Wind Loads on Dynamic Message Cabinets and Behavior of Supporting Trusses, TR-612, 2013

Large Dynamic Message Signs (DMSs) have been increasingly used on freeways, expressways and major arterials to better manage the traffic flow by providing accurate and timely information to drivers. Overhead truss structures are typically employed to support those DMSs allowing them to provide wider display to more lanes. In recent years, there is increasing evidence that the truss structures supporting these large and heavy signs are subjected to much more complex loadings than are typically accounted for in the codified design procedures. Consequently, some of these structures have required frequent inspections, retrofitting, and even premature replacement. Two manufacturing processes are primarily utilized on truss structures - welding and bolting. Recently, cracks at welding toes were reported for the structures employed in some states. Extremely large loads (e.g., due to high winds) could cause brittle fractures, and cyclic vibration (e.g., due to diurnal variation in temperature or due to oscillations in the wind force induced by vortex shedding behind the DMS) may lead to fatigue damage, as these are two major failures for the metallic material. Wind and strain resulting from temperature changes are the main loads that affect the structures during their lifetime. The American Association of State Highway and Transportation Officials (AASHTO) Specification defines the limit loads in dead load, wind load, ice load, and fatigue design for natural wind gust and truck-induced gust. The objectives of this study are to investigate wind and thermal effects in the bridge type overhead DMS truss structures and improve the current design specifications (e.g., for thermal design). In order to accomplish the objective, it is necessary to study structural behavior and detailed strain-stress of the truss structures caused by wind load on the DMS cabinet and thermal load on the truss supporting the DMS cabinet. The study is divided into two parts. The Computational Fluid Dynamics (CFD) component and part of the structural analysis component of the study were conducted at the University of Iowa while the field study and related structural analysis computations were conducted at the Iowa State University. The CFD simulations were used to determine the air-induced forces (wind loads) on the DMS cabinets and the finite element analysis was used to determine the response of the supporting trusses to these pressure forces. The field observation portion consisted of short-term monitoring of several DMS Cabinet/Trusses and long-term monitoring of one DMS Cabinet/Truss. The short-term monitoring was a single (or two) day event in which several message sign panel/trusses were tested. The long-term monitoring field study extended over several months. Analysis of the data focused on trying to identify important behaviors under both ambient and truck induced winds and the effect of daily temperature changes. Results of the CFD investigation, field experiments and structural analysis of the wind induced forces on the DMS cabinets and their effect on the supporting trusses showed that the passage of trucks cannot be responsible for the problems observed to develop at trusses supporting DMS cabinets. Rather the data pointed toward the important effect of the thermal load induced by cyclic (diurnal) variations of the temperature. Thermal influence is not discussed in the specification, either in limit load or fatigue design. Although the frequency of the thermal load is low, results showed that when temperature range is large the restress range would be significant to the structure, especially near welding areas where stress concentrations may occur. Moreover stress amplitude and range are the primary parameters for brittle fracture and fatigue life estimation. Long-term field monitoring of one of the overhead truss structures in Iowa was used as the research baseline to estimate the effects of diurnal temperature changes to fatigue damage. The evaluation of the collected data is an important approach for understanding the structural behavior and for the advancement of future code provisions. Finite element modeling was developed to estimate the strain and stress magnitudes, which were compared with the field monitoring data. Fatigue life of the truss structures was also estimated based on AASHTO specifications and the numerical modeling. The main conclusion of the study is that thermal induced fatigue damage of the truss structures supporting DMS cabinets is likely a significant contributing cause for the cracks observed to develop at such structures. Other probable causes for fatigue damage not investigated in this study are the cyclic oscillations of the total wind load associated with the vortex shedding behind the DMS cabinet at high wind conditions and fabrication tolerances and induced stresses due to fitting of tube to tube connections.

Iowa Budget Report, Building on our Progress: Protecting our Priorities, 2009

*********** Some files are large and will take time to load. *********** Seven Files: 1)Report Cover, 2)Table of Contents, 3)Statewide Financial Summaries, 4)Department Budgets, 5)Capitol Projects, 6)Associated Financial Documents, 7)Budget Report. To Members of the 82nd General Assembly, As we begin the second year of our Administration, we are pleased to submit the Fiscal Year 2009 budget for the State of Iowa pursuant to Iowa Code Section 8.21 and our constitutional authority. This budget recognizes the progress that we began last year with improvements in education, economic development, energy independence, and health care; provides funding for new policy initiatives in these areas; and is based on fiscally sound budget practices. Building on last year’s accomplishments, our Fiscal Year 2009 General Fund budget proposes an additional $75 million for increasing teachers’ salaries as part of our goal to move Iowa closer to the national average. We lay the foundation for student achievement by recommending $32.1 million for pre-school education, and we also propose $177.5 million in total for community colleges and $726.2 million in total for Regents universities. To make our State more energy independent, our General Fund budget appropriates the second-year funding of $25 million for the new Iowa Power Fund. The newly established Office of Energy Independence will soon start making awards from the Power Fund. Apart from the budget, we will be making several proposals to implement the new State energy plan. We have pledged to expand the number of Iowans who have health-care coverage. As a result, we are recommending additional funding for enrollment growth in the State Children Health Insurance Program (SCHIP). These additional funds will help the State provide coverage for another 25 percent of children who are eligible but not yet enrolled in hawk-i and the Iowa Medicaid Program. To protect the safety of Iowans, we are recommending issuance of revenue bonds for approximately $260 million in net proceeds to build a new state penitentiary in Ft. Madison, renovate and expand the Women’s Correctional Institution at Mitchellville, upgrade kitchen facilities at the Rockwell City and Mt. Pleasant Correctional Institutions, and expand Community-Based Correctional Facilities in Ottumwa, Sioux City, Waterloo, and Des Moines. Additionally, we are including funding for developing a prototype program for providing parolees and low-risk offenders with mental health and drug abuse treatment and educational services to help them make a crime-free re-entry into our communities. As part of this Capitals Budget, we also propose using $20 million for the State’s matching share for building new facilities at the Iowa Veterans Home. Iowa Budget Report iv Fiscal Year 2009 Importantly, our budget continues to fully fund our State’s Reserve Funds to help buffer Iowa from any future economic downturn. We recommend reimbursing $78.2 million to the Property Tax Credit Fund as part of our multi-year proposal to correct bad budgeting practices and eventually restore $160.0 million to this Fund. To provide more transparency, we are transferring operational expenditures in the Rebuild Iowa Infrastructure Fund to the General Fund and expenditures from the Endowment for Healthy Iowans and Healthy Iowans Tobacco Trust Funds to the General Fund. We believe that Iowa has charted a new course of becoming energy independent, providing quality pre-school education, recognizing the importance of our teachers, and providing greater health coverage for children. Our Fiscal Year 2009 budget and policy priorities reflect our continuing faith in Iowa’s ability to be the best state in the nation. We look forward to working with you in a bi-partisan and all-inclusive manner to build on our progress and protect our priorities. Sincerely, Chester J. Culver Governor Patty Judge Lt. Governor

Revision to the SUDAS Traffic Signal Standards – Phase 2, Final Report, May 2012

This report provides a summary of the updates to the traffic signal content within the Iowa Statewide Urban Design and Specifications (SUDAS) Design Manual Chapter 13 and Standard Specifications Division 8. Major focal points included pole footing design, cabinets and controllers, monitoring systems, communications systems, and figure updates. This work was completed through a project task force with a variety of participants (contractors, Iowa Department of Transportation, city traffic engineers, consultant, vendors, and University research and support staff).

Revision to the SUDAS Traffic Signal Standards - Phase 2, 2012

This report provides a summary of the updates to the traffic signal content within the Iowa Statewide Urban Design and Specifications (SUDAS) Design Manual Chapter 13 and Standard Specifications Division 8. Major focal points included pole footing design, cabinets and controllers, monitoring systems, communications systems, and figure updates. This work was completed through a project task force with a variety of participants (contractors, Iowa Department of Transportation, city traffic engineers, consultant, vendors, and University research and support staff).