Traffic control systems are technological laggards when compared with modern control systems used in industry today. The traffic control industry lacks—and often refuses to adopt—necessary standards that will allow it to use the benefits of emerging technologies in a cost‐effective, timely fashion. The same industry cannot keep looking at itself if the promise of future data communications and computing technologies are to be used advantageously. This paper discusses the state of traffic signal systems, how they came to be, the technologies they use, and their technological position with respect to state‐of‐the‐art hardware and software systems. Standards bodies that should play a relevant role in the design of tomorrow's traffic control systems are introduced. Surveys of current and future directions for traffic control hardware, software, and data communications facilities are presented. Traffic control's technological generation gap is identified, and a course of action for academia, manufacturers, and users is suggested.

The traffic congestion on our roads today is becoming a critical problem. There is increased fuel consumption as cars wait along poorly timed arterials. Safety is threatened as poor traffic flow leads to collisions. Transport Canada and the Ministry of Transportation Ontario has developed an integrated traffic system (ITS). The system is designed to enable the optimization of traffic flow on existing roadways. The ITS system contains a data‐base management sytem for traffic data (including accidents, roadway volumes, and signal timing details) and links this data base to the traffic analysis programs. This will ease the data management situation within the municipalities and standardize the traffic operations and reduce duplication of computerization development efforts. Development of ITS has just been completed and is being implemented in the demonstration sites for the formal evaluation. Significant demand for the system has resulted in the release of certain modules ahead of schedule. Further development efforts, systems support, and user groups are currently being organized.

Four prototype multimessage fiber‐optic lane control signs were evaluated for the Ministry of Transportation of Ontario to determine their suitability for freeway‐lane‐control‐signing applications. The evaluation consisted of three separate investigations, as follows. In the field test, the signs were situated and operated in an outdoor environment for approximately one year. Control instructions for cycling through each of 11 messages, varying brightness levels, and implementing a flashing mode were generated by an IBM‐PC‐compatible microcomputer using software specifically developed for this application. In the human factors test, a detailed questionnaire completed by volunteers was used to perform a statistical assessment of the visibility, and comprehensibility of each sign display. In the laboratory test, a laboratory evaluation was performed to measure various electrical and optical properties of the signs. The evaluation concluded that fiber‐optic technology can successfully be applied to lane‐specific signing applications. A number of conclusions regarding sign durability and maintenance, optical systems, and display legibility and comprehension were also made.

The network simulation program NETSIM is now a component model of the integrated traffic simulation system TRAF. The current version of the model is therefore referred to as the TRAF‐NETSIM program. As part of an effort aimed at developing, maintaining, and supporting the TRAF simulation system, TRAF‐NETSIM has been extensively modified over the past five years. Four new features have been added to the TRAF‐NETSIM simulation program: actuated controller logic, identical traffic streams, conditional turning movements, and signal transition. Several major modifications have also been made to the simulation logic to resolve the problems encountered during the testing of the simulation program; to enhance the logic to represent complex decision processes; and to enhance and extend the input‐output capabilities, user‐interaction, and the computational efficiency of the program. These new features and the modifications incorporated in the TRAF‐NETSIM simulation model are described in this paper.

Traffic management and control strategies in a network could be improved by employing a method that can simulate and evaluate the expected impacts of alternative strategies on network performance prior to implementation. Existing methods are based on assumptions not readily applicable in freeway corridors. Responding to the need for an approach able to handle composite networks such as freeway corridors and responsive to on‐line control changes, a new method is presented in this paper. The new method, which integrates simulation with conventional assignment, overcomes major disadvantages of existing techniques, thus becoming more suitable for on‐line optimal freeway‐corridor control. The simulation/assignment method was tested with data from a typical freeway corridor in the Twin Cities Metropolitan Area. The test results indicate the ability of the proposed method to more accurately estimate traffic parameters under various traffic management and control strategies implemented in a freeway corridor.

The development of a prototype knowledge‐based expert system (KBES) for selecting appropriate traffic control strategies and management techniques around highway work zones is described. The knowledge base of this KBES is derived from a literature survey on existing techniques and approaches for handling traffic around highway work zones and from interviews with selected experts in charge of the planning and design of traffic control strategies for work zones in Virginia. The developmental process includes steps in formulating the problem and developing an expert system: identification, conceptualization, implementation, and testing. The resulting EXSYS prototype system, TRANZ, is described. TRANZ knowledge base consists of 141 rules. A decision tree is developed to provide an aid to resolve erroneous recommendations by the system. This model shows the range of control options and associated condition variables that intersect to produce control requirements. This EXSYS prototype system is the initial stage in the development of an expert system. Additional testing, validation, and verification, necessary before the system can be recommended for professional applications, is described. Traffic management in work zones is an ideal application area for expert systems, thereby giving TRANZ a high probability of acceptance when the system is fully developed and operating as intended.

Management of traffic safety is a complex process that requires decision making under uncertainty in assessing the influence of different conditions on safety in the selection of the optimal treatment. To deal with the associated uncertainties, one needs to be widely experienced and up to date with all the research and new developments in the domain. Due to budgetary and other resources constraints, many agencies responsible for managing traffic safety have been forced to rely on the traditional techniques given in handbooks and procedural manuals. With properly designed knowledge‐based systems, the experience and knowledge that have evolved from years of research and multimillion‐dollar investments in traffic safety measures can be made accessible to all. This paper describes the application of a knowledge‐based system (intersection safety management information system [ISMIS]) to resolve safety issues at intersections. ISMIS, which contains the opinions of several experienced professionals, can assist a user to make decisions under uncertainty. This menu‐driven, microcomputer‐based system provides users with explanations for certain decisions, references, and measures available for remedying a particular problem. Moreover, it permits the user to perform an analysis of cost‐effectiveness based on statistical decision theory to determine the best alternative remedy.

In an effort to develop tools to help address various aspects of heavy truck size and weight impacts on pavements, bridges, truck safety, and economics, the Roads and Transportation Association of Canada undertakes research to look at the feasibility of applying expert system technology to various aspects of this problem. A prototype expert system capable of assessing the legality of various truck configurations was also developed. The problem definition stage of the work required much greater effort than originally anticipated. Expert systems were found to be applicable in the areas of generating alternative regulations, dealing with operational problems within motor carrier fleets, and in the interpretation of regulations. In other areas, the need for conventional and “hybrid” tools was found. The prototype system addressed the subproblem for which it was conceived, although simplifications were required to achieve this goal within the original budget.

Artificial intelligence, using a prototype expert system, was applied to transportation issues. The specific issue dealt with improving the quality of the dispatch information in emergency situations involving dangerous goods. The system provided, upon notification of a highway traffic accident involving dangerous goods, a weighted probability list of possible dangerous goods expected to be transported over that part of the arterial highway network and instructions for handling the situation. The importance of quick and effective emergency response was addressed, and methods of assisting those directly involved were examined. Following the analysis of all input data, the program displays the given conditions and a complete list of possible commodities, ordered by highest probability and the appropriate emergency response procedures. Once emergency response personnel arrive at the scene of the accident, they may provide further information to the dispatcher or perhaps update earlier conditions since the initial respondent cannot be expected to recall every detail exactly. The system can then reevaluate the new set of conditions and output an updated list of commodities and procedures.

The Texas State Department of Highways and Public Transportation uses the Interactive Graphics roadway design system (IGrds), an AASHTOWARE product of the American Association of State Highway and Transportation Officials (AASHTO). IGrds provides roadway designers two optional methods of operation: one with an extensive set of computation and graphic capabilities through a graphic work station; and the other through input of the data using an alphanumeric terminal and editor and performing the calculations in a noninteractive (background) mode. The department is enhancing IGrds to provide automated plan preparation capabilities to minimize the work of their engineers and draftspersons to produce construction plans. The AASHTO IGrds running on stand‐alone work stations is an integral part of the effort. The Automated Plan Preparation System will be the link that brings together the design systems and minimizes manual drafting of construction plans. The ability to transfer “intelligent” graphics from a design system to a drafting system provides the greatest productivity gains.

The integrated traffic data system (ITDS) is a microcomputer‐based system that is designed to allow traffic engineers to store, maintain, and update traffic network information in a centralized data base. The information can then be used to create input data files for some of the widely used traffic simulation and network signal‐timing optimization models. ITDS uses the concept of integrated traffic data base to provide a friendly front‐end (or preprocessor) to the models such as TRAF‐NETSIM and TRANSYT‐7F. This data base provides a means of storing, maintaining, and retrieving the traffic network data in a generic format. In addition, interactive and static graphics display interfaces have been added to further simplify the task of users. The interactive graphics displays allow the user to graphically create or modify the network geometry. On the other hand, the static graphics displays allow the user to see a detailed graphical depiction of the traffic network geometry and data. This paper describes the evolution of ITDS, the current status of the system, and the development activity currently underway.

Urban development patterns in the United States have made distribution and collection functions in local commerce difficult. Both the geographical spread of commercial activities and local highway traffic interferences complicate efficient operations. The purpose in this paper is to describe computer‐based methods to improve the management of daily movements of vehicles and crews in regional service activities. Data requirements are discussed, and the need to account for traffic volumes in routing decisions is elaborated. Practical considerations from everyday business life present boundary conditions that must be satisfied in operations, and that simplify the classic traveling salesman routing problem. These are matters associated primarily with conditions of access to remote service sites and the times of service that must be honored to satisfy customer requirements or other organizational needs. A set of 12 application programs written for use by schedulers, dispatchers, or operating managers is used as a point of reference in the discussion. A case history illustration taken from collection operations in regional banking is also recounted.

Until recently, most major corridor studies and studies of environmental impact statements have been done using traditional manual methods. The major stumbling block to performing corridor and EIS studies cost‐effectively on computer‐aided design and drafting (CADD) has been that most of the base data was not available in a digital format compatible with most CADD systems. The only methods for inputting this base data were to either digitize or scan a large amount of data, each of which can be costly and time consuming. Now, however, a number of government agencies and private firms have been developing environmental and topographic data into a digital format resulting in cost effective data bases for corridor and EIS studies. As the technology and variety of data bases changes the way we think about our work, it will also change the way we organize resources to accomplish the work. This paper covers sources of digital environmental data, how the data can be used, basic procedures for performing corridor and EIS projects on CADD, and an example of how the Sverdrup Corporation is using CADD on planning projects.

A microcomputer‐based decision support system is developed for transportation network evacuation applications in Taiwan, the Republic of China. Input to the system mainly includes the trip‐generation‐related attributes, the street network topology and traffic data, the control variables regarding the routing of public transportation vehicles, and the use of traffic control measures. A dynamic network simulation model based on traffic flow theory is used to simulate the vehicles' movement on the street network during the evacuation process. For a given evacuation plan, the network simulation module calculates the estimated network clearance time. The intermediate results of each simulation interval are saved in graphic data files. The planner can use the graphic display module of the system to visually observe the dynamic change of traffic congestion on each link of the network throughout the simulated evacuation process. The system thus provides a convenient tool not only for evaluating different evacuation plans but also for identifying and improving the evacuation bottlenecks on the street network. Application examples of hypothetical cases show that appropriate deployment of public transportation vehicles plus adequate use of traffic control measures can save up to 40% of the network clearance time during an emergency evacuation.

Years ago, when the word automation was mentioned, transportation officials immediately visualized large computers generating piles of meaningless printouts that would take weeks to read and provide little or no benefits. Not so today! Present‐day transportation agencies depend on state‐of‐the‐art automation technology to achieve their mission of providing a safe, efficient, cost‐effective highway transportation network for the convenience and use of the people and communities. This statement is certainly true for the Texas State Department of Highways and Public Transportation, which will be the case study for this paper. The use of automation begins with the very earliest stage of planning, and continues through the life cycle of the facility including the use of satellite technology for surveys, automated mapping and terrain measurements, statewide distribution of computer resident graphics data over sophisticated telecommunication networks, engineering programs running on desktop computer graphics terminals, instant hardcopy graphics for plan preparation on electrostatic plotters, automated construction letting procedures, and maintenance management programs.

Highway construction techniques have seen a limited number of changes since the 1950s. The primary changes have seen a slow evolution in productivity improvements such as hydraulic controls, and drivetrain components. A major change in highway construction techniques could occur if current equipment could provide data about position and orientation within the design environment. This paper presents some changes in the highway construction field that could occur with the integration of real‐time positioning data and computer‐aided design (CAD) data. Current research at Virginia Polytechnic Institute and State University, Blacksburg, Virginia, in the area of positioning‐CAD integration is presented. The research uses frequency‐hopping radio waves transmitted from points in space, and through phase‐measurement techniques obtains position information. The current research has potential accuracy limits of $\pm 500\mathrm{mm}\text{.}$ Given this accuracy, some potential applications are presented given the positioning‐CAD integration.