Stringless Portland Cement Concrete Paving, TR-490, 2004

This report describes results from a study evaluating the use of stringless paving using a combination of global positioning and laser technologies. CMI and Geologic Computer Systems developed this technology and successfully implemented it on construction earthmoving and grading projects. Concrete paving is a new area for considering this technology. Fred Carlson Co. agreed to test the stringless paving technology on two challenging concrete paving projects located in Washington County, Iowa. The evaluation was conducted on two paving projects in Washington County, Iowa, during the summer of 2003. The research team from Iowa State University monitored the guidance and elevation conformance to the original design. They employed a combination of physical depth checks, surface location and elevation surveys, concrete yield checks, and physical survey of the control stakes and string line elevations. A final check on profile of the pavement surface was accomplished by the use of the Iowa Department of Transportation Light Weight Surface Analyzer (LISA). Due to the speed of paving and the rapid changes in terrain, the laser technology was abandoned for this project. Total control of the guidance and elevation controls on the slip-form paver were moved from string line to global positioning systems (GPS). The evaluation was a success, and the results indicate that GPS control is feasible and approaching the desired goals of guidance and profile control with the use of three dimensional design models. Further enhancements are needed in the physical features of the slipform paver oil system controls and in the computer program for controlling elevation.

Enhancing Motorcycle Conspicuity Awareness in Iowa, 2010

Previous studies in the United States and internationally suggest that low motorcycle conspicuity, or the inability of the motorcyclist to be seen by other road users, is thought to be an important factor associated with risk of motorcycle crashes. However, there has been limited research on motorcycle conspicuity in the United States in the past two decades, while at the same time; there has been a renewed interest from states in increasing motorcycle conspicuity and motorist awareness. As such, this research revisits the motorcycle conspicuity problem by analysis of helmet-use and motorcycle crash data. First, this study reviews previous studies on motorcycle conspicuity with a focus on the effectiveness of proposed measures for enhancing motorcycle conspicuity. The major trends in motorcycle helmet use by time of day and road type for motorcyclists, as indicated from three roadside observational roadside surveys in Iowa, are also discussed. Then, using motorcycle crash data for Iowa from 2001 to 2008, this research compares single-and two-vehicle motorcycle crashes and examines the distribution of conspicuity related factors in light and dark conditions in two-vehicle crashes that could potentially relate to a collision between a motorcycle and another vehicle. The limitations of examining motorcycle conspicuity by analysis of crash data are also discussed. Finally, this report outlines recommendations based on the key findings of the study.

Temporary Speed Hump Impact Evaluation, 2002

The main objective of this research was to evaluate the impact of temporary speed humps and speed tables on vehicle speeds, vehicle speed profiles, and traffic volumes along local and/or collector streets in several rural Iowa cities. A 25 mile per hour (mph) temporary speed hump and a 30 mph temporary speed table, both made of recycled rubber, were purchased to test the impact of temporary devices. Two cities volunteered and the speed hump/table was installed on two test streets in the city of Atlantic (Roosevelt Drive and Redwood Drive) and one test street in the city of Le Claire (Canal Shore Drive). The speed hump was installed first and then converted to a speed table. Each device was installed for a period of at least two weeks at the same location. Speed, volume, and resident opinion data were then collected and evaluated.