Economics of Using Calcium Chloride vs. Sodium Chloride for Deicing/Anti-Icing, TR-488, 2008

The use of chemicals is a critical part of a pro-active winter maintenance program. However, ensuring that the correct chemicals are used is a challenge. On the one hand, budgets are limited, and thus price of chemicals is a major concern. On the other, performance of chemicals, especially at lower pavement temperatures, is not always assured. Two chemicals that are used extensively by the Iowa Department of Transportation (Iowa DOT) are sodium chloride (or salt) and calcium chloride. While calcium chloride can be effective at much lower temperatures than salt, it is also considerably more expensive. Costs for a gallon of salt brine are typically in the range of $0.05 to $0.10, whereas calcium chloride brine may cost in the range of $1.00 or more per gallon. These costs are of course subject to market forces and will thus change from year to year. The idea of mixing different winter maintenance chemicals is by no means new, and in general discussions it appears that many winter maintenance personnel have from time to time mixed up a jar of chemicals and done some work around the yard to see whether or not their new mix “works.” There are many stories about the mixture turning to “mayonnaise” (or, more colorfully, to “snot”) suggesting that mixing chemicals may give rise to some problems most likely due to precipitation. Further, the question of what constitutes a mixture “working” in this context is a topic of considerable discussion. In this study, mixtures of salt brine and calcium chloride brine were examined to determine their ice melting capability and their freezing point. Using the results from these tests, a linear interpolation model of the ice melting capability of mixtures of the two brines has been developed. Using a criterion based upon the ability of the mixture to melt a certain thickness of ice or snow (expressed as a thickness of melt-water equivalent), the model was extended to develop a material cost per lane mile for the full range of possible mixtures as a function of temperature. This allowed for a comparison of the performance of the various mixtures. From the point of view of melting capacity, mixing calcium chloride brine with salt brine appears to be effective only at very low temperatures (around 0° F and below). However, the approach described herein only considers the material costs, and does not consider application costs or other aspects of the mixture performance than melting capacity. While a unit quantity of calcium chloride is considerably more expensive than a unit quantity of sodium chloride, it also melts considerably more ice. In other words, to achieve the same result, much less calcium chloride brine is required than sodium chloride brine. This is important in considering application costs, because it means that a single application vehicle (for example, a brine dispensing trailer towed behind a snowplow) can cover many more lane miles with calcium chloride brine than with salt brine before needing to refill. Calculating exactly how much could be saved in application costs requires an optimization of routes used in the application of liquids in anti-icing, which is beyond the scope of the current study. However, this may be an area that agencies wish to pursue for future investigation. In discussion with winter maintenance personnel who use mixtures of sodium chloride and calcium chloride, it is evident that one reason for this is because the mixture is much more persistent (i.e. it stays longer on the road surface) than straight salt brine. Operationally this persistence is very valuable, but at present there are not any established methods to measure the persistence of a chemical on a pavement. In conclusion, the study presents a method that allows an agency to determine the material costs of using various mixtures of salt brine and calcium chloride brine. The method is based upon the requirement of melting a certain quantity of snow or ice at the ice-pavement interface, and on how much of a chemical or of a mixture of chemicals is required to do that.

2011 Annual Employment Report on All Projects Let by the Iowa DOT Racial/Ethnic Minorities and Females, September 15, 2011

The following data was derived from 1391 reports of participating contractors for the annual 2002 through 2011 reporting periods. The workforce data is reflective of one peak work week for highway contractors during the most active time of the season, the last full week of July. The summary data on pages 4 and 5 was compiled by Iowa DOT staff from the 1391 reports received. Interesting changes and trends have been addressed in the written analysis.

Economic Aspects of Agricultural and Food Biosecurity in the United States, March 2007

Concerns about biosecurity in the food system raise a variety of issues about how the system is presently organized, why it might be vulnerable, what one could reasonably do to better secure it, and the costs of doing so. After presenting some facts about US agriculture and food, this paper considers three economic aspects of the general problem. One is the global problem, or the way biosecurity measures can affect how countries relate to each other and the global consequences that result. Another is how to best manage the immediate aftermath of a realized threat in order to minimize damage. The third is how to seek to prevent realization of the threat. Some policy alternatives are also presented.

Evaluation of Racial Differences in Seat Belt and Child Restraint Use: A Review of Current Literature, 2004

This report presents the results of a literature review conducted to evaluate differences in seat belt use by race. A literature review was conducted to evaluate overall seat belt use, racial differences in seat belt use, overall child restraint use, racial differences in child restraint use, and information about seat belt and child restraint use specific to Iowa. A number of national studies and regional studies were found and are presented. Mixed results were found as to whether racial differences exist in both seat belt use and child restraint use. However, in the course of the literature review, several items that are of interest to safety in Iowa have emerged, although little data specific to Iowa was encountered. First, national seat belt use appears to be lower among African-Americans than for Caucasians or Hispanics. Second, national crash rates among Hispanics appear to be higher than those for Caucasians, particularly when population and lower vehicle miles traveled (VMT) are considered. One issue that should be considered throughout this literature review is that the Hispanic population may be higher than reported due to large numbers of undocumented persons who do not appear in population estimates, driver’s license, or other databases.

Developing an Effective Construction Training Program for American Supervisors with Hispanic Craft Workers, 2005

In the construction industry, Hispanics have the highest rate of fatal work injuries among the racial/ethnic groups, and productivity in the field is limited by the language barrier between Hispanic workers and their supervisors and the level of education of many Hispanic craft workers. This research developed a training program designed to facilitate the integration process between American supervisors and Hispanic craft workers in a practical and cost-effective way, thus improving productivity and lowering fatality rates. The Iowa State University research team conducted a survey of 38 American supervisors, representing 14 Iowa construction companies. Survey results confirm that communication is the main problem experienced by American supervisors in the job site. Many American supervisors also use or depend on a link-person (an individual who interprets tasks to the rest of the Hispanic crew) to communicate to the Hispanic crew members. Research findings show that language differences affect productivity and workplace safety in the construction industry. Additionally, the educational levels of Hispanic workers indicate that they may not have the literacy skills necessary to understand training materials. This research developed two training courses designed to expand the Spanish communication skills of American supervisors. The research team modified the English-as-a-second-language course developed in Phase I into the Spanish as a Second Language (SSL) Survival Course. A series of technical training courses were also developed, titled Concrete Pavement Construction Basics (CPCB), that cover general practices in concrete pavement construction. They are much shorter and more specialized than the SSL course. The CPCB courses provide American supervisors simple and practical communication tools on a variety of topics to choose from according to their specific needs.