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Project Details
STATUS

Completed

START DATE

03/01/05

END DATE

09/30/08

RESEARCH CENTERS InTrans, CP Tech Center, CTRE
SPONSORS

Connecticut Department of Transportation
Federal Highway Administration
Iowa Department of Transportation
Kansas Department of Transportation
New York State Department of Transportation
Ohio Department of Transportation
Slag Cement Association

Researchers
Principal Investigator
Scott Schlorholtz

Faculty Affiliate

Co-Principal Investigator
Doug Hooton

University of Toronto

About the research

The initial phase of this project was conducted to determine whether adding slag cement to concrete mixtures increases the surface scaling caused by the routine application of deicer salt. A total of 28 field sites that included portland cement concrete pavements and bridge decks containing slag cement were evaluated. Laboratory testing was conducted on 6 in. diameter core samples extracted from 12 field sites and 3 subsites, including 6 pavement sites and 6 bridge decks. The laboratory testing program consisted of scaling tests, rapid chloride permeability tests, surface chloride profile tests, and petrographic examination. The results of this study suggest that construction-related issues played a bigger role in the observed scaling performance than did the amount of slag in the concrete mixture.

Project Details
STATUS

Completed

PROJECT NUMBER

13-451, RB33-013

START DATE

01/01/13

END DATE

12/31/20

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CMAT
SPONSORS

Federal Highway Administration
Iowa Department of Transportation

Researchers
Principal Investigator
Charles Jahren

Associate Director, Construction Materials and Methods / Asset Management

Student Researcher(s)
David Morandeira
Elizabeth Miller

About the research

The Iowa Department of Transportation (DOT) funded a three-phase research project focusing on rapid bridge deck joint repair. Phase I focused on the documentation of current means and methods of bridge expansion joint maintenance and replacement. Under Phase II, a workshop with Iowa DOT personnel, engineers, and researchers identified possible improvements to traditional expansion joint options. From the workshop, a deck over backwall detail was developed that moved the expansion joint away from the bridge deck and instead placed it on the approach slab. This would not only minimize the concrete removal needed for a rehabilitation but would, in turn, prevent deicing chemicals from leaking through the deck joints and damaging the bridge’s substructure. In Phase III, the research team was tasked with the further development of this deck over backwall concept.

Full-scale finite element (FE) models of two different bridges were developed to analyze the impact of the deck over backwall concept. Both models were validated using the original drawing plans and American Association of State Highway and Transportation Officials (AASHTO) specifications.

Through experimental testing and the development of FE models, two reinforcing options within the approach slab and diaphragm sections were considered. The results showed that, when both the top and bottom longitudinal reinforcing was kept continuous through the approach slab and diaphragm section, negative moment was transferred to the bridge deck. This transfer of stress through the top reinforcing caused cracking to occur on the top of the bridge deck, which could lead to harmful chemicals leaking onto the substructure. Conversely, experimental testing showed that these stresses could be eliminated if the top longitudinal reinforcing and concrete cover were saw cut.

A plan for construction observation and post-construction testing was developed that included an instrumentation plan and various real-world truck loading cases to be correlated with the FE models; an initial cost estimate was also developed. Implementation of the deck over backwall concept and the post-construction plan is expected to be conducted in a future Iowa DOT construction season.

Project Details
STATUS

Completed

START DATE

09/30/13

END DATE

09/25/19

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

American Association of State Highway and Transportation Officials (AASHTO)
Federal Highway Administration
National Cooperative Highway Research Program (NCHRP)

Researchers
Principal Investigator
Sri Sritharan

Faculty Affiliate

About the research

According to the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications, minimum reinforcement provisions are intended to reduce the probability of brittle failure by providing flexural capacity greater than the cracking moment. There is a concern with the current AASHTO LRFD minimum flexural reinforcement requirements when it’s applied to pretensioned or post-tensioned concrete flexural members. Increasing the nominal capacity of a member can result in increasing the cracking moment of the same member. This makes the design process iterative, and the current minimum reinforcement requirement for post-tensioned members is difficult to satisfy. This also may lead to less efficient design of pretensioned/post-tensioned concrete flexural members. Provisions for the design of minimum flexural reinforcement must be suitable for all structure and reinforcement types covered by the AASHTO LRFD Bridge Design Specifications and should be consistent with the LRFD design philosophy. The objective of this research is to propose revisions to the AASHTO LRFD Bridge Design Specifications minimum flexural reinforcement provisions. The research should consider reinforced, pre-tensioned, and post-tensioned concrete flexural members (e.g., bonded and unbonded tendons for segmentally and other than segmentally constructed bridges).

 

Project Details
STATUS

Completed

START DATE

12/01/14

END DATE

11/30/17

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Federal Highway Administration
National Center for Rural Road Safety

Researchers
Principal Investigator
Keith Knapp

Director, LTAP

Co-Principal Investigator
Nicole Oneyear

Associate Scientist, CTRE

About the research

The reduction of severe injury and fatal vehicle crashes within the US requires the involvement of transportation professionals from local, state, and federal agencies. Therefore, a need exists to
increase the transportation safety knowledge base at all levels of government. However, the majority of the roadway miles in the US are under local government jurisdiction.

While the wide range of safety knowledge within these local agencies is generally recognized, in many cases, safety is just one of many areas of responsibility for transportation staff within local roadway agencies. Furthermore, rural road maintenance plays a role in safety for roadway users who travel regularly on our secondary roadways.

This project is in response to a proposal that the compilation and summary of information useful to the development of a rural road safety recognition program for local maintenance personnel would be of value to local agency professional development entities (e.g., Local and Tribal Technical Assistance Programs [LTAPs and TTAPs], local road agencies, and state Departments of
Transportation [DOTs]). This information might include the identification of roadway safety learning objectives and subject areas that could be included within a curriculum of instruction, courses that are currently available, and a process of recognition for local maintenance personnel who complete this curriculum.

The implementation of this type of program for local agency maintenance personnel should encourage a greater safety culture and hopefully help lead to severe injury and fatal vehicle crash reductions along rural roadways within the US.

This report provides a summary of information for those considering the implementation of roadway safety curriculum and/or recognition programs for local agency maintenance personnel.

Project Details
STATUS

Completed

START DATE

09/03/11

END DATE

09/02/17

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center
SPONSORS

Federal Highway Administration

Researchers
Principal Investigator
Peter Taylor

Director, CP Tech Center

About the research

A continuing challenge to the concrete paving industry is the ever present need to implement new technologies as they are proven, coupled with the need to educate new employees throughout the industry about best practices. The objective of this project was to help meet this need by conducting technology transfer, delivery, and implementation of best practices for jointed concrete pavements. Activities were focused on these topics:

  • Material-related distress
  • Blended aggregates for concrete mixture optimization
  • Concrete paving mixtures with one or more supplementary cementitious materials
  • Innovative materials and methods for accelerated construction and maintenance of concrete pavements
  • Quality assurance

 

Project Details
STATUS

Completed

START DATE

08/17/12

END DATE

12/05/19

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center, CTRE
SPONSORS

Federal Highway Administration

Researchers
Principal Investigator
James E. Alleman

Faculty Affiliate

Principal Investigator
Michael Heitzman
Co-Principal Investigator
Peter Taylor

Director, CP Tech Center

About the research

Five portland cement concrete (PCC) and five asphalt concrete (AC) pavement locations at each of seven field testing sites in the central and eastern United States represented a range of aggregate types, pavement surface ages, and climates. Albedo, thermal properties, and pavement surface characteristics data were collected, and cores were obtained to measure thermal properties in the laboratory. Test tracks at Auburn University’s National Center for Asphalt Technology (NCAT) and Minnesota’s MnROAD facility were used to collect 24-hour measurements for thermal model validation.

The albedo data showed that different parameters influence albedo for AC and PCC pavements, albedo approaches a steady value over time, and the albedo trends for each site differ. The AC albedo model reasonably predicted albedo over time using pavement age and coarse aggregate color. However, the PCC albedo model did not predict field albedo using pavement age, coarse aggregate color, and surface texture; additional field study is needed. Climate-related factors, particularly winter maintenance activities, may also play a role in pavement albedo.

Pavement thermal modeling required an understanding of the surface and thermal properties, small incremental units of time and layer thicknesses, 10 to 20 days of simulation to achieve balance throughout the pavement and subgrade system, and continuous data over an extended period. The thermal model predicted pavement thermal response in warm, dry conditions but did not account for the influence of moisture and freezing conditions.

Asphalt and concrete thermal properties vary and may have up to a 15% influence on AASHTOWare Pavement ME Design results. Current highway sustainability rating systems have recognized the complexity of pavement albedo, and the current systems either only address qualitative cool pavement goals or have no coverage of albedo-related metrics or outcomes.

Project Details
STATUS

In-Progress

START DATE

11/17/15

END DATE

08/31/19

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Federal Highway Administration
Iowa Department of Transportation

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

Co-Principal Investigator
Omar Smadi

Director, CTRE

Co-Principal Investigator
Peter Savolainen

Affiliate Researcher

Co-Principal Investigator
John Lee

About the research

Safe intersection negotiation depends on drivers being able to recognize the presence of an intersection and then respond appropriately to applicable traffic control devices and prevailing conditions. When drivers are required to yield right-of-way to on-coming traffic, they also need to be able to identify and select appropriate gaps. Consequently, the proposed research for Phase I investigates the feasibility of answering the following research questions, which address the relationship between different stages of intersection negotiation and roadway and driver characteristics.

  • What is the relationship between rural intersection crash risk and driver, roadway, and environmental characteristics?
  • What is the relationship between intersection recognition and stopping behavior and intersection geometry and countermeasures?
  • What are the primary influences for appropriate scanning behavior and gap acceptance at rural intersections?
Project Details
STATUS

Completed

START DATE

06/15/16

END DATE

08/31/16

RESEARCH CENTERS InTrans, CMAT, CTRE
SPONSORS

Federal Highway Administration
Iowa Department of Transportation

Researchers
Principal Investigator
Jennifer Shane

Director, CMAT

About the research

This work supported drafting project management guidance for the Iowa Department of Transportation (DOT). The goal is to incorporate a greater focus on project management in their project development process.

A technical advisory committee (TAC) was assembled to accomplish this effort. The TAC took into consideration the current status of project management with the Iowa DOT, their experience during the demonstration workshop held in Iowa as part of the implementation assistance they received, the project management peer exchange hosted by the Iowa DOT, and additional examples of project management that were presented. With this basis, the TAC participated in a number of discussions to develop draft guidance for the foundation of a Project Management Office (PMO) within the Iowa DOT.

The final report describes the process that was used in establishing this guidance. The report details the decisions and decision process that the TAC employed in this endeavor and provides additional thoughts and insight into the draft guidance. Appendix A includes the draft guidance in the form of PMO function details and detailed lists of project management roles and responsibilities. Appendix B includes a starter list of project management resources for the PMO.

Project Details
STATUS

In-Progress

START DATE

08/20/14

END DATE

08/19/16

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Federal Highway Administration

Researchers
Principal Investigator
Omar Smadi

Director, CTRE

About the research

The objective of this task is to provide for technical analysis to support the bridge condition performance measure rulemaking effort.

 

Project Details
STATUS

Completed

PROJECT NUMBER

13-460

START DATE

05/01/13

END DATE

02/28/18

RESEARCH CENTERS InTrans, CTRE, MTC
SPONSORS

Federal Highway Administration
Iowa Department of Transportation
Midwest Transportation Center
USDOT/OST-R

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

About the research

Although chevron alignment signs have been utilized for some time along horizontal curves, their effectiveness is not well documented. The Crash Modification Factors Clearinghouse includes crash modification factors (CMFs) for chevrons from 0.41 to 1.92 (FHWA 2015).

The lack of documentation on the effectiveness of chevrons and the range of values for CMFs make it difficult for agencies to estimate the cost effectiveness of chevrons. As a result, the objective of this study was to develop a CMF for chevron alignment signs that can be used by Iowa agencies to help address crashes on curves.


Funding Sources:
Federal Highway Administration TSF Funding
Iowa Department of Transportation
Midwest Transportation Center
USDOT/OST-R

Contract Number: DTRT13-G-UTC37

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