2013 Session: 261

• Arterial Traffic Signal Optimization: A Person-Based Approach
  Abstract: This paper presents a traffic responsive signal control system that optimizes signal settings based on minimization of person delay on arterials. The system's underlying mixed integer linear program minimizes person delay by explicitly accounting for the passenger occupancy of autos and transit vehicles. This way it can provide signal priority to transit vehicles in an efficient way even when they travel in conflicting directions.Furthermore, it recognizes the importance of schedule adherence for reliable transit operations and accounts for it by assigning an additional weighting factor on transit delays. This introduces another criterion for resolving the issue of assigning priority to conflicting transit routes. At the same time, the system maintains auto vehicle progression by introducing the appropriate delays for when interruptions of platoons occur. In addition to the fact that it utilizes readily available technologies to obtain the input for the optimization, the system's feasibility in real-world settings is enhanced by its low computation time. The proposed signal control system was tested on a segment of San Pablo Avenue arterial located in Berkeley, California. The findings have shown the system's capability to outperform static optimal signal settings and have demonstrated its success in reducing person delay for bus and in some cases even auto users.
  Authors: Christofa, Eleni; Aboudolas, Konstantinos; Skabardonis, Alexander
  Authors: Christofa, Eleni; Aboudolas, Konstantinos; Skabardonis, Alexander
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-3395
• Optimized Advance Detector Configuration for Option Zone Protection at High-Speed Signalized Intersections
  Abstract: Advance detection and green extension schemes are widely applied in practice as a typical solution to the safety issues associated with the intersection dilemma zone (DZ) problem. Most existing detector configurations were either developed based on the traditional Type I DZ model in which some critical contributing factors were assumed static, or based on generic Type II DZ. A comparison analysis based on field-observed trajectory data showed that option zone estimated the location of dilemma zone most accurately among all the available dilemma zone models. Also, the results of the authors’ recent research on the quantitative modeling of option zone’s contributing factors make it possible to accurately identify the option zone locations. That lays out a solid foundation for developing an option zone based detection scheme to achieve the most effective and efficient dilemma zone protection. This paper presents an alternative advance detector configuration for the option zone protection via optimization trials within a calibrated VISSIM simulation model. The optimization objective was to minimize the combined cost of dilemma hazard (safety) and delay (mobility). Dilemma Conflict Potential, a comprehensive dilemma hazard model was used to quantitatively measure the safety performance, as a replacement for the traditional measure of “number of vehicles in dilemma zone”. The optimal configuration was evaluated and validated via its comparison with four widely-applied detector configurations in the nation. The results revealed the superiority of the developed optimal detector configuration in terms of the best safety performance and the least combined cost of dilemma hazard and delay among all configurations.
  Authors: Li, Zhixia; Wei, Heng; Xiong, Hui; Yan, Xuedong
  Authors: Li, Zhixia; Wei, Heng; Xiong, Hui; Yan, Xuedong
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-3565
• Revisiting the Cycle Length--Lost Time Question with Critical Lane Analysis
  Abstract: During oversaturation, the objective in signal operations is to maximize throughput in order to keep traffic moving. The fact that lost time shrinks as a proportion of total operating time as cycle length increases has long been used as an argument for programming longer cycle lengths into traffic signals. This paper revisits the concept of critical lane analysis to calculate throughput and applies the technique to data collected at an intersection in Indianapolis that is regularly oversaturated during the PM peak hour. Traffic volumes were measured from over 10 weeks while different cycle lengths were tested at the intersection, ranging from 80 to 135 seconds. Somewhat surprisingly, during saturated conditions, no clear improvement in the sum of critical lane throughput was observed, even when the cycle length increased by over 50%. In fact, there was a slight reduction in the total critical lane sum volume at 135 seconds. The findings concur with a recent simulation study by Denney et al.. We attribute the reduction in throughput at the longer cycle length to the reduction of saturation flow, s, during long green times reported in recent studies, and demonstrate that time-dependent functions of s could change forecasts of throughput as a function of cycle length to better reflect field observations. Additionally, the critical lane analysis methodology has applications for agencies to evaluate and rank intersections within corridors as under, near, or over saturation.
  Authors: Day, Christopher M.; Sturdevant, James R.; Li, Howell; Stevens, Amanda; Hainen, Alexander Michael; Remias, Stephen Matthew; Bullock, Darcy M.
  Authors: Day, Christopher M.; Sturdevant, James R.; Li, Howell; Stevens, Amanda; Hainen, Alexander Michael; Remias, Stephen Matthew; Bullock, Darcy M.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-0250
  Practice-Ready: Yes
• Simple Methodology to Estimate Queue Lengths at Signalized Intersections Using Detector Data
  Abstract: This paper presents a simple methodology to estimate queue length on an approach to a signalized intersection. This method has a minimal set of data requirements specifically flow, occupancy, cycle length, and detector setback in contrast to prevailing methods that rely on estimating vehicle trajectories using detailed data defined on a per signal cycle basis. The key element of the algorithm is the estimation of two baseline occupancies that correspond to the relative position of the queue with respect to the detector location. The results of the algorithm have been evaluated using traffic simulation and also compared to field observations. The comparison of the queue estimates suggest that the detector location would be ideal to estimate queues, if under prevailing conditions the tail of the queue is routinely longer than the detector setback. For detectors with appropriate setback, queue estimates match well in both comparisons. This algorithm was developed as part of the Midtown in Motion project and is currently operational in the field, in New York City as one of the elements of the active traffic management.
  Authors: Chang, Jinil; Talas, Mohamad A.; Muthuswamy, Satya
  Authors: Chang, Jinil; Talas, Mohamad A.; Muthuswamy, Satya
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-1279
  Practice-Ready: Yes
• Simple Methodology to Estimate Queue Lengths at Signalized Intersections Using Detector Data
  Authors: Muthuswamy, Satya
  Authors: Muthuswamy, Satya
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-1279
• Revisiting the Cycle Length--Lost Time Question with Critical Lane Analysis
  Authors: Day, Christopher
  Authors: Day, Christopher
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-0250
• Arterial Traffic Signal Optimization: A Person-Based Approach
  Authors: Christofa, Eleni
  Authors: Christofa, Eleni
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-3395
• Optimized Advance Detector Configuration for Option Zone Protection at High-Speed Signalized Intersections
  Authors: Li, Zhixia
  Authors: Li, Zhixia
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management
  Session: 261
  Paper Number: 13-3565