Institute for Transportation

About the research

The objective of this project is to provide support to the Iowa Department of Transportation Traffic and Safety Bureau (TSB), particularly in the following areas: development of safety performance functions (SPFs), evaluation of SPFs, development of crash modification factors (CMFs), evaluation of CMFs, crash redaction tool support, and crash facts support.

About the research

The objective of this project is to provide support to the Iowa Department of Transportation Traffic and Safety Bureau (TSB), particularly in the following areas: crash data visualizations; data extract, transform and load (ETL) process; and database update/maintenance.

About the research

Iowa’s secondary roads provide critical access for rural farming, housing, livestock production, and recreation. As such, their continual maintenance and reconstruction are essential to Iowa county engineers. However, counties often face challenges in estimating future pavement performance and predicting remaining service life (RSL), which indicates how long a pavement will remain serviceable before requiring maintenance, preservation, or rehabilitation. Additionally, the high cost of routine pavement performance data collection highlights the need for a low-cost, nonproprietary system for local public agencies, including Iowa counties. To address these challenges, researchers at Iowa State University, in partnership with the Iowa County Engineers Association Service Bureau, have developed two tools under projects sponsored by the Iowa Highway Research Board: (1) the Iowa Pavement Analysis Techniques or “IPAT” tool (for forecasting pavement performance and RSL), and (2) CyRoads (a prototype smartphone application) and Smart Box (a low-cost nonproprietary tool) for collecting and analyzing pavement roughness data and reporting International Roughness Index (IRI). This proposed follow-up (Phase II) study aims to guide the full implementation of these tools in Iowa county pavement asset management practices. The primary objectives are to conduct a pilot study demonstrating the use of the IPAT tool within actual county workflows and develop use cases for its full implementation. The study will also evaluate and update CyRoads and Smart Box, collect IRI data over at least three consecutive years in two pilot counties, and establish an integrated database via an automated or semi-automated data processing tool. Additionally, the research will focus on enhancing IRI prediction models by incorporating maintenance, preservation, and rehabilitation events. The upgraded IPAT tool will include enhanced functional capabilities, which will empower engineers to make well-informed decisions regarding the maintenance, preservation, and rehabilitation of pavement assets under their supervision.

About the research

The objective of this research project is to develop enhanced guidelines to help transportation practitioners develop temporary traffic control plans for highway construction projects with alternative intersections. Attainment of the project objective will help to fill gaps in existing knowledge and provide transportation practitioners with tools to help improve mobility and safety in work zones on highway construction projects with alternative intersections. The research approach will include a literature review and the gathering of information from various states regarding their best practices for implementing works zones on projects with alternative intersections.

About the research

Nighttime work zones pose increased risks for both drivers and workers due to the challenge of ensuring adequate visibility while minimizing glare. Current lighting practices vary widely across public agencies, often resulting in excessive illumination and poor glare control. This study evaluated the performance of nighttime lighting systems through two phases: (1) an industry survey and (2) a controlled field experiment along with a qualitative task assessment and analysis. The survey, with 116 responses, identified persistent issues related to glare and uneven light coverage, primarily attributed to improper lighting configurations rather than insufficient light output. The field study tested 126 lighting setups using LED and halogen lighting sources set at varying mounting heights, aiming angles, and rotation angles. Measurements included horizontal and vertical illuminance, pavement luminance, and veiling luminance ratio (VLR). Results showed that the lighting setups—rotation angle and mounting height—had the greatest impact on visibility and glare. Optimal configurations (rotation: 40°–50°, height: 12–13 ft, aiming angle: 20°–40°) could provide better visibility and minimize harmful glare in the vicinity of nighttime work zones. The report provides recommendations for optimal lighting configurations, offering agencies practical guidance to improve safety and visibility in nighttime work zones.

About the research

As utility infrastructure increasingly occupies public roadway rights of way (ROWs), Iowa faces growing challenges in coordinating utility installations and managing space efficiently. The lack of standardized oversight across cities, counties, and the Iowa Department of Transportation (DOT) has led to inconsistent practices, disorganized utility placement, and costly delays in highway construction. This research aimed to develop a comprehensive utility management approach by identifying best practices for planning, documenting, and managing utility installations within public ROWs. Through surveys of current practices, gap analysis, and stakeholder engagement, the study produced a framework for improved utility coordination. Key recommendations include statewide standardization of policies, mandatory digital as-built documentation, designated utility corridors, enhanced permitting and oversight, and clear protocols for managing abandoned utilities. The research also resulted in the development of training programs and outreach efforts to support implementation. By adopting these strategies, Iowa can achieve more efficient, coordinated, and sustainable utility management, ultimately reducing project costs and preserving ROW integrity for future infrastructure needs.

About the research

This study assessed the long-term performance of four aggressively rehabilitated gravel road test sections whose roadway cross-sectional profiles were rebuilt by recovering material from the ditches to restore the proper widths, elevations, and slopes of the roadways and the proper profiles of the drainage ditches. Two of the rehabilitated test sections were constructed with an enzymatic chemical soil stabilizer, while the other two were not. For each pair of test sections, one was constructed using smooth-tired compaction, while the other was constructed using sheepsfoot compaction. A fifth control section was also studied to establish a baseline that was representative of the surrounding roads in the project area.

Overall, this study demonstrated the effectiveness of aggressively rehabilitating gravel roads that had been lowered, widened, and flattened by decades of heavy traffic. Rebuilding the roadway cross sections improved the drainage capacity of the test sections relative to the much flatter control section. The enzymatic soil stabilizer showed measurable benefits in terms of strength, stiffness, and surface distresses. The benefits were greatest in the first year after construction but then decreased somewhat by the end of the second year. With additional field testing and observation, it could be determined whether the latter decrease was a temporary trend or whether the rehabilitation and stabilization will produce continued benefits over time.

About the research

The overall goal of this project is to understand the impact of using geocells in granular-surfaced road construction in terms of field performance assessed through measurements of rutting, breakage, stiffness, and strength profiles, as well as resilient properties measured in a large scale laboratory test device with cycling loading. The overall workplan includes construction of field test sections, performance of in-situ tests and sampling through two winter-spring seasons, and laboratory investigations to quantify both the short-term and long-term benefits of geocells to help develop construction guidelines and specifications.

About the research

The Iowa Work Zone Safety Workshops have provided an opportunity for operations personnel from various cities in Iowa to improve their work zone safety and setups when conducting routine street maintenance. Many participants come from cities with a population of less than 10,000 residents and small city budgets for this type of work can sometimes lead to a lack of funding for temporary traffic control devices and the use of signs, barricades, cones, and vests that are deteriorated and may be out of compliance with the 2009 Manual on Uniform Traffic Control Devices (MUTCD).

This project was developed to assist smaller cities with the introduction or upgrade of their temporary traffic control devices and vests to meet current standards for compliance and to make their work zones safer for workers and motorists. The program has grown from 10 applications in 2017, the initial year of the project, to more than 150 in 2024–2025.

The goal of this project is to provide an avenue for smaller cities to be able to obtain a basic work zone sign package that is in compliance with the 2009 MUTCD and to make their work zones safer for operations personnel and motorists. It is currently proposed that the materials to be included in the package will be the following:

• One Lane Road Ahead Signs
• Road Work Ahead Signs with “CLOSED” snap on
• Be Prepared to Stop Signs
• Type III Barricades
• 28” Traffic Cones
• Class 2 Safety Vests
• Sign Stands
• 42 inch Channelizers

More information on the program can be found on the Iowa LTAP Work Zone Sign Package Program page.

About the research

Inclusion of randomly-oriented, discrete fibers in cementitious materials is proven to enhance many of the desired engineering properties, such as fracture toughness, flexural strength, and resistance to the formation and propagation of micro/macro cracks under extreme loads, in addition to reducing the risk of early-age cracks in concrete. The concrete fibers can be broadly categorized to metallic and non-metallic fibers. Among their differences, non-metallic fibers offer high corrosion resistance, in contrast to metallic fibers, which are vulnerable to corrosion, despite offering superior mechanical properties.

This project aims to conduct a holistic investigation of a hybrid of metallic and non-metallic fibers to introduce expected functionalities to fiber-reinforced cementitious materials, especially ultra-high performance concrete (UHPC). Use of alternative fibers for non-structural UHPC applications will particularly reduce costs and eliminate the need for Buy America as required with steel fibers. Considering the latest fiber products available in the market, this project will investigate the promise of a new generation of UHPC mixtures engineered by appropriate choices and dosages of fibers. Based on a suite of laboratory investigations, the ultimate goal of this project will be to develop practical guidelines to select a hybrid of metallic and non-metallic fibers for non-structural UHPC. The fiber selection criteria will be consistent with target applications, providing the desired mechanical and durability properties, paired with high corrosion resistance and adequate bond with the cementitious matrix.