Improvement of Longitudinal Joints in Asphalt Pavement, HR-215, 1987

Research is reported which attempted to identify construction procedures that will provide an improved centerline joint on asphalt concrete pavements. Various construction procedures and their evaluation are described. Core densities were made and visual inspections were made 3 years after construction. Center cracking was measured at 4, 5, and 6 years. The only procedure to rank the same when comparing cracking and density (delete the 1:1 slope shoe on the edge) is described. This procedure had the highest average density and also the least cracking through 1985. This method provided the best performance for 4 years after construction and involved the removal of the 1:1 slope shoe from the paver when placing the surface course. This method had 9.0% cracked after 4 years and 100% cracked after 6 years of service.

2001 Iowa Termination of Pregnancy Report, March 3 2003

The total number of pregnancy terminations decreased from 7,602 in 2000 to 6,845 in 2001. This represents a 10% decrease. Induced termination decreased from 6,059 to 5,722 (a 6% decrease) and spontaneous termination decreased from 1,541 to 1,119 (a 27% decrease). Pregnancy terminations by maternal and child health regions (MCH) • The fertility rate for the state as a whole increased from 62.3 per 1,000 to 62.6 per 1,000, from 2000 to 2001. In 2000, 15 MCH regions had a higher rate than the statewide fertility rate, while in 2001, the number of MCH regions with a higher rate than the statewide fertility rate dropped to 12. Region 7 continued to have the highest fertility rate and region 12 continued to have the lowest rate. • The pregnancy rate decreased from 74.6 per 1,000 to 74.1 per 1,000. Region 16 continued to have the lowest pregnancy rate. However, region 23 had the highest pregnancy rate in 2001, compared to region 7 in 2000. • The induced termination rate decreased 0.6 per 1,000 and down to 9.4 per 1,000 in 2001. Compared to 2000 reports, two fewer regions had a higher rate than the statewide induced termination rate in 2001 (8 regions in 2000 vs. 6 regions in 2001). • The spontaneous termination rate for the state dropped to 1.8 per 1,000 from 2.5 per 1,000. The number of regions with a higher spontaneous termination rate decreased from 9 to 7. Region 14 had the highest rate, and region 20 had the lowest. • The statewide induced termination ratio increased from 145.7 per 1,000 to 149.6 per 1,000. Region 12 had the highest ratio for both years, and region 22 had the lowest ratio. • The statewide spontaneous termination ratio decreased from 39.7 per 1,000 to 29.3 per 1,000. One less region was higher, compared to 2000 data (9 regions in 2000 vs. 8 regions in 2001). In summary, the geographic distribution of the 2001 data showed a pattern similar to that seen in 2000. Generally, the frequency for both induced and spontaneous terminations decreased by month of occurrence, gestational age, marital status, and education level and mother’s age

High Priority Corridors for Access Management Near Large Urban Areas in Iowa, 2002

This research project was intended to produce a strategy for addressing current and future access management problems on state highway routes located just outside urban areas that serve as major routes for commuting into and out of major employment centers in Iowa. There were two basic goals: (1) to develop a ranking system for identifying high-priority segments for access management treatments on primary highways outside metro and urban areas and (2) to focus efforts on routes that are major commuting routes at present and in the future. The project focused on four-lane expressways and two-lane arterials most likely to serve extensive commuter traffic. Available spatial and statistical data were used to identify existing and possible future problem corridors with respect to access management. The research team developed a scheme for ranking commuter routes based on their need for attention to access management. This project was able to produce rankings for corridors based on a variety of factors, including proportion of crashes that appear to be access-related, severity of those crashes, and potential for improvement along corridors. Frequency and loss were found to be highly rank correlated; because of this, these indicators were not used together in developing final priority rankings. Most of the highest ranked routes are on two-lane rural cross sections, but a few are four-lane expressways with at-grade private driveways and public road intersections. The most important conclusion of the ranking system is that many of the poor-performing corridors are located in a single Iowa Department of Transportation district near two urban areas--Des Moines and Ames. A comprehensive approach to managing access along commuting corridors should be developed first in this district since the potential benefits would be highest in that region.

Seismic Wave Velocity as a Means of In-Place Density Measurement, Part 1, HR-114

Velocity-density tests conducted in the laboratory involved small 4-inch diameter by 4.58-inch-long compacted soil cylinders made up of 3 differing soil types and for varying degrees of density and moisture content, the latter being varied well beyond optimum moisture values. Seventeen specimens were tested, 9 with velocity determinations made along two elements of the cylinder, 180 degrees apart, and 8 along three elements, 120 degrees apart. Seismic energy was developed by blows of a small tack hammer on a 5/8-inch diameter steel ball placed at the center of the top of the cylinder, with the detector placed successively at four points spaced 1/2-inch apart on the side of the specimen involving wave travel paths varying from 3.36 inches to 4.66 inches in length. Time intervals were measured using a model 217 micro-seismic timer in both laboratory and field measurements. Forty blows of the hammer were required for each velocity determination, which amounted to 80 blows on 9 laboratory specimens and 120 blows on the remaining 8 cylinders. Thirty-five field tests were made over the three selected soil types, all fine-grained, using a 2-foot seismic line with hammer-impact points at 6-inch intervals. The small tack hammer and 5/8-inch steel ball was, again, used to develop seismic wave energy. Generally, the densities obtained from the velocity measurements were lower than those measured in the conventional field testing. Conclusions were reached that: (1) the method does not appear to be usable for measurement of density of essentially fine-grained soils when the moisture content greatly exceeds the optimum for compaction, and (2) due to a gradual reduction in velocity upon aging, apparently because of gradual absorption of pore water into the expandable interlayer region of the clay, the seismic test should be conducted immediately after soil compaction to obtain a meaningful velocity value.