Edward J. Smaglik

Event-Based Data Collection for Generating Actuated Controller Performance Measures

Cycle-by-cycle data have been shown to be effective in the analysis of a signalized intersection with measures of effectiveness such as volume-to-capacity ratios, arrival type, and average vehicular delay. Currently, actuated traffic controllers are unable to store vehicle counts and vehicle occupancy in cycle-by-cycle bins, requiring extra equipment and personnel to collect data in these bins. The objective of this research was to develop an integrated general purpose data collection module that time-stamps detector and phase state changes within a National Electrical Manufacturers Association actuated traffic signal controller and uses those data to provide quantitative graphs to assess arterial progression, phase capacity utilization, movement delay, and served volumes on a cycle-by-cycle basis. Given that the United States recently received a grade of 61 of 100 on the National Traffic Signal Report Card, it is particularly important that procedures such as these be used to provide performance measures over extended periods so agencies have cost-effective mechanisms for assessing and priority-ranking signal timing efforts.

Evaluation of Lane-by-Lane Vehicle Detection for Actuated Controllers Serving Multilane Approaches

A comparison was conducted of traditional vehicle detection, in which all lanes on an approach are connected to an actuated controller through one amplifier card and input, and lane-by-lane detection, in which each lane is interfaced with the controller through separate amplifier cards and inputs. Both detection strategies were evaluated with various extension time values on the same traffic stream. A total of 430 h of data from two separate approaches was evaluated on an hour-by-hour basis. During certain time periods, lane-by-lane detection provided up to a 13% increase in efficiency. For all 930 h of observations, the median increase in efficiency was 5.2% on an approach with 51-ft-long detection zones and 3.5% on an approach with 38-ft-long detection zones. This increased efficiency corresponds to time that could be allocated to other movements or used to reduce the cycle length. The largest improvements associated with lane-by-lane detection occurred during periods with moderate volume-to-capacity ratios, with smaller benefits observed during periods of heavy or light traffic.

Vendor Comparison of Video Detection Systems

Video detection has become increasingly popular for presence detection at signalized intersections because of its versatility. However, several reports have documented performance problems in specific systems. This paper quantifies the performance of three different commercially available video detection systems. The systems were tested in May and September 2005 for presence detection accuracy. Prior to the May 2005 test, a representative from each vendor configured the video detection zones to match the loop detection zone as closely as possible. The outputs from the loop detection for the through-right and left-turn lane groups were compared with the corresponding output from each of the video detection systems. Whenever there was a discrepancy between the loop and video, a digital video was observed to determine the cause of the discrepancy. Missed calls and false calls were categorized for each system. The errors were also categorized according to the impact that they would have on signal operations. During a 24hr test on two separate days, the number of missed detections longer than 5 seconds ranged from 9 to 147, and the number of false calls longer than 5 seconds ranged from 16 to 149.

Implementation of Lane-by-Lane Detection at Actuated Controlled Intersections

Previous work with lane-by-lane detection has shown efficiency gains during periods of moderate to low volume, as well as a decrease in overall intersection delay when lane-by-lane detection is compared with traditional movement-based detection. This research extends that work with the implementation of lane-by-lane detection at the Indiana Department of Transportations test bed intersection in Noblesville, Indiana. Over a 3-week period with traditional movement-based detection, green interval lengths, volume-to-capacity (v/c) ratios, and cycle lengths were computed for all eight phases. Detection and controller settings were changed to implement lane-by-lane detection on the multilane movements at the test bed, and the same measures of effectiveness were calculated for 3 weeks of lane-by-lane detection. During free operation with low to moderate volume, statistically significant decreases in green durations and cycle times, as well as statistically significant increases in v/c ratios, were observed on movements with lane-by-lane detection. These implementation results corroborate previous simulation results.

Evaluation of Flow-Based Traffic Signal Control Using Advanced Detection Concepts

State-of-the-practice signal timing techniques used at isolated actuated controlled intersections can result in suboptimal operation. This paper proposes a new tactical control algorithm that integrates real-time stop bar presence detection with real-time flow rate information to identify a downstream flow restriction. If a flow restriction is identified, a phase with a constant call could be terminated earlier than its specified maximum or split time. This algorithm was validated with real-time data to predict downstream bottleneck conditions and then by viewing the archived video for confirmation of the condition. The algorithm was applied during a 504-h period of signal operation. During this period, the algorithm identified 76 bottlenecks. Overall, 75.0% of these events were visually confirmed. Algorithm failures were caused by a variety of conditions such as large trucks, inattentive drivers, and detector errors.