This study addresses the issue of whether the message content of variable message signs (VMS) can... more This study addresses the issue of whether the message content of variable message signs (VMS) can be used as a control variable to favorably influence traffic conditions in real-time. The focus is on the level of detail of information displayed on the VMS, and not human factor issues. It implies an understanding of driver sensitivity to information content. Also, for real-time implementation, the displayed information should be consistent, timely, and reliable. A framework is developed for optimizing system performance under incidents using the VMS message content as the primary control parameter. It consists of: (i) an efficient control strategy to enhance system performance using the VMS and information on current traffic conditions received from on-line sensors; (ii) a driver response model to supplied information that addresses the effect of the message content on drivers' en-route switching decisions; and (iii) an incident clearance time prediction model which predicts the expected delay due to an incident.
Variable Message Signs (VMS) represent a cost-effective mechanism for disseminating information t... more Variable Message Signs (VMS) represent a cost-effective mechanism for disseminating information to drivers unequipped to receive personalized information. They can be used under incidents to divert traffic to less congested areas of the network to circumvent lengthy queues, better utilize network capacity, and improve system performance. This paper proposes and evaluates a VMS control heuristic framework that seeks diversion under incidents to enable a traffic system controller to favorably control traffic conditions in real-time. The framework ensures consistency with driver diversion response behavior, is responsive to changing traffic conditions, enables computational tractability through stage-based on-line implementation, and ensures the spatial and temporal consistency of the displayed messages. It uses a hybrid framework that consists of off-line and on-line components to determine the VMS messages. The ability to display messages that are consistent with driver diversion behavior represents a valuable tool for the controller to enhance system effectiveness by simultaneously satisfying system-wide and individual user objectives. Real data on driver VMS response attitudes from the Borman Expressway corridor in northwestern Indiana and simulated experiments are used to derive insights on the practical effectiveness of the proposed VMS control heuristic.
Transportation Research Part B-methodological, 2009
Information on link flows in a vehicular traffic network is critical for developing long-term pla... more Information on link flows in a vehicular traffic network is critical for developing long-term planning and/or short-term operational management strategies. In the literature, most studies to develop such strategies typically assume the availability of measured link traffic information on all network links, either through manual survey or advanced traffic sensor technologies. In practical applications, the assumption of installed sensors on all links is generally unrealistic due to budgetary constraints. It motivates the need to estimate flows on all links of a traffic network based on the measurement of link flows on a subset of links with suitably equipped sensors. This study, addressed from a budgetary planning perspective, seeks to identify the smallest subset of links in a network on which to locate sensors that enables the accurate estimation of traffic flows on all links of the network under steady-state conditions. Here, steady-state implies that the path flows are static. A "basis link" method is proposed to determine the locations of vehicle sensors, by using the link-path incidence matrix to express the network structure and then identifying its "basis" in a matrix algebra context. The theoretical background and mathematical properties of the proposed method are elaborated. The approach is useful for deploying long-term planning and link-based applications in traffic networks.
This paper focuses on the relationship between the content of VMS messages and driver route diver... more This paper focuses on the relationship between the content of VMS messages and driver route diversion rates. Presumably, if different message contents to describe the same situation prompt different diversion rates, then message content can be used as a control variable by the traffic controller to generate favorable network conditions in the real-time operation of the system, while conserving the integrity of information. This has key implications for the design and operation of VMS-based traffic information systems, primarily in terms of credibility and effectiveness of information for motorists. Controlling the level of detail of displayed VMS information without impinging on its veracity can potentially aid user confidence in VMS-based information provision. Also, solution methodologies for networks installed with VMS can focus on message content as a primary mechanism to improve network performance. It should be noted here that message content in our study does not imply human factor-related details such as number of words or lines, size of words, or graphics issues. Message content refers to the amount of information provided on the incident situation.
Iee Proceedings - Intelligent Transport Systems, 2006
This study investigates driver response attitudes to traffic information provided through variabl... more This study investigates driver response attitudes to traffic information provided through variable message signs (VMS). It develops VMS driver response models using stated preference data collected through three different survey administration methods: an onsite survey, a mail-back survey, and an Internet-based survey. In the process, it highlights the strengths and limitations of each method in eliciting driver response attitudes to information provision. The use of different media for the survey administration provides insights for the design of travel surveys. A key study focus is to evaluate the effectiveness of Internet-based surveys for analyzing driver behavior under information provision. The results illustrate that a combination of survey administration methods may generate more representative data. They also indicate a high correlation between VMS message type and driver response. This suggests message content as a control variable for traffic system operators to trigger optimal routing policies under congested conditions to improve network performance. The paper highlights the benefits afforded by Internet-based surveys in the study context. They are cost-effective, amenable to automation, less laborintensive, can target certain market segments more effectively, and can enable greater clarity in the survey through better visual articulation. However, their widespread use requires greater market penetration in terms of Internet access.
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Papers by Srinivas Peeta