Development of a New Process for Determining Design Year Traffic Demands, TR-528, 2007

Researchers should continuously ask how to improve the models we rely on to make financial decisions in terms of the planning, design, construction, and maintenance of roadways. This project presents an alternative tool that will supplement local decision making but maintain a full appreciation of the complexity and sophistication of today’s regional model and local traffic impact study methodologies. This alternative method is tailored to the desires of local agencies, which requested a better, faster, and easier way to evaluate land uses and their impact on future traffic demands at the sub-area or project corridor levels. A particular emphasis was placed on scenario planning for currently undeveloped areas. The scenario planning tool was developed using actual land use and roadway information for the communities of Johnston and West Des Moines, Iowa. Both communities used the output from this process to make regular decisions regarding infrastructure investment, design, and land use planning. The City of Johnston case study included forecasting future traffic for the western portion of the city within a 2,600-acre area, which included 42 intersections. The City of West Des Moines case study included forecasting future traffic for the city’s western growth area covering over 30,000 acres and 331 intersections. Both studies included forecasting a.m. and p.m. peak-hour traffic volumes based upon a variety of different land use scenarios. The tool developed took goegraphic information system (GIS)-based parcel and roadway information, converted the data into a graphical spreadsheet tool, allowed the user to conduct trip generation, distribution, and assignment, and then to automatically convert the data into a Synchro roadway network which allows for capacity analysis and visualization. The operational delay outputs were converted back into a GIS thematic format for contrast and further scenario planning. This project has laid the groundwork for improving both planning and civil transportation decision making at the sub-regional, super-project level.

A Sufficiency Rating System for Secondary Roads in Iowa, HR-264, Volume I, 1985

County engineers in Iowa face the dual problems of rapidly escalating costs and a decreasing rate of growth of revenues. Various priority systems are in use, ranking projects for inclusion in road improvement programs, but they generally have weaknesses when used to compare one project with another in a different location. The sufficiency rating system has proven to be a useful tool in developing a priority list of projects for primary road systems, but there are none currently in use for secondary road systems. The research reported here was undertaken to develop a sufficiency rating system which could be used for secondary roads in Iowa and to produce the necessary forms and instructions to aid county engineering personnel in their efforts to complete the ratings for roads within their county.

Solar Powered Highway Delineator System, HR-367, 1993

Currently, many drivers experience some difficulty in viewing the road ahead of them during times of reduced visibility, such as rain, snow, fog, or the darkness of night- Recent studies done by the National Safety Council provide a detailed contrast between fatal accidents occurring during the day and night. Revealed was that the motor vehicle night death rate (4.41 deaths per 100 million miles driven) was sharply higher than the corresponding death rate during daylight hours (1.21). By providing a delineating system powered by the natural resource of solar power, a constant source of visibility may be maintained throughout the evening. Along with providing enough light to trace the outline of the road, other major goals defined in producing this delineator system are as follows: 1. A strong and durable design that would protect the internal components and survive extreme weather conditions. 2. A low maintenance system where components need few repairs or replacements. 3. A design which makes all components accessible in the event that maintenance is needed, but also prevents vandalism. 4. A design that provides greater visibility to drivers and will not harm a vehicle or its passengers in the event of a collision. This solar powered highway delineator consists of an adjustable solar array, a light fixture, and a standard delineator pole. The solar array houses and protects the solar panels, and can be easily adjusted to obtain a maximum amount of sunlight. The light fixture primarily houses the battery, the circuit and the light assembly. Both components allow for easy accessibility and reduce vandalism using internal connections for bolts and wires. The delineator mounting pole is designed to extensively deform in the event of a collision, therefore reducing any harm caused to the vehicle and/or the passengers. The cost of a single prototype to be produced is approximately $70.00 excluding labor costs. However, these material and labor costs will be greatly reduced if a large number of delineators are produced. It is recommended that the Iowa Department of Transportation take full advantage of the research and development put into this delineator design. The principles used in creating this delineator can be used to provide an outline for drivers to follow, or on a larger scale, provide actual roadway lighting in areas where it was never before possible or economically feasible. In either event, the number of fatal accidents will be decreased due to the improved driver visibility in the evening.

Development of Self-Cleaning Box Culvert Design – Phase II, TR-619, 2013

Culverts are common means to convey flow through the roadway system for small streams. In general, larger flows and road embankment heights entail the use of multibarrel culverts (a.k.a. multi-box) culverts. Box culverts are generally designed to handle events with a 50-year return period, and therefore convey considerably lower flows much of the time. While there are no issues with conveying high flows, many multi-box culverts in Iowa pose a significant problem related to sedimentation. The highly erosive Iowa soils can easily lead to the situation that some of the barrels can silt-in early after their construction, becoming partially filled with sediment in few years. Silting can reduce considerably the capacity of the culvert to handle larger flow events. Phase I of this Iowa Highway Research Board project (TR-545) led to an innovative solution for preventing sedimentation. The solution was comprehensively investigated through laboratory experiments and numerical modeling aimed at screening design alternatives and testing their hydraulic and sediment conveyance performance. Following this study phase, the Technical Advisory Committee suggested to implement the recommended sediment mitigation design to a field site. The site selected for implementation was a 3-box culvert crossing Willow Creek on IA Hwy 1W in Iowa City. The culvert was constructed in 1981 and the first cleanup was needed in 2000. Phase II of the TR 545 entailed the monitoring of the site with and without the selfcleaning sedimentation structure in place (similarly with the study conducted in laboratory). The first monitoring stage (Sept 2010 to December 2012) was aimed at providing a baseline for the operation of the as-designed culvert. In order to support Phase II research, a cleanup of the IA Hwy 1W culvert was conducted in September 2011. Subsequently, a monitoring program was initiated to document the sedimentation produced by individual and multiple storms propagating through the culvert. The first two years of monitoring showed inception of the sedimentation in the first spring following the cleanup. Sedimentation continued to increase throughout the monitoring program following the depositional patterns observed in the laboratory tests and those documented in the pre-cleaning surveys. The second part of Phase II of the study was aimed at monitoring the constructed self-cleaning structure. Since its construction in December 2012, the culvert site was continuously monitored through systematic observations. The evidence garnered in this phase of the study demonstrates the good performance of the self-cleaning structure in mitigating the sediment deposition at culverts. Besides their beneficial role in sediment mitigation, the designed self-cleaning structures maintain a clean and clear area upstream the culvert, keep a healthy flow through the central barrel offering hydraulic and aquatic habitat similar with that in the undisturbed stream reaches upstream and downstream the culvert. It can be concluded that the proposed self-cleaning structural solution “streamlines” the area upstream the culvert in a way that secures the safety of the culvert structure at high flows while producing much less disturbance in the stream behavior compared with the current constructive approaches.

Design Manual for Strengthening of Continuous-Span Composite Bridges, HR-333, 1993

The need for upgrading a large number of understrength bridges in the United States has been well documented in the literature. This manual presents two methods for strengthening continuous-span composite bridges: post-tensioning of the positive moment regions of the bridge stringers and the addition of superimposed trusses at the piers. The use of these two systems is an efficient method of reducing flexural overstresses in undercapacity bridges. Before strengthening a given bridge however, other deficiencies (inadequate shear connection, fatigue problems, extensive corrosion) should be addressed. Since continuous-span composite bridges are indeterminant structures, there is longitudinal and transverse distribution of the strengthening axial forces and moments. This manual basically provides the engineer with a procedure for determining the distribution of strengthening forces and moments throughout the bridge. As a result of the longitudinal and transverse force distribution, the design methodology presented in this manual for continuous-span composite bridges is extremely complex. To simplify the procedure, a spreadsheet has been developed for use by practicing engineers. This design aid greatly simplifies the design of a strengthening system for a given bridge in that it eliminates numerous tedious hand calculations, computes the required force and moment fractions, and performs the necessary iterations for determining the required strengthening forces. The force and moment distribution fraction formulas developed in this manual are primarily for the Iowa DOT V12 and V14 three-span four-stringer bridges. These formulas may be used on other bridges if they are within the limits stated in this manual. Use of the distribution fraction formulas for bridges not within the stated limits is not recommended.

Evaluation of an Epoxy Pavement Marking System, HR-180, 1978

The purpose of this research project is to determine if (1) epoxy lane markings will last an entire winter season without replacement, (2) epoxy lane marking is an economical alternative to standard paint on high-traffic multi-lane roadways where lane changing is frequent, and (3) there are worthwhile benefits derived from thorough cleaning of the pavement surface before painting. The success of epoxy lane marking depends on the success of the equipment with which it is mixed and applied. The epoxy lane marking material, if properly mixed and placed on a clean surface, has the durability required to withstand a high traffic volume and frequent lane changes for at least one year.

Electronic Bulletin Board System, HR-345, 1998

The primary objectives of the Electronic Bulletin Board System (BBS) project were to: (1) Provide an electronic communication tool which would link city and county engineering offices to each other and to other governmental agencies for messaging and data sharing; (2) Provide a dial-up site for reference information or files accessible on-demand; and (3) Provide a "stepping stone" to the world of electronic data transfer, recognizing that most local government employees face a huge complex of technology with limited knowledge of computers and communications tools. The system was designed to be as simple as possible, and to require minimal equipment and software cost to the users. The original system was an Apex 386/25 computer with MS-DOS 5.0 software and the final configuration was an HP Vectra XM Pentium 90 with MS-NT 3.51 and Mustang - Wildcat 5.0 software. The users of the BBS were county engineers and their staff, offices in the central office of the Iowa Department of Transportation (DOT) and Resident Construction Engineers at the Iowa DOT. Much of the activity was between the county engineers, and their staffs, and the Iowa DOT offices with which they have ongoing business activities. The BBS contained files for mapping, Internet e-mail service, Accident Location Analysis System (ALAS) data, Iowa DOT bid lettings, and Autocad and Intergraph maps and standards. The 800 line calls were recorded and gave the best indication of the usage and the trends that were being followed. The usage tended to be higher in the winter months when design activities are occurring and lower in the summer months when the construction is in progress. The project was judged a success. The BBS did provide a "stepping stone" to the world of electronic data transfer.

A Computer Based Information System for County Equipment Cost Records, Interim Report, HR-173, 1975

This report describes the work accomplished to date on research project HR-173, A Computer Based Information System for County Equipment Cost Records, and presents the initial design for this system. The specific topics discussed here are findings from the analysis of information needs, the system specifications developed from these findings, and the proposed system design based upon the system specifications. The initial system design will include tentative input designs for capturing input data, output designs to show the output formats and the items to be output for use in decision making, file design showing the organization of information to be kept on each piece of equipment in the computer data file, and general system design explaining how the entire system will operate. The Steering Committee appointed by Iowa Highway Research Board is asked to study this report, make appropriate suggestions, and give approval to the proposed design subject to any suggestions made. This approval will permit the designer to proceed promptly with the development of the computer program implementation phase of the design.

Concrete Pavement Mixture Design and Analysis (MDA): Evaluation of Foam Drainage Test to Measure Air Void Stability in Concrete

The stability of air bubbles in fresh concrete can have a profound influence of the potential durability of the system, because excessive losses during placement and consolidation can compromise the ability of the mixture to resist freezing and thawing. The stability of air void systems developed by some air entraining admixtures (AEAs) could be affected by the presence of some polycarboxylate-based water reducing admixtures (WRAs). The foam drainage test provides a means of measuring the potential stability of air bubbles in a paste. A barrier to acceptance of the test was that there was little investigation of the correlation with field performance. The work reported here was a limited exercise seeking to observe the stability of a range of currently available AEA/WRA combinations in the foam drainage test; then, to take the best and the worst and observe their stabilities on concrete mixtures in the lab. Based on the data collected, the foam drainage test appears to identify stable combinations of AEA and WRA.

Design of Piles for Integral Abutment Bridges, HR-252, 1984

More and more, integral abutment bridges are being used in place of the more traditional bridge designs with expansion releases. In this study, states which use integral abutment bridges were surveyed to determine their current practice in the design of these structures. To study piles in integral abutment bridges, a finite element program for the soil-pile system was developed (1) with materially and geometrically nonlinear, two and three dimensional beam elements and (2) with a nonlinear, Winkler soil model with vertical, horizontal, and pile tip springs. The model was verified by comparison to several analytical and experimental examples. A simplified design model for analyzing piles in integral abutment bridges is also presented. This model grew from previous analytical models and observations of pile behavior. The design model correctly describes the essential behavioral characteristics of the pile and conservatively predicts the vertical load-carrying capacity. Analytical examples are presented to illustrate the effects of lateral displacements on the ultimate load capacity of a pile. These examples include friction and end-bearing piles; steel, concrete, and timber piles; and bending about the weak, strong, and 45° axes for H piles. The effects of cyclic loading are shown for skewed and nonskewed bridges. The results show that the capacity of friction piles is not significantly affected by lateral displacements, but the capacity of end-bearing piles is reduced. Further results show that the longitudinal expansion of the bridge can introduce a vertical preload on the pile.

Report and Specification for Transportation Program Management System, HR-394, 1997

TPMS is proposed as a distributed, PC-based system for automating two processes required for road improvements in Iowa: a) the annual preparation, submission, and approval of road improvement programs. b) the ongoing process of developing plans and obtaining approval for projects to be let for bids.

Transportation Program Management System, HR-394, 2003

HR-394 was a software and database development project. Via funding provided by the Iowa Highway Research Board, the Iowa County Engineer's Association Service Bureau oversaw the planning and implementation of an Internet based application that supports two major local-government transportation project activities: Project programming and Development tracking. The goals were to reduce errors and inconsistencies, speed up the processes, link people to both project data and each other, and build a framework that could eventually support a 'paperless' work flow. The work started in 1999 and initial development was completed by the fall of 2002. Since going live, several 'piggy back' applications have been required to make the Programming side better fit actual work procedures. This part of the system has proven adequate but will be rewritten in 2004 to make it easier to use. The original development side module was rejected by the users and so had to be rewritten in 2003. The second version has proven much better, is heavily used, and is interconnected with Iowa DOT project data systems. Now that the system is in operation, it will be maintained and operated by the ICEA Service Bureau as an ongoing service function.

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.

Design Guide for Improved Quality of Roadway Subgrades and Subbases, TR-525, 2008

The performance of a pavement depends on the quality of its subgrade and subbase layers; these foundational layers play a key role in mitigating the effects of climate and the stresses generated by traffic. Therefore, building a stable subgrade and a properly drained subbase is vital for constructing an effective and long lasting pavement system. This manual has been developed to help Iowa highway engineers improve the design, construction, and testing of a pavement system’s subgrade and subbase layers, thereby extending pavement life. The manual synthesizes current and previous research conducted in Iowa and other states into a practical geotechnical design guide [proposed as Chapter 6 of the Statewide Urban Design and Specifications (SUDAS) Design Manual] and construction specifications (proposed as Section 2010 of the SUDAS Standard Specifications) for subgrades and subbases. Topics covered include the important characteristics of Iowa soils, the key parameters and field properties of optimum foundations, embankment construction, geotechnical treatments, drainage systems, and field testing tools, among others.

Design, Construction, and Field Testing of an Ultra High Performance Concrete Pi-Girder Bridge, TR-574, 2011

Among the variety of road users and vehicle types that travel on U.S. public roadways, slow moving vehicles (SMVs) present unique safety and operations issues. SMVs include vehicles that do not maintain a constant speed of 25 mph, such as large farm equipment, construction vehicles, or horse-drawn buggies. Though the number of crashes involving SMVs is relatively small, SMV crashes tend to be severe. Additionally, SMVs can be encountered regularly on non-Interstate/non-expressway public roadways, but motorists may not be accustomed to these vehicles. This project was designed to improve transportation safety for SMVs on Iowa’s public roadway system. This report includes a literature review that shows various SMV statistics and laws across the United States, a crash study based on three years of Iowa SMV crash data, and recommendations from the SMV community.