Technology News, March 1994

Technology News is a newsletter produced by the Iowa Department of Transportation to provide information to the transportation specialist in Iowa's cities and counties. Technology News is one of CTRE's primary avenues for exchanging transportation-related information with local agencies. The bimonthly newsletter gives an up-to-date look to the up-to-date information our 2,500+ readers have grown to expect.

Technology News, October 1994

Technology News is a newsletter produced by the Iowa Department of Transportation to provide information to the transportation specialist in Iowa's cities and counties. Technology News is one of CTRE's primary avenues for exchanging transportation-related information with local agencies. The bimonthly newsletter gives an up-to-date look to the up-to-date information our 2,500+ readers have grown to expect.

Summary of FY 1995 Budget and Governor's Recommendations, January 1994

The purpose of this document is to provide the General Assembly with information related to FY General Fund estimated receipts and the Governor’s recommendations. This information provides an overall summary of the State budget and is intended to help the General Assembly take a proactive approach toward the budgeting process.

State of Iowa FY 1994 Governor's Recommendations Summary, January 1993

The purpose of this document is to provide the General Assembly with information related to FY General Fund estimated receipts and the Governor’s recommendations. This information provides an overall summary of the State budget and is intended to help the General Assembly take a proactive approach toward the budgeting process.

Highway/Railroad Grade Crossings Identification and Signing, HR-254, 1987

In 1982, Iowa's crossing warning identification system and signage at rail crossings were outdated, inconsistent and inadequate. Iowa's railroad system had been reduced and reorganized during the 1970's and many of the surviving railroad companies were unable to install new signs or devote staff to updating information. The preliminary engineering part of this project improved the information inventory about each crossing, provided for installation of identification tags and resulted in a comprehensive list of posts and signs eligible for replacement. The sign installation portion of this project resulted in erection of nearly 10,000 new crossbuck signs and 10,000 advance warning signs with high intensity reflectorization. In addition, new posts and multiple track signs were replaced where appropriate. Increased visibility of crossings for the motoring public has resulted from proper sign placement and use of high intensity reflectorization. The tagging has provided a consistent correct identification of crossings for accident reporting. The computer inventory of information about the crossings is now correct and provides for informed decision making to administrators of Federal and State crossing safety funds.

The Relationship of Ferroan Dolomite Aggregate to Rapid Concrete Deterioration, HR-266, 1987

Some of Iowa's 13,200 miles of portland cement concrete (pcc) pavement have remained structurally sound for over 50 years while others have suffered premature deterioration. Research has shown that the type of coarse aggregate used in the pcc is the major cause of this premature deterioration. Some coarse aggregates for concrete exhibit a nonuniform performance history. They contribute to premature deterioration on heavily salted primary roadways while providing long maintenance-free life on unsalted secondary pavements. This inconsistency supports the premise that there are at least two mechanisms that contribute to the deterioration. Previous research has shown that one of these mechanisms is a bad pore system. The other is apparently a chemical reaction. The objective of this research is to develop simple rapid test methods to predict the durability of carbonate aggregate in pcc pavement. X-ray diffraction analyses of aggregate samples have been conducted on various beds from numerous quarries producing diffraction plots for more than 200 samples of dolomitic or dolomite aggregates. The crystalline structures of these dolomitic aggregates show maximum-intensity dolomite/ankerite peaks ranging from a d-spacing of 2.884 angstroms for good aggregates to a d-spacing of 2.914 angstroms for nondurable aggregates. If coarse aggregates with known bad pore systems are removed from this summary, the d-spacing values of the remaining aggregates correlate very well with expected service life. This may indicate that the iron substitution for magnesium in the dolomite crystal is associated with the instability of the ferroan dolomite aggregates in pcc pavement.

Pile Design and Tests for Integral Abutment Bridges, HR-273, Addendum, 1987

Addendum to HR-273

Training Aids to Reduce Potential County Liability, HR-289, Draft, 1987

Iowans who travel secondary roads regard these roads as a very important part of their lives. These highways provide a means of transporting products to market and children to school. They are also links to nearby cities and towns. Nearly 3.8 billion vehicle miles of travel occur each year on Iowa's nearly 90,000 mile secondary road system. Accidents do happen. However, improvements in highways, in vehicles, in driver education, in legislation, and in enforcement have combined to make driving in Iowa very safe. If our highways are to remain safe, these efforts need to be continued. This presentation was developed to help county highway department personnel in their effort to maintain and improve highway safety. The presentation is not a standard, specification or regulation.

Image Analysis of PCC and AC Pavements Using SEM Images, HR-346, 1994

The major objective of this work was to evaluate the potential of image analysis for characterizing air voids in Portland cement Concrete (PCC), voids and constituents of Asphalt Concrete (AC) and aggregate gradation in AC. Images for analysis were obtained from a scanning electron microscope (SEM). Sample preparation techniques are presented that enhance signal differences so that backscattered electron (BSE) imaging, which is sensitive to atomic number changes, can be effectively employed. Work with PCC and AC pavement core samples has shown that the low vacuum scanning electron microscope (LVSEM) is better suited towards rapid analyses. The conventional high vacuum SEM can also be used for AC and PCC analyses but some distortion within the sample matrix will occur. Images with improved resolution can be obtained from scanning electron microscope (SEM) backscatter electron (BSE) micrographs. In a BSE image, voids filled with barium sulfate/resin yield excellent contrast in both PCC and AC. There is a good correlation between percent of air by image analysis and linear traverse.

Precast Concrete Panel Thickness for Epoxy-Coated Prestressing Strands, Volume 2, HR-353, 1994

This final report for Phase 1 of the research on epoxy-coated, prestressing strands in precast prestressed concrete (PC) panels has been published in two volumes. Volume 1--Technical Report contains the problem description, literature review, and survey results; descriptions of the test specimens, experimental tests, and analytical models; discussions of the analytical and experimental results; summary, conclusions, and recommendations; list of references; and acknowledgments. Volume 2--Supplemental Report contains additional information in the form of appendix material for Volume 1 on the questionnaires, strand forces, geometry of the specimens, concrete crack patterns that formed in the strand transfer length and strand development length specimens, concrete strains in the strand transfer length specimens, and load-point deflections and strand-slip measurements for the strand development length specimens. Appendix A contains the questionnaires that were sent to the design agencies and precast concrete producers. A summary of the results to the questions on the surveys are given as the number of respondents who provided the same answers and as paraphrased comments from the respondents. Appendix B contains graphs of strand force versus time, strand force versus temperature, and strand force versus strand cutting sequence for the concrete castings. Appendix C contains figures that show the location of each specimen in the prestress bed, the geometrical configurations for the strand transfer length (T-type) specimens and strand development length (D-type) specimens, and the concrete cracks that developed in some of the T-type specimens when they were prestressed. Appendix D contains figures that show the concrete cracks that developed in the D-type specimens during the strand development length tests. For each of these tests, the sequence of the failure for the specimen is specified. Appendix E contains graphs of concrete strain versus distance from the end of the T-type specimens that were instrumented with internal embedment strain gages. Appendix F contains graphs of load versus load-point deflection and load versus strand-slip for the strand development length tests of the D-type specimens.

The Role of Magnesium in Concrete Deterioration, HR-355, Appendix, 1994

In the main report concerning the role that magnesium may have in highway concrete aggregate, over 20,000 electron microprobe data were obtained, primarily from automated scans, or traverses, across dolomite aggregate grains and the adjacent cement paste. Representative traverses were shown in figures and averages of the data were presented in Table II. In this Appendix, detailed representative and selected analyses of carbonate aggregate only are presented. These analyses were not presented in the main report because they would be interesting to only a few specialists in dolomite· rocks. In this Appendix, individual point analyses of mineral compositions in the paste have been omitted along with dolomite compositions at grain boundaries and cracks. Clay minerals and quartz inclusions in the aggregate are also not included. In the analyses, the first three column headings from left to right show line number, x-axis, and y-axis (Line number is an artifact of the computer print-out for each new traverse. Consecutive line numbers indicate a continuous traverse with distances between each point of 1.5 to a few μ-m. X-axis and y-axis are coordinates on the electron microscope stage). The next columns present weight percent oxide content of FeO, K20, CaO, Si02, Al203, MgO, SrO, BaO, MnO, Na20, and C02 (calculated assuming the number of moles of C02 is equal to the sum of moles of oxides, chiefly CaO and MgO), TOTAL (the sum of all oxides), and total (sum of all oxides excluding COi). In many of the analyses total is omitted.

Lexan Gate Arm, HR-536, 1987

Innovative Rail Ltd. of Cedar Rapids, Iowa produced a new rail/highway crossing gate arm that shows promise in two areas: a. Minimizing arm breakage, and b. Added target value to motorists. The new gate was demonstrated to the Chicago and North Western Transportation Company, and that railroad has requested its use at two crossings on an "experimental basis" to determine if its installation provides relief in those areas. On April 18, 1986, the Department observed a test of the material under field conditions with the Transportation Company. The gate received four mid-center strikes at 5 MPH by a company truck while in the lowered position, and showed no damage. In a fifth mid-center strike at 15 MPH, the gate was visibly damaged at the connection to its raising mechanism, but continued to function though at a 5-10 degree drop. Several pictures of the gate and its saddle mechanism are shown in Appendix A of this report. Innovative Rail established distributorships in the United States and Canada, and has since gone out of business.

Iowa DOT Evaluation of the PASCO Road Survey System, HR-539, 1987

The report compares and contrasts the automated PASCO method of pavement evaluation to the manual procedures used by the Iowa Department of Transportation (DOT) to evaluate pavement condition. Iowa DOT's use of IJK and BPR roadmeters and manual crack and patch surveys are compared to PASCO's use of 35-mm photography, artificial lighting and hairline projection, tracking wheels and lasers to measure ride, cracking and patching, rut depths, and roughness. The Iowa DOT method provides a Present Serviceability Index (PSI) value and PASCO provides a Maintenance Control Index (MCI). Seven sections of Interstate Highway, county roads and city streets, and one shoulder section were tested with different speeds of data collection, surface types and textures, and stop and start conditions. High correlation of results between the two methods in the measurement of roughness (0.93 for the tracking wheel and 0.84 for the laser method) were recorded. Rut depth correlations of 0.61 and cracking of 0.32 are attributed to PASCO's more comprehensive measurement techniques. A cost analysis of the data provided by both systems indicates that PASCO is capable of providing a comparable result with improved accuracy at a cost of $125-$150 or less per two-lane mile depending on survey mileage. Improved data collection speed, accuracy, and reliability, and a visible record of pavement condition for comparable costs are available. The PASCO system's ability to provide the data required in the Highway Pavement Distress Identification Manual, the Pavement Condition Rating Guide, and the Strategic Highway Research Program Long Term Pavement Performance (LTPP) Studies, is also outlined in the report.

Pressure Relief and Other Joint Rehabilitation Techniques, HR-1042, 1987

A study of four major concrete pavement joint rehabilitation techniques has been conducted, including: pressure relief joints, full-depth repairs, partial-depth repairs and joint resealing. The products of this research include the following for each technique: a summary of published research, detailed documentation of the design and performance of the 36 projects, conclusions and recommendations of the state highway engineers panel, "Design and Construction Guidelines" and "Guide Specifications." The latter two products are prepared for use by state highway agencies. The results of this study are based upon a review of literature, extensive field surveys and analysis of 36 rehabilitation projects, and the experience of an expert panel of state highway engineers.

Review of State Comprehensive Computerized Highway Information System, HR-1053, 1987

This report presents an overview of where the computerized highway information system is now, and its status as a planning and programming tool for state highway agencies. A computerized highway information system is simply a computer linked system which can be used by many divisions of a transportation agency to obtain information to meet data reporting, analyses or other informational needs. The description of the highway information system includes: current use and status, applications, organization and system development, benefits and problems.