Evaluation of Integrated Platoon-Priority and Advance Warning Flasher System at High-Speed Intersections

Abstract

the interconnected intersections or there is unpredictability in traffic demand. Recently, active platoon-priority signal control systems that operate on the basis of real-time traffic conditions have been developed to deal with this problem (6-8).Furthermore, advance warning flashers (AWFs) are used on major approaches at rural high-speed signalized intersections to warn motorists of the end of the green. The conventional method uses a trailing overlap green (9). A fixed-length green hold, typically 7 to 8 s, is placed at the end of the phase. The advance warning beacons located upstream of the intersection start flashing along with the trailing overlap green. In addition, dilemma-zone detectors are used on high-speed approaches to prevent a gap-out when there is a vehicle in the dilemma zone. But when AWFs are used, there is a fixed-length hold over the phase after gap-out and no more green extensions are given afterward. This setup replaces the dilemma-zone protection (DZP) provided by the detectors, and the routinely placed fixed-time hold at the end of the phase increases delay on the minor approach.An advance warning end-of-green system (AWEGS) has been developed by Texas Transportation Institute (TTI) to provide advance warning without the necessity of holding the green (10). Several research studies have been done on the effectiveness of AWF signs. The accident studies conducted on isolated high-speed signalized intersections (11-13) indicated that the advance warning signs are effective in reducing accidents. Although the results of an accident study in Minnesota (14) were mixed, the study recommended advance warning signs on approaches with a posted speed limit of 55 mph or higher.Both platoon-priority and AWEGS have a great deal in common in terms of hardware requirements and operation. Both systems use advance detection to collect information regarding future vehicle arrivals at the intersection and analyze collected information in regard to respective system objectives and, when necessary, override normal signal controller operations to achieve their purpose. However, there has not been a research effort to integrate these systems. The purpose of this research study is to develop and evaluate the benefits of an integrated system that provides platoon priority, advance warning of the end of green, and also DZP at the end of green.The developed system is tested on a cabinet-in-the-loop system with a real scenario to evaluate its benefits. Figure 1 illustrates the integrated system (IS) architecture. Similar architecture has been used in previous studies (7, 10). The IS uses advance detectors and a computer installed with IS software to detect future events such as platoon arrivals and phase detector actuation Most rural or suburban high-speed isolated intersections have higher traffic volumes on the major approach compared with the minor approach. Often these intersections are not close enough to one another to provide coordination and are not far enough apart to disperse vehicle platoons completely on...

Detecting Sybil attacks in vehicular networks

“…Platoon dispersion has been well studied in transportation engineering [15][16][17][25][26][27][28][29][30][31], via two mathematical models. One is the (more popular) Robertson's geometric distribution model [16] and the other is the Pacey's normal distribution model [15].…”