Analysis of Peer Intersection Data for Arterial Traffic Signal Coordination Decisions

This is the author-accepted manuscript version of Day, C.M., T.M. Brennan, H. Premachandra, J.R. Sturdevant, and D.M. Bullock, “Analysis of Peer Data on Intersections for Decisions About Coordination of Arterial Traffic Signal,”Transportation Research Record: Journal of the Transportation Research Board, No. 2259, Transportation Research Board of the National Academies, Washington, D.C., pp. 23–36, 2011, copyright National Academy of Sciences.http://dx.doi.org/10.3141/2259-03 Its corresponding poster can be found here:http://docs.lib.purdue.edu/atspmw/2016/Posters/3

Leveraging High Resolution Signalized Intersection Data to Characterize Discharge Headway Distributions and Saturation Flow Rate Reliability

As highway systems become more congested, it becomes increasingly important to understand the reliability with which we can estimate important performance measures such as volume to capacity ratios, particularly as we move toward leveraging field infrastructure to obtain real-time performance measures. In 1947, Greenshields wrote a paper that characterized “green time consumed” by “car-in-line-number” that ultimately was called headway. Average headway is one of principles used by the highway capacity manual to estimate saturation flow rate at signalized intersections. However, the current analytical techniques calculate a deterministic value for saturation flow rate that does not consider the stochastic variation of saturation flow rate. This paper reviews techniques used to estimate saturation flow rate, and proposes enhanced calculation methods to group saturation flow rate estimates by queue length. Grouping saturation flow rate estimates by queue length provides a convenient framework to evaluate saturation flow rate reliability. The inter-quartile range (25% - 75%) of saturation flow rates was calculated to be 1000vph based on Greenshields’ calculation techniques. Using the proposed enhanced calculation characterizing saturation flow rate, the inter-quartile range of saturation flow rate was shown to decrease from approximately 400 vph with 5 cars in a queue to 300 vph with 10 cars in queue. Because saturation flow rate is a fundamental input to volume-to-capacity performance measures, characterizing the stochastic variation of saturation flow rates provides a basic input for assessing how reliably one can estimate important performance measures such as volume-to-capacity ratios, as well as other performance measures that build upon volume-to-capacity ratios

Performance Evaluation of Traffic Sensing and Control Devices

High quality vehicle detection is essential to properly operate actuated phases at traffic signals and to facilitate effective management of technician and engineering resources. INDOT operates over 2600 traffic signal controllers, approximately 2000 of which use some form of vehicle detection. The private sector continues to develop innovative sensing technologies that may potentially benefit Indiana motorists and taxpayers by improving system efficiency and lowering installation and maintenance costs. However, the acceptance of new sensing technology requires careful evaluation because to ensure that they provide robust performance 24 hours a day, 365 days a year, with minimal impact on maintenance resources. This study developed a technical protocol for evaluating vehicle detector performance and applied those techniques to both video detection (in partnership with Texas) and wireless magnetometers. Based on experiences in designing the detector test bed, recommendations are given for stop bar detection zone design using wireless magnetometers. Additional results include a detailed study of the inductive loop detector sensing range for several loop geometries, and an innovative method for interrogating NTCIP-compliant traffic signal systems to allow quality control on signal timing plan implementation. Since this project spanned several years, interim results were documented in the professional literature as they became available. This technical report summarizes those results and provides references to the published papers

Procurement Procedures and Specifications for Performance Measure Capable Traffic Infrastructure Data Collection Systems

Traffic signal systems represent a substantial component of the highway transportation network in the United States. It is challenging for most agencies to find engineering resources to properly update signal policies and timing plans to accommodate changing traffic demands. Upgrading existing systems can achieve incremental benefits, but do not address the fundamental problem that information about system performance is not communicated to the agency in a meaningful or systematic way. This project developed a collaborative pilot deployment partnership between a large public agency, university, and commercial equipment manufacturers to define an architecture for a centralized traffic signal management system that can be used on a large geographic scale by both maintenance and technical services staff. This architecture leverages wireless IP communications to integrate performance measures into a database environment and a performance measure dashboard. In addition to this architecture, several uses of high resolution signal controller event data are presented. An extended discussion of a visualization technique called the “Purdue Coordination Diagram” is presented, which enables new methods for visualizing and assessing 24-hour corridor operations without field visits or searching through hours of recorded video. A new methodology for using data from peer intersections to estimate fundamental traffic flow characteristics is proposed. In this methodology, phase status from an upstream intersection is fused with downstream detector status to obtain link travel time and platoon dispersion characteristics. Finally, this data is integrated into an optimization engine for determining cycle length, phase sequence, and offsets

Quantifying Benefits of Traffic Signal Retiming

Improvements in the quality of service on a signalized intersection or arterial can be interpreted as a reduction in the user cost of service, which is expected to induce demand based on economic theory. This report presents a methodology for measuring and interpreting changes to user costs, and determining whether demand was induced. High-resolution signal event data and Bluetooth device MAC address matching are demonstrated in three case studies with the purpose of quantifying the impacts of changes in signal timing plans. In the first case study, 21 months of vehicle volume data are used to test whether demand was induced by optimizing offsets on a Saturday plan. In the second case study, the increase in demand for pedestrian service is quantified with respect to the implementation of an exclusive pedestrian phase using an econometric model taking the effects of season, weather, and special events into account. Finally, the third case study demonstrates the use of vehicle travel time data in quantifying changes in user costs and environmental impact (tons of carbon). A method of describing changes in travel time reliability is also presented

Indiana Traffic Signal Hi Resolution Data Logger Enumerations

Assessing the operational performance of traffic signals required detailed information regarding sensors inputs and controller actions. In 2012, a series of enumerations used to encode traffic signal events at a 100 millisecond was developed and published at https://doi.org/10.4231/K4RN35SH. Techniques for using that data are published in https://doi.org/10.5703/1288284315333 and https://doi.org/10.5703/1288284316063 As part of a multi-state Federal Highway Administration pooled fund study, TPF-5(377), a series of stakeholder engagements and panel meetings were conducted in 2018 and 2019 to update these enumerations. In 2020, updates to the enumerations included minor changes to event codes 14, 17, and 54

Indiana Traffic Signal Hi Resolution Data Logger Enumerations

This document defines the enumerations used to encode events that occur on a traffic signal controllers with high resolution data loggers. The time resolution is to the nearest 100 milliseconds. Background information on the development of high resolution controller data in Indiana can be found at: Smaglik E.J., A. Sharma, D.M. Bullock, J.R. Sturdevant, and G. Duncan, “Event-Based Data Collection for Generating Actuated Controller Performance Measures, Transportation Research Record, #2035, TRB, National Research Council, Washington, DC, pp.97-106, 2007.http://dx.doi.org/10.3141/2035-11 Recent applications of high resolution data to develop traffic signal performance measures in Indiana can be found at: Outcome-Oriented Performance Measures for Management of Signalized Arterial Capacity http://dx.doi.org/10.3141/2192-03 Track Clearance Performance Measures for Railroad-Preempted Intersections http://dx.doi.org/10.3141/2192-06 Reliability, Flexibility, and Environmental Impact of Alternative Objective Functions for Arterial Offset Optimization http://dx.doi.org/10.3141/2259-02 Visual Education Tools to Illustrate Coordinated System Operation http://dx.doi.org/10.3141/2259 -0