Intelligent Transportation System Infrastructure Research Articles

Comparison of Local Feedback Controllers for the Mainstream Traffic Flow on Freeways Using Variable Speed Limits

Mainstream traffic flow control (MTFC) on freeways, enabled via variable speed limits (VSL), is a traffic management tool capable of avoiding or, at least, postponing congestion formation on freeway bottlenecks, and may complement other existing measures. Two simple feedback controllers for local MTFC via VSL are proposed. Both controllers are evaluated and compared to a previously developed local MTFC feedback cascade controller and to a sophisticated optimal control approach. All feedback controllers rely on readily available real-time measurements, are simple and robust, and take into account a number of practical and safety restrictions; therefore, they are suitable for implementation in the field as a new or as part of an existing intelligent transportation systems infrastructure. The evaluations are conducted for a hypothetical freeway network by use of a validated second-order macroscopic traffic flow model. The results show that the feedback controllers exhibit a satisfactory control behavior and, indeed, approach the optimal control results. Recommendations for the operation of the feedback controllers are given.

Developing an Evaluation Approach to Assess Large-Scale Improvements in Intelligent Transportation System Infrastructure

Intelligent transportation systems (ITS) can include multiple technologies and applications to improve the efficiency and effectiveness of a transportation system or network. These applications are deployed with the hope of achieving the goals and objectives of multiple stakeholders. This research includes a methodology to evaluate large-scale ITS infrastructure projects using the I-91 ITS project as a case study. The methodology includes a literature review; a clear definition of project goals, objectives, and intended outcomes; development of hypotheses for project outcomes; specific measures of effectiveness; data-collection methods; and criteria to measure the success of achieving the objective. The I-91 ITS project team should consider the following recommendations as next steps in conducting an ITS evaluation: identify and prioritize the goals and objectives, develop a multiphase evaluation approach, identify existing sources of predeployment data, identify missing data requirements, and document the existing communication protocol before deployment. Such a large-scale evaluation requires extensive effort, and priority should be given to developing a multiphase approach. This research may be used to develop an evaluation plan, which is recommended as a component of the six-step process outlined in the evaluation guidelines from the U.S. Department of Transportation.

Getis–Ord Spatial Statistics to Identify Hot Spots by Using Incident Management Data

Traditionally, data have been collected to measure and improve the performance of incident management (IM). While these data are less detailed than crash records, they are timelier and contain useful attributes typically not reported in the crash database. This paper proposes the use of Getis–Ord (Gi*) spatial statistics to identify hot spots on freeways from an IM database while selected impact attributes are incorporated into the analysis. The Gi* spatial statistics jointly evaluate the spatial dependency effect of the frequency and attribute values within the framework of the conceptualized spatial relationship. The application of the method was demonstrated through a case study by using the incident database from the Houston, Texas, Transportation Management Center (TranStar). The method successfully identified the clusters of high-impact accidents from more than 30,000 accident records from 2006 to 2008. The accident duration was used as a proxy measure of its impact. The proposed method could be modified, however, to identify the locations with high-valued impacts by using any other attributes, provided that they were either continuous or categorical in nature and could provide meaningful implications. With improved intelligent transportation system infrastructure and communication technology, hot spot analyses performed with IM data of freeway network and arterials in the vicinity have become a much more promising alternative. Freeway management agencies can use the results of hot spot analysis to provide visualized information to aid the decision-making process in the design, evaluation, and management of IM strategies and resources. The limitations of the method and possible future research are discussed in the closing section of the paper.

A Feasibility Study of Highway Traffic Monitoring using Small Unmanned Aerial Vehicle

Traffic and emergency monitoring systems are essential constituents of Intelligent Transportation System (ITS) technologies, but the lack of traffic monitoring has become a primary weakness in providing prompt emergency services. Demonstrated in numerous military applications, unmanned aerial vehicles (UAVs) have great potentials as a part of ITS infrastructure for providing quick and real-time aerial video images of large surface area to the ground. Despite of obvious advantages of UAVs for traffic monitoring and many other civil applications, it is rare to encounter success stories of UAVs in civil application including transportation. The objective of this paper is to report the outcomes of research supported by the state agency in US to investigate the feasibility of integrating UAVs into urban highway traffic monitoring as a part of ITS infrastructure. These include current technical and regulatory issues, and possible suggestions for a future UAV system in civil applications.

A New Speed Calibration System Design for Vehicles Based on MWS

Development of a rapid and precise an onboard speedometer for vehicles is a major concern for emerging Intelligent Transportation System's infrastructure. This paper presents a highly precise speed calibration system for vehicles based on Micro Wave Sensor (MWS) technology. The new system has two invisible antennas which are laid out in a horizontal and a vertical-shape, respectively. The system's architecture includes ultra-low power consumption microcontroller loaded with a software program which has intelligent capabilities such as self and auto- calibration features.