Safety Impacts of Pavement Edge Drop-offs, 2006

A vehicle may leave its travel lane for a number of reasons, such as driver error, poor surface conditions, or avoidance of a collision with another vehicle in the travel lane. When a vehicle leaves the travel lane, pavement edge drop-off poses a potential safety hazard because significant vertical differences between surfaces can affect vehicle stability and reduce a driver’s ability to handle the vehicle. Numerous controlled studies have tested driver response to encountering drop-offs under various conditions, including different speeds, vehicle types, drop-off height and shape, and tire scrubbing versus non-scrubbing conditions. The studies evaluated the drivers’ ability to return to and recover within their own travel lane after leaving the roadway and encountering a drop-off. Many of these studies, however, have used professional drivers as test subjects, so results may not always apply to the population of average drivers. Furthermore, test subjects are always briefed on what generally is to be expected and how to respond; thus, the sense of surprise that a truly naïve driver may experience upon realizing that one or two of his or her tires have just dropped off the edge of the pavement, is very likely diminished. Additionally, the studies were carried out under controlled conditions. The actual impact of pavement edge drop-off on drivers’ ability to recover safely once they leave the roadway, however, is not well understood under actual driving conditions. Additionally, little information is available that quantifies the number or severity of crashes that occur where pavement edge drop-off may have been a contributing factor. Without sufficient information about the frequency of edge drop-off-related crashes, agencies are not fully able to measure the economic benefits of investment decisions, evaluate the effectiveness of different treatments to mitigate edge drop-off, or focus maintenance resources. To address these issues, this report details research to quantify the contribution of pavement edge drop-off to crash frequency and severity. Additionally, the study evaluated federal and state guidance in sampling and addressing pavement edge drop-off and quantified the extent of pavement edge drop-off in two states. This study focused on rural two-lane paved roadways with unpaved shoulders, since they are often high speed facilities (55+ mph), have varying levels of maintenance, and are likely to be characterized by adverse roadway conditions such as narrow lanes or no shoulders.

Stabilization Procedures to Mitigate Edge Rutting for Granular Shoulders - Phase II, TR-591, 2011

A multifaceted investigation was undertaken to develop recommendations for methods to stabilize granular road shoulders with the goal of mitigating edge ruts. Included was reconnaissance of problematic shoulder locations, a laboratory study to develop a method to test for changes in granular material stability when stabilizing agents are used, and the construction of three sets of test sections under traffic at locations with problematic granular shoulders. Full results of this investigation are included in this report and its appendices. This report also presents conclusions and recommendations based on the study results.

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.

Safety Edge Crash Modification Factors, Tech Brief, 2016

This study evaluated the safety impact of the Safety Edge for construction projects in 2010 and 2011 in Iowa to assess the effectiveness of the treatment in reducing crashes.

Iowa Plan for Brain Injury, October 2002 – September 2005

Cutting edge emergency services now allow many Iowans to survive a traumatic brain injury (TBI) that would have caused death just a decade ago. The discharge planners at medical centers struggle with dramatically shorter acute inpatient stays, increased caseloads, and over 2000 brain injury admissions each year. Historically, following discharge from the hospital, Iowans with brain injury and their families have been left with little understanding of brain injury, its long-term effects, or where to go for services and supports.

Calibration and Validation of SWAT for the Upper Maquoketa River Watershed, June 2005

A validation study has been performed using the Soil and Water Assessment Tool (SWAT) model with data collected for the Upper Maquoketa River Watershed (UMRW), which drains over 16,000 ha in northeast Iowa. This validation assessment builds on a previous study with nested modeling for the UMRW that required both the Agricultural Policy EXtender (APEX) model and SWAT. In the nested modeling approach, edge-offield flows and pollutant load estimates were generated for manure application fields with APEX and were then subsequently routed to the watershed outlet in SWAT, along with flows and pollutant loadings estimated for the rest of the watershed routed to the watershed outlet. In the current study, the entire UMRW cropland area was simulated in SWAT, which required translating the APEX subareas into SWAT hydrologic response units (HRUs). Calibration and validation of the SWAT output was performed by comparing predicted flow and NO3-N loadings with corresponding in-stream measurements at the watershed outlet from 1999 to 2001. Annual stream flows measured at the watershed outlet were greatly under-predicted when precipitation data collected within the watershed during the 1999-2001 period were used to drive SWAT. Selection of alternative climate data resulted in greatly improved average annual stream predictions, and also relatively strong r2 values of 0.73 and 0.72 for the predicted average monthly flows and NO3-N loads, respectively. The impact of alternative precipitation data shows that as average annual precipitation increases 19%, the relative change in average annual streamflow is about 55%. In summary, the results of this study show that SWAT can replicate measured trends for this watershed and that climate inputs are very important for validating SWAT and other water quality models.

Laboratory Study of Structural Behavior of Alternative Dowel Bars, April 2006

Load transfer across transverse joints has always been a factor contributing to the useful life of concrete pavements. For many years, round steel dowels have been the conventional load transfer mechanism. Many problems have been associated with the round steel dowels. The most detrimental effect of the steel dowel is corrosion. Repeated loading over time also damages joints. When a dowel is repeatedly loaded over a long period of time, the high bearing stresses found at the top and bottom edge of a bar erode the surrounding concrete. This oblonging creates multiple problems in the joint. Over the past decade, Iowa State University has performed extensive research on new dowel shapes and materials to mitigate the effects of oblonging and corrosion. This report evaluates the bearing stress performance of six different dowel bar types subjected to two different shear load laboratory test methods. The first load test is the AASHTO T253 method. The second procedure is an experimental cantilevered dowel test. The major objective was to investigate and improve the current AASHTO T253 test method for determining the modulus of dowel support, k0. The modified AASHTO test procedure was examined alongside an experimental cantilever dowel test. The modified AASHTO specimens were also subjected to a small-scale fatigue test in order to simulate long-term dowel behavior with respect to concrete joint damage. Loss on ignition tests were also performed on the GFRP dowel specimens to determine the resin content percentage. The study concluded that all of the tested dowel bar shapes and materials were adequate with respect to performance under shear loading. The modified AASHTO method yielded more desirable results than the ones obtained from the cantilever test. The investigators determined that the experimental cantilever test was not a satisfactory test method to replace or verify the AASHTO T253 method.

Living Snow Fences, 2006

Blowing snow can cause significant problems for mobility and safety during winter weather in three distinct ways. It may drift onto the road, thus requiring almost continuous plowing while the wind is blowing (which may occur when a given winter storm is over). Snow may drift onto wet pavement (perhaps caused by ice control chemicals) and dilute out the chemicals on the road, creating ice on the road. And sufficient blowing snow can cause a major deterioration in visibility on the road, a factor which has been shown to be significant in winter crashes. The problem of blowing snow can be very effectively addressed by creating a snow storage device upwind of the road that requires protection from snow drifting. Typically, these storage devices are fences. Extensive design guidance exists for the required height and placement of such fences for a given annual snowfall and given local topography. However, the design information on the placement of living snow fences is less complete. The purpose of this report is to present the results of three seasons of study on using standing corn as snow fences. In addition, the experience of using switch grass as a snow storage medium is also presented. On the basis of these experimental data, a design guide has been developed that makes use of the somewhat unique snow storage characteristics of standing corn snow fences. The results of the field tests on using standing corn showed that multiple rows of standing corn store snow rather differently than a traditional wooden snow fence. Specifically, while a traditional fence stores most of the snow downwind from the fence (and thus must be placed a significant distance upwind of the road to be protected, specifically at least 35 times the snow fence height) rows of standing corn store the majority of the snow within the rows. Results from the three winters of testing show that the standing corn snow fences can store as much snow within the rows of standing corn as a traditional fence of typical height for operation in Iowa (4 to 6 feet) can store. This finding is significant because it means that the snow fences can be placed at the edge of the farmer’s field closest to the road, and still be effective. This is typically much more convenient for the farmer and thus may mean that more farmers would be willing to participate in a program that uses standing corn than in traditional programs. ii On the basis of the experimental data, design guidance for the use of standing corn as a snow storage device in Iowa is given in the report. Specifically, it is recommended that if the fetch in a location to be protected is less than 5,000 feet, then 16 rows of standing corn should be used, at the edge of the field adjacent to the right of way. If the fetch is greater than 5,000 feet, then 24 rows of standing corn should be used. This is based on a row spacing of 22 inches. Further, it should be noted that these design recommendations are ONLY for the State of Iowa. Other states of course have different winter weather and without extensive further study, it cannot be said that these guidelines would be effective in other locations with other winter conditions.

LSTA Five Year Plan, 1998-2002, 2002

The LSTA goals for Iowa, FY98-FY02, are as follows: 1. Provide all Iowans with expanded access to information and materials through the State of Iowa Libraries Online (SILO) network. 2. Improve library service to Iowans through knowledgeable, well-trained staff and wellinformed public library trustees and library users. 3. Meet Iowans’ increasing demands for information and library services by identifying and encouraging resource sharing and partnerships. 4. Provide state level leadership and services to accomplish the LSTA Five-Year Plan. The primary objectives of this evaluation are to provide: $ An assessment of the overall impact of Iowa’s LSTA funding and success in achieving the goals identified in the state’s five-year plan. $ An in-depth analysis of two specific goals from the plan: providing Iowans with expanded access to information and materials through the State of Iowa Libraries Online (SILO) network; and improving library service to Iowans through knowledgeable, well-trained staff and well-informed public library trustees and library users. LSTA built on accomplishments made possible with the federal HEA II-B grant awarded to the State Library in 1995. This grant led the way in bringing technology to Iowa libraries by creating an electronic library network for resource sharing. SILO (State of Iowa Libraries Online) became fully functional in 1997. The State Library continued funding SILO with LSTA money when the grant ended. This funding supports the SILO infrastructure, providing equitable access to information through cutting edge technology to Iowans in both small and large, rural and urban, communities. Access to electronic material and information has encouraged public libraries to increase the number of computers and public access to the Internet. LSTA funding was used to increase training opportunities for library staff and trustees. Many programs, such as librarian certification, were strengthened by an increase in continuing education opportunities.

LSTA Five Year Plan, 1998-2002, 2002

The LSTA goals for Iowa, FY98-FY02, are as follows: 1. Provide all Iowans with expanded access to information and materials through the State of Iowa Libraries Online (SILO) network. 2. Improve library service to Iowans through knowledgeable, well-trained staff and wellinformed public library trustees and library users. 3. Meet Iowans’ increasing demands for information and library services by identifying and encouraging resource sharing and partnerships. 4. Provide state level leadership and services to accomplish the LSTA Five-Year Plan. The primary objectives of this evaluation are to provide: $ An assessment of the overall impact of Iowa’s LSTA funding and success in achieving the goals identified in the state’s five-year plan. $ An in-depth analysis of two specific goals from the plan: providing Iowans with expanded access to information and materials through the State of Iowa Libraries Online (SILO) network; and improving library service to Iowans through knowledgeable, well-trained staff and well-informed public library trustees and library users. LSTA built on accomplishments made possible with the federal HEA II-B grant awarded to the State Library in 1995. This grant led the way in bringing technology to Iowa libraries by creating an electronic library network for resource sharing. SILO (State of Iowa Libraries Online) became fully functional in 1997. The State Library continued funding SILO with LSTA money when the grant ended. This funding supports the SILO infrastructure, providing equitable access to information through cutting edge technology to Iowans in both small and large, rural and urban, communities. Access to electronic material and information has encouraged public libraries to increase the number of computers and public access to the Internet. LSTA funding was used to increase training opportunities for library staff and trustees. Many programs, such as librarian certification, were strengthened by an increase in continuing education opportunities.

LSTA Five Year Plan Evaluation, 1998-2002, 2002

The LSTA goals for Iowa, FY98-FY02, are as follows: 1. Provide all Iowans with expanded access to information and materials through the State of Iowa Libraries Online (SILO) network. 2. Improve library service to Iowans through knowledgeable, well-trained staff and wellinformed public library trustees and library users. 3. Meet Iowans’ increasing demands for information and library services by identifying and encouraging resource sharing and partnerships. 4. Provide state level leadership and services to accomplish the LSTA Five-Year Plan. The primary objectives of this evaluation are to provide: $ An assessment of the overall impact of Iowa’s LSTA funding and success in achieving the goals identified in the state’s five-year plan. $ An in-depth analysis of two specific goals from the plan: providing Iowans with expanded access to information and materials through the State of Iowa Libraries Online (SILO) network; and improving library service to Iowans through knowledgeable, well-trained staff and well-informed public library trustees and library users. LSTA built on accomplishments made possible with the federal HEA II-B grant awarded to the State Library in 1995. This grant led the way in bringing technology to Iowa libraries by creating an electronic library network for resource sharing. SILO (State of Iowa Libraries Online) became fully functional in 1997. The State Library continued funding SILO with LSTA money when the grant ended. This funding supports the SILO infrastructure, providing equitable access to information through cutting edge technology to Iowans in both small and large, rural and urban, communities. Access to electronic material and information has encouraged public libraries to increase the number of computers and public access to the Internet. LSTA funding was used to increase training opportunities for library staff and trustees. Many programs, such as librarian certification, were strengthened by an increase in continuing education opportunities.

Impact of High Crop Prices on Environmental Quality: A Case of Iowa and the Conservation Reserve Program, 2007

Growing demand for corn due to the expansion of ethanol has increased concerns that environmentally sensitive lands retired from agricultural production into the Conservation Reserve Program (CRP) will be cropped again. Iowa produces more ethanol than any other state in the United States, and it also produces the most corn. Thus, an examination of the impacts of higher crop prices on CRP land in Iowa can give insight into what we might expect nationally in the years ahead if crop prices remain high. We construct CRP land supply curves for various corn prices and then estimate the environmental impacts of cropping CRP land through the Environmental Policy Integrated Climate (EPIC) model. EPIC provides edge-of-field estimates of soil erosion, nutrient loss, and carbon sequestration. We find that incremental impacts increase dramatically as higher corn prices bring into production more and more environmentally fragile land. Maintaining current levels of environmental quality will require substantially higher spending levels. Even allowing for the cost savings that would accrue as CRP land leaves the program, a change in targeting strategies will likely be required to ensure that the most sensitive land does not leave the program.

Effective Shoulder Design and Maintenance, 2007

Granular shoulders are an important element of the transportation system and are constantly subjected to performance problems due to wind- and water-induced erosion, rutting, edge drop-off, and slope irregularities. Such problems can directly affect drivers’ safety and often require regular maintenance. The present research study was undertaken to investigate the factors contributing to these performance problems and to propose new ideas to design and maintain granular shoulders while keeping ownership costs low. This report includes observations made during a field reconnaissance study, findings from an effort to stabilize the granular and subgrade layer at six shoulder test sections, and the results of a laboratory box study where a shoulder section overlying a soft foundation layer was simulated. Based on the research described in this report, the following changes are proposed to the construction and maintenance methods for granular shoulders: • A minimum CBR value for the granular and subgrade layer should be selected to alleviate edge drop-off and rutting formation. • For those constructing new shoulder sections, the design charts provided in this report can be used as a rapid guide based on an allowable rut depth. The charts can also be used to predict the behavior of existing shoulders. • In the case of existing shoulder sections overlying soft foundations, the use of geogrid or fly ash stabilization proved to be an effective technique for mitigating shoulder rutting.

Iowa Innovators, January 2007

The “Iowa Innovators” series is a joint project of the Iowa Newspaper Association and the Iowa Department of Economic Development (IDED). The series is an outgrowth of an idea from member INA publishers. “Iowa Innovators” articles describe initiatives that Iowa communities have used to improve their ability to attract business and industry and demonstrate community innovation. The articles also describe Iowa companies on the leading edge of technology, business expansion, workforce development and recycling.

Iowa Innovators, March 2007

The “Iowa Innovators” series is a joint project of the Iowa Newspaper Association and the Iowa Department of Economic Development (IDED). The series is an outgrowth of an idea from member INA publishers. “Iowa Innovators” articles describe initiatives that Iowa communities have used to improve their ability to attract business and industry and demonstrate community innovation. The articles also describe Iowa companies on the leading edge of technology, business expansion, workforce development and recycling.