Pipe Rehabilitation with Polyethylene Pipe Liners, HR-370, Construction Report, 1995

Corroded, deteriorated, misaligned, and distorted drainage pipes can cause a serious threat to a roadway. Normal practice is to remove and replace the damaged drainage structure. An alternative method of rehabilitating these structures is to slip line them with a polyethylene liner. Twelve drainage structures were slip lined with polyethylene liners during 1994 in Iowa. Two types of liners installed were "Culvert Renew" and "Snap-Tite". It was found that the liners could be easily installed by most highway, county, and city maintenance departments. The liners restore the flow and increase the service life of the original drainage structure. The liners were found to be cost competitive with the removal and replacement of the existing drainage structure. Slip lining has the largest economic benefit when the roadway is paved, the culvert is under a deep fill, or traffic volumes are high. The annular space between the original pipe and the liner was filled with flowable mortar. Care should be taken to properly brace and grout the annular space between the liner and the culvert.

New Method for Breaking High Strength Prestress Cable, MLR-97-6, 1997

A new method was developed for breaking high strength prestressed cable. The old method used an aluminum oxide grit packed into a special gripping jaw. The new method uses aluminum shims wrapped around the cable and then is gripped with a V-grip. The new method gives nearly 100% "good breaks" on the cable compared to approximately 10% good breaks with the old method. In addition, the new cable breaking method gives higher ultimate tensile strengths, is more reproducible, is quicker, cleaner and easier on equipment.

Development of an Improved Agricultural-Based Deicing Product, TR-581, 2010

Snow and ice removal on public streets is a critical part of the work of departments of transportation in northern U.S. states, including Iowa. Iowa is also a state rich in agricultural resources, some of which undergo industrial processes that generate a number of byproducts, e.g., in converting corn to ethanol or soy to biodiesel. It would be desirable to find those that, with a minimum of additional processing, can be used as a deicing compound, either alone or in combination with products currently in use. The focus of this work is therefore to investigate by-products from agricultural processes that may be suitable for use as deicing applications. This topic has been investigated in the past by others, with many patented products described in the literature. An initial screening was carried out to assess the potential acceptability of selected commercial products, as well as a glycerol developed for this project. Based on the variety of parameters tested, the product combination that shows the greatest promise for future application consists of 80% glycerol with 20% NaCl.

Iowa 2014 Transportation Map, 2014

Transportation map of Iowa, updated march 1, 2014. map focuses on interstate highways, primary and secondary state roads, county roads, and scenic byways. Also includes railroad lines, airports, waterways, and locks and dams. All 99 counties are represented, as well as approximately 1,000 cities and towns. Points of interest are also marked.

Performance of Various Thicknesses of P.C. Concrete Secondary Pavement, HR-9, 1979

In 1951 Greene County and the Iowa Highway Research Board paved County Road E-33 from Iowa Highway No. 17 (now Iowa 4) to Farlin with various thicknesses [ranging from 4.5 in. (11.4 cm) to 6 in. (15.2 cm)] of portland cement concrete pavement. The project, designated HR-9, was divided into ten research sections. This formed pavement was placed on the existing grade. Eight of the sections were non-reinforced except for centerline tie bars and no contraction joints were used. Mesh reinforcing and contraction joints spaced at 29 ft 7 in. (9.02 m) intervals were used in two 4.5-in. (11.4-cm) thick sections. The concrete in one of the sections was air entrained. Signs denoting the design and limits of the research sections were placed along the roadway. The pavement has performed well over its 28-year life, carrying a light volume of traffic safely while requiring no major maintenance. The 4.5-in. (11.4-cm) thick mesh-reinforced pavement with contraction joints has exhibited the best overall performance.

Evaluation of Experimental Data Obtained from Lightweight Aggregate Bridge Girders, HR-104, 1968

The use of lightweight aggregates in prestressed concrete is becoming more of a reality as our design criteria become more demanding. Bridge girders of greater lengths have been restricted from travel on many of our highways because the weight of the combined girders and transporting vehicle is excessive making hauls of any distance prohibitive. This, along with new safety recommendations, prompted the State of Iowa to investigate the use of lightweight aggregate bridge girders. A series of three projects was started to investigate the possibility of using lightweight aggregate in prestressed concrete. The object of this project is to study the effect which lightweight aggregate concrete has on the camber of bridge girders when used in a field situation.

Field Observation of Five Lightweight Aggregate Pretensioned Prestressed Bridge Beams, HR-104, 1969

The use of lightweight aggregates in pretensioned prestressed concrete beams is becoming more advantageous as our design criteria dictate longer span concrete bridges. Bridge beams of greater lengths have been restricted from travel on many of our highways because the weight of the combined beams and transporting vehicle was excessive, making hauls of any distance prohibitive. This, along with the fact that new safety requirements necessitate the use of longer spans in grade separation structures over major highways, prompted the State of Iowa to investigate the use of lightweight aggregate bridge beams. The objective of this project is the collection of field deflection measurements for five pretensioned prestressed lightweight aggregate concrete bridge beams fabricated by conventional plant processes; also the comparison of the actual cambers and deflections of the beams with that predicted from the design assumptions.

Thermoplastic Pavement Markings, HR-172, 1975

It is difficult to maintain reflectorized lane markings on high-traffic, multi-lane highways. This is particularly true of sections in urban areas where there are frequent lane changes, such as on the Des Moines Freeway, I-235. In spite of the fact that the lane markings are painted on an average of three times a year, they are frequently absent during a considerable portion of the winter period. In the summer of 1973, the office of Highway Maintenance suggested a research project using a new thermoplastic paint developed by the Prismo Universal Corporation. Because of difficulties in scheduling the work, a definite proposal was not submitted until 1974. Upon the recommendation of the Iowa Highway Research Board, the project was approved by the Iowa State Highway Commission on August 7, 1974.

Bridge Deck Delamination Study, HR-179, 1978

The Delamtect was introduced to the Iowa Department of Transportation through a 1975 Federal Highway Administration demonstration project. The Delamtect is a small mobile unit for conducting a rapid bridge deck survey to determine the extent of delaminations (subsurface fractures). Comparison of the Delamtect with manual sounding methods and drilled cores has demonstrated its reliability. This research has shown the Delamtect to be a more effective, more economical and safer method of surveying bridge decks than manual sounding methods. The Delamtect can also be used to provide a measure of the bond within membrane systems.

Macadam Base Shoulders, HR-181, 1977

Highway safety and pavement performance can be directly influenced by the type of shoulders that are constructed. Shoulder design alternatives have always been rather limited. Moreover, the use of some of the alternatives has always been restricted by funding limitations. This research project seeks to explore the use of modified macadam base construction for shoulders. This type of shoulder design could offer the designer another option when paved or stabilized shoulders are being considered. Macadam base construction has in the past been shown to be quite strong and freedraining. Two macadam base shoulder designs were developed and constructed for this research project. A new roadway embankment and P.C.C. pavement were constructed on a section of US 6 east of Adel in Dallas County. The macadam base shoulders were constructed adjacent to the pavement as part of the project. The north shoulder was finished with a choke stone course and bituminous surface treatment and the south shoulder was finished with a two (2) inch layer of Type B Class II asphalt concrete. The initial results are considered satisfactory. Follow-up performance evaluation and load bearing tests are planned.

Portable School Stop Signs and Other Non-Uniform School Stop Control Devices, HR-190, 1978

Portable (roll-out) stop signs are used at school crossings in over 300 cities in Iowa. Their use conforms to the Code of Iowa, although it is not consistent with the provisions of the Manual on Uniform Traffic Control Devices adopted for nationwide application. A survey indicated that most users in Iowa believe that portable stop signs provide effective protection at school crossings, and favor their continued use. Other non-uniform signs that fold or rotate to display a STOP message only during certain hours are used at school crossings in over 60 cities in Iowa. Their use does not conform to either the Code of Iowa or the Manual on Uniform Traffic Control Devices. Users of these devices also tend to favor their continued use. A survey of other states indicated that use of temporary devices similar to those used in Iowa is not generally sanctioned. Some unsanctioned use apparently occurs in several states, however. A different type of portable stop sign for school crossings is authorized and widely used in one state. Portable stop signs similar to those used in Iowa are authorized in another state, although their use is quite limited. A few reports in the literature reviewed for this research discussed the use of portable stop signs. The authors of these reports uniformly recommended against the use of portable or temporary traffic control devices. Various reasons for this recommendation were given, although data to support the recommendation were not offered. As part of this research, field surveys were conducted at 54 locations in 33 communities where temporary stop control devices were in use at school crossings. Research personnel observed the obedience to stop control and measured the vehicular delay incurred. Stopped delay averaged 1.89 seconds/entering vehicle. Only 36.6 percent of the vehicles were observed to come to a complete stop at the study locations controlled by temporary stop control devices. However, this level of obedience does not differ from that observed at intersections controlled by permanent stop signs. Accident experience was compiled for 76 intersections in 33 communities in Iowa where temporary stop signs were used and, for comparative purposes, at 76 comparable intersections having other forms of control or operating without stop control. There were no significant differences in accident experience An economic analysis of vehicle operating costs, delay costs, and other costs indicated that temporary stop control generated costs only about 12 percent as great as permanent stop control for a street having a school crossing. Midblock pedestrian-actuated signals were shown to be cost effective in comparison with temporary stop signs under the conditions of use assumed. Such signals could be used effectively at a number of locations where temporary stop signs are being used. The results of this research do not provide a basis for recommending that use of portable stop signs be prohibited. However, erratic patterns of use of these devices and inadequate designs suggest that improved standards for their use are needed. Accordingly, nine recommendations are presented to enhance the efficiency of vehicular flow at school crossings, without causing a decline in the level of pedestrian protection being afforded.

Evaluation of Dense Bridge Floor Concrete using Superplasticizer, HR-192, 1977

Much effort is being expended by various state, federal, and private organizations relative to the protection and preservation of concrete bridge floors. The generally recognized culprit is the chloride ion, from the deicing salt, reaching the reinforcing steel, and along with water and oxygen, causing corrosion. The corrosion process exerts pressure which eventually causes cracks and spalls in the bridge floor. The reinforcing· has been treated and coated, various types of "waterproof" membranes have been placed on the deck surface, decks have been surfaced with dense and modified concretes, decks have been electrically protected, and attempts to internally seal the concrete have been made. As of yet, no one method has been proven and accepted by the various government agencies as being the "best" when considering the initial cost, application effort, length and effectiveness of protection, etc.

Dust Control Using an Asphalt Emulsion, HR-196, 1977

In an effort to control fugitive dust on a gravel surfaced roadway in Boone County, a cationic asphalt emulsion was blended with warm water and applied with an asphalt distributor. The test included various application procedures. After visual observations, it was concluded that this procedure utilizing a dilute asphalt emulsion was not an effective method of dust control.

Sprinkle Treatment of Asphalt Surfaces, HR-199, 1984

Methods of improving highway safety are of major concern to everyone who is involved in the planning, development and construction of improvements of our vast highway network. Other major concerns are the conservation of our rapidly disappearing sources of energy and quality building materials. This research is devoted to further exploration of a process which will: 1. help preserve higher quality aggregates; and, 2. improve the frictional characteristics and surface texture of asphalt pavement surfaces. Sprinkle treatment of asphalt concrete pavement surfaces with a non-polishing aggregate, a procedure which was developed in Europe, is one method which has shown promise in accomplishing the above listed objectives. This research seeks to explore the feasibility and cost effectiveness of using standard asphalt mixtures of local, less expensive aggregates for surface courses followed by a surface sprinkle treatment of a hard, durable, non-polishing layer of precoated chips to produce a durable, non-skid pavement surface for safe highway travel. Three standard mixture types are being evaluated for aggregate retention characteristics and six sprinkle aggregates are being evaluated for durability, polishing and friction characteristics. In addition, measurements of the surface texture by the silicone putty method are being made. Another feature of this research is the evaluation of a rubberized asphalt material called Overflex MS as a crack filler. It has been reported that the material could be beneficial in reducing reflective cracking. The project was begun in July of 1978 and was completed in August. A review made in the spring of 1979 indicates very satisfactory performance. It was determined from slide photos taken after construction and again in the spring that aggregate retention was very good. However, many cracks had reflected indicating that the Overflex MS had not been effective. Follow up friction test results and texture analysis were also very good. The results of these tests are shown in Appendix A.

Performance of Randomly Oriented, Fiber-Reinforced Roadway Soils, HR-211, 1982

Several primary techniques have been developed through which soil aggregate road material properties may be improved. Such techniques basically involve a mechanism of creating a continuous matrix system of soil and/or aggregate particles, interlocked through the use of some additive such as portland cement, lime, or bituminous products. Details by which soils are stabilized vary greatly, but they are dependent on the type of stabilizing agent and nature of the soil, though the overall approach to stabilization has the common feature that improvement is achieved by some mechanism(s) forcing individual particles to adhere to one another. This process creates a more rigid material, most often capable of resisting the influx of water during freezing, loss of strength due to high moisture content and particle dispersion during thawing, and loss of strength due to migration of fines and/or water by capillarity and pumping. The study reported herein, took a new and relatively different approach to strengthening of soils, i.e., improvement of roadway soils and/or soil-aggregate materials by structural reinforcement with randomly oriented fibers. The purpose of the study was to conduct a laboratory and field investigation into the potential of improving (a) soil-aggregate surfaced and subgrade materials, including those that are frost-prone and/or highly moisture susceptible, and (b) localized base course materials, by uniting such materials through fibrous reinforcement. The envisioned objective of the project was the development of a simple construction technique(s) that could be (a) applied on a selective basis to specific areas having a history of poor performance, or (b) used for improvement of potential base materials prior to surfacing. Little background information on such purpose and objective was available. Though the envisioned process had similarities to fibrous reinforced concrete, and to fibrous reinforced resin composites, the process was devoid of a cementitious binder matrix and thus highly dependent on the cohesive and frictional interlocking processes of a soil and/or aggregate with the fibrous reinforcement; a condition not unlike the introduction of reinforcing bars into a concrete sand/aggregate mixture without benefit of portland cement. Thus the study was also directed to answering some fundamental questions: (1) would the technique work; (2) what type or types of fibers are effective; (3) are workable fibers commercially available; and (4) can such fibers be effectively incorporated with conventional construction equipment, and employed in practical field applications? The approach to obtaining answers to these questions, was guided by the philosophy that an understanding of basic fundamentals was essential to developing a body of engineering knowledge, that would serve as the basis for eventual development of design procedures with fibrous products for the applications previously noted.