Wet-Reflective Pavement Marking Demonstration Project, November 2011

One of the leading complaints from drivers is the inability to see pavement markings under wet night conditions. This issue is a major source of dissatisfaction in state department of transportation (DOT) customer satisfaction surveys. Driving under wet night conditions is stressful and fatiguing for all drivers, but particularly so for the more vulnerable young and older driver age groups. This project focused on the development of a two-year, long-line test deck to allow for the evaluation and demonstration of a variety of wet-reflective pavement marking materials and treatments under wet night conditions. Having the opportunity to document the performance of these various products and treatments will assist the Iowa DOT and local agencies in determining when and where the use of these products might be most effective. Performance parameters included durability, presence, retroreflectivity, and wet night visibility. The test sections were located within Story County so that Iowa DOT management and staff, as well as local agencies, could drive these areas and provide input on the products and treatments.

Report on a review of State employee grievance processes, settlement agreements entered into by the State and payments made during the period July 1, 2010 through June 30, 2014

Report on a review of State employee grievance processes, settlement agreements entered into by the State and payments made during the period July 1, 2010 through June 30, 2014

Mission-Oriented Dust Control and Surface Improvement Processes for Unpaved Roads, HR-194, 1981

Six subject areas prompted the broad field of inquiry of this mission-oriented dust control and surface improvement project for unpaved roads: • DUST--Hundreds of thousands of tons of dust are created annually by vehicles on Iowa's 70,000 miles of unpaved roads and streets. Such dust is often regarded as a nuisance by Iowa's highway engineers. • REGULATIONS--Establishment of "fugitive dust" regulations by the Iowa DEQ in 1971 has created debates, conferences, legal opinions, financial responsibilities, and limited compromises regarding "reasonable precaution" and "ordinary travel," both terms being undefined judgment factors. • THE PUBLIC--Increased awareness by the public that regulations regarding dust do in fact exist creates a discord of telephone calls, petitions, and increasing numbers of legal citations. Both engineers and politicians are frustrated into allowing either the courts or regulatory agencies to resolve what is basically a professional engineering responsibility. • COST--Economics seldom appear as a tenet of regulatory strategies, and in the case of "fugitive dust," four-way struggles often occur between the highway professions, political bodies, regulatory agencies, and the general public as to who is responsible, what can be done, how much it will cost, or why it wasn't done yesterday. • CONFUSION--The engineer lacks authority, and guidelines and specifications to design and construct a low-cost surf acing system are nebulous, i.e., construct something between the present crushed stone/gravel surface and a high-type pavement. • SOLUTION--The engineer must demonstrate that dust control and surface improvement may be engineered at a reasonable cost to the public, so that a higher degree of regulatory responsibility can be vested in engineering solutions.

Low Profile Marker for Wet/Night Visibility, HR-1005, 1977

Conventional highway lane markings are ineffective at night, particularly when the pavement is wet. There is a recognized need for a system that is effective at night under wet conditions and where there is no reduction in current daytime standards. To be effective at all times the system must maintain wet-night retroreflective properties while resisting deterioration caused by snowplows, studded tires, sand and salt applications, and lane changing maneuvers by traffic. This project tested a system of low-profile lane markers developed by Battelle Columbus Laboratory under contract with the Implementation Division of the Federal Highway Administration.

Determination and Evaluation of Alternate Methods for Managing and Controlling Highway-Related Dust, TR-449, 2002

Road dust is caused by wind entraining fine material from the roadway surface and the main source of Iowa road dust is attrition of carbonate rock used as aggregate. The mechanisms of dust suppression can be considered as two processes: increasing particle size of the surface fines by agglomeration and inhibiting degradation of the coarse material. Agglomeration may occur by capillary tension in the pore water, surfactants that increase bonding between clay particles, and cements that bind the mineral matter together. Hygroscopic dust suppressants such as calcium chloride have short durations of effectiveness because capillary tension is the primary agglomeration mechanism. Somewhat more permanent methods of agglomeration result from chemicals that cement smaller particles into a mat or larger particles. The cements include lignosulfonates, resins, and asphalt products. The duration of the cements depend on their solubility and the climate. The only dust palliative that decreases aggregate degradation is shredded shingles that act as cushions between aggregate particles. It is likely that synthetic polymers also provide some protection against coarse aggregate attrition. Calcium chloride and lignosulfonates are widely used in Iowa. Both palliatives have a useful duration of about 6 months. Calcium chloride is effective with surface soils of moderate fine content and plasticity whereas lignin works best with materials that have high fine content and high plasticity indices. Bentonite appears to be effective for up to two years and works well with surface materials having low fines and plasticity and works well with limestone aggregate. Selection of appropriate dust suppressants should be based on characterization of the road surface material. Estimation of dosage rates for potential palliatives can be based on data from this report, from technical reports, information from reliable vendors, or laboratory screening tests. The selection should include economic analysis of construction and maintenance costs. The effectiveness of the treatment should be evaluated by any of the field performance measuring techniques discussed in this report. Novel dust control agents that need research for potential application in Iowa include; acidulated soybean oil (soapstock), soybean oil, ground up asphalt shingles, and foamed asphalt. New laboratory evaluation protocols to screen additives for potential effectiveness and determine dosage are needed. A modification of ASTM D 560 to estimate the freeze-thaw and wet-dry durability of Portland cement stabilized soils would be a starting point for improved laboratory testing of dust palliatives.