Task Order 5324
Traffic Operations Research

Cartesius and CTNET - Integration and Field Operational Test

Michael McNally
Civil and Environmental Engineering
University of California, Irvine

Objectives

Non-recurrent congestion presents a difficult problem for existing localized automated traffic control systems such as the Caltrans Traffic Signal Management and Surveillance System (CTNET), which is a client/server software system for integrated management of traffic signals that allows operators to remotely manage, view, and log real-time traffic signal field data. These systems operate with control parameters that are fine-tuned to meet the normal demands of recurrent congestion in the system. Incidents in the system can create disturbances that are beyond the control of such localized systems, rendering them incapable of mitigating the resultant delays. This creates a compelling justification for interfacing the CTNET signal control subsystem with a global traffic management subsystem to develop a general corridor traffic management architecture that can dynamically respond to incidents in the system. The Coordinated Adaptive Real-Time Expert System for Incident management in Urban Systems (CARTESIUS) is such a tool. It consists of a set of software agents that each monitor and control a subset of the complete network, with emphasis on the coordination between multiple decision-makers in a multi-criteria environment. The analysis of the network state and the search for suitable control plans is based on a structured combination of heuristic approaches and well established traffic control algorithms in a general distributed framework that provides the means for cooperation and conflict resolution.

The proposed research is a two year project to first integrate these CARTESIUS and CTNET projects to produce a functioning traffic management system and then evaluate the integrated system under controlled conditions in a field operational test. The research in the first year will involve review of both CARTESIUS and CTNET to develop a software integration plan leading toward a working laboratory prototype of an integrated CARTESIUS/CTNET software agent by the end of the first year. This prototype will be evaluated for usability with the CTNET system as well as its ability to act as a working CARTESIUS agent in a distributed incident management system. In addition to the software integration, a review will identify potential sites for a CARTESIUS/CTNET FOT. At the end of year one, a final report will be delivered that provides a detailed analysis of a year two FOT feasibility.

The second year of research will involve a Field Operational Test of CARTESIUS that uses a freeway management agent, the integrated CARTESIUS/CTNET agent, and possibly an additional municipal CARTESIUS agent. Work will utilize the results of the first year feasibility analysis to develop an experimental method that will guide final site selection and preparation, including verifying that the necessary infrastructure is in place and operational based on CARTESIUS/CTNET requirements. FOT execution will lead toward a final report detailing the performance of CARTESIUS/CTNET responses to incidents that occur during the FOT and recommending future directions for the integrated system.

Methodology

YEAR ONE

1.1 Complete functional analysis

In year one, alternate ways to integrate CARTESIUS and CTNET will be explored, beginning with an in-depth analysis of both CARTESIUS and CTNET using the documentation, source code, and published protocols of both systems. First, the available documentation for both CARTESIUS and CTNET will be studied to generate a list of the functional capabilities and limitations of each tool. This will include mapping each toolÕs features to the NITSA standard to identify how the tools complement each other (which will guide the integration of the tools to make them more functionally efficient). Second, a complete set of requirements for deploying the integrated system will be generated using documentation and/or direct interviews with original developers of the systems. The deployment requirements will include itemizations of necessary traffic control and communications infrastructure, institutional agreements, and technical staff capabilities. Third, the programming interfaces for each tool will be identified using the the source code or published protocols (if the source is proprietary). Emphasis will be given to identifying how the CTNET server communicates to its clients and what expectations CARTESIUS places on the roadway systems for read/write access to traffic monitoring and control devices.

1.2 Software development

A tool integration design will be based on the functional analysis and will focus on merging capabilities of the individual systems while preserving modularity of the components without excessive functional redundancy. A integrated software will be produced that performs both CARTESIUS and CTNET client functionality. This software application will be able to operate both as a CTNET client that interfaces with the CTNET server as an agent within the CARTESIUS distributed traffic management system.

Two alternate designs are: (1) CARTESIUS would be modified to act as a CTNET client, using its own user interface and relying on the CTNET system solely to provide access to the underlying traffic signal controllers, and (2) the CARTESIUS algorithm would be ported to the existing CTNET client program. The selected design will be implemented and the system will be tested and evaluated using the Paramics simulation environment.

1.3 FOT site requirements, identification, and recommendation

Planning for the second year FOT will utilize the identified deployment requirements for the integrated system. Also, Caltrans and municipal TMC operators will be surveyed to determine the infrastructure features, functional capabilities, personnel availablity, and general interest of various agencies in participating in the FOT. Preliminary criteria for an FOT site are that it include a freeway/arterial corridor in which the arterial network includes at least one major arterial that is managed by CTNET and that the adjacent freeway network is fully instrumented to provide relevant data. A secondary criterion is that the agency responsible for managing the adjacent arterial network also has real-time communication with its field controllers.

YEAR TWO

Year two methodology is dependent on the outcome of year one research. Assuming that the integrated CARTESIUS/CTNET client is successfully implemented and that a suitable FOT site is identified, the following tasks are planned:

1. FOT planning and development of institutional agreements.
2. Deploy hardware and software, verify communications links, and update datasets.
3. Execute a controlled trial of the joint CARTESIUS/CTNET system and measure the performance of the system in response to incidents.
4. Analysis and Final Report.