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SPR Active Projects
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Article Content  |
| SPR 685 |
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Safety Evaluation of Curve Warning Advisory Speed Signs
| Project Coordinator: |
June Ross |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Karen Dixon, Ph.D., P.E. |
| Start Date for ODOT: |
October 2008 |
| Completion Date for ODOT: |
September 2009 |
OBJECTIVES:
The goal of this proposed research is to ensure that advisory speeds are adequately posted in the state of Oregon in a manner that helps improve safety and with particular emphasis on higher speed rural horizontal curve locations. To accomplish this goal, the research proposed in this study will address several key objectives. These are summarized as follows:
· Using the randomly selected curve locations including upstream and downstream corridor segments, the research team can contrast the historic safety record at these curve locations to the advisory speeds posted as well as the required advisory speed thresholds for Oregon and national standards.
· Evaluate potential advisory speed posting assessment procedures that can be performed prior to or instead of the current ball-bank field evaluation. These alternative procedures may ultimately provide more consistent and cost effective advisory speed posting techniques.
3.1 Benefits
If this research is not performed, ODOT will have potentially unsafe conditions at improperly signed horizontal curve locations. Proposed changes to the MUTCD recommend a modified threshold for advisory speeds that varies significantly from the current Oregon threshold. Decision makers in Oregon must determine if they want to adopt new MUTCD thresholds or retain Oregon thresholds. In the event current Oregon thresholds are retained, the recent advisory speed study demonstrated that many of the current advisory speed signs do not meet Oregon criteria. The decision to invest in replacing these signs must also be considered. This research will aid Oregon decision makers by determining specific safety implications of current posted advisory speeds and the implications of either modifying the posting threshold or enforcing the current threshold. This proposed research will also help identify priorities for sign upgrades by determining the safety implications of the various compliance levels.
Additionally, since current advisory speed warning sign posting procedures require expensive site visits and field testing to determine the appropriate speed to post, the research team will determine if a more cost effective “office” technique for identifying advisory sign requirements may be feasible through the use of aerial photos or design plans.
OVERVIEW:
The use and placement of advisory speed signs at horizontal curve locations in the state of Oregon is determined by guidance in the Oregon Department of Transportation (ODOT) Traffic Manual and the ODOT Sign Policy and Guidelines. These regional guidelines are supplemented by the Manual of Uniform Traffic Control Devices (MUTCD). The 2003 MUTCD, however, included a change in recommended guidance for establishing advisory speeds on Exit, Ramp, and Curve Speed Signs. Traditionally, advisory speeds have been established by driving a vehicle equipped with a ball-bank indicator around a curve at a specified speed and noting the ball-bank indicator reading. The MUTCD notes that a 10-degree ball-bank indicator reading was formerly used in determining advisory speeds, based on research from the 1930’s. The 2003 Edition of the MUTCD (FHWA 2003) changed the 10-degree reading to a 16-degree ball-bank indicator reading, based on perceived performance of modern vehicles and speeds at which most drivers’ judgment recognizes “incipient instability” along a ramp or curve. Subsequent to the publication of the 2003 Edition of the MUTCD, the Advisory Speed Task Force of the National Committee on Uniform Traffic Control Devices Regulatory and Warning Signs Technical Committee identified inconsistencies in the MUTCD text regarding the advisory speed issue and began re-evaluating this modified advisory speed posting guidance. The Committee has recommended that the criteria for advisory speed engineering studies can be based on ball-bank criteria, accelerometer readings, or calculations using side friction factors. Included in the proposed procedures is a modification to the required ball-bank indicator reading (using a 16-, 14-, and 12-degree threshold based on curve speed).
PROPOSED ACTIVITIES:
The research team will make presentations to the appropriate officials as deemed necessary by the technical advisory committee in order to disseminate this information to ODOT and other appropriate Oregon transportation agencies. In addition, the research team will summarize the project results in an article suitable for publication in an archival journal or presentation at a national conference.
It is expected that updated advisory speed posting procedures, including new methods for consistently evaluating speed posting evaluation methods, will result from this research. Ultimately, the research results may be included in modified state-wide advisory speed posting procedures.
SAFETY EVALUATION OF CURVE WARNING ADVISORY SPEED SIGNS WORK PLAN
Quarterly Reports:
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| SPR 710 |
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Analysis and Design of Pipe Ramming Installations
| Project Coordinator: |
Matthew Mabey |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Armin Stuedlein |
| Start Date for ODOT: |
December 2009 |
| Completion Date for ODOT: |
August 2012 |
OBJECTIVES:
The main objectives of this study are to increase the understanding of the mechanics of pipe ramming and to develop an engineering framework for the design and evaluation of pipe ramming projects. One or more instrumented pipes, installed using pipe ramming techniques, will be monitored under field conditions to assess the mechanics of pipe installation including hammer performance, wave travel along the pipe in soil and upon breakout (i.e., exiting the embankment), and the development of internal and external shaft resistance. If the results of the field study indicate that the wave travel within the pipe is not significantly affected by stress gradients across the pipe section, the suitability of existing wave equation techniques will be evaluated (e.g., GRL WEAP, finite element). Otherwise, if the results indicate that the stress waves propagate in 2-D, a new finite element- or finite difference-based analytical tool will be developed to assess installation behavior. This research will develop a comprehensive framework for the methodological evaluation of pertinent pipe ramming variables to assist designers in optimizing safe and successful pipe ramming installations. It is emphasized that adaptation of existing techniques will be preferred over the development of new tools to maximize integration with the state of practice.
OVERVIEW:
While there has been adequate research into some aspects of pipe ramming, such as settlement, much of the process is based on doing what worked on previous projects. There is currently no method available to assess the suitability of proposed materials, equipment and installation techniques. Therefore, there is a need to develop a reliable framework for analyzing the structural and geotechnical engineering aspects of pipe ramming projects, including: (1) a methodology to evaluate a proposed site for suitability of pipe ramming, (2) assess combinations of proposed pipe materials (e.g., grade of steel), diameter, wall thickness, and length of pipe for a proposed project, and (3) design and specify the pipe ramming operation accordingly (e.g., hammer size, blow rate, lubrication, spoils removal).
PROPOSED ACTIVITIES:
Meetings will be held with ODOT personnel to present research findings and progress reports. The frequency of these meetings will be determined by the ODOT TAC members, however, at a minimum, there will be one progress meeting with ODOT at 18 months following the start of the contract. The results of this research will be drafted in a formal report and be primarily aimed towards assessing proposed pipe ramming installations prior to the start of a project. Following completion of the experimental, analytical evaluation, and parametric study, a meeting with the TAC committee will be conducted for the purpose of discussing the proposed design guidelines. The TAC committee will be able to shape the guidelines to maximize the impact and implementation of the research. The draft guidelines and procedures for assessing pipe ramming installations generated as part of this study will be presented to the ODOT TAC members for review two months prior to close of the contract It is anticipated that the guidelines and design specifications presented in the final report will be referenced and/or implemented in the ODOT Hydraulics, Geotechnical, and Structural Design Manuals for use by State engineers and design consultants. Additionally, the findings of this study will be disseminated through state and national presentations, conference proceedings, and journal publications.
ANALYSIS AND DESIGN OF PIPE RAMMING INSTALLATIONS WORK PLAN
Quarterly Reports:
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| SPR 711 |
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Internal Curing of Concrete Bridge Decks
| Project Coordinator: |
Steve Soltesz |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Jason Ideker |
| Start Date for ODOT: |
July 1, 2009 |
| Completion Date for ODOT: |
December 31, 2011 |
OBJECTIVES:
The goal of this research project is to determine if the incorporation of saturated lightweight aggregate into high-performance concrete bridge deck mixtures can significantly reduce external curing requirements (currently 14 days) while maintaining crack-free or crack-resistant concrete. While research has already shown the benefits of reducing cracking risk due to autogenous shrinkage through the incorporation of saturated fine LWA it is necessary to further this technology to quantify the potential reductions in external curing.
Specific research objectives are:
– Identify high-performance concrete mixture proportions incorporating saturated fine LWA which will provide sufficient internal curing to reduce autogenous shrinkage and subsequent cracking risk
– Identify significantly shortened external curing regimes that will complement the use of internal saturated fine LWA to reduce early-age cracking risk in high performance concrete bridge decks
– Demonstrate effectiveness of selected strategies in small scale field trials/applications identified through collaborative efforts with ODOT
– Provide guidelines for contractors and finishers to take advantage of new materials/mixture proportions identified in this research program to provide internal curing in high performance concrete applications
– Expand existing literature and state-of-knowledge in this area and bring new expertise to the state of Oregon related to internal curing through use of lightweight saturated aggregate
OVERVIEW:
Current Oregon Department of Transportation (ODOT) Standard Specifications for curing of high-performance bridge deck concrete requires wet curing be initiated within 20 minutes of the final pass of the finishing machine and not greater than 20 feet from the back of the pavement machine. This wet cure is specified for a duration of 14 days with longer curing possible if cooler ambient temperatures (T < 45 °F) are encountered during the initial 14-day period. This long wet cure reduces evaporation that can lead to cracking, and it provides water to the bulk concrete to participate in the chemical reactions in the cement paste during curing. While this curing period reduces bridge deck cracking, the time requirement represents a significant burden on constructability and project scheduling. There is a need for accelerated/alternate curing techniques that will allow for increased construction efficiency while still producing crack-free or crack-resistant high-performance concrete bridge decks.
PROPOSED ACTIVITIES:
While interim reports and a final report will be issued as part of this research project, providing detailed summation of all work performed under this project to complement the ODOT research database it will also be essential to disseminate information in a variety of other ways. Actively involved in ACI, Dr. Ideker and his research team will make at least one presentation at a national meeting of ACI regarding the research findings of this project. It is also anticipated that the graduate student researcher will make a presentation early-on at a national ACI Convention, either in a Research in Progress Session or Open Paper Session. As a voting member of ASTM C01 and C09 (cement and concrete/aggregates subcommittees, respectively), knowledge gained under this project will allow Dr. Ideker to provide expertise to this key international standardization body. Dr. Ideker and his research team will also publish several technical journal articles related to the research findings in the top technical journals in the field of concrete materials research (Cement and Concrete Research, ACI Materials Journal, ASCE Journal of Materials in Civil Engineering, etc.).
In addition to technical presentations and articles, the research team will work closely with ODOT to ensure involvement from a variety of agencies during field trials/investigations. Key personnel from ODOT, FHWA, and the Oregon Concrete and Aggregate Producers Association will observe the field trials during casting and finishing and at key stages of curing. Input from these personnel will be critical for developing guidelines that are realistic for concrete production and construction practices that can be incorporated into ODOT specifications. Dr. Ideker will work closely with ODOT to ensure that an updates to ODOT specifications, as a result of this research project are clearly defined, updated and disseminated to relevant parties. Dr. Ideker will be glad to help ODOT in the development of a training workshop or manual to better provide contractors with information to successfully incorporate strategies identified in this research project to reduce early-age cracking in high-performance concrete.
INTERNAL CURING OF CONCRETE BRIDGE DECKS WORK PLAN
Quarterly Reports:
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| SPR 713 |
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Asphalt Binder Grade Selection for HMAC with RAP/RAS
| Project Coordinator: |
Norris Shippen |
| Research Agency: |
Oregon State University |
| Principal Investigator: |
Todd Scholz |
| Start Date for ODOT: |
November 10, 2009 |
| Completion Date for ODOT: |
March 31, 2011 |
OBJECTIVES:
The objectives of this research effort are to develop recommendations for:
1. A design process for selecting the grade of virgin asphalt binder for HMAC mixtures containing RAP or RAS, or combinations of RAP and RAS, such that the blended binder meets the design grade for the mixture;
2. A procedure for effectively and efficiently recovering asphalt binder from recycled asphalt shingles;
3. A procedure for batching virgin materials (binder and aggregate) with RAP or RAS, or combinations of RAP and RAS, for mix design purposes and ignition oven tests;
4. A procedure for determining ignition oven calibration factors for HMAC mixtures containing RAP and/or RAS;
5. QC/QA test procedures for mixtures incorporating RAP or RAS, or combinations of RAP and RAS, as well as independent assurance parameters associated with determining asphalt binder content based on incineration (ignition oven tests); and
The recommendations will be incorporated in a field pilot study that will evaluate the procedures when RAP and RAS are used in HMAC.
OVERVIEW:
Oregon currently allows up to 30% recycled asphalt pavement (RAP) by weight to be used in hot mixed asphalt concrete (HMAC). While not in current practice at ODOT, the use of blending charts for RAP proportions greater than 15% by weight is recommended to: a) establish the maximum RAP proportion so that the virgin binder properties are not adversely affected; or b) adjust the grade of the virgin binder so that the blended binder possesses the desired properties.
ODOT has also been approached about allowing the use of recycled asphalt shingles (RAS) in HMAC. The two principal sources of recycled asphalt shingles include manufacturer waste (which is in limited supply in Oregon), and post-consumer waste arising from removal of old shingles from roofs (which are commonly referred to as tear-off shingles, and are in abundant supply in Oregon). Irrespective of the source, RAS contains asphalt binder that is substantially stiffer than that used in HMAC in Oregon; hence, inclusion of RAS in HMAC could significantly impact the properties of the blended asphalt binder.
A preliminary investigation is currently underway at ODOT and Oregon State University to investigate how varying percentages of added RAP with a single percentage of added RAS impact the blended binder properties. Additional research is needed to extend the preliminary investigation to include a wider range of percentages of RAP and RAS, to develop a design process for selecting the virgin binder grade based on the varying proportions of RAP and RAS, and to investigate how inclusion of RAP and RAS affects the mix design process for HMAC that include these materials. In addition, significant difficulties with regard to recovering the asphalt binder from shingles were encountered in the preliminary investigation; hence, additional work is needed to identify or develop an effective and efficient procedure for doing so.
A key issue concerning the design, manufacture, and acceptance of HMAC mixtures (with or without RAP and/or RAS) is accurately determining the content of the asphalt binder in the mixture. ODOT currently uses calibrated ignition ovens (incinerators) for determining asphalt binder content of HMAC for mix design verification purposes as well as for both quality control (QC) and quality assurance (QA) purposes. However, over the past few years ODOT has been experiencing an increasing number of issues in validating the contractor’s test results for the asphalt binder content of mixtures containing RAP. Binder contents derived from QC/QA testing are used to determine pay quantities, payment for asphalt binder escalation, and price adjustments based on the ODOT statistical analysis processes. Accurate determination of the asphalt binder content (which requires an accurate determination of the calibration factor for a particular mixture and a particular ignition oven) is therefore essential for determining appropriate pay quantities and payment for asphalt binder in HMAC.
PROPOSED ACTIVITIES:
The recommended procedures will be utilized in the design and QC/QA processes for HMAC mixtures that incorporate RAP and/or RAS. They will also be used to determine more accurate pay quantities and price adjustments.
ASPHALT BINDER GRADE SELECTION FOR HMAC WITH RAP/RAS WORK PLAN
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