Evaluation of U.S. and European Concrete Pavement Noise Reduction Methods, July 2006

Highway noise is one of the most pressing of the surface characteristics issues facing the concrete paving industry. This is particularly true in urban areas, where not only is there a higher population density near major thoroughfares, but also a greater volume of commuter traffic (Sandberg and Ejsmont 2002; van Keulen 2004). To help address this issue, the National Concrete Pavement Technology Center (CP Tech Center) at Iowa State University (ISU), Federal Highway Administration (FHWA), American Concrete Pavement Association (ACPA), and other organizations have partnered to conduct a multi-part, seven-year Concrete Pavement Surface Characteristics Project. This document contains the results of Part 1, Task 2, of the ISU-FHWA project, addressing the noise issue by evaluating conventional and innovative concrete pavement noise reduction methods. The first objective of this task was to determine what if any concrete surface textures currently constructed in the United States or Europe were considered quiet, had long-term friction characteristics, could be consistently built, and were cost effective. Any specifications of such concrete textures would be included in this report. The second objective was to determine whether any promising new concrete pavement surfaces to control tire-pavement noise and friction were in the development stage and, if so, what further research was necessary. The final objective was to identify measurement techniques used in the evaluation.

Sediment Control in Bridge Waterways, February 1990

The objective of this study was to develop guidelines for use of the Iowa Vanes technique for sediment control in bridge waterways. Iowa Vanes are small flow-training structures (foils) designed to modify the near-bed flow pattern and redistribute flow and sediment transport within the channel cross section. The structures are installed at an angleof attack of 15 - 25' with the flow, and their initial height is 0.2 - 0.5 times water depth at design stage. The vanes function by generating secondary circulation in the flow. The circulation alters magnitude and direction of the bed shear stress and causes a reduction in velocity and sediment transport in the vane controlled area. As a result, the river bed aggrades in the vane controlled area and degrades outside. This report summarizes the basic theory, describes results of laboratory and field tests, and presents the resulting design procedure. Design graphs have been developed based on the theory. The graphs are entered with basic flow variables and desired bed topography. The output is vane layout and design. The procedure is illustrated with two numerical examples prepared with data that are typical for many rivers in Iowa and the midwest. The report also discusses vane material. In most applications, the vane height will be between 30% and 50% of bankfull flow depth and the vane length will be two to three times vane height. The vanes will be placed in arrays along the bank of the river. Each array will contain two or more vanes. The vanes in an array will be spaced laterally a distance of two to three times vane height. The streamwise spacing between the arrays will be 15 to 30 times vane height, and the vane-to-bank distance will be three to four times vane height. The study also show that the first (most upstream) array in the vane system must be located a distance of at least three array spacings upstream from the bridge, and there must be at least three arrays in the system for it to be effective at and downstream from the third array.

Construction and Evaluation of Submerged Vanes for Stream Control, HR-274, 1988

The objective of this study was to determine the practicality and effectiveness of using submerged vanes ("Iowa Vanes") to control bank erosion in a bend of East Nishnabotna River, Iowa. The vane system was constructed during the summer of 1985. It functions by eliminating, or reducing, the centrifugally induced helical motion of the flow in the bend, which is the root cause of bank undermining. The system was monitored over a 2-year period, from September 1985 to October 1987. Two surveys were conducted in the spring of 1986 in which data were taken of depths and velocities throughout the bend and of water-surface slope. The movement of the bank was determined from aerial photos and from repeated measurements of the vane-to-bank distance. The bankfull scour depths and velocities along the bank have been reduced significantly; and the movement of the bank has been stopped or considerably reduced. The improvements were obtained without changing the energy slope of the channel. Areas of design improvements were identified.

Control of Concrete Deterioration Due to Trace Compounds in Deicers, HR-299, 1992

This report describes the research completed under the research contract entitled "Development of a Conductometric Test for Frost Resistance of Concrete" undertaken for the Iowa Highway Research Board. The objective of the project was to develop a test method which can be reasonably and rapidly performed in the laboratory and in the field to predict, with a high degree of certainty, the behavior of concrete subjected to the action of alternate freezing and thawing. The significance of the results obtained, and recommendations for use and the continued development of conductometric testing are presented in this final report. In this project the conductometric evaluation of concrete durability was explored with three different test methods. The test methods and procedures for each type of test as well as presentation of the results obtained and their significance are included in the body of the report. The three test methods were: (1) Conductometric evaluation of the resistance of concrete to rapid freezing and thawing, (2) Conductometric evaluation of the resistance of concrete to natural freezing and thawing, and (3) Conductometric evaluation of the pore size distribution of concrete and its correlation to concrete durability. The report also includes recommendations for the continued development of these test methods.

Recycled Paper Erosion Control Mat, HR-349, 1994

The objective of this research project was to evaluate field application results and determine whether the Earth-Gard mat made from recycled material would successfully control erosion and allow vegetation to establish in ditch bottoms and steep slopes. The research would also help determine how steep a grade in the ditch bottoms can be protected from rill and gully erosion and how steep and long a backslope or foreslope can be protected from sheet and rill erosion by the recycled material and allow establishment of vegetation. The Earth-Gard gave satisfactory performance on areas with limited drainage and gradual slopes. Earth-Gard had a longevity of only six months. It was eroded away when used on areas with greater flow or steeper slopes.

A Multi-Project Scheduling Procedure for Transportation Projects, Part II, HR-339, 1994

The Iowa Department of Transportation (IDOT) has been requiring Critical Path Method (CPM) schedules on some larger or more schedule sensitive projects. The Office of Construction's expectations for enhanced project control and improved communication of project objectives have not been fully met by the use of CPM. Recognizing that the current procedures might not be adequate for all projects, IDOT sponsored a research project to explore the state-of-the-art in transportation scheduling and identify opportunities for improvement. The first phase of this project identified a technique known as the Linear Scheduling Method (LSM) as an alternative to CPM on certain highway construction projects. LSM graphically displays the construction process with respect to the location and the time in which each activity occurs. The current phase of this project was implemented to allow the research team the opportunity to evaluate LSM on all small groups of diverse projects. Unlike the first phase of the project, the research team was closely involved in the project from early in the planning phase throughout the completion of the projects. The research strongly suggests that the linear scheduling technique has great potential as a project management tool for both contractors and IDOT personnel. However, before this technique can become a viable weapon in the project management arsenal, a software application needs to be developed. This application should bring to linear scheduling a degree of functionality as rich and as comprehensive as that found in microcomputer based CPM software on the market today. The research team recommends that the IDOT extend this research effort to include the development of a linear scheduling application.

Glasgrid Fabric to Control Reflective Cracking, HR-535, 1990

The major problem with durability of asphalt cement concrete (ACC) overlays to rehabilitate jointed portland cement concrete (PCC) pavement comes from reflective cracking. The objective of this research was to evaluate the effectiveness of Glasgrid in regard to preventing reflection cracking. Glasgrid is a glass fiber mesh with 1/2 inch by 1 inch openings (Figure 1). Each strand is composed of many small glass fibers. After the grid is formed, it is coated with a polymer modified asphalt cement. In 1986, four experimental Glasgrid test sections were incorporated into Polk County project IR-35-2(191)67--12-77 on Interstate 35 from IA 5 to the west 1-80 interchange on the west edge of Des Moines, Single and double layers of Glasgrid were placed over transverse cracks and joints of the existing PCC pavement. The Glasgrid was placed on the PCC pavement for one section and between lifts of the ACC resurfacing on the other three sections. The four Glasgrid sections were compared to two sections without Glasgrid for four years. The sections were reviewed annually to determine how many cracks or joints had reflected through the resurfacing. Glasgrid placed on the PCC pavement was more effective at preventing reflection cracking than Glasgrid between lifts of AC resurfacing. In general, Glasgrid yielded a small reduction or retardation in the amount of reflection cracking, but not sufficient to justify additional expense for the use of Glasgrid.

Evaluation of Photoacoustic Spectroscopy for Quality Control of Cement, TR-409, 1998

This report discusses the feasibility of using infrared photoacoustic spectroscopy (PAS) as a viable technique that can quickly provide information on cement composition prior to use. The PAS technique is of interest because the cost is much lower than for other types of instrumentation used for mineral analysis, it requires virtually no sample preparation, and it can perform multi-component analysis in a matter of minutes. Feasibility of the technique was based on the ability of PAS to identify and quantify sulfate species and major cement matrix components. Strengths and limitations of the technique are presented.

Assessment of Nondestructive Testing Technologies for Quality Control/Quality Assurance of Asphalt Mixtures, TR-653, 2015

Asphalt pavements suffer various failures due to insufficient quality within their design lives. The American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG) has been proposed to improve pavement quality through quantitative performance prediction. Evaluation of the actual performance (quality) of pavements requires in situ nondestructive testing (NDT) techniques that can accurately measure the most critical, objective, and sensitive properties of pavement systems. The purpose of this study is to assess existing as well as promising new NDT technologies for quality control/quality assurance (QC/QA) of asphalt mixtures. Specifically, this study examined field measurements of density via the PaveTracker electromagnetic gage, shear-wave velocity via surface-wave testing methods, and dynamic stiffness via the Humboldt GeoGauge for five representative paving projects covering a range of mixes and traffic loads. The in situ tests were compared against laboratory measurements of core density and dynamic modulus. The in situ PaveTracker density had a low correlation with laboratory density and was not sensitive to variations in temperature or asphalt mix type. The in situ shear-wave velocity measured by surface-wave methods was most sensitive to variations in temperature and asphalt mix type. The in situ density and in situ shear-wave velocity were combined to calculate an in situ dynamic modulus, which is a performance-based quality measurement. The in situ GeoGauge stiffness measured on hot asphalt mixtures several hours after paving had a high correlation with the in situ dynamic modulus and the laboratory density, whereas the stiffness measurement of asphalt mixtures cooled with dry ice or at ambient temperature one or more days after paving had a very low correlation with the other measurements. To transform the in situ moduli from surface-wave testing into quantitative quality measurements, a QC/QA procedure was developed to first correct the in situ moduli measured at different field temperatures to the moduli at a common reference temperature based on master curves from laboratory dynamic modulus tests. The corrected in situ moduli can then be compared against the design moduli for an assessment of the actual pavement performance. A preliminary study of microelectromechanical systems- (MEMS)-based sensors for QC/QA and health monitoring of asphalt pavements was also performed.

Implementation of a Pilot Continuous Monitoring System: Iowa Falls Arch Bridge, HR-1088, 2015

The goal of this work was to move structural health monitoring (SHM) one step closer to being ready for mainstream use by the Iowa Department of Transportation (DOT) Office of Bridges and Structures. To meet this goal, the objective of this project was to implement a pilot multi-sensor continuous monitoring system on the Iowa Falls Arch Bridge such that autonomous data analysis, storage, and retrieval can be demonstrated. The challenge with this work was to develop the open channels for communication, coordination, and cooperation of various Iowa DOT offices that could make use of the data. In a way, the end product was to be something akin to a control system that would allow for real-time evaluation of the operational condition of a monitored bridge. Development and finalization of general hardware and software components for a bridge SHM system were investigated and completed. This development and finalization was framed around the demonstration installation on the Iowa Falls Arch Bridge. The hardware system focused on using off-the-shelf sensors that could be read in either “fast” or “slow” modes depending on the desired monitoring metric. As hoped, the installed system operated with very few problems. In terms of communications—in part due to the anticipated installation on the I-74 bridge over the Mississippi River—a hardline digital subscriber line (DSL) internet connection and grid power were used. During operation, this system would transmit data to a central server location where the data would be processed and then archived for future retrieval and use. The pilot monitoring system was developed for general performance evaluation purposes (construction, structural, environmental, etc.) such that it could be easily adapted to the Iowa DOT’s bridges and other monitoring needs. The system was developed allowing easy access to near real-time data in a format usable to Iowa DOT engineers.

A Multi-Project Scheduling Procedure for Transportation Projects, Final Report, HR-339, 1993

This report proposes, that for certain types of highway construction projects undertaken by the Iowa Department of Transportation, a scheduling technique commonly referred to as linear scheduling may be more effective than the Critical Path Method scheduling technique that is currently being used. The types of projects that appear to be good candidates for the technique are those projects that have a strong linear orientation. Like a bar chart, this technique shows when an activity is scheduled to occur and like a CPM schedule it shows the sequence in which activities are expected to occur. During the 1992 construction season, the authors worked with an inlay project on Interstate 29 to demonstrate the linear scheduling technique to the Construction Office. The as-planned schedule was developed from the CPM schedule that the contractor had developed for the project. Therefore, this schedule represents what a linear representation of a CPM schedule would look like, and not necessarily what a true linear schedule would look like if it had been the only scheduling technique applied to the project. There is a need to expand the current repertoire of scheduling techniques to address those projects for which the bar chart and CPM may not be appropriate either because of the lack of control information or due to overly complex process for the actual project characteristics. The scheduling approaches used today on transportation projects have many shortcomings for properly modeling the real world constraints and conditions which are encountered. Linear project's predilection for activities with variable production rates, a concept very difficult to handle with the CPM, is easily handled and visualized with the linear technique. It is recommended that work proceed with the refinement of the method of linear scheduling described above and the development of a microcomputer based system for use by the Iowa Department of Transportation and contractors for its implementation. The system will be designed to provide the information needed to adjust schedules in a rational understandable method for monitoring progress on the projects and alerting Iowa Department of Transportation personnel when the contractor is deviating from the plan.

Traffic Control in Work Zones with Edge Drop-Offs, 2002

Pavement and shoulder edge drop-offs commonly occur in work zones as the result of overlays, pavement replacement, or shoulder construction. The depth of these elevation differentials can vary from approximately one inch when a flexible pavement overlay is applied to several feet where major reconstruction is undertaken. The potential hazards associated with pavement edge differentials depend on several factors including depth of the drop-off, shape of the pavement edge, distance from traveled way, vehicle speed, traffic mix, volume, and other factors. This research was undertaken to review current practices in other states for temporary traffic control strategies addressing lane edge differentials and to analyze crash data and resultant litigation related to edge drop-offs. An objective was to identify cost-effective practices that would minimize the potential for and impacts of edge drop crashes in work zones. Considerable variation in addressing temporary traffic control in work zones with edge drop-off exposure was found among the states surveyed. Crashes related to pavement edge drop-offs in work zones do not commonly occur in the state of Iowa, but some have resulted in significant tort claims and settlements. The use of benefit/cost analysis may provide guidance in selection of an appropriate mitigation and protection of edge drop-off conditions. Development and adoption of guidelines for design of appropriate traffic control for work zones that include edge drop-off exposure, particularly identifying effective use of temporary barrier rail, may be beneficial in Iowa.