Simulation and Analysis of Arterial Traffic Operations Along the U.S. 61 Corridor in Burlington, Iowa, 1998

The Center for Transportation Research and Education (CTRE) used the traffic simulation model CORSIM to access proposed capacity and safety improvement strategies for the U.S. 61 corridor through Burlington, Iowa. The comparison between the base and alternative models allow for evaluation of the traffic flow performance under the existing conditions as well as other design scenarios. The models also provide visualization of performance for interpretation by technical staff, public policy makers, and the public. The objectives of this project are to evaluate the use of traffic simulation models for future use by the Iowa Department of Transportation (DOT) and to develop procedures for employing simulation modeling to conduct the analysis of alternative designs. This report presents both the findings of the U.S. 61 evaluation and an overview of model development procedures. The first part of the report includes the simulation modeling development procedures. The simulation analysis is illustrated through the Burlington U.S. 61 corridor case study application. Part I is not intended to be a user manual but simply introductory guidelines for traffic simulation modeling. Part II of the report evaluates the proposed improvement concepts in a side by side comparison of the base and alternative models.

Paved Shoulders on Primary Highways in Iowa: An Analysis of Shoulder Surfacing Criteria, Costs, and Benefits, 2001

The value of providing paved shoulders adjacent to many higher volume roadways has been accepted in many states across the country. Iowa’s paved shoulder policy is considerably more conservative than neighboring states, particularly on rural four-lane and high-volume two-lane highways. The objectives of this research are to examine current design criteria for shoulders employed in Iowa and surrounding states, compare benefits and costs of alternative surface types and widths, and make recommendations based on this analysis for consideration in future design policies for primary highway in Iowa. The report finds that many safety and maintenance benefits would result from enhancing Iowa’s paved shoulder and rumble strip design practices for freeways, expressways, and Super 2 highway corridors. The benefits of paved shoulders include reduced numbers of certain crashes, higher capacity potentials, reduced maintenance, enhanced opportunities for other users such as bicyclists, and even possible increased longevity of pavements. Alternative paved shoulder policies and programming strategies are also offered, with detailed assessments of the benefits, costs, and budget impacts.

Guidelines for the Conversion of Urban Four-Lane Undivided Roadways to Three-Lane Two-Way Left-turn Lane Facilities, April 2001

Four-lane undivided roadways in urban areas can experience a degradation of service and/or safety as traffic volumes increase. In fact, the existence of turning vehicles on this type of roadway has a dramatic effect on both of these factors. The solution identified for these problems is typically the addition of a raised median or two-way left-turn lane (TWLTL). The mobility and safety benefits of these actions have been proven and are discussed in the “Past Research” chapter of this report along with some general cross section selection guidelines. The cost and right-of-way impacts of these actions are widely accepted. These guidelines focus on the evaluation and analysis of an alternative to the typical four-lane undivided cross section improvement approach described above. It has been found that the conversion of a four-lane undivided cross section to three lanes (i.e., one lane in each direction and a TWLTL) can improve safety and maintain an acceptable level of service. These guidelines summarize the results of past research in this area (which is almost nonexistent) and qualitative/quantitative before-and-after safety and operational impacts of case study conversions located throughout the United States and Iowa. Past research confirms that this type of conversion is acceptable or feasible in some situations but for the most part fails to specifically identify those situations. In general, the reviewed case study conversions resulted in a reduction of average or 85th percentile speeds (typically less than five miles per hour) and a relatively dramatic reduction in excessive speeding (a 60 to 70 percent reduction in the number of vehicles traveling five miles per hour faster than the posted speed limit was measured in two cases) and total crashes (reductions between 17 to 62 percent were measured). The 13 roadway conversions considered had average daily traffic volumes of 8,400 to 14,000 vehicles per day (vpd) in Iowa and 9,200 to 24,000 vehicles per day elsewhere. In addition to past research and case study results, a simulation sensitivity analysis was completed to investigate and/or confirm the operational impacts of a four-lane undivided to three-lane conversion. First, the advantages and disadvantages of different corridor simulation packages were identified for this type of analysis. Then, the CORridor SIMulation (CORSIM) software was used x to investigate and evaluate several characteristics related to the operational feasibility of a four-lane undivided to three-lane conversion. Simulated speed and level of service results for both cross sections were documented for different total peak-hour traffic, access densities, and access-point left-turn volumes (for a case study corridor defined by the researchers). These analyses assisted with the identification of the considerations for the operational feasibility determination of a four -lane to three-lane conversion. The results of the simulation analyses primarily confirmed the case study impacts. The CORSIM results indicated only a slight decrease in average arterial speed for through vehicles can be expected for a large range of peak-hour volumes, access densities, and access-point left-turn volumes (given the assumptions and design of the corridor case study evaluated). Typically, the reduction in the simulated average arterial speed (which includes both segment and signal delay) was between zero and four miles per hour when a roadway was converted from a four-lane undivided to a three-lane cross section. The simulated arterial level of service for a converted roadway, however, showed a decrease when the bi-directional peak-hour volume was about 1,750 vehicles per hour (or 17,500 vehicles per day if 10 percent of the daily volume is assumed to occur in the peak hour). Past research by others, however, indicates that 12,000 vehicles per day may be the operational capacity (i.e., level of service E) of a three-lane roadway due to vehicle platooning. The simulation results, along with past research and case study results, appear to support following volume-related feasibility suggestions for four-lane undivided to three-lane cross section conversions. It is recommended that a four-lane undivided to three-lane conversion be considered as a feasible (with respect to volume only) option when bi-directional peak-hour volumes are less than 1,500 vehicles per hour, but that some caution begin to be exercised when the roadway has a bi-directional peak-hour volume between 1,500 and 1,750 vehicles per hour. At and above 1,750 vehicles per hour, the simulation indicated a reduction in arterial level of service. Therefore, at least in Iowa, the feasibility of a four-lane undivided to three-lane conversion should be questioned and/or considered much more closely when a roadway has (or is expected to have) a peak-hour volume of more than 1,750 vehicles. Assuming that 10 percent of the daily traffic occurs during the peak-hour, these volume recommendations would correspond to 15,000 and 17,500 vehicles per day, respectively. These suggestions, however, are based on the results from one idealized case xi study corridor analysis. Individual operational analysis and/or simulations should be completed in detail once a four-lane undivided to three-lane cross section conversion is considered feasible (based on the general suggestions above) for a particular corridor. All of the simulations completed as part of this project also incorporated the optimization of signal timing to minimize vehicle delay along the corridor. A number of determination feasibility factors were identified from a review of the past research, before-and-after case study results, and the simulation sensitivity analysis. The existing and expected (i.e., design period) statuses of these factors are described and should be considered. The characteristics of these factors should be compared to each other, the impacts of other potentially feasible cross section improvements, and the goals/objectives of the community. The factors discussed in these guidelines include • roadway function and environment • overall traffic volume and level of service • turning volumes and patterns • frequent-stop and slow-moving vehicles • weaving, speed, and queues • crash type and patterns • pedestrian and bike activity • right-of-way availability, cost, and acquisition impacts • general characteristics, including - parallel roadways - offset minor street intersections - parallel parking - corner radii - at-grade railroad crossings xii The characteristics of these factors are documented in these guidelines, and their relationship to four-lane undivided to three-lane cross section conversion feasibility identified. This information is summarized along with some evaluative questions in this executive summary and Appendix C. In summary, the results of past research, numerous case studies, and the simulation analyses done as part of this project support the conclusion that in certain circumstances a four-lane undivided to three-lane conversion can be a feasible alternative for the mitigation of operational and/or safety concerns. This feasibility, however, must be determined by an evaluation of the factors identified in these guidelines (along with any others that may be relevant for a individual corridor). The expected benefits, costs, and overall impacts of a four-lane undivided to three-lane conversion should then be compared to the impacts of other feasible alternatives (e.g., adding a raised median) at a particular location.

Review of Inconsistencies Between SUDAS and Iowa DOT Specifications, May 2006

The objectives of this multi-part project were to review the Iowa DOT Specifications and SUDAS Specifications section by section and develop recommendations for possible changes that will allow the two specifications to be used together.

Developing a Simple and Rapid Test for Monitoring the Heat Evolution of Concrete Mixtures for Both Laboratory and Field Applications, January 2006

Various test methods exist for measuring heat of cement hydration; however, most current methods require expensive equipment, complex testing procedures, and/or extensive time, thus not being suitable for field application. The objectives of this research are to identify, develop, and evaluate a standard test procedure for characterization and quality control of pavement concrete mixtures using a calorimetry technique. This research project has three phases. Phase I was designed to identify the user needs, including performance requirements and precision and bias limits, and to synthesize existing test methods for monitoring the heat of hydration, including device types, configurations, test procedures, measurements, advantages, disadvantages, applications, and accuracy. Phase II was designed to conduct experimental work to evaluate the calorimetry equipment recommended from the Phase I study and to develop a standard test procedure for using the equipment and interpreting the test results. Phase II also includes the development of models and computer programs for prediction of concrete pavement performance based on the characteristics of heat evolution curves. Phase III was designed to study for further development of a much simpler, inexpensive calorimeter for field concrete. In this report, the results from the Phase I study are presented, the plan for the Phase II study is described, and the recommendations for Phase III study are outlined. Phase I has been completed through three major activities: (1) collecting input and advice from the members of the project Technical Working Group (TWG), (2) conducting a literature survey, and (3) performing trials at the CP Tech Center’s research lab. The research results indicate that in addition to predicting maturity/strength, concrete heat evolution test results can also be used for (1) forecasting concrete setting time, (2) specifying curing period, (3) estimating risk of thermal cracking, (4) assessing pavement sawing/finishing time, (5) characterizing cement features, (6) identifying incompatibility of cementitious materials, (7) verifying concrete mix proportions, and (8) selecting materials and/or mix designs for given environmental conditions. Besides concrete materials and mix proportions, the configuration of the calorimeter device, sample size, mixing procedure, and testing environment (temperature) also have significant influences on features of concrete heat evolution process. The research team has found that although various calorimeter tests have been conducted for assorted purposes and the potential uses of calorimeter tests are clear, there is no consensus on how to utilize the heat evolution curves to characterize concrete materials and how to effectively relate the characteristics of heat evolution curves to concrete pavement performance. The goal of the Phase II study is to close these gaps.

Design and Evaluation of a Single-Span Bridge Using Ultra- High Performance Concrete, September 2009

Research presented herein describes an application of a newly developed material called Ultra-High Performance Concrete (UHPC) to a single-span bridge. The two primary objectives of this research were to develop a shear design procedure for possible code adoption and to provide a performance evaluation to ensure the viability of the first UHPC bridge in the United States. Two other secondary objectives included defining of material properties and understanding of flexural behavior of a UHPC bridge girder. In order to obtain information in these areas, several tests were carried out including material testing, large-scale laboratory flexure testing, large-scale laboratory shear testing, large-scale laboratory flexure-shear testing, small-scale laboratory shear testing, and field testing of a UHPC bridge. Experimental and analytical results of the described tests are presented. Analytical models to understand the flexure and shear behavior of UHPC members were developed using iterative computer based procedures. Previous research is referenced explaining a simplified flexural design procedure and a simplified pure shear design procedure. This work describes a shear design procedure based on the Modified Compression Field Theory (MCFT) which can be used in the design of UHPC members. Conclusions are provided regarding the viability of the UHPC bridge and recommendations are made for future research.

Wind Monitoring of the Saylorville and Red Rock Reservoir Bridges with Remote, Cellular-Based Notifications, May 2012

Following a high wind event on January 24, 2006, at least five people claimed to have seen or felt the superstructure of the Saylorville Reservoir Bridge in central Iowa moving both vertically and laterally. Since that time, the Iowa Department of Transportation (DOT) contracted with the Bridge Engineering Center at Iowa State University to design and install a monitoring system capable of providing notification of the occurrence of subsequent high wind events. In subsequent years, a similar system was installed on the Red Rock Reservoir Bridge to provide the same wind monitoring capabilities and notifications to the Iowa DOT. The objectives of the system development and implementation are to notify personnel when the wind speed reaches a predetermined threshold such that the bridge can be closed for the safety of the public, correlate structural response with wind-induced response, and gather historical wind data at these structures for future assessments. This report describes the two monitoring systems, their components, upgrades, functionality, and limitations, and results from one year of wind data collection at both bridges.

Evaluation of Dense Bridge Floor Concrete Using High Range Water Reducer, May 1983

The objectives of this research project are: (1) To determine the feasibility of proportioning, mixing, placing and finishing a dense portland cement concrete in a bridge floor using conventional mixing, placing and finishing equipment. (2) To determine the economics, longevity, maintenance performance and protective qualities of a dense portland cement concrete bridge floor when using a high rangewater reducing admixture. The purpose of a high range water reducing admixture is to produce a dense, high quality concrete at a low water-cement ratio witj adequate workability. A low water-cement ratio contributes greatly to increased strength. The normal 7 day strength of untreated concrete would be expected i n 3 days using a superplasticizer. A dense concrete also has the desirable properties of excellent durability and reduced permeability. It is felt that a higher quality, denser, higher strength portland cement concrete can be produced and placed, using conventional equipment, by the addition of a high range water reducing admixture. Such a dense concrete, w i t h a water/cement ratio of approximately 0.30 to 0.35, would be expected to be much less permeable and thus retard the intrusion of chloride. With care and attention given to obtaining the design cover over steel (2% inches clear), it i s hoped that protection for the design life of the structure will be obtained. Evaluation of this experimental concrete bridge floor included chloride content and delamination testing of the concrete floor five years after construction. A comparitive evaluation o f a control section o f concrete without the water reducing admixture was conducted. Other items o f comparison include workability during construction, strength, density, water-cement ratio and chloride penetration.

Automated Recording of Bridge Inspection Data in the Pontis Format Final Report, HR-364 April 1995

A large percentage of bridges in the state of Iowa are classified as structurally or fiinctionally deficient. These bridges annually compete for a share of Iowa's limited transportation budget. To avoid an increase in the number of deficient bridges, the state of Iowa decided to implement a comprehensive Bridge Management System (BMS) and selected the Pontis BMS software as a bridge management tool. This program will be used to provide a selection of maintenance, repair, and replacement strategies for the bridge networks to achieve an efficient and possibly optimal allocation of resources. The Pontis BMS software uses a new rating system to evaluate extensive and detailed inspection data gathered for all bridge elements. To manually collect these data would be a highly time-consuming job. The objective of this work was to develop an automated-computerized methodology for an integrated data base that includes the rating conditions as defined in the Pontis program. Several of the available techniques that can be used to capture inspection data were reviewed, and the most suitable method was selected. To accomplish the objectives of this work, two userfriendly programs were developed. One program is used in the field to collect inspection data following a step-by-step procedure without the need to refer to the Pontis user's manuals. The other program is used in the office to read the inspection data and prepare input files for the Pontis BMS software. These two programs require users to have very limited knowledge of computers. On-line help screens as well as options for preparing, viewing, and printing inspection reports are also available. The developed data collection software will improve and expedite the process of conducting bridge inspections and preparing the required input files for the Pontis program. In addition, it will eliminate the need for large storage areas and will simplify retrieval of inspection data. Furthermore, the approach developed herein will facilitate transferring these captured data electronically between offices within the Iowa DOT and across the state.

Utilization of Remote Traffic Monitoring Devices for Urban Freeway Work Zone Assessment Final Report, January 2012

The objective of this project was to promote and facilitate analysis and evaluation of the impacts of road construction activities in Smart Work Zone Deployment Initiative (SWZDI) states. The two primary objectives of this project were to assess urban freeway work-zone impacts through use of remote monitoring devices, such as radar-based traffic sensors, traffic cameras, and traffic signal loop detectors, and evaluate the effectiveness of using these devices for such a purpose. Two high-volume suburban freeway work zones, located on Interstate 35/80 (I-35/I-80) through the Des Moines, Iowa metropolitan area, were evaluated at the request of the Iowa Department of Transportation (DOT).

Field Evaluation of Timber Preservation Treatments for Highway Applications Final Report, December 2007

Timber material repair and replacement cost for timber bridges is a considerable expense to highway agencies in Iowa, especially to county road departments. To address these needs, the objectives of this investigation was to study the field effectiveness of various treatment alternatives used on Iowa roadway projects and to determine if the current specifications and testing are adequate for providing proper wood preservation. To satisfy the research needs, the project scope involved a literature review, identification of metrics, questionnaire survey of Iowa counties, onsite inspections, and a review of current specifications and testing procedures. Based on the preservative information obtained, the following general conclusions were made: Copper naphthenate is recommended as the plant-applied preservative treatment for timber bridges. Best Management Practices should be followed to ensure quality treatment of timber materials. Bridge maintenance programs need to be developed and implemented. The Iowa Department of Transportation specifications for preservative treatment are the regulating specification for bridges constructed with state or federal funding in Iowa and are also recommended for all other bridges.

Investigation of Warm-Mix Asphalt Using Iowa Aggregates Final Report, April 2011

The implementation of warm-mix asphalt (WMA) is becoming more widespread with a growing number of contractors utilizing various WMA technologies. Early research suggests WMA may be more susceptible to moisture damage than traditional hot-mix asphalt (HMA) mixes. The objectives of this study are to test the binder and mix properties of WMA technologies for both field- and laboratory-produced mixes to determine the performance of WMA compared to traditional HMA. Field- and laboratory-produced mixes were studied. The laboratory-produced mixes compared HMA control mixes with WMA mixes that had the same mix design. The WMA technologies used for the laboratory study were Advera, Sasobit, and Evotherm. The field study tested four WMA field-produced mixes. Each of the four mixes had a corresponding control HMA mix. The WMA technologies used in the field study included: Evotherm 3G/Revix, Sasobit, and Double Barrel Green Foaming. The three main factors for this study were WMA/HMA, moisture-conditioned/not moisture-conditioned, and reheated/not reheated. Mixes were evaluated based on performance tests. Binder testing was performed to determine the rheological differences between HMA and WMA binders to determine if binder grade requirements change with the addition of WMA additives. The conclusions of this study are as follows:  Reduced mixing and compaction temperatures were achieved.  Statistical differences were found when comparing tensile strength ratio (TSR) values for both laboratory- and field-produced mixes. In the laboratory, none of the WMA additives performed as well as the HMA. For the field mixes, all TSR values passed Iowa’s minimum specification of 0.8 but, on average, WMA is lower compared to HMA TSR values.  Dynamic modulus results show that, on average, HMA will have higher dynamic modulus values. This means the HMA exhibits stiffer material properties compared to WMA; this may not necessarily mean superior performance in all cases.  Flow number results show that WMA has reduced flow number values compared to HMA. The only exception was the fourth field mix and weather delayed production of the control mix by nine days. The laboratory mixes showed that flow number values increased significantly with the addition of recycled asphalt pavement (RAP).  In the laboratory study, Advera reduced TSR values. Given that Advera is a foaming agent, the increase in moisture susceptibility is likely attributed to the release of water necessary for the improvement of the workability of the asphalt mixture.

Assessment of Medicaid and SCHIP Quality Improvement Activities for the State of Iowa, September, 2008

CMS has established the medicaid Quality Improvement which serves to fulfill the objectives of they Medicaid Quality goal established through the Federal Government Performance and Results At. One of the objectives of the goal calls for the Centers foe Medicare and Medicaid Services to work in partnership with State Medicaid Directors to develop a Nation Medicaid Quality Framework that will articulate broad principles and a common vision of quality for the program.

Evaluation of Low Cost Traffic Calming for Rural Communities – Phase II, April 2013

The main goal of the research described in this report was to evaluate countermeasures that agencies can use to reduce speeds as drivers enter rural communities located on high-speed roadways. The objectives of this study were as follows: * Identify and summarize countermeasures used to manage speeds in transition zones * Demonstrate the effectiveness of countermeasures that are practical for high- to low-speed transition zones * Acquire additional information about countermeasures that may show promise but lack sufficient evidence of effectiveness * Develop an application toolbox to assist small communities in selecting appropriate transition zones and effective countermeasures for entrances to small rural communities The team solicited small communities that were interested in participating in the Phase II study and several communities were also recommended. The treatments evaluated were selected by carefully considering traffic-calming treatments that have been used effectively in other countries for small rural communities, as well as the information gained from the first phase of the project. The treatments evaluated are as follows: * Transverse speed bars * Colored entrance treatment * Temporary island * Radar-activated speed limit sign * Speed feedback sign The toolbox publication and four focused tech briefs also cover the results of this work.

Performance Evaluation Of Iowa Bridge Decks Constructed With Epoxy-Coated Reinforcing Bars, RB06-011, 2011

Epoxy coatings have been used on the embedded reinforcing bars of bridge decks since the mid-1970s to mitigate deterioration caused by chloride-induced corrosion. The use of chloride-based deicers became common in the early 1960s and caused corrosion of conventional uncoated bars in bridge decks within 5 to 10 years of commencement of deicer applications. In response to this rapid deterioration, the National Bureau of Standards researched coatings to protect the reinforcement (National Bureau of Standards, 1975), resulting in the development of epoxy-coated reinforcing bars, which were used in bridge decks beginning in 1973. While corrosion-related deterioration has been prevalent on bridge decks with uncoated reinforcing bars in northern climates where the use of deicing salts is common, bridge decks constructed after 1973 with epoxy-coated reinforcing have shown good corrosion resistance with only limited exceptions. On the whole, previous laboratory and field studies regarding the performance of epoxy-coated reinforcing bars are very promising; however, some laboratory and field studies have yielded differing results. In recent years, maintenance personnel for the Iowa Department of Transportation (Iowa DOT) have reportedly performed patch repairs to some bridge decks reinforced with epoxy-coated bars. At one such bridge, the southbound US 65 bridge (Bridge No. 7788.5L065) over the Union Pacific Railroad near Bondurant in Polk County, Iowa, deck repairs were performed by Iowa DOT maintenance personnel in the Spring of 2010, based on our communications regarding this topic with Mr. Gordon Port of the Iowa DOT. These repairs were observed by engineers from the Iowa DOT Office of Bridges and Structures, who reported that significant corrosion was found at a number of epoxy-coated reinforcing bars uncovered during this patch work. These repairs were reportedly performed at spalls and delaminated areas corresponding to cracks over transverse reinforcing bars, and involved careful removal of the concrete from over the bars. Figures 1 through 4 contain photographs provided by Iowa DOT personnel showing the removal process (Figure 1), the conditions encountered (Figures 2 and 3), and close-up views of the corroded reinforcing (Figure 4). As a result of these observations, the Iowa Department of Transportation has requested this study to gain further understanding of the long-term performance of bridge decks reinforced with epoxy-coated bars. The two main objectives of this study are to determine the long-term effectiveness of the epoxy coatings and to determine the potential causes for the deterioration at locations where corrosion has occurred. Wiss, Janney, Elstner Associates, Inc. (WJE) and the Iowa DOT identified eight different bridge decks across Iowa for this study that were constructed using epoxy-coated reinforcing bars. A field investigation consisting of visual inspections, a delamination survey, a concrete cover survey, electrical testing for susceptibility to corrosion, and concrete sampling was conducted within a survey area deemed to be representative of the condition of each bridge deck. Laboratory testing, including chloride ion content testing, characterization of the extracted bars, petrographic examination of the concrete, and carbonation testing, was conducted on the core samples taken from each bridge deck.