagnostic is completed entirely from the traffic controller. 2. Periodic communications with all pedestrian stations facilitates rapid failure detection. 3. Pedestrian communications failures are time-stamped and logged on the AAPS controller. 4. Pedestrian communications failures cause a red LED to be illuminated of the AAPS I controller unit. Existing pedestrian station field wiring can be utilized for connecting the Advanced Pedestrian Buttons (APB) located in the intersection crosswalks and the Advanced Pedestrian Coordinator (APC) located in the traffic cabinet. The AAPS I is powered by 120 VAC in the traffic controller cabinet and distributes VAC power to all pedestrian stations. The AAPS I uses a web based interface eliminating the need for application specific software. The APC contains no key pads or text display thus reducing both size and expense. 1. Computers used for system setup and diagnostics need only a standard web browser. 2. Audio files can be changed in the field for any pedestrian station at the intersection using the web interface. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 20

26 3. The AAPS system is completely configured using web based menus and selection boxes. 4. System pedestrian station operations, pedestrian signals status, and pedestrian call operations is monitored and displayed on the AAPS system webpage. 5. A real-time clock with battery backup allows time-of-day audio volume control. 6. Maintenance operations are logged and time-stamped on the APC and can be downloaded to a computer using the interface webpage. 7. The Ethernet interface facilitates remote connection to the AAPS system for diagnostics and monitoring of pedestrian calls. 8. Web security was provided by password protection. The APC monitors the pedestrian signals for all pedestrian stations from inside the traffic controller cabinet. The APC interfaces with the traffic control system using direct wiring between the APC and the 120 VAC outputs to the pedestrian signals and the conventional pedestrian station inputs. APB stations are completely self-contained. No field wiring is required between individual pedestrian signals and pedestrian stations. AAPS I - A Networked Based APS System - Theory of Operation Introduction The AAPS system was designed to address many of the issues noted in the paragraphs above. The network approach makes use of the fact that microprocessors are already required to implement the complex control needed to play different audio messages depending upon pedestrian signal status and the operation of pedestrian buttons. Using distributed processing technologies allows bidirectional communication of information relating to operating controls and possible failure modes. Ethernet was chosen for communications because of its high bandwidth, wide spread use in industrial controls and the availability of low cost electronic hardware to support this technology. Although some of the operating features will be described below, the hardware to support the AAPS is highly scalable in both number of pedestrian buttons and the modes of ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 21

27 operation. The basic hardware and software are the result of research in the application of distributed systems concepts at the University of Idaho that has been reported on, starting in 2006 [9,10,11]. Using a distributed approach, each pedestrian button is uniquely distinguishable thus enabling the use of beaconing on one side of an intersection only. AAPS I System Architecture Figure 6 shows the system architecture for the AAPS I system. The hardware consists of an APC and one or more APB connected by a low voltage power conductor and a common ground or reference conductor. The APC interfaces with the traffic controller cabinet using existing field wiring terminals. The APC senses the pedestrian signal status by monitoring the 120 VAC load switch outputs. Pedestrian calls are placed by the APC using the conventional terminals for pedestrian button inputs. Although not shown in Figure 6, it is possible to simultaneously operate both conventional APS and AAPS pedestrian stations provided the two systems use separate conductors for power and communications. TS1/TS2 170/270/2070 Traffic Controller Signal Load Switches Existing Pedestrian Call Inputs Advanced Pedestrian Controller Low Voltage Power Distribution and Communications Network APB 1 APB 2 APB n Existing Traffic and Pedestrian Signals Cabinet Power APC Maintenance Interface Figure 6. AAPS I System Block Diagram ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 22

28 The AAPS is powered from 120 VAC used to power the traffic controller cabinet. The 120 VAC is stepped down to 12 to 18 VAC to power the APC and all APB stations. The communications is implemented using EoP technology over the 12 VAC conductors distributed to all of the AAPS APBs. The APC servicing interface is an independent Ethernet connection to a service computer for installation and maintenance. The function of this interface will be discussed later in this document. The Advanced Pedestrian Controller As shown in Figure 7, the APC consists of a commercial off-the-shelf Linux based single board computer with a 70 MHz ARM 7 microprocessor and a traffic cabinet interface board of proprietary design. All interfaces with the traffic controller cabinet use optical isolation and transient protection components. The system is capable of interfacing with eight pedestrian signal pairs to sense the 120 VAC WALK (W) and DON T WALK (DW) load switch outputs. An 18 light emitting diode (LED) array is the only local display that indicates AAPS operating status. All other human-machine interaction (HMI) is achieved via the second Ethernet port connected to a service computer or laptop computer. The simple HMI on the APC eliminates the cost and space otherwise needed to support wide temperature range Liquid Crystal Displays (LCD) displays and key panels. The Ethernet interface will be described later in this paper. A real-time clock with battery backup is provided to support an optional time of day operation. The APC-APB network interface uses a MX5500 EoP modem that supports the 85 Mbps Ethernet using the HomePlug 1.0 standard [12]. Similar devices are commercially available that operate on 120 to 220 VAC. Our proprietary design is needed for the AAPS system to operate on the 12 VAC power used to power the pedestrian stations. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 23

29 Traffic Controller Pedestrian Button Inputs Pedestrian Signal Load Switch Outputs LED Panel AC/DC Switch Clock AC Sensor AVR32 Linux Based Single Board Computer Ethernet Port #1 APC EoP Modem Power Supply VAC Service Computer Ethernet Port #2 120VAC Figure 7: Block Diagram of Advanced Pedestrian Coordinator The Advanced Pedestrian Button The block diagram for the proprietary APB electronics is shown in Figure 8. The APB uses a NXP LPC2468 processor based upon a 32-bit, 72 MHz ARM 7 processor architecture. This particular processor was chosen because it supported a media independent interface (MII) needed to communicate with the EoP modem and the 512 kb flash memory that is used to store the data files for the audio messages. Apart from the communications, only 5 of the 208 processor pins are needed for input and output. Two inputs are used. One input is used for the audio microphone used for ambient noise compensation. The second is used for the pedestrian button. The three outputs are used for a call acknowledge LED, the vibrotactile control, and the audio output for the speech messages. The LED on the pedestrian button that is activated when the button is pressed is only illuminated when the APC acknowledges to the APB the call has been place to the traffic controller. The MII interface for the EoP communications requires 18 processor pins. Additional outputs to control LEDs are used for diagnostics and development. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 24

30 On the surface, the processor chosen appears to be more than required for this application. However, the functionality designed into the NXP processor reduced system cost and physical size of the APB circuit board. LED Array Serial Port Vibrotactile Motor EoP Modem RF Coupler EoP Modem INT55MX NXP LPC2478 Call Placed LED Preamp Microphone VAC Zero Crossing Det Power Supply Pedestrian Button LM4755T Power Amplifier Audio Speaker 1.8V 3.3V 5.0V 8V Figure 8: Block Diagram of Advanced Pedestrian Button AAPS I Communications Network communications is our approach to address safety concerns raised in the introduction of this paper. The APC continually sends data messages containing the status of the pedestrian signals to each individual APB in a round robin fashion. Each APB responds back to the APC indicating the reception of the data. Any APB not responding in a preset time is identified on the APC s front panel LED. The time of the failure is also recorded in the maintenance log that is viewable via the service webpage. The data in the APB response message includes the current audio tone or message being played. This is checked against the ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 25

31 status of the signals to verify that there is not a conflict in pedestrian controls as indicated by a DW signal status. The APB sends an unsolicited message to the APC whenever a pedestrian has activated its button input. The APC immediately passes the request on to the traffic controller by activating the appropriate pedestrian input terminal in the cabinet. Network Communications Ethernet Layers A protocol stack is a collection of software functions for managing network communications. Frequently the functionality of the protocol stack uses a graphical diagram that represents the flow of data through computer processes to ensure secure and timely communications. The diagram in Figure 9 is an example of a protocol stack. As the data travels down the stack, computer processes add routing information to the basic message. This routing information is removed from the network packet by the receiving computer as the data travels back up through the protocol stack processes. Information that is to be sent from one traffic control element to another organizes the data into objects that indicate how the data is to be decoded as well as the specific information communicated. The simple network management protocol (SNMP) layer will pass this information to the user datagram protocol (UDP) layer of the stack. Figure 9 is a partially modified diagram of the National Transportation Communications for ITS Protocol (NTCIP) Standards Framework that the AAPS implements. The heavy solid lines represent the data path for the operational portion of the AAPS. The lighter solid line represents the data path used for transferring audio speech and tones files from the APC to individual APBs. Figure 9 is modified in that the EoP is added at the physical layer along with the twisted pair. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 26

32 ITS Data Model ITS Data Dictionary Files Data Objects Reference Model ITS Mesasage Set Dynamic Objects COBRA DATEX FTP TFTP SNMP STMP TCP UDP IP Ethernet Twisted Pair EoP Figure 9. Partial NTCIP Standards Framework Communications Service and Maintenance The maintenance and setup of the system uses web based controls through a webpage that is hosted by the APC single board computer. The computer used for maintenance and servicing does not require proprietary software; only a standard web browser such as Internet Explorer or Mozilla Firefox. The webpage organizes the data into three types: system operational status, configuration settings and log files. The top frame of the webpage presents real-time system status information concerning the pedestrian signals and pedestrian calls waiting to be serviced. Status information includes the state of APC inputs and outputs as well as the state of all APBs. This frame is always displayed so that the current operating status is always viewable. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 27

33 There are six display options for the contents of the bottom frame of the service page: System Status, System Configuration, Time Configuration, Station Settings, File Upload, and View Log Files. Configuration settings are organized into two types: system wide and APB specific settings. The bottom frame is where data is entered to make changes to the system functionality. These settings are used to select the operating modes for the APC and those options that are common to all APB stations. Audio File Management Audio files are generated and stored on the service computer. The files are transferred to the APC one at a time. After receiving each audio file, it is passed on to the specified APB using the file transfer protocol (FTP). The audio file information is stored in a file system in the APB processor s nonvolatile memory space. Each file has a unique name that must match an entry in a predefined table before the file will be saved one the target APB. These file names correspond to the message that is being saved. The file names are wait, walk, location, locator, initiation_beacon tone, and target_beacon tone. In addition, there are preempt and a custom audio message. The AAPS uses sound files in an 8bit, 8 khz pulse-code modulation (PCM) format. The sampling rate and data word size is chosen as a balance between sound quality and file size. The human voice contains frequencies that are primarily less than 4 khz. Therefore, the 8 khz sampling rate is sufficient to capture human speech according to the Nyquist s Theorem [13]. Eight data bits is the smallest word width in the PCM format but supplies enough dynamic resolution to faithfully reproduce recorded speech. PCM requires little processing effort by the computer playing the sound files. The only processing required for playback involves volume control. With 8 bit, 8 khz PCM audio, it ultimately requires 8kB of nonvolatile memory on the APB to store one second of recorded audio. Audio files are transferred from the service computer to the APC using hypertext markup language (HTML) multipart/form-data. The sound file and other fields of the form are packaged and sent to the APC web host and processed by a common gateway interface ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 28

34 (CGI) script. There are five fields sent to the APC web host: stationid, fileid, resid, the sound file, and the submit field. The stationid field indicates which APB the audio file is to be directed. Fileid is the number identifying which file is being sent. Resid is a text string used by the Advanced Accessible Pedestrian Management System (AAPMS) webpage to notify the user of the status of each file transfer. The submit field is the value of the value of the Submit button that was pressed. In the multipart-form transfer, each field is separated by a field boundary. The boundary is specific in the header information of the transfer file and varies depending upon the browser being used and the content of the file. When the APC receives the HTML form data transfer, the first step is separating each field along its boundary and storing the contents of each in the appropriate place in memory. The AAPMS webpage is then notified about the file transfer. If the audio file was not in the correct format or the file or station identification numbers are not valid, the webpage notifies the user. Next, the sound file is processed to prepare the sound files for transmission to the APBs. The APC strips all of the file information from the file to reduce the memory requirements. The resulting binary information contains only the PCM binary data. This file is then sent to the APB specified by stationid as file fileid. At the beginning of the file transfer, the APB is placed into a silent mode so that no audio files are accessed during a file upload. Upon a successful transfer, the AAPMS webpage displays a conformation to the user. The configuration settings of the AAPS on the AAPMS webpage are submitted using URL encoded data. When the user submits configuration data via the AAPMS webpage, a CGI scripts parses the URL encoded data and processes it accordingly. First, the APC parses the incoming data and saves it to non-volatile memory so that it will be retained during a power loss or system restart. Then, the configuration data is applied to the different parts of the AAPS. For APC specific configurations, the appropriate operating system services are restarted, allowing them to re-read their specific configuration files. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 29

35 APB configuration options are handled much differently than APC options. First, the APB s receiving new configurations are placed into a mode in which the APB operates at the basic level, i.e.as a common button. This prevents misoperations while the new configurations are being loaded. Next, the new configuration for that button is sent via SNMP. Upon a successful reconfiguration of the APB, it is placed back into the mode it was previously configured. Communications System Operations Since the AAPS is a standalone system and operates on an isolated network, any network protocol could have been used. In order to allow future integration with NEMA TS2 traffic controllers, we chose to implement the AAPS using NTCIP recommendations. We recognized that many of the objects we needed are not included in the NTCIP 1202 guide and hence we developed a specific set of objects which are described below [10]. A significant portion of the communications protocol used to implement on the AAPS is based upon work reported on by Devoe, et.al.. SNMPv2 SNMP was developed in the 1980 s to provide standard extensible management of local area network based products [14]. Even though SNMP has been updated to version 3, our use is limited to operation of version 2 since it provides the communication protocol necessary for the AAPS operations. The AAPS supports a subset of the SNMP functions for the APC-APB network system only. The SNMP messages enable the APC to validate this communication with each APB and that each APB is capable of verifying that a call has been placed to the APC. For normal operation the APC periodically generates a SetRequest message that updates each system APB that, in turn, responds back to the APC a GetResponse message. This exchange of information provides verification to the APC that each APB is operational and has received the correct information. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 30

36 When a user has pressed a pedestrian button, the station APB sends a Trap message to the APC. A Trap is an unsolicited message generated by the APB that the APC does not respond to. The reception of the Trap is verified on the next periodic SetRequest received. If the next SetRequest message from the APC does not indicate that a call has been placed, the APB will generate another Trap. The program Wireshark [15] was instrumental as a development tool for designing the application to build the SNMP packet. It displays individual packets in real-time as they occur on the Ethernet physical layer. In its display it breaks the packets down in user identifiable layers as well as the actual hexadecimal bytes in the packet. SNMP OID s SNMP protocol data units (PDU) are used to manipulate object values. These values are identified by Object Identifiers (OID). An OID uniquely identifies the value. NTCIP 1202 [16] describes the OID s that involve traffic controllers. NTCIP 1202 does not provide adequate objects to support the operation of the AAPS system hence we generated a custom set of objects following the NTCIP style. The SNMP OID s that are needed for operation of the AAPS system are described in Table 1 through 3 below. The Intersection Node object is the objects that are sent from the APC to each APB at periodic intervals. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 31

37 Table 1: Intersection OID Definitions Node OID Type Description APB Device Node Root node for APBs, 14 on end may change Intersection Status Node apb.2 Bits Intersection Status Don't Walks apb.2.1 Bits Bits. If set to 1 that phase is in the don't walk state Intersection Status Ped apb.2.2 Bits Clears Bits. If set to 1 that phase is in the Ped clear state Intersection Status Walks apb.2.3 Bits Bits. If set to 1 that phase is in the Walk state Intersection Status Calls apb.2.4 Bits Bits. If set to 1 that phase has a call pending Intersection Status APS Calls apb.2.5 Bits Bits. If set to 1 that group has an APS call pending Intersection Status Beacon apb.2.6 Bits Source The source of an APS call Intersection Status Beacon apb.2.7 Bits Destination The destination of an APS call Intersection Status Block Object apb.2.8 OS Octet string containing all of the intersection and station status objects Station Status Node apb.3 Station Audio Message Apb.3.1 Int Audio message currently being played Station State Apb.3.2 Int Button state number SNMP TRAP The SNMP trap PDU is required to contain two items: the system up time or time since its last reboot and the device OID. Any additional information can be added beyond the required items. The APB will add either an Intersection Status Calls or APS Calls value, depending on the type of input detected from the user of the button, to the trap message. Each APB will use its preconfigured Station Phase value in the value field of this Trap PDU. Table 2 contains the list of objects that can be sent when a SNMP trap is sent from the APB to the APC. Table 2: Station Trap OID Definitions Node OID Type Description Intersection Status Calls apb.2.4 Bits Bits. If set to 1 that phase has a call pending Bits. If set to 1 that phase has an APS call Intersection Status APS Calls apb.2.5 Bits pending ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 32

38 APB Configuration Objects The Configuration variables are also set using the SNMP protocol. Unlike the Status objects, these variables are configured once, therefore these objects are saved to nonvolatile memory. This allows for the system to recover from a power loss with no loss programming. Table 3 describes the configuration information for each button. Each APB is initially programmed with default values for each variable. The default values allow a new button to be found when added to the network. This means that all buttons are programmed exactly alike and then configured to be unique in the system, using the maintenance interface. Table 3: Configuration OID Definitions Node OID Type Description APB Device Node Root node for APBS, 14 on end may change Station ID apb.1.1 int Station ID number. Values 1-16 (0 for not configured) Station Night Mode apb.1.2 int 1 If night mode is on Station Day Locator Volume apb.1.3 int Values Station Day Speech Volume apb.1.4 int Values Station Night Locator Volume apb.1.5 int Values Station Night Speech Volume apb.1.6 int Values Station IP Address apb.1.7 OS 4 byte octet string of the stations IP address Station Mode apb.1.8 int 0-4 AAPS operation mode Station Identify apb.1.9 int 0 for identify off. 1 for LED blink/vib Station Phase apb.1.10 bits Bit corresponds to Station's phase Station Group apb.1.11 bits Bit corresponds to Station's group Station Beacon Mode apb.1.12 int AAPS Beacon operational mode Conclusions The AAPS presented uses a hardware architecture that has the capability to meet the expanding requirements of APS systems. A system that uniquely identifies each pedestrian station can now be programmed so that pairs of pedestrian stations can operate in concert to facilitate beaconing with no additional wiring. Time of day operation can be used to reduce volume depending upon local requirements. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 33

39 Using network communications enables observations of operations for a microprocessor located outside the traffic controller cabinet. Audio files that are played at each pedestrian station are compared to be consistent with the pedestrian signal status. Each communications transaction is verified to detect equipment and wiring errors as well as communication errors. The constant communications allows the system to detect pedestrian station failures at the traffic controller cabinet even when there is no pedestrian button activity. A web interface eliminates the need for application specific PC software for system maintenance and diagnostics. The system logs maintenance operations and system failures which can be archived for systems documentation. The web interface allows one person to view the entire system operations from one location. WEB Access Security Systems with operation and service that can be accessed and/or modified by an internet connection always raise the concern of system security. The potential risk is that audible messages can be altered such that they can provide incorrect and possible dangerous information. This is particularly hazardous for blind pedestrians who do not have vision to verify the validity of the audio information. There are two philosophies used for system protection: provide security for each device or provide a secure network environment isolated from easily accessible communications. The AAPS consists of two isolated network systems that are wire based so that they require physical connection. The operational network provided by the EoP network directly manages the information between the APC and the numerous APS sites. This information is produced and used exclusively by the APC and APB units. The only access to an EoP network is from inside the traffic controller cabinet or by physically connecting an EoP modem to the 18VAC wires that connect the APC to the APB units. Security of access to those facilities are beyond the scope of the AAPS system and are the responsibility of the traffic agency maintaining the system. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 34

40 The highest vulnerability for unauthorized access to the AAPS system is through the webpage interface. The APC can interface to the World Wide Web or outside network only if the traffic agency provides such a connection. Otherwise, the primary defense against unauthorized access is the security of the traffic cabinet itself. The webpage is password protected. This level of access protection is highly dependent on the number and sequence of characters used in the password. Traffic agencies are expected to have a network security policy in place to guarantee that the proper level of password obfuscation is used. AAPS I Hardware Documentation AAPS I APC Hardware Figure 10. Installation of the AAPS I at 6th and Deakin Streets in Moscow, ID. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 35

41 APC NGW100 Linux Processor Figure 11. ATMEL NGW100 with AVR32 Processor and Linux Operating System See: and ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 36

42 AAPS I - APC Parts Layout Figure 12. Picture of APC I PCB Side A ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 37

43 AAPS I - APB Parts Layout Figure 13. Picture of APB I PCB Side A Figure 14. Picture of APB PCB Side B ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 38

44 APPENDIX D - Review of Initial Test Field Installation On February 16, 2010 at a temperature below 10 degrees, the first generation of the Smart Signals Technology design for Accessible Pedestrian Signals (APS) was installed at a public intersection in a suburb of St. Paul, Minnesota. Figure 15 and Figure 16 show the environment as a team of researchers from the University of Idaho that have been involved in the development of the new system were observed technicians with the Minnesota Department of Transportation install the systems at two intersections. After the hardware installation, the students demonstrated how each signal can be customized using a laptop computer and a conventional web browser. To date, the Advanced Accessible Pedestrian Signals (AAPS) is chirping away. (The chirp is the locator tone that helps low vision pedestrians to locate the pedestrian button.) Figure 15. Climate Conditions during the Initial Minnesota Field Installation ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 39

45 Figure 16. Minnesota Installation Activity Smarts Signals is an enabling technology initially conceived by Professor Richard Wall in 2004 as a means to improve the capability and safety of controlling traffic signals at intersections using distributed microprocessor based controls that use safety critical network design methodologies. The focus has been placed on improving access and safety for low vision and mobility impaired pedestrians. A partnership was developed with Campbell Company of Boise, Idaho who manufactures the AAPS systems. AAPS is different from conventional pedestrian buttons in that information is exchanged between the Advanced Pedestrian Controller (APC) in the traffic controller cabinet and each individual Advanced Pedestrian Button (APB) at the rate of four times a second. Power and communication is distributed by APBs by employing Ethernet over Power Line (EoP) technology on an 18 VAC power system. The Minnesota installation demonstrated that the AAPS can be easily retrofitted in existing intersection controls using the preexisting pedestrian button conductors. The internet connectivity allows traffic agency technicians to view the AAPS system operations remotely to determine the current status of individual pedestrian buttons. The operational data that is logged by the APC can also be ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 40

46 viewed over the internet. This data includes hardware failures and the number of calls placed by individual APBs. Feedback from the Minnesota installation has been very positive and constructive. Although the installed AAPS is fully functional, ideas for improvement were recorded and have already integrated with the new design. Many ideas arise from the statement Since we have network communications, can we now do Without a tight rein on our imaginations feature creep would never allow us to get out of the laboratory. One of the ideas recently implemented is the ability to update the application program remotely, thus allowing Campbell Company to update existing systems over the internet. The web interface reduces hardware costs and physical size by eliminating displays and keypads. The step of street deployment is important to the future of Smart Signals because it demonstrates that such systems are extensible by being capable of easily providing advanced features. The communications with the terminal devices (lights, detectors, pedestrian buttons, etc.) facilitates early failure detection. Future research will focus on further simplifying the system installation in order to make the system truly plug and play. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 41

47 APPENDIX E - AAPS II Technical Description To communicate unambiguously and accurately the state of the visual traffic signals with minimum distraction, the AAPS II cabinet interface unit was designed. Current versions of APS systems need to check the current state of pedestrian signals, so they are wired directly to field terminals within a traffic cabinet that control the pedestrian signals; this information is communicated to each pedestrian station. However, this method of signal sensing is complicated to install, and because of the connection to live 120 VAC signals at the field terminals, it requires special certification in some states within the US. Furthermore, connecting to 120 VAC signals require that APS systems include transient voltage protection. The protection circuitry creates a load in parallel with the load of the signal light. Additional loading on the load switch outputs of any type is to be avoided whenever possible to prevent the Malfunction Management Unit (MMU) from sensing a voltage that otherwise results from an inoperative signal. AAPS II Advance Pedestrian Coordinator The block diagram for the second generation APC is shown in Figure 17. It consists of four functional elements: the system control computer, the Ethernet communications shown in Figure 18 and Figure 19, interface, the traffic cabinet interface shown in Figure 21 and Figure 22, and a local status display shown in Figure 23. The function of the APC is to manage the system operation parameters, report the status of the intersection WALK and DON T WALK signals, and place pedestrian calls to the traffic controller. Although the APC communicates pedestrian signal status with each pedestrian button four times a second, a pedestrian call initiated by a button press is initiated by the pedestrian button station instantly. The single board computer used in this design is commercially available from Technologic Systems. Although there are many suitable single board computers that use a Linux operating system, the special requirements include two Ethernet ports and having hardware that is compliant with operating at industrial temperatures. The front panel display is unchanged from the first generation AAPS design. ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 42

48 Linux Single Board Computer WWW System Configuration Connection AAPS Communication Cabinet Interface Pedestrian Button Network Service Ethernet Port Cabinet SDLC Bus Cabinet PED Call Front Panel Indication Figure 17. AAPS II APC Block Diagram APC II Communications Module Zero Crossing Detector COMM Port 1 COMM Port 2 RJ45 Magnetics RJ45 Magnetics Ethernet 3 Port Smart Router MMI HP II EoP Modem HP I EoP Modem RF Coupler 18VAC Power 8VDC APC Power 3.3VDC Figure 18. APC II Communications and Power Supply Module Block Diagram ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 43

49 Figure 19. AAPS II Communication Unit Printed Circuit Board The block diagram of the circuit board that provides the interface between the APC and the equipment in the traffic controller cabinet is shown in Figure 20. The Cabinet Interface Unit is a proprietary circuit to interface with the NEMA TS2 SDLC bus. The Cabinet Interface Unit has been tested using both simulated SDLC Type 129 messages as well as actual SDLC Type 129 messages from a NEMA TS2 traffic controller cabinet. The new SDLC interface uses a low cost complex programmable logic device to decode messages and allow the data contained within the SDLC Type 129 message to be accessed over a common I2C network. Pedestrian Signal Load Switch Outputs AC Detectors MachX02 CPLD SDLC Drivers Solid State Relays Cabinet SDLC Bus Cabinet PED Call Inputs Figure 20. AAPS II Cabinet Interface Module Block Diagram ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 44

50 Figure 21. AAPS II Cabinet Interface Unit Parts Layout Side A Photo ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 45

51 Figure 22. AAPS II Cabinet Interface Unit Parts Layout Side B Photo ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 46

52 Figure 23. Front Panel Display Used for AAPS I and AAPS II AAPS II Advanced Pedestrian Button (APB) The block diagram of the second generation APB is shown in Figure 25 and shows the two sides of the PCB for the single board computer is shown in Figure 26 and Figure 26. Volumetric size restriction dictated that components that extend more than 0.25 above the surface of the circuit board be mounted on the same side of the circuit board. This size restriction is imposed by the desirable physical size of the pedestrian button. As one concludes from Figure 25, we are close to if not actually at the maximum number of electronic components. As it is, there are components sandwiched under the EoP module that has the bel label as seen in Figure 25 (The bel label identifies the manufacturer of the EoP module, Bel Fuse Corporation of Jersey City, New Jersey). The four-layer circuit board uses the surface layers as heat sinks dissipate heat produced by electronic components. Using ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 47

53 I2C RMII the circuit board conductors to dissipate component generated heat saves circuit board real estate and part cost. Software has been developed to verify that all hardware components are functional. Software drivers have been developed that allow the various hardware components to be included in the operations of the button. SD Card Mass Memory Mass Memory EEPROM Future External Devices SPI SPI BUS SPI Vibrating Motor Button LED Asynchronous Serial Communications Temperature Sensor (MCP9700T) SPI LPC1768 Processor Remote Control I2S L3Bus UDA1345TS Audio Codec Amplifier Button Input JTAG Debug Microphone Future External Devices I2C BUS I2C Speaker 1 Speaker 2 12VAC System Power Power Supply 3.3V Power AC Zero Crossing Signal 10/100 Ethernet Switch (KSZ8863RLL) Port 2 Port 1 Ethernet Port Test and Future Devices RF Coupler EoP HP AV MII Ethernet PHY (KSZ8001SL) Figure 24. AAPS II Accessible Pedestrian Button Block Diagram ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 48

54 Figure 25. AAPS II ABP Printed Circuit Board - Side A Photo Figure 26. AAPS II ABP Printed Circuit Board - Side B Photo ADVANCED ACCESSIBLE PEDESTRIAN SYSTEMS 49