Implementing the Mechanistic-Empirical Pavement Design Guide: Technical Report, May 2005

With the release of the new Mechanistic-Empirical Pavement Design Guide (MEPDG), pavement design has taken a “quantum” leap forward. The current 1993 design guide is solidly based on the empirical interpretation of the results of the 1960 American Association of State Highway and Transportation Officials (AASHTO) Road Test. This report seeks to outline the technical aspects of the new MEPDG. Full detail is essentially impossible and impractical, since the release of the MEPDG was accompanied by eighteen volumes of technical justification and background. Consequently, this report seeks only to provide a potential user with a practical understanding of the workings of the new guide, with only sufficient technical depth to aid in understanding.

Intensive Watershed Investigations at Iowa Beaches, 2005

This monthly report from the Iowa Department of Transportation is about the water quality management of Iowa's rivers, streams and lakes.

A Mechanistic Explanation of The Physical Properties of Undisturbed Loess, February, 1968

The relation between the properties and the water content of an undisturbed loess were investigated to provide insight into the mechanical behavior of the natural soil. Hand-carved samples from a single deposit, at their natural water contents, and at water contents modified in the laboratory to provide a range from 870 to 3270, were subjected to unconsolidated-undrained triaxial compression tests, consolidation tests, and initial negative pore water pressure tests. In addition, the clay-size fraction was separated from the remainder of the loess for a separate series of tests to establish its properties. The natural water content of the deposit in the field was measured at regular intervals for one year to provide an example of the range in properties that would be encountered. at this site. The test results are presented and their interpretation leads to conclusions regarding the volumetric relations that exist as the water content varies. The significance of the water content in relation to the properties of the natural soil is explored and the concept of a critical water content for loess is introduced.

Task 4: Testing Iowa Portland Cement Concrete Mixtures for the AASHTO Mechanistic-Empirical Pavement Design Procedure, May 2008

The present research project was designed to identify the typical Iowa material input values that are required by the Mechanistic-Empirical Pavement Design Guide (MEPDG) for the Level 3 concrete pavement design. It was also designed to investigate the existing equations that might be used to predict Iowa pavement concrete for the Level 2 pavement design. In this project, over 20,000 data were collected from the Iowa Department of Transportation (DOT) and other sources. These data, most of which were concrete compressive strength, slump, air content, and unit weight data, were synthesized and their statistical parameters (such as the mean values and standard variations) were analyzed. Based on the analyses, the typical input values of Iowa pavement concrete, such as 28-day compressive strength (f’c), splitting tensile strength (fsp), elastic modulus (Ec), and modulus of rupture (MOR), were evaluated. The study indicates that the 28-day MOR of Iowa concrete is 646 + 51 psi, very close to the MEPDG default value (650 psi). The 28-day Ec of Iowa concrete (based only on two available data of the Iowa Curling and Warping project) is 4.82 + 0.28x106 psi, which is quite different from the MEPDG default value (3.93 x106 psi); therefore, the researchers recommend re-evaluating after more Iowa test data become available. The drying shrinkage (εc) of a typical Iowa concrete (C-3WR-C20 mix) was tested at Concrete Technology Laboratory (CTL). The test results show that the ultimate shrinkage of the concrete is about 454 microstrain and the time for the concrete to reach 50% of ultimate shrinkage is at 32 days; both of these values are very close to the MEPDG default values. The comparison of the Iowa test data and the MEPDG default values, as well as the recommendations on the input values to be used in MEPDG for Iowa PCC pavement design, are summarized in Table 20 of this report. The available equations for predicting the above-mentioned concrete properties were also assembled. The validity of these equations for Iowa concrete materials was examined. Multiple-parameters nonlinear regression analyses, along with the artificial neural network (ANN) method, were employed to investigate the relationships among Iowa concrete material properties and to modify the existing equations so as to be suitable for Iowa concrete materials. However, due to lack of necessary data sets, the relationships between Iowa concrete properties were established based on the limited data from CP Tech Center’s projects and ISU classes only. The researchers suggest that the resulting relationships be used by Iowa pavement design engineers as references only. The present study furthermore indicates that appropriately documenting concrete properties, including flexural strength, elastic modulus, and information on concrete mix design, is essential for updating the typical Iowa material input values and providing rational prediction equations for concrete pavement design in the future.

Task 6: Material Thermal Input for Iowa Materials, May 2008

The present research project was designed to determine thermal properties, such as coefficient of thermal expansion (CTE) and thermal conductivity, of Iowa concrete pavement materials. These properties are required as input values by the Mechanistic-Empirical Pavement Design Guide (MEPDG). In this project, a literature review was conducted to determine the factors that affect thermal properties of concrete and the existing prediction equations for CTE and thermal conductivity of concrete. CTE tests were performed on various lab and field samples of portland cement concrete (PCC) at the Iowa Department of Transportation and Iowa State University. The variations due to the test procedure, the equipment used, and the consistency of field batch materials were evaluated. The test results showed that the CTE variations due to test procedure and batch consistency were less than 5%, and the variation due to the different equipment was less than 15%. Concrete CTE values were significantly affected by different types of coarse aggregate. The CTE values of Iowa concrete made with limestone+graval, quartzite, dolomite, limestone+dolomite, and limestone were 7.27, 6.86, 6.68, 5.83, and 5.69 microstrain/oF (13.08, 12.35, 12.03, 10.50, and 10.25 microstrain/oC), respectively, which were all higher than the default value of 5.50 microstrain/oF in the MEPDG program. The thermal conductivity of a typical Iowa PCC mix and an asphalt cement concrete (ACC) mix (both with limestone as coarse aggregate) were tested at Concrete Technology Laboratory in Skokie, Illinois. The thermal conductivity was 0.77 Btu/hr•ft•oF (1.33 W/m•K) for PCC and 1.21 Btu/hr•ft•oF (2.09 W/m•K) for ACC, which are different from the default values (1.25 Btu/hr•ft•oF or 2.16 W/m•K for PCC and 0.67 Btu/hr•ft•oF or 1.16 W/m•K for ACC) in the MEPDG program. The investigations onto the CTE of ACC and the effects of concrete materials (such as cementitious material and aggregate types) and mix proportions on concrete thermal conductivity are recommended to be considered in future studies.

MEPDG Work Plan Task No. 5: Characterization of Unbound Materials (Soils/Aggregates) for Mechanistic-Empirical Pavement Design Guide, 2009

The resilient modulus (MR) input parameters in the Mechanistic-Empirical Pavement Design Guide (MEPDG) program have a significant effect on the projected pavement performance. The MEPDG program uses three different levels of inputs depending on the desired level of accuracy. The primary objective of this research was to develop a laboratory testing program utilizing the Iowa DOT servo-hydraulic machine system for evaluating typical Iowa unbound materials and to establish a database of input values for MEPDG analysis. This was achieved by carrying out a detailed laboratory testing program designed in accordance with the AASHTO T307 resilient modulus test protocol using common Iowa unbound materials. The program included laboratory tests to characterize basic physical properties of the unbound materials, specimen preparation and repeated load triaxial tests to determine the resilient modulus. The MEPDG resilient modulus input parameter library for Iowa typical unbound pavement materials was established from the repeated load triaxial MR test results. This library includes the non-linear, stress-dependent resilient modulus model coefficients values for level 1 analysis, the unbound material properties values correlated to resilient modulus for level 2 analysis, and the typical resilient modulus values for level 3 analysis. The resilient modulus input parameters library can be utilized when designing low volume roads in the absence of any basic soil testing. Based on the results of this study, the use of level 2 analysis for MEPDG resilient modulus input is recommended since the repeated load triaxial test for level 1 analysis is complicated, time consuming, expensive, and requires sophisticated equipment and skilled operators.

MEPDG Work Plan Task No. 7: Existing Pavement Input Information for the Mechanistic-Empirical Pavement Design Guide, 2009

The objective of this study is to systematically evaluate the Iowa Department of Transportation’s (DOT’s) existing Pavement Management Information System (PMIS) with respect to the input information required for Mechanistic-Empirical Pavement Design Guide (MEPDG) rehabilitation analysis and design. To accomplish this objective, all of available PMIS data for interstate and primary roads in Iowa were retrieved from the Iowa DOT PMIS. The retrieved data were evaluated with respect to the input requirements and outputs for the latest version of the MEPDG software (version 1.0). The input parameters that are required for MEPDG HMA rehabilitation design, but currently unavailable in the Iowa DOT PMIS were identified. The differences in the specific measurement metrics used and their units for some of the pavement performance measures between the Iowa DOT PMIS and MEPDG were identified and discussed. Based on the results of this study, it is recommended that the Iowa DOT PMIS should be updated, if possible, to include the identified parameters that are currently unavailable, but are required for MEPDG rehabilitation design. Similarly, the measurement units of distress survey results in the Iowa DOT PMIS should be revised to correspond to those of MEPDG performance predictions. *******************Large File**************************

MEPDG Work Plan Task No. 8: Validation of Pavement Performance Curves for the Mechanistic-Empirical Pavement Design Guide, 2009

The objective of this research is to determine whether the nationally calibrated performance models used in the Mechanistic-Empirical Pavement Design Guide (MEPDG) provide a reasonable prediction of actual field performance, and if the desired accuracy or correspondence exists between predicted and monitored performance for Iowa conditions. A comprehensive literature review was conducted to identify the MEPDG input parameters and the MEPDG verification/calibration process. Sensitivities of MEPDG input parameters to predictions were studied using different versions of the MEPDG software. Based on literature review and sensitivity analysis, a detailed verification procedure was developed. A total of sixteen different types of pavement sections across Iowa, not used for national calibration in NCHRP 1-47A, were selected. A database of MEPDG inputs and the actual pavement performance measures for the selected pavement sites were prepared for verification. The accuracy of the MEPDG performance models for Iowa conditions was statistically evaluated. The verification testing showed promising results in terms of MEPDG’s performance prediction accuracy for Iowa conditions. Recalibrating the MEPDG performance models for Iowa conditions is recommended to improve the accuracy of predictions. ****************** Large File**************************

DCI Voter Fraud Investigations Report, May 8, 2014.

In March of 2012, the Iowa Secretary of State’s office compared Iowa’s voter registration records with the driver’s license record s of individuals that identified themselves as non-citizens with the Iowa Department of Transportation. After comparing those records, the Iowa Secretary of State’s office found that more than 3,000 individuals registered to vote that had previously identified themselves as non-citizens. More than 1,000 of these individuals had also cast a ballot. The Iowa Secretary of State’s office was not given timely access to the federal Systematic Alien Verification for Entitlements (SAVE)database, and therefore was unable to determine if any of these individuals had become citizens before they registered to vote or cast a ballot. On June 21, 2012, the Iowa Secretary of State’s office entered into an agreement with the Iowa Department of Public Safety’s Division of Criminal Investigation (DCI) to review potential election misconduct crimes and improve the administration of federal elections. Over the last two years,DCI agents have reviewed thousands of instances of possible election misconduct. DCI’s review included cases referred by the Iowa Secretary of State’s office as well as by other state and local government agencies.

Implementing the Mechanistic-Empirical Pavement Design Guide: Implementation Plan, TR-509, 2005

The current 1993 American Association of State Highway and Transportation Officials (AASHTO) Pavement Design Guide is based on the empirical interpretation of the results of the 1960 AASHTO Road Test. With the release of the new Mechanistic-Empirical (M-E) Pavement Design Guide, pavement design has taken a "quantum" leap forward. In order to effectively and efficiently transition to the M-E Pavement Design Guide, state DOTs need a detailed implementation and training strategy. This document is a plan for the M-E Pavement Design Guide to be implemented in Iowa.

Mississippi River investigations. Project no. F-109-R-1, 1986.

Two investigations are included in this document: 1) An Evaluation of Largemouth Bass Populations in the Upper Mississippi River and 2) An Evaluation of the Effects of a Change in Commercial Harvest Regulations on the Channel Catfish Population Inhabiting the Upper Mississippi River

The EPI Manual: Guide to surveillance, investigations, and reporting, January 2014

A reference for all health care providers at the time of a suspected case, a particular disease or condition, or at the time of an outbreak of a communicable disease to institute public health prevention and control measures.