Institute for Transportation

About the research

Ultra-high-performance concrete (UHPC) has great potential as a structural material for bridge engineering due to its excellent strength, ductility, and durability. However, the high Portland cement content required by conventional UHPC poses a major obstacle to widespread practical application because of its high cost and CO₂ emissions. Introducing any sort of composites as replacements for Portland cement would have a positive impact on the practical applications of UHPC. This research project investigated the mechanical properties (such as compression, tension, bending strength, and modulus of elasticity) of geopolymer-based UHPC and a type of composite UHPC using Iowa materials to explore the feasibility of their use in UHPC for transportation infrastructure.

In this study, different ultra-high-performance geopolymer (UHPG) mixes were formulated, their mechanical properties were evaluated, and effects of curing methods on the UHPG strength were investigated. The results indicated that usable UHPG can be achieved through engineered formulation using locally available concrete materials. The UHPG sample made in China and tested at Iowa State University (ISU) showed a compressive strength of 123 MPa (17,868 psi) and maximum compressive strain of 0.0047 micro-strain. The UHPG samples made with a slag-fly ash blend and a liquid (activator solution)-to-binder (slag and fly ash) of 0.27 had 28-day compressive strength of 102 MPa (14,800 psi). When reinforced with 2% (by volume) of polyvinyl alcohol (PVA) fiber, the UHPG mixes developed at ISU exhibited strain and displacement hardening behavior in tension and flexure, indicating significant ductility. Replacement of slag for fly ash improved strengths and elastic modulus, but noticeably reduced the deflection at failure and ductility of UHPG. Steam curing at 50°C appeared to be the optimal condition for the UHPG strength development.

Funding Sources:
Iowa Department of Transportation
Iowa Highway Research Board ($10,000.00)
Midwest Transportation Center
USDOT/OST-R ($35,000.00)
Total: $45,000.00

Contract Number: DTRT13-G-UTC37

About the research

Shoulder rumble strips (SRS) and centerline rumble strips (CLRS) on two-lane rural highways are proven safety countermeasures. Placement of both SRS and CLRS can usually be accommodated within wide pavements (24 ft or greater paved width) without issue. However, proper placement of one or both is less straightforward for highways with paved widths less than 24 ft. Placement becomes especially difficult as widths approach 20 ft.

Contributing factors such as traffic volume, roadway alignment, and the posted speed limit may suggest the use of one type of rumble strip over another. However, limited guidance currently exists regarding the minimum paved width necessary to install both SRS and CLRS, or which of the two to install when the installation of both is not feasible.

The purpose of this study is to provide guidance to assist county road agencies, as well as the Iowa Department of Transportation (DOT), in determining when to install rumble strips based on various site-specific factors.

Funding Sources:
Iowa Department of Transportation ($50,000.00)
Iowa Highway Research Board ($60,000.00)
Midwest Transportation Center
USDOT/OST-R ($50,000.00)
Total: $160,000.00

Contract Number: DTRT13-G-UTC37

About the research

Lane departure crashes make up a large percentage of rural crashes for states in the midwest. Since agencies have limited resources, they rely on studies that demonstrate the effectiveness of a particular countermeasure in order to make decisions about which countermeasures should be selected. Most agencies prefer countermeasure effectiveness to be stated in terms of crash modification factors (CMFs) since they are easily understood and commonly used by agencies. Developing data driven performance measures for safety is one of the main Midwest Transportation Center (MTC) themes and robust CMFs have not been developed for a number of lane departure countermeasures.

The objective of this research is to develop CMFs for several lane departure countermeasures that have been used in Iowa. The research includes selecting sites where the countermeasures have been installed, identifying control sites, extracting site characteristics, reducing crash data, conducting analyses, and summarizing results. The team developed tech briefs for the following lane departure countermeasures as determined by the technical advisory committee:

• Safety Edge
• Chevrons
• Destination lighting at stop-controlled intersections
• Stop-sign beacons

Funding Sources:
Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation ($98,448.00)
Midwest Transportation Center
USDOT/OST-R ($72,182.00)
Total: $170,630.00

Contract Number: DTRT13-G-UTC37

About the research

Consistent efforts with dense sensor deployment and data gathering processes for bridge big data have accumulated profound information regarding bridge performance, associated environments, and traffic flows. However, direct applications of bridge big data to long-term decision-making processes are hampered by big data-related challenges, including the immense size and volume of datasets, too many variables, heterogeneous data types, and, most importantly, missing data. The objective of this project was to develop a foundational computational framework that can facilitate data collection, data squashing, data merging, data curing, and, ultimately, data prediction. By using the framework, practitioners and researchers can learn from past data, predict various information regarding long-term bridge performance, and conduct data-driven efficient planning for bridge management and improvement.

This research project developed and validated several computational tools for the aforementioned objectives. The programs include (1) a data-squashing tool that can shrink years-long bridge strain sensor data to manageable datasets, (2) a data-merging tool that can synchronize bridge strain sensor data and traffic flow sensor data, (3) a data-curing framework that can fill in arbitrarily missing data with statistically reliable values, and (4) a data-prediction tool that can accurately predict bridge and traffic data. In tandem, this project performed a foundational investigation into dense surface sensors, which will serve as a new data source in the near future. The resultant hybrid datasets, detailed manuals, and examples of all programs have been developed and are shared via web folders.

The conclusion from this research was that the developed framework will serve practitioners and researchers as a powerful tool for making big data-driven predictions regarding the long-term behavior of bridges and relevant traffic information.

Funding Sources:
Iowa State University ($80,000.00)
Midwest Transportation Center
USDOT/OST-R ($80,000.00)
Total: $160,000.00

Contract Number: DTRT13-G-UTC37

About the research

The objective of this project was to create a sustainable asset management transportation and safety model for a designated area of St. Louis, Missouri, that can be replicated in other municipalities.

Funding Sources:
Harris-Stowe State University ($16,000.00)
Midwest Transportation Center
USDOT/OST-R ($35,000.00)
Total: $51,000.00

Contract Number: DTRT13-G-UTC37

About the research

The goal of this project was to study the fleet sizing problem in the context of an urban transit system with several unique features: (1) a fleet with a heterogeneous mixture of vehicles; (2) integrated decision support, including acquisition, retirement, and allocation decisions over multiple time periods; and (3) various uncertainties regarding demand for origin-destination (OD) pairs and vehicle efficiency. Over the course of a one-year grant effort, the researchers first developed a deterministic optimization model to minimize the total fleet acquisition and operation costs for all time periods within the planning horizon. Then, a two-stage stochastic programming (SP) model was devised to explicitly cope with uncertainty. The model minimizes the expected total costs by optimizing (1) the here-and-now fleet acquisition and retirement decisions in the first stage and (2) the allocation recourse decisions in the second stage after the random parameters are realized.

The research team collaborated with a local third-party logistics (3PL) company in St. Louis, Missouri, who provided real-world data for this project. Computational studies were conducted to show the benefit of the two-stage SP model by comparing it to the deterministic model using point estimates of random parameters.

Funding Sources:
Midwest Transportation Center
University of Missouri – Saint Louis ($20,000.00)
USDOT/OST-R ($25,000.00)
Total: $45,000.00

Contract Number: DTRT13-G-UTC37

About the research

What effect does work activity have on traffic conditions in a work zone? This question has still not been answered satisfactorily in practice. Without knowing the true effect a work activity has on traffic, practitioners are forced to make assumptions while scheduling work. This report attempts to answer this question by studying the traffic flow characteristics for various work activities, i.e., traffic speed versus flow curves, capacity reduction factors, and free-flow speed reduction factors.

The importance of the speed-flow curves and reduction factors for work zone planning is also stressed in the latest edition of the Highway Capacity Manual (HCM). The HCM recommends capacity and speed reduction factors for work zones yet does not include specific guidance for including the impact of work activities.

Three traffic stream models, Gipps, Newell-Franklin, and Van Aerde, were calibrated using field data from St. Louis, Missouri.

The Van Aerde model offered the best fit with the field data compared to the other two models. Using the Van Aerde model-generated speed-flow curves, it was found that the capacity for bridge-related activities varied from 1,416 vehicles per hour per lane (vphpl) to 1,656 vphpl and for pavement-related activities from 1,120 vphpl to 1,728 vphpl.

The capacity reduction factor for different work activities was found to be in the range of 0.68 to 0.95, while the free-flow speed reduction factor was found to be in the range of 0.78 to 1.0. The methodology proposed in this report allows the incorporation of work activity effects into traffic impact assessment tools and results in quantitative guidance for work zone planning and design.

Funding Sources:
Midwest Transportation Center
Smart Work Zone Deployment Initiative ($57,942.00)
USDOT/OST-R ($50,185.00)
Total: $108,127.00

Contract Number: DTRT13-G-UTC37

About the research

Gantry crane pavements and foundations represent a significant asset within intermodal facilities. Subjected to high variation in loading and critical to safe operations, traffic interruptions, and costs associated with maintaining and rehabilitating distressed or failed pavements in these areas is of particular importance. The purpose of this study is to improve the performance and increase the lifespan of gantry crane pavements and foundations by assessing the interactions between pavements, subgrades, operational loading conditions, and performance of the gantry crane pavements and foundations.

Three data gathering efforts will be undertaken: a desk study of design, operations, and performance of existing intermodal gantry crane facilities, a field evaluation of existing and new construction, and monitoring of in-place instrumentation at a new facility. The data will be analyzed to develop recommendations to improve performance of existing and newly constructed pavement systems.

Funding Sources:
Midwest Transportation Center
Union Pacific Railroad ($75,000.00)
USDOT/OST-R ($75,000.00)
Total: $150,000.00

Contract Number: DTRT13-G-UTC37

About the research

This project was conducted to estimate crash modification factors (CMFs) for lane departure countermeasures in Kansas. Cross-sectional, case-control, and before-and-after empirical Bayes (EB) methods were employed. Results showed that centerline rumble strips on rural two-lane road segments have crash-reduction effects on all lane departure and fatal and injury lane departure crashes on both tangent and curved road segments. Shoulder rumble strips were effective in reducing all lane departure and fatal and injury lane departure crashes on tangent road segments but showed less effectiveness on curved road segments. The combination of centerline and shoulder rumble strips showed significant safety effectiveness on both tangent and curved road segments.

Shoulder rumble strips on four-lane road segments also showed crash-reduction effects on all lane departure and fatal and injury lane departure crashes on both tangent and curved road segments. Cable median barriers showed a crash-reduction effect on all lane departure crashes, and fatal and injury lane departure crashes on four-lane divided road segments. Chevrons and post-mounted delineators also showed effectiveness on both all lane departure crashes and fatal and injury lane departure crashes. The safety edge treatment also showed a crash-reduction effect on all lane departure crashes and fatal and injury lane departure crashes.

Finally, all models were validated to check for accuracy. Models developed for the cross-sectional method were validated using mean square error and mean of the residuals. Case-control models were validated using the specificity, accuracy, and sensitivity of the models. The significance of the CMFs developed using the before-and-after EB method was realized using the method given in the Highway Safety Manual.

Funding Sources:
Kansas Department of Transportation ($50,000.00)
Midwest Transportation Center
USDOT/OST-R ($50,000.00)
Total: $100,000.00

Contract Number: DTRT13-G-UTC37

About the research

Home delivery by drones as an alternative or complement to traditional delivery by trucks is attracting considerable attention from major retailers and services, as well as startups. While drone delivery may offer considerable economic savings, the fundamental issues of how best to deploy drones for home delivery are not well understood. Our research provides a strategic analysis for the design of hybrid truck-drone delivery systems using continuous approximation modeling techniques to derive general insights. We formulated and optimized models of hybrid truck-drone delivery, where truck-based drones make deliveries simultaneously with trucks, and compared their performance to truck-only delivery. Our results suggest that truck-drone delivery can be very advantageous economically in many settings, especially with multiple drones per truck, but the benefits depend strongly on the relative operating costs and marginal stop costs.

Funding Sources:
Midwest Transportation Center
University of Missouri – Saint Louis ($25,000.00)
USDOT/OST-R ($25,000.00)
Total: $50,000.00

Contract Number: DTRT13-G-UTC37