Design Procedures and Field Monitoring of Submerged Barbs for Streambank Protection, June 2007

The main objective of this study was to evaluate the hydraulic performance of riprap spurs and weirs in controlling bank erosion at the Southern part of the Raccoon River upstream U.S. Highway 169 Bridge utilizing the commercially available model FESWMS and field monitoring. It was found based on a 2 year monitoring and numerical modeling that the design of structures was overall successful, including their spacing and stability. The riprap material incorporated into the structures was directly and favorably correlated to the flow transmission through the structure, or in other words, dictated the permeable nature of the structure. It was found that the permeable dikes and weirs chosen in this study created less volume of scour in the vicinity of the structure toes and thus have less risk comparatively to other impermeable structures to collapse. The fact that the structures permitted the transmission of flow through them it allowed fine sand particles to fill in the gaps of the rock interstices and thus cement and better stabilize the structures. During bank-full flows the maximum scour hole was recorded away from the structures toe and the scourhole size was directly related to the protrusion angle of the structure to the flow. It was concluded that the proposed structure inclination with respect to the main flow direction was appropriate since it provides maximum bank protection while creating the largest volume of local scour away from the structure and towards the center of the channel. Furthermore, the lowest potential for bank erosion also occurs with the present set-up design chosen by the IDOT. About 2 ft of new material was deposited in the area located between the structures for the period extending from the construction day to May 2007. Surveys obtained by sonar and the presence of vegetation indicate that new material has been added at the bank toes. Finally, the structures provided higher variability in bed topography forming resting pools, creating flow shade on the leeward side of the structure, and separation of bed substrate due to different flow conditions. Another notable environmental benefit to rock riprap weirs and dikes is the creation of resting pools, especially in year 2007 (2nd year of the project). The magnitude of these benefits to aquatic habitat has been found in the literature that is directly related to the induced scour-hole volume.

Wet-Reflective Pavement Marking Demonstration Project, November 2011

One of the leading complaints from drivers is the inability to see pavement markings under wet night conditions. This issue is a major source of dissatisfaction in state department of transportation (DOT) customer satisfaction surveys. Driving under wet night conditions is stressful and fatiguing for all drivers, but particularly so for the more vulnerable young and older driver age groups. This project focused on the development of a two-year, long-line test deck to allow for the evaluation and demonstration of a variety of wet-reflective pavement marking materials and treatments under wet night conditions. Having the opportunity to document the performance of these various products and treatments will assist the Iowa DOT and local agencies in determining when and where the use of these products might be most effective. Performance parameters included durability, presence, retroreflectivity, and wet night visibility. The test sections were located within Story County so that Iowa DOT management and staff, as well as local agencies, could drive these areas and provide input on the products and treatments.

Final Report for Research Project HR-181, Macadam Base Shoulders, September 1981

Highway safety and pavement performance can be directly influenced by the type of shoulders that are constructed. Shoulder design alternatives have always been rather limited. Moreover, the use of some of the alternatives has always been restricted by funding limitations. This research project seeks to explore the use of modified macadam base construction for shoulders. This type of shoulder design could offer the designer another option when paved or stabilized shoulders are being considered. Macadam base construction has in the past been shown to be quite strong and free draining. Two macadam base shoulder designs were developed and constructed for this research project. A new roadway embankment and P.C.C. pavement were constructed on a section of US 6 east of Adel in Dallas County. The macadam base shoulders were constructed adjacent to the pavement as part of the project. The north shoulder was finished with a choke stone course and bituminous surface treatment and the south shoulder was finished with a two (2) inch layer of Type B Class I1 asphalt concrete. Macadam stone base shoulders can be built with relatively minor construction problems with comparable strength and less cost than asphalt treated base shoulders. The macadam stone base shoulders have performed well with very little maintenance necessary. The improved drainage substantially reduces deterioration of the pavement joints.

Federal Highway Administration Finding of No Significant Impact for the Council Bluffs Interstate System Improvements Project, August 23, 2012

FHWA and the Iowa Department of Transportation are proposing geometric and capacity improvements to the Interstate 29 and Interstate 80 mainline in Segment 3 and the I-80/I-29 East System interchange, the South Expressway interchange, the U.S. Highway 275 interchange, and the Madison Avenue interchange to to safely and efficiently of transportation in the City of Council Bluffs, the Iowa DOT is also proposing to eliminate several railroad alignments and to develop new, consolidated tracks in Segment 3.

I-74 Iowa/Illinois Corridor Study Aesthetic Design Guideline April 6, 2009

The I-74 Aesthetic Design Guideline (ADG) document has two primary goals: To establish and identify an overall design theme To prioritize enhancement opportunities within the framework of corridor elements The recommendations of this report have been developed based on an “unconstrained” framework for future corridor–wide enhancements. Future funding availability, along with the recommendations of this report, will guide the final design process. ADG Future Uses: This document is intended to be used as a reference to future processes in the following ways: Guidance for I-74 final design teams Reference document for future local community redevelopment initiatives Inspiration for identification and development of other I-74 corridor aesthetic enhancement opportunities Process: As illustrated in Figure 1.3, the overall process for corridor aesthetics began traditionally with inventory and identification of potential aesthetic applications. The ADG does not document all the reports and presentations related to these early design stages, but has incorporated these efforts into the design theme, guiding principles and prioritized enhancements shown on the following pages of this report. The I-74 final design phase will incorporate these recommendations into the project. The consultant design team and representatives of the DOTs have worked with the CAAT members to facilitate community input and have helped develop recommendations for improving I-74 corridor aesthetics. CAAT recommendations have been advanced to the I-74 Advisory Committee for review and endorsement. Both DOTs have reviewed the CAAT recommendations and have endorsed the contents of this report. Figure 1.4 illustrates the status of corridor aesthetic design development. As of the date of this report, aesthetic design is approximately 50% complete. Future detailed design, cost evaluation, feasibility and prioritizations all need to occur for this process to be successfully completed.

Council Bluffs Interstate System Improvements Project Pottawatomie County, Iowa and Douglas County, Nebraska Project Number: IM-029-3(62)54-13-78, November 2004

The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing to improve the interstate system around Council Bluffs with improvements extending across the Missouri River on I-80 to east of the I-480 interchange in Omaha, Nebraska, see Figure 1-1. The study considers long-term, broad-based transportation improvements along I-80, I-29, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs. In 2001, Iowa DOT and FHWA initiated the Council Bluffs Interstate System (CBIS) Improvements Project. The agencies concluded that the environmental study process would be conducted in two stages; that is, a tiered approach would be applied. The project is being conducted pursuant to the National Environmental Policy Act (NEPA) regulations issued by the Council on Environmental Quality (CEQ), 40 Code of Federal Regulations (CFR) Part 1502.20, and FHWA 23 CFR Part 771.111, that permit tiering for large, complex NEPA studies. Tier 1 is an examination of the overall interstate system improvement needs, including a clear explanation of the area’s transportation needs, a study of alternatives to satisfy them, and broad consideration of potential environmental and social impacts. The Tier 1 evaluation is at a sufficient level of engineering and environmental detail to assist decision makers in selecting a preferred transportation strategy. Tier 1 includes preparation of a draft and final Environmental Impact Statement (EIS) that would disclose the potential environmental and social effects (evaluated at a planning level that considers a variety of conceptual designs) of the proposed improvements. The final EIS will conclude with a Record of Decision (ROD) that states the preferred plan for improvements to be implemented. Essentially, the Tier 1 document will establish the planning framework for the needed improvements. Because the scope of the overall system improvements is large, the interstate improvements would be implemented as a series of individual projects that fit into the overall planning framework. The Tier 1 Area of Potential Impact, which is discussed in detail in Section 4 is an alternative that considers a combination of the most reasonable concepts that have been developed, buffered by approximately 100 or more feet to ensure that any Tier 2 design modifications would remain inside the outer boundary.

Record of Decision Council Bluffs Interstate System (I-29, I-80 and I-480) Improvements Project TIER 1 Environmental Impact Statement Council Bluffs, Iowa to Omaha, Nebraska FHWA-IA- EIS-04-01F Project Number: IM-029-3(62)54—13-78 Submitted Pursuant to 42 USC 4332(2)(c) and 49 USC 303, October 2008

The Federal Highway Administration (FHWA) approves the selection of the Reconstruction of All or Part of the Interstate (Construction Alternative) as the Preferred Alternative to provide improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 to east of the Interstate 480 interchange in Omaha, Nebraska. The study considered long-term, broad-based transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. FHWA also approves the decisions to provide full access between West Broadway and I-29, design the I-80/I-29 overlap section as a dual-divided freeway, and locating the new I-80 Missouri River Bridge north of the existing bridge. Improvements to the interstate system, once implemented, would bring the segments of I-80 and I-29 (see Figure 1) up to current engineering standards and accommodate future traffic needs. This Record of Decision (ROD) concludes Tier 1 of the Council Bluffs Interstate System (CBIS) Improvements Project. Tier 1 included an examination of the area’s transportation needs, a study of alternatives to satisfy them, and broad consideration of potential environmental and social impacts. The Tier 1 evaluation consisted of a sufficient level of engineering and environmental detail to assist decision makers in selecting a preferred transportation strategy. During Tier 1 a Draft EIS (FHWA-IA- EIS-04-01D) was developed which was approved by FHWA, Iowa DOT, and Nebraska Department of Roads (NDOR) in November 2004 with comments accepted through March 15, 2005. The Draft EIS summarized the alternatives that were considered to address the transportation needs around Council Bluffs; identified reconstruction of all or part of the interstate, the “Construction Alternative,” as the Preferred Alternative; identified three system-level decisions that needed to be made at the Tier 1 level; and invited comment on the issues. The Final EIS (FHWA-IA- EIS-04-01F) further documented the Construction Alternative as the Preferred Alternative and identified the recommended decisions for the three system level decisions that needed to be made in Tier 1. This ROD defines the Selected Alternative determined in the Tier 1 studies.

Council Bluffs Interstate System Improvements Project Pottawattamie County, IA and Douglas County, Nebraska, July 19, 2005

The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 (I-80) to east of the Interstate 480 (I-480) interchange in Omaha, Nebraska (see Figure 1-1). The study considers long-term, broad-base transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs.

Council Bluffs Interstate System Improvements Project Pottawattamie County, IA and Douglas County, Nebraska, July 19, 2005

The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 (I-80) to east of the Interstate 480 (I-480) interchange in Omaha, Nebraska (see Figure 1-1). The study considers long-term, broad-base transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs.

Signing on Very Low Volume Rurd Roads Iowa DOT Project HR-262, July, 1984

Research was undertaken to define an appropriate level of use of traffic control devices on rural secondary roads that carry very low traffic volumes. The goal of this research was to improve the safety and efficiency of travel on the rural secondary road system. This goal was to be accomplished by providing County Engineers with guidance concerning the cost-effective use of traffic control devices on very low volume rural roads. A further objective was to define the range of traffic volumes on the roads for which the recommendations would be appropriate. Little previous research has been directed toward roads that carry very low traffic volumes. Consequently, the factual input for this research was developed by conducting an inventory of the signs and markings actually in use on 2,069 miles of rural road in Iowa. Most of these roads carried 15 or fewer vehicles per day. Additional input was provided by a survey of the opinions of County Engineers and Supervisors in Iowa. Data from both the inventory and the opinion survey indicated a considerable lack of uniformity in the application of signs on very low volume rural roads. The number of warning signs installed varied from 0.24 per mile to 3.85 per mile in the 21 counties in which the inventory was carried out. The use of specific signs not only varied quite widely among counties but also indicated a lack of uniform application within counties. County officials generally favored varying the elaborateness of signing depending upon the type of surface and the volume of traffic on different roads. Less elaborate signing would be installed on an unpaved road than on a paved road. A concensus opinion was that roads carrying fewer than 25 vehicles per day should have fewer signs than roads carrying higher volumes. Although roads carrying 0 to 24 vehicles per day constituted over 24% of the total rural secondary system, they carried less than 3% of the total travel on that system. Virtually all of these roads are classified as area service roads and would thus be expected to carry only short trips primarily by local motorists. Consequently, it was concluded that the need for warning signs rarely can be demonstrated on unpaved rural roads with traffic volumes of fewer than 25 vehicles per day. It is recommended that each county designate a portion of its roads as an Area Service Level B system. All road segments with very low traffic volumes should be considered for inclusion in this system. Roads included in this system may receive a lesser level of maintenance and a reduced level of signing. The county is also afforded protection from liability arising from accidents occurring on roads designated as part of an Area Service Level B system. A uniform absence of warning signs on roads of this nature is not expected to have any discernible effect on the safety or quality of service on these very low volume roads. The resources conserved may be expended more effectively to upgrade maintenance and traffic control on roads carrying higher volumes where the beneficial effect on highway safety and service will be much more consequential.

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.

Performance of Strip Seals in Iowa Bridges, Project TR-437, January 2001

A pilot study was conducted on the premature failures of neoprene strip seals in expansion joints in Iowa bridges. In a relatively large number of bridges, strip seals have pulled out of the steel extrusions or otherwise failed well before the expected life span of the seal. The most serious consequence of a strip-seal failure is damage to the bridge substructure due to salt, water, and debris interacting with the substructure. A literature review was performed. Manufacturers’ specifications and recommendations, practices in the states bordering Iowa, and Iowa DOT design and installation guidelines were reviewed. Discussions were held with bridge contractors and the installation of a strip seal system was observed. Iowa DOT bridge databases were analyzed. A national survey was conducted on the use and performance of strip seals. With guidance from the Iowa DOT, twelve in-service bridges with strip-seal expansion joints were selected for detailed investigation. Effective bridge temperatures and corresponding expansion-joint openings were measured, DOT inspection reports were reviewed, and likely cause(s) of premature failures of strip seals were proposed. All of the seals used in the twelve bridges that had the most serious failures were in concrete girder bridges. Experimental results show that for a majority of these serious failures, the joint opening at 0° F predicted by the Iowa DOT design equations, the joint opening at 0° F extrapolated from the experimental data, or both, are larger than the movement rating of the strip seal specified on the bridge plans. Other likely causes of premature failures of seals in the twelve bridges include debris and ice in the seal cavity, a large skew and the corresponding decrease in the movement rating of the seal, improper installation, and improper setting of the initial gap.

Roadway Design Standards for Rural and Suburban Subdivisions Final Report, June 2007

In Iowa, there are currently no uniform design standards for rural and suburban subdivision development roadways. Without uniform design standards, many counties are unable to provide adequate guidance for public facilities, particularly roadways, to be constructed as part of a rural subdivision development. If a developer is not required to install appropriate public improvements or does not do so properly, significant liability and maintenance expenses can be expected, along with the potential for major project costs to correct the situation. Not having uniform design standards for rural and suburban subdivision development improvements in Iowa creates situations where there is potential for inconsistency and confusion. Differences in the way development standards are applied also create incentives or disincentives for developers to initiate subdivision platting in a particular county. With the wide range of standards or lack of standards for local roads in development areas, it is critical that some level of uniformity is created to address equity in development across jurisdictional lines. The standards must be effective in addressing the problem, but they must not be so excessive as to curtail development activities within a local jurisdiction. In order to address the concerns, cities and counties have to work together to identify where growth is going to be focused. Within that long-term growth area, the roadways should be constructed to urban standards to provide an easier transition to traditional urban facilities as the area is developed. Developments outside of the designated growth area should utilize a rural cross section since it is less likely to have concentrated urban development. The developers should be required to develop roadways that are designed for a minimum life of 40 years, and the county should accept dedication of the roadway and be responsible for its maintenance.

Design and Performance Verifcation of Ultra-High Performance Concrete Piles for Deep Foundations Final Report, November 2008

The strategic plan for bridge engineering issued by AASHTO in 2005 identified extending the service life and optimizing structural systems of bridges in the United States as two grand challenges in bridge engineering, with the objective of producing safer bridges that have a minimum service life of 75 years and reduced maintenance cost. Material deterioration was identified as one of the primary challenges to achieving the objective of extended life. In substructural applications (e.g., deep foundations), construction materials such as timber, steel, and concrete are subjected to deterioration due to environmental impacts. Using innovative and new materials for foundation applications makes the AASHTO objective of 75 years service life achievable. Ultra High Performance Concrete (UHPC) with compressive strength of 180 MPa (26,000 psi) and excellent durability has been used in superstructure applications but not in geotechnical and foundation applications. This study explores the use of precast, prestressed UHPC piles in future foundations of bridges and other structures. An H-shaped UHPC section, which is 10-in. (250-mm) deep with weight similar to that of an HP10×57 steel pile, was designed to improve constructability and reduce cost. In this project, instrumented UHPC piles were cast and laboratory and field tests were conducted. Laboratory tests were used to verify the moment-curvature response of UHPC pile section. In the field, two UHPC piles have been successfully driven in glacial till clay soil and load tested under vertical and lateral loads. This report provides a complete set of results for the field investigation conducted on UHPC H-shaped piles. Test results, durability, drivability, and other material advantages over normal concrete and steel indicate that UHPC piles are a viable alternative to achieve the goals of AASHTO strategic plan.

Visualization Resources for Iowa State University and the Iowa DOT: An Automated Design Model to Simulator Converter, November 2012

This project developed an automatic conversion software tool that takes input a from an Iowa Department of Transportation (DOT) MicroStation three-dimensional (3D) design file and converts it into a form that can be used by the University of Iowa’s National Advanced Driving Simulator (NADS) MiniSim. Once imported into the simulator, the new roadway has the identical geometric design features as in the Iowa DOT design file. The base roadway appears as a wireframe in the simulator software. Through additional software tools, textures and shading can be applied to the roadway surface and surrounding terrain to produce the visual appearance of an actual road. This tool enables Iowa DOT engineers to work with the universities to create drivable versions of prospective roadway designs. By driving the designs in the simulator, problems can be identified early in the design process. The simulated drives can also be used for public outreach and human factors driving research.