Effect of High and Low Temperatures on UPS systems for Intersection Traffic Signals

Temperature significantly affects the performance of UPS systems. Four different UPS systems were evaluated at sub-zero temperatures and hot temperatures from -25 °C to +72 °C (-13 °F to +162 °F). At high temperatures, tests were performed to ascertain the run times under normal signal operation, whether the UPS shutsdown the charging and that there is no gassing of the batteries. At sub-zero temperatures tests were performed to find the run times under normal, flashing and a combination of normal and flashing modes of operation. All the UPS systems showed longer run times as the temperature increased and drastically shorter run times as the temperature decreased. For normal operation at +72 °C condition, the percentage change in run time relative to room temperature ranged from +6% to +26%. Relative to room temperature the percentage change in run time at -25 °C condition ranged from -32% to -80% for normal operation. At the coldest temperature, the increase in duration of flashing compared to duration of normal operation ranged from 89% to 158% and the increase in combination of normal and flashing duration compared to normal operation duration ranged from 35% to 81%. It is recommended to switch to flashing or a combination of normal and flashing mode of operation in cold temperatures to increase the run time. It was also found that a UPS with a greater battery capacity may not yield greater run times under all temperature conditions.The Illinois Department of Transportationpublished or submitted for publicationnot peer reviewe

Sustainability effects of next-generation intersection control for autonomous vehicles

Transportation sustainability is adversely affected by recurring traffic congestions, especially at urban intersections. Frequent vehicle deceleration and acceleration caused by stop-and-go behaviours at intersections due to congestion adversely impacts energy consumption and ambient air quality. Availability of the maturing vehicle technologies such as autonomous vehicles and Vehicle-To-Vehicle (V2V) / Vehicle-To-Infrastructure (V2I) communications provides technical feasibility to develop solutions that can reduce vehicle stops at intersections, hence enhance the sustainability of intersections. This paper presents a next-generation intersection control system for autonomous vehicles, which is named ACUTA. ACUTA employs an enhanced reservation-based control algorithm that controls autonomous vehicles’ passing sequence at an intersection. Particularly, the intersection is divided into n-by-n tiles. An intersection controller reserves certain time-space for each vehicle, and assures no conflict exists between reservations. The algorithm was modelled in microscopic traffic simulation platform VISSIM. ACUTA algorithm modelling as well as enhancement strategies to minimize vehicle intersection stops and eventually emission and energy consumption were discussed in the paper. Sustainability benefits offered by this next-generation intersection were evaluated and compared with traditional intersection control strategies. The evaluation reveals that multi-tile ACUTA reduces carbon monoxide (CO) and Particulate Matter (PM) 2.5 emissions by about 5% under low to moderate volume conditions and by about 3% under high volume condition. Meanwhile, energy consumption is reduced by about 4% under low to moderate volume conditions and by about 12% under high volume condition. Compared with four-way stop control, single-tile ACUTA reduces CO and PM 2.5 emissions as well as energy consumption by about 15% under any prevailing volume conditions. These findings validated the sustainability benefits of employing next-generation vehicle technologies in intersection traffic control. In addition, extending the ACUTA to corridor level was explored in the paper

Evaluation of Video Detection Systems Volume 4 - Effects of Adverse Weather Conditions in the Performance of Video Detection Systems

The performance of three video detection systems (VDS): Iteris, Autoscope, and Peek, was evaluated using a side-by-side installation at a signalized intersection under various adverse weather conditions including rain and snow in both day and nighttime, and light fog and dense fog in daytime. Four types of detection errors (false, missed, stuck-on, and dropped calls) were quantified at stop bar and advance detection zones, and all errors were visually verified using video images from the intersection. Results indicate that VDS performance was not greatly impacted under daytime light fog or rain conditions without wind, but significant changes were observed under dense fog and snow in daytime, and snow and rain in nighttime. During dense fog conditions Iteris and Autoscope changed their operating mode and placed constant calls due to image contrast loss, with potential for significant effects on traffic operation, while Peek significantly increased its missed calls. Snow in daytime and nighttime greatly increased false calls for the three systems (more than 50% of the VDS calls were false), but it had limited effects on missed, stuck-on, and dropped calls. False calls during rainy conditions without wind also increased, during both daytime (around 10%) and nighttime (between 10% and 50%), mostly due to the reflection of headlights of vehicles in the adjacent lanes. Detailed performance of the three VDS in each of the three stop bars and the three advance zones, as well as potential causes and effects of the most prominent error types are presented.ICT- R43published or submitted for publicationis peer reviewe

Evaluation of Video Detection Systems (VDS), Volume I: Effects of Configuration Changes in the Performance of VDS

The effects of modifying the configuration of three video detection (VD) systems (Iteris, Autoscope, and Peek) are evaluated in daytime and nighttime conditions. Four types of errors were used: false, missed, stuck-on, and dropped calls. The three VD systems were installed side-by-side at an intersection in Rantoul, IL. The configurations were modified by the vendors to improve their performance. The modifications to Peek VD configuration effectively reduced dropped calls at the stop bar zones; however, that was at the expense of increasing false calls during daytime and missed and false calls during night time. Similarly, in the advance zones, in both daytime and nighttime, there was a clear tradeoff between decreasing missed calls and increasing false calls. The modifications to Autoscope VD configuration did not provide a clear improvement at the stop bar zones during daytime; however, during nighttime, false calls increased and missed calls were eliminated. In the advance zones, the Autoscope changes significantly reduced missed calls in both day and night, reduced false calls in daytime, but increased in false calls during nighttime. The modifications to Iteris VD configuration were slight and overall effects of the changes were relatively small. This resulted in a tradeoff between false and missed calls. The results for three systems indicate that there are tradeoffs when the goal is to improve the overall performance of VD systems. Thus, after making modifications to the configuration of VD systems, the effects of these changes should be monitored not only for improvements on the previously detected errors, but also for potential new errors of a different type.ICT- R-43published or submitted for publicationis peer reviewe

Evaluation of Video Detection Systems Volume 3 - Effects of Windy Conditions in the Performance of Video Detection Systems

The performance of three Video Detection Systems (VDS), namely Autoscope, Iteris, and Peek, was evaluated at stop bar and advance locations, at an instrumented signalized intersection located in Rantoul, Illinois, utilizing a side-by-side installation and large data sets covering a variety of conditions. This report contains the analysis and findings of the VDS performance under windy conditions during cloudy noon, sunny morning, and nighttime. There are three other reports that describe the effects of adverse weather, illumination, and adjusting the configuration of the VDS zones. The performance of the VDS in windy conditions was assessed based on the frequency of false, missed, stuck-on, and dropped calls (errors in detection); and was compared to calm weather scenarios (without wind). Results indicate minor wind effects during cloudy conditions at the stop bar zones, and less than 10% increases in the false calls at advance zones. In the sunny morning scenario (where long shadows were observed) false calls increased significantly at both stop bar (22-39%) and advance zones (20- 70%), missed calls increased at advance zones for one VDS, while they decreased for the other two VDS, and stuck-on calls increased by less than 2% due to the shadow of the crossing street pole. At nighttime, false calls increased at stop bar zones (5-53%), and at advance zones (2-27%), and there were small fluctuations in the percentage of missed calls.ICT-R43published or submitted for publicationis peer reviewe

Evaluation of Video Detection Systems (VDS) Volume 2: Effects of Illumination Conditions

The evaluation of three Video Detection Systems (VDS) at an instrumented signalized intersection in Rantoul Illinois, at both stop bar and advance detection zones, was performed under a wide range of lighting and weather conditions. The evaluated VDS are: Autoscope, Iteris and Peek. This document describes the effects of different illumination conditions (dawn, sunny morning, cloudy noon, dusk, and night) on false, missed, stuck-on, and dropped calls (errors in detection). Results showed that the illumination conditions significantly affect the performance of VDS. The best performance was found during cloudy noon conditions, with false calls lower than 4% for four of the six detection zones, but for the other two zones false calls were up to 18% and up to 21%, missed calls lower than 1% at stop bar, and up to 2.8% at advance zones, stuck-on calls lower than 1%, and no dropped calls. During dawn, false calls increased for the three VDS (up to 23%), and missed calls increased by 18% only in one system in one specific zone. During a sunny morning, false calls increased in greater proportion in zones where vehicle shadows were more prominent (up to 21% at stop bar and up to 43% at advance zones). Results during the dusk condition followed trends similar to the dawn, but with higher increases in false calls (ranging from no change to about 50% increase), and higher increases in the missed calls observed for one VDS. Lastly, during night, false calls increased for specific zones and systems, and various trends with relatively small changes were found in terms of missed calls. The findings of this study are published in four separate volumes. The other three volumes cover the effects of detection zone configuration changes, windy conditions, and adverse weather conditions.ICT- R43published or submitted for publicationis peer reviewe

Drivers' Evaluation of Performance of LED Traffic Signal Modules

This study evaluated the performance of the LED modules from four manufacturers (Leotek, Gelcore, Dialight and Precision Solar) who provided the required number of LEDs for testing and evaluation at the Traffic Operations Lab. The criteria for evaluation were drivers’ perception of brightness, dottiness, and color compared to incandescent lenses. For circular red indication, brightness, dottiness, and color of Dialight LED module was similar to incandescent lens, but the other three were brighter, more dottier, and darker than incandescent lens. For circular yellow indication, brightness of Precision Solar LED was the same while the others were brighter than incandescent lens; they all were dottier and darker (orange-yellow) than incandescent lens. For circular green indication all the LED modules were brighter, dottier, darker (bluish) than incandescent lens. For yellow arrow indication, Leotek and Dialight are the same while Gelcore and Precision Solar were brighter than incandescent lens; all the LED modules were dottier and darker than incandescent lens. For green arrow indication, Leotek was the same as incandescent while Dialight, Gelcore and Precision Solar were brighter than incandescent lens; all the LED modules were dottier and darker than incandescent lens. The findings, though limited, indicated that there could be a significant difference in the perception of the LED modules by the older drivers. It is recommended to further study the effect of aging on the perception of the LED modules.The Illinois Department of Transportationpublished or submitted for publicationnot peer reviewe

Evaluation of UPS for Intersection Traffic Signals with LED: Findings for Alpha Novus 1000 UPS

Uninterruptible Power Supply (UPS) systems are used to power the intersection traffic signals that have Light Emitting Diode (LED) signal modules, in case of a power failure. The objective of this study was to test the Novus 1000 UPS manufactured by Alpha Technologies and verify if it meets the Illinois DOT’s specification for UPS. Multiple tests with full load (approximately 700 W) and partial loads (flashing reds with about 350W) were conducted at room temperature to determine charge and discharge times. The time to fully charge the batteries was on average 16hrs 37min. The UPS powered a full load for 3hrs 27mins. When powering a full load, the UPS took 1hr 56min to reach 40% battery level. After reaching the 40% level, the UPS powered the flashing reds for 3hr 30min. Alpha Novus 1000 UPS meets the majority of the IDOT Specification requirements. It has two major and some minor shortcomings that can be corrected to satisfy all IDOT Specification requirements. The major shortcomings of this model are: this model does not have a NO and NC contact closure for indicating inverter/charger failure. The manufacturer gives a 16 hr burn-in period to each unit.The Illinois Department of Transportationpublished or submitted for publicationnot peer reviewe