Low Water Stream Crossing: Design and Construction Recommendations, December 2001

Most counties have bridges that are no longer adequate, and are faced with large capital expenditure for replacement structures of the same size. In this regard, low water stream crossings (LWSCs) can provide an acceptable, low cost alternative to bridges and culverts on low volume and reduced maintenance level roads. In addition to providing a low cost option for stream crossings, LWSCs have been designed to have the additional benefit of stream bed stabilization. Considerable information on the current status of LWSCs in Iowa, along with insight of needs for design assistance, was gained from a survey of county engineers that was conducted as part of this research (Appendix A). Copies of responses and analysis are included in Appendix B. This document provides guidelines for the design of LWSCs. There are three common types of LWSCs: unvented ford, vented ford with pipes, and low water bridges. Selection among these depends on stream geometry, discharge, importance of road, and budget availability. To minimize exposure to tort liability, local agencies using low water stream crossings should consider adopting reasonable selection and design criteria and certainly provide adequate warning of these structures to road users. The design recommendations included in this report for LWSCs provide guidelines and suggestions for local agency reference. Several design examples of design calculations are included in Appendix E.

Low Water Stream Crossing: Design and Construction Recommendations, Decemeber 2001

Most counties have bridges that are no longer adequate, and are faced with large capital expenditure for replacement structures of the same size. In this regard, low water stream crossings (LWSCs) can provide an acceptable, low cost alternative to bridges and culverts on low volume and reduced maintenance level roads. In addition to providing a low cost option for stream crossings, LWSCs have been designed to have the additional benefit of streambed stabilization. Considerable information on the current status of LWSCs in Iowa, along with insight of needs for design assistance, was gained from a survey of county engineers that was conducted as part of this research (Appendix A). Copies of responses and analysis are included in Appendix B. This document provides guidelines for the design of LWSCs. There are three common types of LWSCs: unvented ford, vented ford with pipes, and low water bridges. Selection among these depends on stream geometry, discharge, importance of road, and budget availability. To minimize exposure to tort liability, local agencies using low water stream crossings should consider adopting reasonable selection and design criteria and certainly provide adequate warning of these structures to road users. The design recommendations included in this report for LWSCs provide guidelines and suggestions for local agency reference. Several design examples of design calculations are included in Appendix E.

Evaluation of Mitigation for Safety Concerns on Low-Volume, Unpaved Rural Roads, 2013.

The Institute for Transportation (InTrans) at Iowa State University completed work on an in-depth study of crash history on lowvolume, rural roads in Iowa in December 2010. Results indicated that unpaved roads with traffic volumes greater than 100 vehicles per day (vpd) exhibit significantly higher crash frequencies, rates, and densities than any other class of low-volume road examined, paved or unpaved. The total mileage for this class of roadway in Iowa is only about 4,400 miles, spread over 99 counties in the state, which is certainly a manageable number of miles for individual rural agencies. The purpose of this study was to identify and examine several unpaved, local road segments with higher than average crash frequencies, select and undertake potentially-beneficial mitigation, and evaluate the results as time allowed. A variety of low-cost options were considered, including engineering improvements, enhanced efforts by law enforcement, and educational initiatives. Using input, active support, and participation from local agencies and state and Federal safety advocates, the study afforded a unique opportunity to examine useful tools for local rural agencies to utilize in addressing safety on this particular type of roadway.

Evaluation of Mitigation for Safety Concerns on Low-Volume, Unpaved Rural Roads: Tech Transfer Summary, 2013.

The Institute for Transportation (InTrans) at Iowa State University completed work on an in-depth study of crash history on lowvolume, rural roads in Iowa in December 2010. Results indicated that unpaved roads with traffic volumes greater than 100 vehicles per day (vpd) exhibit significantly higher crash frequencies, rates, and densities than any other class of low-volume road examined, paved or unpaved. The total mileage for this class of roadway in Iowa is only about 4,400 miles, spread over 99 counties in the state, which is certainly a manageable number of miles for individual rural agencies. The purpose of this study was to identify and examine several unpaved, local road segments with higher than average crash frequencies, select and undertake potentially-beneficial mitigation, and evaluate the results as time allowed. A variety of low-cost options were considered, including engineering improvements, enhanced efforts by law enforcement, and educational initiatives. Using input, active support, and participation from local agencies and state and Federal safety advocates, the study afforded a unique opportunity to examine useful tools for local rural agencies to utilize in addressing safety on this particular type of roadway.

An Investigation of Emulsion Stabilized Limestone Screenings, HR-309, 1994

A significant amount of waste limestone screenings is produced during aggregate production. This waste material cannot be used in highway construction because it does not meet current highway specifications. The purpose of this research was to determine if a waste limestone screenings/emulsion mix could be used to construct a base capable of supporting local traffic. A 1.27 mile (2.04 km) section of roadway in Linn County was selected for this research. The road was divided into seven sections. Six of the sections were used to test 4 in. (100 mm) and 6 in. (150 mm) compacted base thicknesses containing 2.5%, 3.5%, and 4.5% residual asphalt contents. The seventh section was a control section containing untreated waste limestone screenings. This research on emulsion stabilized limestone screenings supports the following conclusions: (1) A low maintenance roadway can be produced using a seal coat surface on 6 in. (150 mm) of stabilized limestone screenings with 4.5% asphalt cement; (2) A 6 in. (150 mm) emulsion stabilized base with less than 3.5% asphalt cement does not produce a satisfactory low cost maintenance roadway; (3) A 4 in. (100 mm) emulsion stabilized base does not produce a satisfactory low cost maintenance roadway; and (4) A 2 in. (50 mm) asphalt concrete surface would be necessary on many roads to provide a low maintenance roadway using emulsion stabilized limestone screenings.

A Feasibility Study on Embedded Micro-Electromechanical Sensors and Systems (MEMS) for Monitoring Highway Structures, TR-575, 2011

Micro-electromechanical systems (MEMS) provide vast improvements over existing sensing methods in the context of structural health monitoring (SHM) of highway infrastructure systems, including improved system reliability, improved longevity and enhanced system performance, improved safety against natural hazards and vibrations, and a reduction in life cycle cost in both operating and maintaining the infrastructure. Advancements in MEMS technology and wireless sensor networks provide opportunities for long-term continuous, real-time structural health monitoring of pavements and bridges at low cost within the context of sustainable infrastructure systems. The primary objective of this research was to investigate the use of MEMS in highway structures for health monitoring purposes. This study focused on investigating the use of MEMS and their potential applications in concrete through a comprehensive literature review, a vendor survey, and a laboratory study, as well as a small-scale field study. Based on the comprehensive literature review and vendor survey, the latest information available on off-the-shelf MEMS devices, as well as research prototypes, for bridge, pavement, and traffic applications were synthesized. A commercially-available wireless concrete monitoring system based on radio-frequency identification (RFID) technology and off-the-shelf temperature and humidity sensors were tested under controlled laboratory and field conditions. The test results validated the ability of the RFID wireless concrete monitoring system in accurately measuring the temperature both inside the laboratory and in the field under severe weather conditions. In consultation with the project technical advisory committee (TAC), the most relevant MEMS-based transportation infrastructure research applications to explore in the future were also highlighted and summarized.

Surface Improvement and Dust Palliation of Unpaved Secondary Roads and Streets, Progress Report, HR-151, 1971

A combined study of dust control and low-cost surface improvements of soil and aggregate materials for immediate (and intermediate) use as a treated surface course is being conducted in three concurrent phases: (1) laboratory screening of various additives thought to have potential for long-lasting dust palliation, soil-additive strength, durability, and additive retention potential; (2) test road construction, using those additives from the screening studies that indicate promise for performance and serviceability; and (3) observation and tests of constructed sections for evaluation of the additive's contribution to performance and serviceability as well as relationship to initial costs. A brief review is presented of the problem, some methods of measuring it, previously adopted approaches to it, project field tests and a portion of the results thus far, and portions of the laboratory work accomplished in the screening studies.

Evaluation of the Confirmation Light System at Signalized Intersections in Medium to Large Iowa Communities to Reduce Red Light Running Violations”, TR-657, 2015

Red light running continues to be a serious safety concern for many communities in the United States. The Federal Highway Administration reported that in 2011, red light running accounted for 676 fatalities nationwide. Red light running crashes at a signalized intersections are more serious, especially in high speed corridors where speeds are above 35 mph. Many communities have invested in red light countermeasures including low-cost strategies (e.g. signal backplates, targeted enforcement, signal timing adjustments and improvement with signage) to high-cost strategies (e.g. automated enforcement and intersection geometric improvements). This research study investigated intersection confirmation lights as a low-cost strategy to reduce red light running violations. Two intersections in Altoona and Waterloo, Iowa were equipped with confirmation lights which targeted the through and left turning movements. Confirmation lights enable a single police officer to monitor a specific lane of traffic downstream of the intersection. A before-after analysis was conducted in which a change in red light running violations prior to- and 1 and 3 months after installation were evaluated. A test of proportions was used to determine if the change in red light running violation rates were statistically significant at the 90 and 95 percent levels of confidence. The two treatment intersections were then compared to the changes of red light running violation rates at spillover intersections (directly adjacent to the treatment intersections) and control intersections. The results of the analysis indicated a 10 percent reduction of red light running violations in Altoona and a 299 percent increase in Waterloo at the treatment locations. Finally, the research team investigated the time into red for each observed red light running violation. The analysis indicated that many of the violations occurred less than one second into the red phase and that most of the violation occurred during or shortly after the all-red phase.

Total Cost of Transportation Analysis of Road and Highway Issues, HR-388, 2002

In the administration, planning, design, and maintenance of road systems, transportation professionals often need to choose between alternatives, justify decisions, evaluate tradeoffs, determine how much to spend, set priorities, assess how well the network meets traveler needs, and communicate the basis for their actions to others. A variety of technical guidelines, tools, and methods have been developed to help with these activities. Such work aids include design criteria guidelines, design exception analysis methods, needs studies, revenue allocation schemes, regional planning guides, designation of minimum standards, sufficiency ratings, management systems, point based systems to determine eligibility for paving, functional classification, and bridge ratings. While such tools play valuable roles, they also manifest a number of deficiencies and are poorly integrated. Design guides tell what solutions MAY be used, they aren't oriented towards helping find which one SHOULD be used. Design exception methods help justify deviation from design guide requirements but omit consideration of important factors. Resource distribution is too often based on dividing up what's available rather than helping determine how much should be spent. Point systems serve well as procedural tools but are employed primarily to justify decisions that have already been made. In addition, the tools aren't very scalable: a system level method of analysis seldom works at the project level and vice versa. In conjunction with the issues cited above, the operation and financing of the road and highway system is often the subject of criticisms that raise fundamental questions: What is the best way to determine how much money should be spent on a city or a county's road network? Is the size and quality of the rural road system appropriate? Is too much or too little money spent on road work? What parts of the system should be upgraded and in what sequence? Do truckers receive a hidden subsidy from other motorists? Do transportation professions evaluate road situations from too narrow of a perspective? In considering the issues and questions the author concluded that it would be of value if one could identify and develop a new method that would overcome the shortcomings of existing methods, be scalable, be capable of being understood by the general public, and utilize a broad viewpoint. After trying out a number of concepts, it appeared that a good approach would be to view the road network as a sub-component of a much larger system that also includes vehicles, people, goods-in-transit, and all the ancillary items needed to make the system function. Highway investment decisions could then be made on the basis of how they affect the total cost of operating the total system. A concept, named the "Total Cost of Transportation" method, was then developed and tested. The concept rests on four key principles: 1) that roads are but one sub-system of a much larger 'Road Based Transportation System', 2) that the size and activity level of the overall system are determined by market forces, 3) that the sum of everything expended, consumed, given up, or permanently reserved in building the system and generating the activity that results from the market forces represents the total cost of transportation, and 4) that the economic purpose of making road improvements is to minimize that total cost. To test the practical value of the theory, a special database and spreadsheet model of Iowa's county road network was developed. This involved creating a physical model to represent the size, characteristics, activity levels, and the rates at which the activities take place, developing a companion economic cost model, then using the two in tandem to explore a variety of issues. Ultimately, the theory and model proved capable of being used in full system, partial system, single segment, project, and general design guide levels of analysis. The method appeared to be capable of remedying many of the existing work method defects and to answer society's transportation questions from a new perspective.