Tag Archives: RICWS

New Project: Protecting RICWS and DMS From Wind Damage

MnDOT recently entered into a contract with the University of Minnesota (UMN) to complete a research project to keep wind from damaging rural intersection conflict warning signs (RICWS) and other digital message signs (DMS).

The project is titled “Understanding and Mitigating the Dynamic Behavior of RICWS and DMS Under Wind Loading.” Lauren Linderman, assistant professor at UMN’s Department of Civil, Environmental and Geo-Engineering, will serve as the principal investigator. Jihshya Lin of MnDOT will serve as technical liaison.

“This project will find out the behavior of the DMS and RICWS under AASHTO defined design loads and develop the retrofitting system to avoid the experienced problems that will improve the public safety, reduce the maintenance cost and minimize impact to the traffic,” Lin said.

Background

RICWS have exhibited excessive swaying under wind loads, leading to safety concerns regarding failure of the support structure at the base. It is believed the heavy weight of these signs has brought the frequency range of these systems too close to that of the wind excitations. There is a need to investigate the wind-induced dynamic effects on these sign structures and to propose modifications to the systems to reduce the likelihood of failure. There is also interest in investigating the dynamic behavior of the DMS, particularly the loads on the friction connection.

This research project involves a field investigation to determine the structural performance of these two types of sign structures. Laboratory tests using a towing tank facility and a wind tunnel will be performed on scaled models and opportunely modified models to improve performance and minimize unsteady loads.

The outcome of this project is expected to develop an understanding of the RICWS and DMS sign structures and to provide modifications to improve the structural performance of the RICWS sign structures while maintaining the crashworthy requirements. The results will help to ensure the uninterrupted service of these sign structures, which are important to public safety.

 

Project Tasks

  • Task 1A: Development of Field Instrumentation Plan and Instrumentation Purchase
  • Task 1B: Experimental Determination of Load Effects and Dynamic Characteristics of Post Mounted DMS in Field
  • Task 2A: Development of Numerical Models to Investigate Post Mounted DMS Sign Demands and Fatigue
  • Task 2B: Validation of Numerical Models to Investigate Post Mounted DMS Sign Demands and Fatigue
  • Task 3A: Investigation of Design Loads and Relevant Fatigue Considerations for DMS
  • Task 3B: Analysis of Design Loads and Anticipated Fatigue Life of DMS
  • Task 4: Experimental Determination of Dynamic Characteristics of RICWS in Field
  • Task 5: Development and Validation of Numerical Models to Investigate RICWS Signs
  • Task 6: Numerical and Experimental Investigation of Drag and Vortex Shedding Characteristics of RICWS Signs Using Scaled Models
  • Task 7: Numerical and Small-Scale Experimental Investigation of Modifications to RICWS Sign Panel to Reduce Effects of Vortex Shedding
  • Task 8: Numerical and Analytical Investigation of Noncommercial Means to Damp Motion of RICWS Blankout Sign Structure
  • Task 9A: Research Benefits and Implementation Steps Initial Memorandum
  • Task 9B: Research Benefits and Develop Implementation Steps
  • Task 10: Compile Report, Technical Advisory Panel Review and Revisions
  • Task 11: Editorial Review and Publication of Final Report

The project is scheduled to be completed in March 2019.

New technology aimed at making rural intersections safer

This video above showcases a new kind of intersection conflict warning system being developed for use primarily by local agencies at rural, two-way stop intersections. Called the ALERT System, it uses a simple but ingenious combination of radar, wireless communication and flashing LEDs to alert drivers to the presence of approaching vehicles, thereby helping them identify safe gaps in the cross traffic and avoid potentially deadly collisions.

These types of systems are nothing new; MnDOT and other state DOTs have been developing them for more than a decade under the ENTERPRISE pooled fund program. MnDOT also recently kicked off a three-year project to deploy 20–50 of its Rural Intersection Conflict Warning Systems at selected at-risk intersections across the state. The main difference with the ALERT System is that it’s designed to be cheaper and easier to deploy than existing ICWS technologies. While that might sound like an incremental improvement, the difference for cash-strapped local agencies could be huge.

Since the ALERT System uses solar power, it doesn’t have to be hooked up to the power grid — which means that, in theory, county public works crews could install it themselves. The system also uses a simplified controller that doesn’t require a traffic signal technician to install and maintain, and detects vehicles using radar rather than in-pavement sensors. These factors might encourage greater adoption of ICWS technologies, which studies have shown to reduce both the frequency and severity of crashes.

The project is now in its second phase. It still faces a number of hurdles before could be ready to deploy, but Vic Lund, the traffic engineer for St. Louis County and the project’s main champion, says the results so far have been encouraging. In the video below, Lund shares his thoughts on the project, its challenges and the future of Intelligent Transportation Systems in Minnesota.

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