Institute for Transportation

About the research

During flood events, it can be difficult finding relevant hydrologic and hydraulic information for assessing the vulnerability of infrastructure. In many cases, information is not available or can be very time consuming to obtain and evaluate. Without good information regarding the hydraulic relationship between the infrastructure and flood discharges, it is difficult to be proactive with regard to the protection of lives, property and infrastructure. Too often DOTs, and other infrastructure owners, are reactive instead of proactive regarding flood events resulting in unnecessary damages and risks to public safety.

In 2008, an extreme flood event occurred along many large stream basins in the central and eastern part of Iowa, which impacted Interstate 80 and many other primary routes. During these flood events it was critical to assess and predict which highway locations had the potential for overtopping from flood waters so that safe detour routes could be identified for the traveling public. The effort to evaluate the vulnerability of the roadway to flooding required significant DOT staff time and resources to reconcile project datums and correlate hydraulic estimates to determine accurate stage vs. discharge relationships (rating curves) at specific bridge/highway locations.

The Iowa Department of Transportation was fortunate that a bridge replacement project was under construction on I-80 over the Cedar River at the time of the 2008 floods. Since the DOT had design information regarding the low roadway and detailed hydraulic data (a rating curve), the Interstate was closed before flood waters impacted the traveling public. Traffic was proactively detoured along other primary routes preventing significant traffic delays and diversion of traffic into the local roadway system. This event was the impetus for the development of an innovative Riverine Infrastructure Data Base (RIDB).

About the research

The ability to acquire and set up work zone-related devices that are in compliance with the 2012 revisions to the 2009 Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) can sometimes be difficult for smaller cities. The smaller budgets for these cities can result in a lack of inventory and/or the use of signs that are in poor condition.

The goal of the project was to provide an avenue for small cities to obtain a basic package of work zone signs and personal protection vests that could help them improve the safety of their work zone setups and increase the safety of their workers and the traveling public.

About the research

Selecting the right treatment for the right pavement at the right time has been a fundamental principle to pavement preservation success. The objective of this project is to develop “Iowa’s Pavement Preservation Guide,” a document tailored to serving the needs of Iowa practitioners who have active pavement preservation programs or plan to implement a pavement preservation program.This proposal outlines a research approach based on national-best practices for pavement preservation program implementation. Many states have developed pavement preservation manuals. The research addresses six areas including: (1) project selection, (2) anticipated benefit/costs of pavement preservation treatments at the network-and project-level, (3) implementing pavement preservation into system-wide strategic planning, (4) preservation treatment considerations, (5) construction/specifications, and (6) materials training. It is important that pavement preservation guidance include project-level and system-level selection strategies project-level decisions have a network-wide impact. Practitioners who use this guidance will be able to communicate pavement preservation benefits at the project-and network-levels, identify candidate roadways for preservation treatments, and utilize the guide to enhance project delivery of pavement preservation treatments.

About the research

Snow and ice removal operations in winter road maintenance are essential for the Iowa Department of Transportation (DOT) as well as counties and cities in Iowa to ensure the safety, mobility, and efficiency of their transportation infrastructure systems. As an innovative snow and ice removal alternative, the researchers at Iowa State University (ISU) have developed (1) new mix design and production methods of heated concrete (dubbed electrically conductive concrete [ECON], hereafter) and (2) new structural and system design approaches for a heated pavement system (HPS) using the new ECON developed. Based on successful real-world implementation of ECON HPS recently demonstrated by the ISU research team for airport pavement and roadway construction projects, the City of Iowa City has expressed strong interest to the Iowa DOT and ISU research team in implementing ECON HPS for their new bus stop stations as well as the bus stop loading area under an upcoming pedestrian crossing and bus stop enhancement project at Muscatine Avenue in the City of Iowa City. This research is proposed in response to such keen interest by the City of Iowa City. A set of proposed research tasks (to implement ECON HPS for the bus stop station application) include the development of ECON mix design and ECON HPS system design options for construction, comprehensive performance monitoring and evaluation, as well as economic analysis of the constructed full-scale ECON HPS at least over two consecutive winter cycles, and a survey and interview on the implementation of heated pavements for winter maintenance and management practices. The primary outcome of this research will be the draft of a technical guide/specification (comparable with the current Iowa DOT specifications and Iowa Statewide Urban Design and Specifications [SUDAS]) that Iowa DOT and Iowa’s counties and cities could use for future ECON HPS implementation projects under their public works departments for enhancing sustainable and resilient winter maintenance and management practices.

About the research

Iowa State University (ISU) has assembled a team of experts in Civil, Chemical, and Industrial and Manufacturing Systems Engineering to address the challenges of integrating scrap and end-of-life rubbers to supplant the use of up to 140,000 tons/year of virgin polymer used in asphalt pavements. The team proposes the use off-specification polybutadiene to modify ground tire rubber (GTR) particles, from recycled tires, and use them as an asphalt modifier to replace widely used SBS elastomers. GTR is currently being used as a modifier, which offers comparable improvements with respect to SBS polymers such as rutting resistance and elastic recovery, with advantages such as improved traction and reduced noise. However, because of the difference in density with asphalt it suffers from inadequate storage stability, rendering it an unpreferred material in asphalt modification. ISU has developed a technology that density matches GTR with asphalt with simple compounding techniques, producing a GTR product that meets storage stability specifications and would be accepted by the market. If 100% of virgin polymer were replaced with recycled GTR, up to 140,000 tons/year could be reclaimed nationwide. Moreover, asphalt pavements are 100% recyclable, including as a major component of new roadways, which means that GTR used in pavements will continue to be reused.

About the research

The goal of this project is to assess potential and develop protocols for the use of high-resolution LiDAR and multispectral imagery to evaluate environmental characteristics of Department of Transportation (DOT) project areas. Specifically, the research team will evaluate how LiDAR and multispectral imagery can support the assessment of design alternatives, and if these data could help DOT staff select alternatives earlier and with less fieldwork required.

In addition to capturing normal land survey and engineering data concurrently, which is invaluable to the design and project development process, we will augment this data with high-resolution remotely-obtained data. This will allow us to assess the extent to which the following can be completed using such imagery: (a) wetland spatial extent and vegetation characterization; (b) stream channel morphology determination (depth, width, centerline location); and (c) tree assessment (tree stand density and health, individual tree heights, diameter and health).

In addition to land survey data for engineering purposes, the DOT also believes this remote sensed data (in the form of high-resolution multispectral orthoimagery and LIDAR) will provide ancillary benefit that will allow potential threatened and endangered species habitat to be identified early as well as an Archaeological Landform and Architectural Building/Setting Assessment to be investigated further through correlation of field collected data. While these additional assessments are not part of this study, the images and data gathered in this project will be available for future investigation.

Current DOT methods for environmental assessment require a significant amount of manual and on-site work, driving up the costs and time associated with these phases of projects. This project will determine what savings might be realized through use of high-resolution imagery and what the break-even point for this type of data collection might be in terms of the size of the study area. Specifically, the research team intends to evaluate the use of three types of imagery at approximately a 15 to 50 cm spatial resolution: standard (near infrared) LiDAR elevation and terrain data, multispectral color (blue, green, red, and near infrared) reflectance data, and narrow-band green LiDAR imagery which penetrates into water surfaces and gives information relevant to topography under shallow water.

About the research

Rear-end crashes are one of the primary crash types in work zones and frequently occur at the back-of-queue (BOQ). Some agencies have utilized back-of-queue warning systems (QWSs), where real-time sensors are located upstream of stopped or slowed traffic, either to actually detect BOQs or monitor conditions to predict BOQ locations. QWSs then provide notifications of traffic conditions to drivers, which ideally lead to lower speeds and drivers being prepared to react to the BOQ, resulting in fewer crashes and conflicts. However, a driver needs to be properly monitoring the roadway environment to receive the warning and, then, needs to be prepared to take the appropriate actions when necessary. In many cases, drivers are distracted and fail to recognize warnings, or they receive the warning but fail to comply with appropriate speeds. As a result, one of the main needs to address BOQ situations is to understand what drivers are doing so that a QWS can get a driver’s attention. Additionally, driver behavior may indicate that other countermeasures, such as speed management, may be as effective as formal QWSs. The research described in this report aims to address this knowledge gap through the following objectives:

• Identify common types of QWSs
• Summarize QWSs used in Smart Work Zone Deployment Initiative (SWZDI) states
• Identify driver behaviors in BOQ scenarios
• Make recommendations
• Summarize needs for connected vehicle applications

Safety critical events (SCEs) were evaluated for back-of-queue situations using two different datasets. The first was a set of BOQ SCEs that were reduced from camera image captures at BOQ locations in work zones in Iowa during the 2019 construction season. Analysis of these data indicated speeding, following too closely, and forced merges were the primary characteristics associated with BOQ. The second dataset was an analysis of BOQ events in the second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study (NDS). Analysis of these data indicated that following too closely and glances away from the roadway task of 1 or more seconds were statistically significant.

About the research

The ability to acquire and set up work zone-related devices that are in compliance with the 2012 revisions to the 2009 Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) can sometimes be difficult for smaller cities. The smaller budgets for these cities can result in a lack of inventory and/or the use of signs that are in poor condition.

The goal of the project was to provide an avenue for small cities to obtain a basic package of work zone signs and personal protection vests that could help them improve the safety of their work zone setups and increase the safety of their workers and the traveling public.

About the research

In the Work Zone Activity Data Logging Phase I project, state transportation agencies in the SWZDI states and beyond expressed a strong need for better information about the location, extent, and timing of lane closures. More than a dozen use cases for detailed lane closure data were identified and prioritized, such as helping first-responders avoid closures, providing more accurate public information about closure locations and timing, and more efficiently conducing post-construction work zone traffic management effectiveness reviews. Phase I affirmed that the vast majority of state DOTs currently lack the ability to track lane closures at the level of temporal and spatial detail required for these uses. Among the very few agencies that have the technical ability to record this information, the data lacks reliability. Closures on county and municipal routes were seldom, if ever, tracked.

Phase I showed that existing data sources are not sufficient to support the high-priority use cases. For example, although underperforming work zones sometimes show up in traffic management center (TMC) delay data, it is difficult to distinguish work zone delays from delays caused by traffic crashes. Since the exact closure location, timing, and extent are seldom recorded, even agencies with lane closure permitting systems are experiencing great difficulty relating work zone performance to closure characteristics. Moreover, TMC databases provide almost no information about well-performing work zones, making it extraordinarily difficult to pinpoint factors of success.

To address these needs, the Phase I project gathered information about existing work zone data sources, identified relevant standards, and developed a series of sketches that lay out a vision for an easy-to-use lane closure data collection application or website. The goal of this project is to transform these conceptual sketches into a working prototype that generates data in a format that could eventually be integrated with TMC data and other existing data sources to provide a more complete picture of work zone performance.

About the research

This project extends the research and development of a novel sensing technology previously investigated in the pooled fund initiative TPF-5(328). The technology is a soft elastomeric capacitor (SEC) developed at Iowa State University. It is a geometrically large strain gauge, and its measurement principle is based on transducing changes in strain into measurable changes in capacitance. Arranged in a network configuration, it can monitor strain over a large area at a given resolution. The SEC technology is inexpensive and easy to deploy, therefore highly scalable. It follows that the technology can be used to discover new fatigue cracks, and track and quantify damage, an important challenge to numerous state departments of transportation. The overarching objective of project is to enable large-scale deployments in the United States by addressing further essential development needs uncovered during the previous research to achieve more robust, accurate, and flexible crack monitoring using the wireless skin sensor network. In particular, within this three-year research phase (Phase 1), the research team will 1) refine the design of the SEC for robust long-term field deployment; 2) provide the technology with improved wireless and augmented sensing capabilities; 3) refine a crack detection algorithm that accommodates more diverse structural configurations and can be directly used by engineers for decision making; 4) further damage quantification capabilities for complex geometries and composite materials; and 5) validate and demonstrate the improved version of the wireless crack sensing technology on a bridge in the fields through long-term deployments.