Proceedings of the North-Central States M-E PDG User Group ... · Proceedings of the . North-Central States . M-E PDG User Group Meeting . This document captures the information shared

Proceedings of the

North-Central States M-E PDG User Group Meeting

This document captures the information shared by the nine north-central States

on M-E PDG implementation efforts. The meeting was held in Ames, Iowa on February 19-20, 2008. These proceedings use the abbreviation M-E PDG except where specific presentation titles use the abbreviation MEPDG. Both abbreviations refer to the same pavement design guide documentation and software package initiated by the NCHRP 1-37A project.

Table of Contents Sponsoring Organizations and Planning Committee.....................................................2 Background ...................................................................................................................3 Agenda..........................................................................................................................4 Session – 1 General Overview.....................................................................................5 Session – 2 Technical Issues (Climate, Validation and Calibration)............................11 Session – 3 Technical Group Discussions (Concrete, Traffic, Asphalt, Soils)............15 Session – 4 Closing and Future Direction ..................................................................23 Resources (Regional Experts, Reports) ......................................................................28 Appendices (Power Point Presentations) A – Session 1 – FHWA, National Update of MEPDG Activities B – Session 1 – ARA, MEPDG Overview & National Perspective C – Session 1 – IL, Mechanistic-Empirical Pavement Design in Illinois D – Session 1 – IA, Overview of Iowa DOT Implementation of the MEPDG E – Session 1 – KS, Implementation of M-E PDG in Kansas F – Session 1 – IN, Indiana Implementation Initiatives (part 1) G – Session 1 – IN, Indiana Implementation Initiatives (part 2) H – Session 1 – NE, Preliminary Implementation of MEPDG in NE I – Session 1 – MI, M-E PDG Activities in Michigan J – Session 2 – IA, Task 2 - Climate K – Session 2 – IL, Rigid Pavement Climatic Effects in Illinois L – Session 3 – IA, Task 4:Testing PCC & Task 6:Material Thermal Input M – Session 3 – MO, Missouri PCC Calibration Update N – Session 3 – IL, Characterizing Traffic for Rigid Pavements in Illinois O – Session 3 – IN, Weigh-In-Motion Data Processing for MEPDG P – Session 3 – MO, Missouri Traffic Data Calibration Update Q – Session 3 – IA, M-E PDG Traffic Support R – Session 3 – NCSC, Incorporation of HMA Dynamic Modulus in the M-E PDG S – Session 3 – IN, Brief Overview of MEPDG Sensitivity in Indiana HMA Pavements T – Session 3 – MO, Creep Compliance and Tensile Strength of HMA Wearing Courses U – Session 3 – IN, Implementation of Subgrade Soils focusing on Resilient Modulus V – Session 4 – IL, M-E Pavement Design Guide V1.0 Comments

Illinois Indiana Iowa Kansas Michigan Minnesota Missouri Nebraska Wisconsin

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Sponsoring Organizations FHWA Design Guide Implementation Team National Center for Asphalt Technology National Concrete Pavement Technology Center Iowa DOT Planning Committee Chris Brakke, P.E. Pavement Design/Management Engineer Office of Design Iowa Department of Transportation Michael Eacker Pavement Design Engineer Construction and Technology Support Area Michigan Department of Transportation Brandon Varilek Assistant Pavement Engineer Materials and Research Nebraska Dept of Roads Jerry Geib Pavement Design Engineer Office of Materials Minnesota DOT Amy Schutzbach, P.E. Engineer of Physical Research Bureau of Materials and Physical Research Illinois Department of Transportation John P. Donahue, P.E. Pavement Engineer Missouri DOT Tommy E. Nantung Section Manager Indiana Department of Transportation

Andy Gisi Kansas DOT Laura L Fenley, P.E. Pavement Engineer Bureau of Technical Services Wisconsin Department of Transportation Gary L. Crawford Concrete Quality Engineer Federal Highway Administration Lisa Rold FHWA – Iowa Division Tom Cackler National Concrete Pavement Technology Center Sharon Prochnow National Concrete Pavement Technology Center Michael Heitzman, PhD, PE Assistant Director National Center for Asphalt Technology

Office of Research and Development


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Background

Implementation of the M-E PDG is proceeding nationwide. The M-E PDG is an extensive improvement over the existing pavement design process and requires many new input variables. Each State agency will need to develop and execute an implementation plan to meet their pavement design process. While there are unique features of each State’s pavement design process, there are common elements in the recommended implementation plan: sensitivity, databases, validation, and calibration.

The M-E PDG implementation is comparable to the Superpave implementation. Both are extensive changes to the previous standards. One of the successful components to the Superpave implementation program was the development of the regional user/producer groups to share expertise and experience. Proposal

To convene a north-central States User Group meeting to share M-E PDG implementation efforts, identify implementation components that could benefit from regional collaboration, and consult with national experts and lead states (MO, MN, WI) on the design guide. Particular topics that may be included in the agenda are: o Inter-agency and intra-agency networking o Agency challenges and barriers to implementation o Identification and collaboration on training needs o Sharing pavement performance data to strengthen calibration of performance models o Material testing procedures and round-robin calibration assurance testing o Regional materials testing for unique test protocols, like thermal properties o Synthesis of sensitivity studies of M-E PDG Version 1.0 o Identification of Version 1.0 tools, limitations, software issues, and tips & tricks Action Plan

The User Group meeting will be developed through a series of parallel efforts. The key M-E PDG implementation representative from each State will communicate to develop an agenda and target attendees list. Iowa DOT will coordinate (host) the meeting location and lodging. Each State will assemble the appropriate group to participate in the meeting and prepare presentations and documents. This group should represent pavement design, pavement management, traffic, climate, HMA materials, PCC materials, unbound materials, and FHWA.


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AGENDA Session – 1 General Overview

o National update FHWA – Gary Crawford ARA – Harold Von Quintus

o State Implementation plans & progress Wisconsin Missouri Minnesota Illinois Iowa Kansas Indiana Nebraska Michigan

Session – 2 Technical Issues

o Influence of Climate input data o IA – Task 2 - Climate o IL – Rigid Pavement Climatic Effects in Illinois

o How to validate performance curves o How to calibrate performance curves

Session – 3 Technical Group Discussions

o Concrete o IA – Task 4:Testing PCC & Task 6:Material Thermal Input o IL – sensitivity of CTE & impact of absorptivity o MO – Missouri PCC Calibration Update

o Traffic o IL – Characterizing Traffic for Rigid Pavements in Illinois o IN – Weigh-In-Motion Data Processing for M-E PDG o MO – Missouri Traffic Data Calibration Update o IA – M-E PDG Traffic Support

o Asphalt o NCSC – Incorporation of HMA Dynamic Modulus in the M-E PDG o IN – Brief Overview of M-E PDG Sensitivity in Indiana HMA Pavements o MO – Creep Compliance and Tensile Strength of HMA Wearing Courses

o Soils & Unbound Materials o IN – Implementation of Subgrade Soils focusing on Resilient Modulus

Session – 4 Closing and Future Direction

o Regional challenges and barriers o Identify specific M-E PDG limitations and issues

o IL – M-E Pavement Design Guide V1.0 Comments o Identify regional experts on specific topics o Need for regional pooled fund studies o Need for future NC M-E PDG UG meeting


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Session – 1 General Overview National update FHWA – National Update of MEPDG Activities Gary Crawford, FHWA Office of Pavement Technology [PPT presentation Appendix-A] • Gary Crawford has been on the design guide implementation team (DGIT) for the past 3

years. The FHWA has been working on technology transfer and education through sponsoring NHI workshops, websites, webcasts, forums, etc. In addition, ARA is maintaining a website database for technical issues/problems that will be used in improving the M-E PDG and for additional tech transfer and forums.

o 36 workshops to date o 4 NHI courses o Community practice website www.fhwa.dot.gov/pavement/dgit

• Support lead state group, 18 states volunteered to be lead states-has not been as effective as hoped; currently over 80% of the states have an implementation plan; 2 states using it now with the others phasing in as confidence is developed with the models

• A survey, with 100% response rate, asked states to respond regarding implementation. Implementation plans that were submitted will be on the website to help others.

• Regional meetings, user groups, are needed to facilitate regional implementation. The FHWA wants to know what states need.

ACPA is initiating a design guide catalog. The program will ask participants to enter information on 7 areas (i.e., co-efficient thermal expansion, weather data, traffic data, dowel bars, etc.), and the program will respond with 10 top design suggestions.

ARA – MEPDG Overview & National Perspective Harold Von Quintus [PPT presentation Appendix-B] • Through ARA, Harold was the principal investigator designing a manual of practice for the

M-E PDG. The manual is undergoing an editorial review through AASHTO and should be out later this year.

• Harold reminded the participants of the history of pavement design: • 1958; Road Test initiated • 1962; AASHO Road Test complete • 1972; Interim Design Guide • 1986; Update • 1993; Update • 2007; still not perfect • 1989; LTPP initiated • 1998; M-E PDG initiated • 2007; M-E PDG delivered

• The M-E PDG is not perfect, but if states wait until there are no more changes, it will never be used. If states wait for perfection, it will be impractical and cost will restrict its use.

• Local calibration is very important even though NCHRP 1-39A and 1-40D started implementation efforts on a national basis

• Montana was first state to begin local calibration, using data from LTPP sites

http://www.fhwa.dot.gov/pavement/dgit


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• NCHRP 1-40B Manual of Recommended Practice for Calibration of M-E PDG • User groups, with diversity of calibration and validation, sharing information would lead to

increased implementation. • Both global (i.e. distress prediction equations, revisions to the software functionality) and

local/regional (i.e. default values revisions, transfer function and calibration coefficients revisions) enhancements are needed.

• New construction design strategies include: Conventional flexible pavements; Deep strength; Full depth while excluded strategies are: Aggregate surfaced roadways; Semi-rigid pavements; Staged construction; Asphalt treated permeable base; Geogrids, fabrics, & other strengthening materials. Integration into practice is the major issue facing the states.

State Implementation plans & progress Wisconsin Laura L Fenley, Wisconsin DOT

• Most of research being done by Wisconsin Highway Research Program, UW Madison • www.whrp.org has many related reports. • Still need to decide on distress levels • Goal is to implement this year • ARA is assisting with calibration

Missouri John P. Donahue, Missouri DOT The Missouri DOT has been using specific nationally-calibrated PCC and HMA distress models within the M-E PDG for new pavement designs since 2005. Concurrent with this use, MoDOT has been calibrating the M-E PDG distress models for local conditions. This work is being performed under contract with the pavement consultant ARA. The initial calibration effort will be completed in May 2008. Local calibration work has included selecting and collecting performance data from in-service pavement sections, representative of current pavement design types; extracting and testing material samples from the in-service sections and from active projects; analyzing and grouping truck traffic data from WIM and AVC into local classification groups; executing M-E PDG runs with collected data for sensitivity/validation/calibration; and creating materials database libraries. Minnesota Jerry Geib, Minnesota DOT Implementation plan was based on 2002 release of M-E PDG. Waiting for updated version V2.0 release (estimate 2012 -2015).

• Univ. of Minnesota is assisting with calibration • $300K July 2004 >>>summer 2008 completion • Task 1 – pavement section types • HMA sensitivity using Level 3 inputs (thermal cracking is critical) • PCC sensitivity (frost depth is critical) • MN uses a standard 13’ wide slab in passing lane and a 14’ wide slab for right lane. • Thermal cracking of HMA is of interest in particular. • Designing for frost is important. Frost depth in some areas can be 5 to 6 feet!

http://www.whrp.org/


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Illinois – Mechanistic-Empirical Pavement Design in Illinois Amy Schutzbach, Illinois DOT [PPT presentation Appendix-C] The Illinois Department of Transportation (IDOT) has been using a mechanistic-empirical form of pavement design for both full-depth Hot Mix Asphalt (HMA) and jointed plain concrete pavement (JPCP) since 1989. Continuously reinforced concrete pavement (CRCP) design is based on a modified AASHTO design. They use CRCP for roads with 20-year designs of greater than 35 million ESAL. Dr. Jeff Roesler is helping them tweak the IL ME procedure, in light of M-E PDG. Performance has been good to date, with no failures. Performance would indicate that the designs are conservative. Between the additional performance data, changing materials, new ways of characterizing materials, and the evolution of design technology, IDOT felt it was time to revisit the existing mechanistic-empirical design procedures for full-depth HMA and JPCP and develop a mechanistic-empirical pavement design procedure for CRCP. Research into design revisions/new design development is being conducted through the Illinois Center for Transportation by researchers at the University of Illinois (Marshall Thompson and Sam Carpenter for full-depth HMA (IHR-39-1, “Validation of Extended Life”), and Jeff Roesler for JPCP and CRCP (IHR-57, “Evaluation and Implementation of Improved CRCP and JPCP Design Methods for Illinois”)). Major changes to the full-depth HMA design include changing the dynamic modulus prediction model inputs, changing to a less conservative fatigue algorithm, and adopting an endurance limit for extended life designs. For JPCP design, the main efforts include revisiting shoulder type, base type and effect of base erosion, concrete fatigue algorithm, reliability, and cracking/damage calibration. The CRCP design will be based on University of Illinois research, the M-E PDG, and work done by Dan Zollinger in Texas. The M-E PDG has been used to look at the effects of climate and traffic variations on the JPCP and CRCP thickness designs for Illinois inputs. Performance data compiled for the M-E PDG will be used for verification of JPCP and CRCP designs. Iowa – Overview of Iowa DOT Implementation of the MEPDG Chris Brakke, Iowa DOT [PPT presentation Appendix-D] The Iowa DOT began implementation in 2005 based on the recommendations of a plan developed by Iowa State University. The ISU plan identified input areas that likely had sufficient data available and those that would require further data collection. Based on the recommendations the Iowa DOT put together a series of research projects to address areas where additional data or information was needed in order to fully implement the MEPDG. To fund the implementation a phased approach to the research was used with the initial phase addressing high priority input data. Depending on the results and demonstrated needs for additional data the remaining phases may be fully or partially funded.

• Tri-state meeting in 2003 with Minnesota, Wisconsin, and Iowa • ISU assisted in development of an implementation plan in 2004 • This plan resulted in a series of priority projects that are being worked on currently that

will enable the initial use of the guide • The 3 phase plan totals $740,000


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Kansas – Implementation of M-E PDG in Kansas Mustaque Hossain, Kansas State University [PPT presentation Appendix-E]

• KS DOT worked with Drs. Ramanoschi and Hussain (KSU) on implementation of M-E PDG and are about to publish their results.

• Collaborated with New York to compare predicted vs. measured values on HMA • For concrete pavements used 8 in service projects with LTPP sections • Found that Kansas traffic is lighter than in the national model • APT pooled fund study to rutting and fatigue in each states’ mixes

Indiana – Indiana Implementation Initiatives Tommy Nantung and Dave Andrewski, Indiana DOT [PPT presentation Appendix-F and Appendix-G] The Indiana Department of Transportation (INDOT) will implement the M-E PDG in 2008 using Level 3 defaults. Calibrated inputs that have been determined may be utilized so that a hybrid Level 2 / Level 3 design would be determined. As a reality check designs will be compared to the AASHTO 93, PerRoad 3.2, and an ACPA mechanistic design. Any differences will be investigated and group engineering judgment will determine the direction that INDOT would take. Implementing Level 3 will facilitate the calibration process by our Research Office.

Other comments:

• M-E PDG studies began in 2004 • Sensitivity studies was investigated in composite pavements • Looked at bias and residual errors • Traffic and soils data can significantly change the design results • M-E PDG better that what we have currently • Participated in NCAT test track • Cooperating on experiment in China • Pressure to thin the pavements • Reflective cracking and age cracking are the common failure modes of HMA

Nebraska – Preliminary Implementation of MEPDG in NE Brandon Varilek, Nebraska DOR [PPT presentation Appendix-H] NE is in an investigative stage prior to the expected implementation of the M-E PDG. The NE Department of Roads (NDOR) currently has two research projects with the University of NE to help assist in this effort. The first research project, Implementation of M-E Pavement Design in NE, concentrates on PCC only based on its relative simplicity as compared to the AC model. Phase I (Jul 06-Jun 08) includes a sensitivity analysis, preliminary evaluation of M-E PDG predictions vs. actual conditions, and will ultimately result in a recommended “Roadmap” of how best to begin implementation. Phase II (Jul 07-Jun 2010) will instrument at least 2 rigid pavement sections for short/long term monitoring and testing. Results from this phase will result in calibration of the M-E PDG to NE specific conditions.


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The second research project, Layer Moduli of NE Pavements, (Jan 08-Jun 2010) focuses on inputs for the AC model. It will create a database of dynamic and resilient modulus values for materials used in NE. It will also evaluate and calibrate the moduli calculations in the M-E PDG.

Michigan – M-E PDG Activities in Michigan Neeraj Buch and Karim Chatti, Michigan State University [PPT presentation Appendix-I]

• MSU participants are representing 4 universities plus DOT • More of on evaluation phase at this point • MSU researchers have been looking into various aspects (e.g., traffic inputs and effects

of axle load spectra, CTE data, MR values for subgrade, etc.) of the M-E PDG for MDOT.

• Dr. Hodek from MTU studied MR for bases in MI. • Currently checking the robustness of the model • Strong need to do round robin on CTE • Also have a project to back calculate subgrade values using the FWD • Implementation phase is not programmed at this time

Session Discussion 1. Quality vs Quantity Heitzman: One of the issues with implementation is quality vs quantity. How much data do you really need to validate or calibrate the models? Everyone would like to have both, but in reality most states reported today they were more focused on quality not quantity. However, ARA suggested 30-40 data points were needed. Is this feasible for most states? IL: Quality more important. WI: Limited in quantity of tests so combining with other states would be advantageous. IN: quantity is needed. Quality is what we’re chasing now NE: not in calibration stage yet. IA: Right now only 5 sites for existing pavements, more is dependent on funding. MO: Hands tied on quantity; limited number of projects with performance data. We’ll keep collecting data and recalibrate as we go along. KS: Quality due to funding for quantity. MN: MnRoad site has high quality and quantity of performance and lab data. MI: Quantity is needed for validation. Quality data from a few projects can still be valuable for calibration and material variability. Heitzman: It will be important to develop a methodology for sharing of information as personnel and projects change. A joint database? Each state has a pavement management system. Are states’ PMSs in line with M-E PDG to run the roadway management system? What is Minnesota collecting pertinent to the guide? Rating pavements: A combined scoring index for quantity and severity of cracks is needed. M-E PDG only predicts quantity not severity. All of the severity had to be re-rated. MN: Quality data from existing PMS. Roads are built with conservative design and when examined, roads are indicating 80% of design life. Failures are not easily categorized (many reasons), so care must be taken when using these roads in M-E PDG calibration. Catastrophic failures are a different story. Sections past 10 years are not usually failing.


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Iowa DOT John Hinrichson: Missouri said there was a standard error. Primary reason for using M-E PDG is standard error. Are other states gathering data for calibration error? Are you seeing deviation in standard error? Can I get away with using a thinner pavement? Are we seeing a significant deviation? Von Quintus: standard error is still very large. In some cases more # than global. LTPP database is a high quality database. One of the largest errors is measurement error on distress. There is no model for measurement errors. Need to get more consistent measurements of stresses. Von Quintus: comments: Designing sections regarding global models. LTPP models that started cracking, rutting, etc. that were showing stripping. M-E PDG doesn’t address stripping. 2. Reliability How are states dealing with reliability? IL: doesn’t use reliability IN: reliability = how conservative are you going to go? What is the outcome of the IRI? IA: implementation plan: ISU recommended designing at the 50% level. MO: using 50% reliability level when using global design. Good construction controls IRI. When perfectly constructed (i.e. MnRoad test site) design is less important. Construction out weighs design; quality control is most critical component. KS: 75% reliability for initial runs, backed off to 50% for unrealistic bumps MN: not sure where we run. MnRoad built on moisture sensitive subbase. Disaster to build it. Outstanding performance on some cells, probably more realistic construction than we thought it would be. MI: Concurs 50% was reality of reliability; reevaluation will be possible when more data is collected. Heitzman: Was there any reliability built into the Illinois model? IL: reliability is built in from the standpoint of overall class of pavement. On the State system the level of reliability is high. The local roads and streets manual drops down to 70-90%. Deflection variability associated with flexible pavements is factored in. Algorithms allow us to examine deflection variability and how it relates to pavement fatigue failure. As you move down to lower type pavements, those values are reduced and thus we get some fatigue failure. For JPCP, reliability is similar to the M-E PDG.


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Session – 2 Technical Issues Climate IA – Implementing the M-E PDG in Iowa, Task 2 - Climate Chris Williams et.al., Iowa State University [PPT presentation Appendix-J]

• Agronomy has developed 50-year historic climatic files for most of the 99 Iowa counties • Compared 50-year historic data to M-E PDG • 24 Counties were selected to represent the state and were analyzed. • Compare results achieved using files generated from historical data and from the data

available in the design guide. • Rutting in asphalt layer examined for low, medium and high traffic areas • IRI examined for low, medium, and high traffic areas • Conclusions

o Interpolated climatic files could not be created for three counties out of the 24 under analysis. The three counties (Fremont, Monona, and Pottawattamie) are in the western part of the state. o The climatic files that were interpolated from the data available within the design guide predicted higher rutting for the northern part of the state compared to the files created. o The climatic files that were interpolated from the data available within the design guide predicted lower thermal cracking compared to the files created. o The climatic files that were interpolated from the data available within the design guide predicted lower IRI compared to the files created. o IRI vales are about 10% higher with actual 50-year historic data as compared to the default M-E PDG files.

• Summary o Climatic input in the Guide can shift the network level of pavement performance ….. It should be more substantially considered! o Forecast models show differences between historical data and the future ……… climate change has an impact!

Questions: NE: were forecast models designed similarly to design models? Williams: They were all modeled by M-E PDG. Header information is different in M-E PDG; different than what was previously used, but otherwise easily converted.

IL – Rigid Pavement Climatic Effects in Illinois Jeff Roesler, University of Illinois [PPT presentation Appendix-K]

• Illinois has existing M-E JPCP method by Zollinger and Barenberg (1989) o No thickness design changes for climate change

• Illinois DOT has an semi-empirical method to determine CRCP thickness o Based on modified AASHTO method with no direct climate consideration

• Update/refine existing JPCP procedure and develop M-E CRCP design method based on many of the recent developments published in the M-E PDG and other work

• M-E PDG Evaluation o Determine effect of Climate on PCC thickness in Illinois o Is there a need for a geography / climate-based design method in Illinois?


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• Climate Effects Inputs o Changes in Climatic Effects o Climate data for several Illinois cities ran with E-ICM o Concrete thickness was changed to ensure less than 20% slab cracking for each

climate No faulting or IRI failure criteria limit utilized

• Summary o Climate may change a slab thickness

V0.8 - limited effect V0.91 - 1.5” statewide

o All cracking is top-down except Class 5 vehicle analysis • Findings – CLIMATE –JPCP

o Climate sensitive (1.5” to 2”) but very sensitive to microclimate around the Chicago area

o Curling o Using nonlinear temperature profile is more representative

• Initial M-E PDG (v1.0) CRCP Analysis o Concrete Materials o Reinforcement o steel depth: o -10°F Built-in Curl

• CRCP Summary o CRCP M-E PDG w/ AC shoulder most similar to IDOT method o Climate affects thickness o 30 year design gives greater thickness than 20 year design @ constant ESAL

• Summary o There is a temperature effect but difficult to make it into a simple statewide

design method and trends are not always the same as JPCP. o For JPCP: use joint spacing specifications to account for climate changes o For CRCP: initial construction temperatures very important

Comments: • Could adjust joint spacing to reflect climate differences in lieu of changing thickness • CRCP has some interesting response: sensitive to climate on opening and closing of cracks,

climate can make approximately 1 inch difference in thickness • Joint specification change would be more effective for Illinois • Built in curling has as much an effect for cracking as climate and doesn’t get the attention it

maybe should have. Looking at having different joint spacing due to curling. • Likely will break the state into N-S zones with different joint spacing. Question: Marshall Thompson: Based on your analysis, is the bottom line that we can do just as well on analysis of ESALs instead of load spectrum? Jeff Roesler: Yes, at this time I would agree with this statement.


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How to validate and / or calibrate performance curves Validation = checking to see if your models are working correctly Calibration = the process of modifying the models to make them work better General Discussion: 1. Heitzman: Are you planning to go immediately into calibration with the understanding that national models will not be correct, or are you going to start by validating national models? MI: We’ve gone through validation, now need to do calibration. KS: 137A charge was to find existing models and work with them. Researchers were not given the charge to develop new models. Models are supposed to have been validated. It’s our job to calibrate them. Will there be a better model? Perhaps. Then they will have to be validated nationally again. MO: Validation is easy part. Real work is collecting performance data and running design guide to see if you are the same as national averages. IA: Agree with MO. Go through validation to see if models as they exist with Iowa data come up with reasonable results – if they are fine, good; if not, calibration process will be needed NE: played with the models. National defaults will not be accurate enough. Calibration will be needed. IN: reviewed the performance curve. Higher curve is out of wack, middle good, lower end is ok. Regarding faulting. 0 faulting at joints shows us model is incorrect. Keep gathering data, keep validating and calibrating. Need national committees to address some of the weaknesses WI: Before doing calibration you have to collect data for validation IL: Comfortable with IL design guide already. Use M-E PDG to adjust model. Use data gathered to validate and calibrate. Calibrating globally will give you local state accuracy. “give you numbers you want” 2. How will data collected be evaluated in PMS? We’re given number of cracks but not severity. M-E PDG uses different criteria. How good is your PMS database to do either validation or calibration? KS: We have noticed inconsistencies when looking at database measurements. For example, transverse cracking with various severity levels are counted. Second year, transverse cracks haven’t “healed”, so when the second year has different data what should be done with it? The first year data was incorrect. Von Quintus: local calibration guide uses 3-4 data points to describe discrepancies. LTPP database has same discrepancy – measurement errors. Don’t recommend smoothing data. Anomalies be identified – perhaps the crack was sealed? With PMS data it is hard to determine what is a discrepancy and what is an outlier. i.e., MT has an aggressive pavement rehab program and uses a seal coat resulting in fewer number of cracks on the next “count”. Design guide doesn’t account for pavement preservation. Have to look at overall trends for what they are predicting and what design guide predicts. MI: PMS/M-E PDG relationship has two components. Output side – performance data; stress database. MI has a wealthy very detailed database from 1992. Not all stresses as defined by MDOT design guide agrees with M-E PDG. Raw database needs to be looked at to compare with LTPP, Input side: traffic, climate, construction data that goes with performance data. PMS is not available for input side – LTPP and M-E PDG will need to be used for input guide. Quality assurance is not available. IA: implementation plan looking at this question. Material looks good, but implementation will determine whether it is as good as it looks.


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MN: PMS data is very good. We don’t have everything that is needed but MN rating process is unique to MN. Cracked panel goes away and becomes a broken panel. We don’t have any data on as-builts as it pertains to PMS data. IRI is collected continuously. Be careful when using PMS data for calibration. TX: don’t try to change your PMS. Take a representative sample of your data and use it. Don’t try to use all your data. IN: PMS will give you relative health of system, but you don’t’ know what that health means. May tell you it’s getting rough, but you don’t know why. Rutting – why? Tells you there is a problem, but not why. Can’t use it for validation of model. Need to look at each stress indicator. IN has automated system that gives crack data only after ¼ inch wide. MO: PMS is not project level data so it is not appropriate for validation. Need to do surveys similar to LTPP for detailed data. Consistency of data is key – LTPP sites have all the data. IL: Had a comprehensive database for interstates but hasn’t been staffed since 2000 – would like to salvage data but big job. Connecting all the databases is big job. NE: We’re gathering project level information to do calibration. WI: Network data for IRI and rutting is ok but cracking data is not detailed enough. Maintenance activities are not recorded in PMS. Separate databases make for difficulties. Heitzman: 1970s in Iowa climatologists counted 700 events as high climate events, in the 1980s, 2000 events, and in the 1990s, 200 events. Which decade are you going to use for climate data? Did the rutting go away in 90s due to pavement changes or due to climate changes? 3. Heitzman: Validation and calibration. If you are looking at the chess board, looking at Version-1.0 or Version-2.0, you are going to go through either validation or calibration to get model how you want it. In 5-7 years there will be improved models. Have you thought about how you are going to validate or calibrate the new improved models? Are you going to use the same data, or will you use new data? Where are you storing your data? Von Quintus: The empirical side always needs to be checked over time. NCHRP created a database for housing information, performance data, traffic data, climate data, etc. in a database. This will be completed this year. Information will be available through FHWA. As states do calibration, their information could be part of this database. It is a database to support calibration of future M-E PDG techniques. MN: collect information for calibration, new models in the next decade, new data should be used. Techniques, material etc are different every decade – this is a dynamic system. Models need to change decade to decade. IL (Jeff): new models will need new data because they will require different data. We have the capability to measure different things all the time and a new model will require new info IN: When Superpave came out, lots of practitioners and twigs got together to make changes. IA (Chris): When you use M-E PDG it will need to be a big commitment to staffing, continuously updating. MO: upper management is committed to it because they knew pavements would be thinner and save money. Whether we will be able to continue to dedicate personnel to performance data collection no one knows.


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Session – 3 Technical Group Discussions Concrete IA – Task 4:Testing Iowa PCC Mixtures & Task 6:Material Thermal Input for Iowa Materials Kejin Wang and Jiong Hu, Iowa State University [PPT presentation Appendix-L]

• AASHTO Mechanistic-Empirical Pavement Design Procedure • Task 4: Testing Iowa Portland Cement Concrete Mixtures

o Task 4.1: To Compile and Analyze the Available Data o Task 4.2: To Examine Existing Predictive Equations o Task 4.3: To Investigate Equipment for Concrete Shrinkage Tests

• Task 6: Material Thermal Input for Iowa Materials o Task 6.1: Determining Variations of CTE Measurements o Task 6.2: Conducting the CTE Tests for PCC with Different Types of Aggregate o Task 6.3: Analyzing the PCC Test Results and Establish Prediction Equations o Task 6.4 & 6.5: Studying Thermal Conductivity of a typical PCC and ACC mix o Summary of Task 6 variations of CTE tests

Due to the test procedure/test equipment/batch materials Effects of aggregate type on CTE test results The thermal conductivity The investigations onto the CTE of ACC and the effects of concrete

materials (such as cementitious material and aggregate types) and mix proportions on concrete thermal conductivity are recommended to be considered in the future study.

Questions:

• Regarding CTE, what time period was run, how many days after casting? o DOT collected the core samples, don’t know how many days

• MI: 28 day CTE, or 14 or 90 makes a difference depending on the aggregate, so what do you recommend?

o We don’t have enough data to make a recommendation. IL – Jeff Roesler – sensitivity of CTE & impact of absorptivity Discussed in previous presentation, see Appendix-K -10 degrees is a decent estimate for built-in curling in IL conditions, based on a FWD back-calculation study.

MO – Missouri PCC Calibration Update John Donahue, Missouri DOT [PPT presentation Appendix-M] As part of the local calibration effort for the PCC distress models in the M-E PDG, MoDOT collected and tested numerous cores from in-service sections and cylinders from active projects for coefficient of thermal expansion (CTE) testing. MoDOT economically built its own CTE. The CTE purposely employs an invar frame to take advantage of its low CTE relative to concrete. The average CTE for in-service cores, all containing limestone for the coarse aggregate fraction, were very close to the M-E PDG default value (~5.50 ms/ºF); while the average CTE from active project cylinders (combined 7-, 28-, and 90-day) was a full 1.00 ms/ºF lower. No clear trend for CTEs developed among the different day-age cylinders. The explanation for the


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CTE discrepancy between in-service and active projects is not known, but may be related to age or type of specimen (core vs. cylinder).

o The default CTE values in M-E PDG can be very misleading sometimes. But in some cases, like in MO (based on John Donahue’s research), default CTE is OK, as local mixes have comparable CTE values. Donahue found that CTE from field core samples is about 1 microstrains/oF less than CTE from concrete cylinders cast using fresh concrete.

o Thermal Cracking Module Level 1 Inputs o AASHTO T 322 Basics o True creep load profile: Instantaneous Loading/Unloading o Assumed creep load: non-instantaneous loading o Comparison of calculation methods o Plant-Produced Mixes

Questions: o What factors are sensitive for PCC design?

o CTE, effective temp differential (curl/warp), joint spacing, widened lane o At the network level, are you measuring that, or are you using the fault meter software?

o all measurements were taken manually, original Georgia fault meter. o We’ve seen some cracking at dowel bar baskets, did they not saw early enough? Or because

of misaligned dowel bars? o My impression is that we are going to see that at construction or shortly after

while the contractor is still liable, so he still has to fix it. I don’t think that will be issue 5-7 years later. If it is going to be a problem it’s manifest early – construction issue

Topic Discussion - CONCRETE Heitzman Most of you have done some sensitivity analysis. What were you finding were the more sensitive parameters for concrete? MI: We’re in discovery phase. It’s dangerous to look at only one variable in sensitivity. Can’t just look at CTE, need to also look at other variables. Study interactive affects, i.e. CTE and joint spacing. IA: CTE and also temperature difference and effect on curling and warping. Built in temperature gradient important IN: sensitivity KS: couldn’t fill concrete lane IL: CTE – standard deviation is pretty low for Illinois. Can’t only focus on CTE. Absorptivity which is directly related to color, and thermal conductivity are both important in the temperature profile development. Looking at only CTE will give you skewed sensitivity. WI: don’t have concrete person

Heitzman Any other comments on concrete: many interactions between variables, is positive aspect of M-E PDG IA; thermal numbers were not what was in M-E PDG. Are high numbers better for conductivity? Lower number becomes an insulator. Low number would give low conductivity. Heitzman: LEED criteria - Environmental standards for green stars. Reflectivity and absorptivity etc will be issue.


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Traffic

IL – Characterizing Traffic for Rigid Pavements in Illinois Jeff Roesler, University of Illinois [PPT presentation Appendix-N]

Illinois has existing M-E JPCP method by Zollinger and Barenberg (1989) IDOT has an empirical method to determine CRCP thickness Update/refine existing JPCP procedure and develop M-E CRCP design method Traffic Questions

• How does load spectra affect thickness design of concrete? • Is load spectra necessary over ESALs? • For IDOT, expensive to collect load spectra

Traffic Effects (V 0.9) • Five different traffic situations- what’s the effect of truck wheelbase

o Standard wheel base distribution o Long Wheelbase o Short Wheelbase o Class 5 – 100% single axles o Class 9 – tandem axles

V.0.91 M-E PDG Summary (Feb. 2007) • Vehicle classification and axle type changes affected design thickness by 0.5 in.

only • ESALs appear to give similar cracking levels for an extreme range of load

spectra • All cracking is top-down except Class 5 analysis

ESALs vs. Load Spectra Analysis • Illinois axle load spectra is lighter than the assumed distributions in the M-E PDG • Number of trucks to accumulate 112M ESALS is smallest for M-E PDG (heavier

axles) compared to Illinois data • Load spectra gave different cracking levels at only very high overload values. No

thickness design difference between LS and ESAL at legal loads or moderate overloads.

• JPCP Traffic Assumptions • Traffic Summary

o For existing axle load limits in Illinois: ESALs will give reasonable thickness results vs. load spectra for fatigue cracking prediction

o Recommend to IDOT to continue with ESALs as traffic input for rigid pavement design.

o Load spectra has greater future potential and thus these conclusions should not be taken as load spectra is not useful.

Questions: Why is load spectra the way of the future if IL found that ESALs worked? The current way IL uses the ESAL information works fine. For future development, IL sees LS playing a larger role in future model developments, but for the cases analyzed in the M-E PDG, ESALs and LS give similar results for IL conditions.

IN – Weigh-In-Motion Data Processing for MEPDG Shuo Li et.al., Indiana DOT and Purdue [PPT presentation Appendix-O]


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Primary issues: • WIM data readily available, data quality not sure • No reports on axle configuration and axle load distribution • Huge database, large file size, data processing labor intensive and time consuming • 48 WIM sites with different sensors distributed statewide • Up to 30% of the total vehicle counts not classified • Development of computer program

Progress • Work on unclassified vehicles in progress • HMA Pavement distress versus AADTT error • Sensitivities of HMA Pavement Distresses to Truck Traffic Characteristics • WIM data QC/QA completed by Purdue University • Computer program for WIM data processing completed • 2002 and 2004 WIM data analysis completed. Target data analysis 3-5 years

Work on traffic inputs for Levels 1, 2, and 3 on going

MO – Missouri Traffic Data Calibration Update John Donahue, Missouri DOT [PPT presentation Appendix-P] MoDOT’s local calibration work includes truck traffic data analysis of WIM/AVC sites in Missouri. A total of 16 sites were selected after undergoing quality control screening. The analysis steps taken included normalizing vehicle class distributions and load spectra by vehicle class per month, creating axle number per class coefficients, determining annual growth rates, and calculating monthly and hourly truck volume factors. The 16 sites were combined into four logical groups associated with a specific truck traffic classification (TTC) in the M-E PDG. Overall, the MoDOT vehicle class distributions created from the analysis agreed very well with national defaults in the M-E PDG; however, axle load spectra has more significant variability. WIM/AVC sites were predominately rural Interstate, so urban and low volume route traffic distributions remain underrepresented. ARA helped them with looking into traffic aspects for M-E PDG. ARA has proprietary software that can use raw traffic data to generate axle load spectra (Cambridge Systematics’ TrafLoad can also do it?). WIM data in MO matched well with some default M-E PDG spectra. But MO is not able to collect good WIM data in urban areas (St. Louis) due to security reasons! WIM Data Observations Traffic Analysis Related Observations and Conclusions WIM Site Analysis Steps

IA – M-E PDG Traffic Support Phil Meraz, Iowa DOT [PPT presentation Appendix-Q] Iowa has been using LS since 1983. Though rare in typical DOTs, traffic department at IA is working with pavement department

to figure out what they’d need to collect for pavement design using M-E PDG. Looking at Count program – how could we collect data that would be more useful. And how

could we do for the future. What would be needed for the M-E PDG?


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For validation of WIM data, we take actual trucks, load them and do 30 passes in each lane with each loaded truck to see if WIM data is correct. Within 2%.

Keep track of calibration on a weekly basis – able to see anomalies very quickly and address them.

WIM sites are added when development is forecasted. Computer model – basically psychology of travel. If roadways are changed, how will that

change how and where people drive. Trucks and cars make different decisions. We can forecast truck traffic based on MPA plan. Most states have not done any study of forecasting. LS, ESALs, etc. It doesn’t make any difference if you don’t know how many vehicles are on the road. Large study on forecasting – selection of datasets, work with M-E PDG.

FHWA mandates all urban areas have traffic forecasting models, but the models are still not good enough estimate reasonably well.

Challenges: money is biggest challenge.

Questions: IA: One of the issues Phil saw was that it wasn’t making a difference to IL, but in looking at overweight studies, Pit scales skew data dramatically. Scale avoidance is huge. IA (Chris W): gas prices go up, tire inflation goes up, damage goes up. Load distribution for size of lane also affected. More concentrated loading on urban narrower lanes Topic Discussion - TRAFFIC For all of states: what WIM equip do you have? What is your confidence in that system? WI: 25 continuous WIMs, other permanent but not continuous collection, 65 permanent ABCs NE: only 3 permanent WIMs run by state patrol, not useful information for M-E PDG, some temporary sites with questionable accuracy MO: 6 portable WIMS, good quality MN: 10 WIMS, Kizler quartz, pulled out bending plates. No formal calibration – did it this year. Portable WIMs may be coming in the future MI: 40 permanent WIMs, 30 quartz, 3 bending plates, formal calibration program, once per year KS: 30 movable WIMs that are moved 3 times. Some bending plates, large number of vehicle counters. IN: 48 WIMS, 60 ABC sites. Calibration program

Asphalt

NCSC – Incorporation of HMA Dynamic Modulus in the M-E PDG Eyal Levenberg, North Central Superpave Center [PPT presentation Appendix-R]

• Complex Modulus Testing • Raw Dynamic Modulus Test Data • Analysis of Dynamic Modulus Test Data • Dynamic Modulus Master Curve

o M-E PDG (input data ->mechanistic analysis. computer responses ->empirical equations. projected performance ->

o Incorporation of HMA Dynamic Modulus in the M-E PDG o M-E PDG sensitivity to Dynamic Modulus

IN – Brief Overview of MEPDG Sensitivity in Indiana HMA Pavements Jusang Lee, Indiana DOT [PPT presentation Appendix-S]


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• Inputs and Variations • Distresses (AC Rutting, Fatigue Cracking, Longitudinal Cracking, Thermal Cracking) • HMA Layer Thickness • Air Voids • Asphalt Binder • Indiana M-E PDG Initiative

o Generate a database for dynamic modulus, creep compliance, and IDT strength of common HMA mixtures.

o Redesign existing LTPP and other test sections using the M-E design guide, and compare predicted performance to the measured. Determine distress model calibration factors if necessary.

o Validate calibrated models using INDOT accelerated pavement testing and the future Indiana mini-LTPP sections.

MO – Creep Compliance and Tensile Strength of HMA for Wearing Courses in Missouri David Richardson and Mike Lusher, Missouri University of Science & Technology [PPT presentation Appendix T]

• New HMA Factorial o 6 MODOT projects; 22 500-ft sample sections o Sections between 5 to 10 years of age in 2007 o 14 LTPP 500-ft sections (not used in global calibration) o Sections between 10 and 35 years of age o Crushed stone base sections with Marshall and Superpave mixes predominate o Most sections are > 8 inches thick

• A general overview was given of the determination of creep compliance and tensile strength of hot mix asphalt typically used for wearing courses in Missouri, and how these material characterization tests relate to the M-E PDG.

Creep compliance and tensile strength of hot mix asphalt are two inputs to the Thermal Cracking module in the M-E PDG. Determination of these two inputs is set out in the American Association of State Highway and Transportation Officials (AASHTO) test method T 322. Basic information about the two Thermal Cracking module inputs and test method T 322 were discussed in the presentation. Specific issues encountered during the testing in regard to the T 322 protocol were raised. A brief summary of the results of the testing performed at the Missouri University of Science and Technology on behalf of the Missouri Department of Transportation was also given. Topic Discussion – HMA Question from Internet re HMA layers Chris Williams: if you are going to test mixes it won’t make a difference re M-E PDG. You will find surface mixtures that are polymer…… won’t be true for deeper layers KS: we did study early on binders, 28 on surface, down in depth to 22 or even lower. What would be modulus based on grades of asphalt. We found out two types of binder – one for surface and one for other layers. -28 on top four inches, everything below that is 22. That was the best solution economically. No benefit to cost or structure to do further changes. Heitzman: if mix design is done correctly, should be no difference in virgin mix or mix with RAP in it. If it's done correctly. IA (Chris W); you are right. But if you are using a standard set of dynamics……. Binder properties, when selecting …… be careful of standardizing


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IN: if everything is done right – RAP has to be processed, it has to be broken correctly. If you have an interstate crossover, the construction will have exposed RAP and everything is new. IL: we have questions on it. Industry wants higher RAP, and dynamic modulus and fatigue stresses study to see results of RAP IL (Jeff): In terms of current inputs this statement is true (similar modulus and tensile strength) However, the fracture properties for example are not the same from virgin to recycled materials but this is not an input in the MEPDG. One would expect materials with different fracture properties to not perform the same despite similar tensile capacity and modulus values. The failure and response properties of recycled materials need to be looked at

Soils & Unbound Materials

IN – Implementation of MEPDG-Subgrade Soils focusing on Resilient Modulus Daehyeon Kim and Tommy Nantung, Indiana DOT [PPT presentation Appendix-U] • New M-E Design: hierarchical design approach

o Level 1: Obtain k1, k2, k3 through Lab Resilient modulus Test o Level 2: Correlations with other material properties o Level 3): Typical resilient modulus value

• What Indiana did for M-E PDG o Developed a predictive model based on UC strength tests and resilient modulus

tests o Developed a predictive model based on Mr tests and soils properties o Sensitivity Analysis and extensive review of the M-E PDG Software

• What Indiana is doing for M-E PDG o Calibration between Lab Mr. and In-situ FWD back-calculated modulus for existing

pavements (12 sections) and newly constructed pavements (5 sections) o Seasonal variations

• Indiana’s Perspective o In the past: CBR, Now: Resilient modulus o Our practice: Geotechnical engineers evaluate resilient modulus of subgrade soils

from the repeated tri-axial test and give it to pavement engineers o 2 resilient modulus test units (Research office and Geotechnical office) o INDOT targets Level 1 Design for resilient modulus

• Further Work o More sensitivity analysis with the M-E PDG software o More work on coarse grained soils, stabilized soils using chemicals and

geosynthetics o Effect of drainage and freeze-thaw of unbound materials on the performance of

pavement Topic Discussion – UNBOUND MATERIALS: Heitzman: How much soil testing are you doing relevant to getting parameters for M-E PDG? What have your Sensitivity studies indicated as relevant? MN: lab is selecting samples from projects, trying to get wide range based on chart MI: in the 90s we did lots of sampling, now for M-E PDG there is an ongoing study, fwd project NE: just starting – will get samples this summer KS: limited, WI: soils map, got samples from 20 selected sites, lots of variations, no sensitivity analysis, but resilient modulus.


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IA: no soil sampling yet, planning to do 20 sites IL: done extensive soil characterization. In IL, k-value less than 50 is “poor”, between 50 and 100 is “fair” and above 200 is “granular”; this classification is one of the inputs in their current rigid pavement design procedure. On the full-depth HMA procedure, soil inputs are “poor” (2 ksi), “fair” (5 ksi), or “granular”. MN: the sensitivity of the soil itself, to density, moisture etc. Construction quality control issues for building long life pavement. How good is QC program for any construction – important for any design MO: one of the issues is compaction. Can we use other things to check subgrade – moisture probe, soil suction curve, “smart compaction”? When you compact the soil, this stiffness changes with more layers. Stiffness is not the only criteria. Session Discussion IA: Should we be testing the soil at actual rather than maximum? Inputting for M-E PDG at actual rather than maximum? Von Quintus: if you are recalibrating use the actual. If you are using global calibration use the maximums given. Software question: Re.getting info from TrafFlow software – is it good? What should we use? IN: not using TrafFlow. Using a simple program for traffic design. Simple GIS map. Need to customize program. Find out how planning got their data – planning may have only used peak data. MN: needs lots of data, but with enough data it seems to work. KS: continuous data 24/365 from WIMS then run it through TrafFLow. KS uses 48 hr data with some success MI: TrafFlow. It is format sensitive, but used it successful with M-E PDG. Initial evaluation it seems to work. Hydraulic systems question: How many labs are checking calibration of equipment? Iowa: Lots of testing for quality info. Test protocol will substantially impact master curve. Need to understand what equip is providing MO: Our CCEE dept checks calibration of every piece of equip every year. Data is only as good as how certain the results are. Tensile strength machines need to be checked OFTEN. IN: How many states are instrumenting pavements to see correlation between that and labs WI: Instrumented two sites: WIM site and other. Less than optimum MnRoad: instrumented from day 1. This year major new construction. Lots of data – but how to look at it, how it relates to design guide. NE: Omaha to Lincoln will be instrumented for stress and strain


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Session – 4 Closing and Future Direction IL – M-E Pavement Design Guide V1.0 Comments Marshall Thompson, University of Illinois [PPT presentation Appendix-V]

• Level 2 • “User defined” monthly inputs • For all pavement layers ( including the subgrade ) • Provide capability for “out-putting” selected pavement responses • Provide capability of specifying the HMA fatigue algorithm • Not limited to “TWEEKING” • National calibration!!!! • TRANSFER FUNCTIONS ARE VERY IMPORTANT!!!

Von Quintus: Re. subgrade modulus, you can do it now with M-E PDG Marshall’s request that individuals be able to input on k1, 2, 3 and inputs to the guide IN: I’m going to agree with you on monthly inputs. In China we built roads that in summer had different results. We need to be able to change inputs

Regional challenges and barriers o Working with reliability (very high group interest) – Current reliability values are

based on broad national pavement performance data. To improve the reliability values (reduce data variability), the region/state needs a sufficient pavement performance data base to compute statistical properties. In general, improving reliability will decrease pavement thickness. Narrowing the focus of the pavement type and application should narrow the performance data (reducing the variability and improving the reliability). North Central States need to set up a regional database of pavement performance to have a sufficient amount of data to develop reliability values.

o Confidence in field instrumentation – Most of the north central States have had

problems with the quality of the WIM data. WIM data quality is directly related to the frequency and details of the WIM calibration process. Traffic count and truck weight programs are commonly performed in the planning office and truck enforcement. These offices do not typically have an interest in pavement design details or full spectra axle classification. A regional approach to technology transfer on equipment calibration and data processing would greatly improve the quality (and confidence) of the traffic data.

o Proper traffic counts – Similar to field WIM instrumentation, proper traffic counts are

critical to the traffic input for M-E PDG analysis. A regional technology transfer effort would improve the quality of the traffic count data.

o Working with rehab – The subject of pavement performance data for pavement

rehab strategies is very limited. Most States are initially focusing on validation and calibration for new construction. Separate pavement performance models will be


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needed for each rehabilitation strategy. Data for developing these models will be needed.

o Test standardization – A large number of material inputs are required for M-E PDG.

If the States are going to share some of these material characteristic values, the same test protocol should be used. Test standardization is a difficult issue that has been discussed for many years, even for relatively common simple tests. The HMA paving industry would like more standardization for quality control technicians working multiple States. AASHTO/ASTM test protocols should offer some consistency, but often permit multiple test procedures under the same protocol. If regional material databases are developed, they should include cells to describe the test procedure used to obtain the measured value.

Identify specific M-E PDG limitations and issues

o Broad level-II inputs – States would like options to use input values that are not currently permitted in the M-E PDG software (version 1.0). States have extensive data on certain materials, but this data is not based on the material characteristic (test) required for the guide. This is a difficult limitation to address. The mechanistic theories and equations embedded in the M-E PDG are built on the specified input values. Can the M-E PDG software include guidance on the correlation between required M-E PDG input values and other common values?

o Computed stress and strain and predicted distress output (very high group

interest) – The States would like the ability to examine the computed and predicted values generated during the analysis process. These values would be very valuable for engineers and researchers who instrument pavement sections as part of the local calibration effort.

o Improve HMA fatigue empirical performance models – A detailed evaluation of the

fatigue data was not tasked as part of the M-E PDG development. Forensic evaluations of pavement sections should be done to determine if the observed cracking is “classical” fatigue or related to poor construction. Weak subgrade and delaminated HMA layers cause fatigue type cracking that was not intended by the designed pavement structure.

o Improve the HMA rutting empirical performance model. The current national model

uses total pavement structure rutting and applies general rules to assign the rutting between pavement structure layers. Separate rutting models should be developed for each layer based on measured layer rutting and mechanistic theory.

o Drainage (high group interest) – Differences in the drainage characteristics of the

pavement section are not given adequate attention.

o Improve HMA computational time (high group interest) - (variable time increment) – The time required to run the HMA program needs to be improved. Software experts should be contracted to find opportunities to improve the run time.


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o FWD input for new and rehab pavements – Many agencies are using FWD to measure the response of in-place materials. The guide should add input features that would allow the agency to directly input FWD results.

o Compare AASHTO and M-E PDG thickness – the M-E PDG software should

incorporate the existing DARWIN software and provide the engineer with the computed DARWIN thickness in addition to the M-E PDG pavement performance predictions.

o % Trucks in the design lane – Include the option to give percent trucks in the design

lane as an input, in place of load spectrum.

o Supporting documents – Update the supporting documents.

o Research version of the software (very high group interest) - The agencies and researchers would like the ability to examine (and modify) the M-E PDG software source code. As the M-E PDG is transferred from NCHRP to AASHTO, the decisions on the use of the software will be made by the AASHTO DARWIN M-E task group. The current proposal by the task group would give source code authority to those agencies (and others?) that participate in the pooled fund effort for M-E PDG software. “You must pay to play.” NOTE: This general understanding of the direction for the M-E PDG software was confirmed by Laura Fenley (Wisconsin DOT) based on an email from Linda Pierce (Washington State DOT) and chair of the DARWIN M-E task group.

o Improve PCC cracking model – Cracking is lumped together. Need to have them

separated so we can see built-in curling and fatigue. o Models for premature failures – The software should consider models for premature

failures. In theory, the current models should predict if premature failure will occur, but the performance models are generally based on good performance and may not adequately address critical premature conditions. The software should specifically highlight distress parameters that are predicted to be in excess of the normal range and may cause premature failure.

o HMA layer flexibility – more flexibility is needed to describe layer characteristics.

The sequence of layer properties should allow “softer” layers over “harder” layers.

o Software parallel processing – This methodology should be examined as a means to speed the computer run time.

o Depth of FHWA support and resource centers – Implementation of the Guide will

require strong leadership and resources from the FHWA. For the Guide to continue to develop and improve, FHWA will need to take on the role of advocate, leader, and mentor.


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o Funding – The Guide will require a significant and continued funding commitment to achieve the desired goal of an “all encompassing” pavement design tool. Pavement experts and practitioners will need to demonstrate to the funding managers that the funding to maintain and improve the Guide will be cost beneficial. Each task to develop the Guide must improve performance or reduce cost.

General Comments: Version 1.0 is what you are going to get. This is an analysis tool, a NCHRP report. AASHTO is looking at making this a design tool with faster computation time, more input possibilities, source code development (AASHTO Darwin ME program). Darwin task force has a list of software issues – what the task force gets to do will be dependent on funding. There is a meeting in April 2008 to put together a solicitation for funding to improve M-E PDG. States will get solicitation for funding – would like to have 2.0 by 2010. Wiring diagram has been requested and will likely be available yet this year. Continue to send your bugs to bugtracker. There are a few state that have implementation plans on the web – may have a website started. Need for regional pooled fund studies The participants identified the following opportunities for regional pooled fund efforts on the M-E PDG.

• Share WIM data and other traffic information • Regional data-base web site • Share sensitivity studies • Improve reliability • Regional calibration/validation • Use regional T2 dollars

Need for future NC M-E PDG UG meeting The participants of the North Central M-E PDG workshop agreed that additional meetings on a 6 to 12 month cycle would be beneficial towards their implementation effort.

o WI: get together every 6 -12 mo o IL: looking at doing their own. Not sure value in getting together o NE: Best practices ideas – yearly meetings would be helpful o IN: Beneficial. Do it twice a year for the first few years and then yearly when it’s more

established. Include more networking time o MO: yearly. But not February in Iowa o IA: very beneficial. 6 month schedule with amount of research going on would be helpful o MN: beneficial. Federal highways money is necessary. Can’t travel on local DOT budget o KS: good meeting. Implementation/calibration is resource intense effort, so sharing ideas

is very helpful o MI: Michigan is unsure of future usage, so UG meetings would be very beneficial.


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Closing Comments Von Quintus: Great idea having a user group. Prepare list of changes for AASHTO task force. Encourage groups of states that have similar policies and similar ways of managing pavement to do regional calibration cheaper and faster. States will see differences between global calibrations, design features not included in global calibration will make a difference. Crawford: FHWA would like to develop a clearinghouse. Originally that was the plan for lead states – that failed. FHWA will facilitate user groups on regional basis


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RESOURCES List of regional experts Eyal Levenberg, NCSC, HMA lab performance testing Jerry Geib, MN DOT [email protected] Pavement Design Engineer 651-366-5496 Erland Lukanen, MN DOT [email protected] Pavement Preservation Engineer 651-366-5460 Bruce Chadbourn, MN DOT [email protected] Asst Pavement Design Engineer 651-366-5422 Matt Oman, MN DOT [email protected] Weight Data Engineer 651-366-3855 Tom Burnham, MN DOT [email protected] Concrete Research Engineer 651-366-5452 Amy Schutzbach, IL DOT [email protected] (217) 782-2631 (None of the IDOT staff are qualified to be "experts" on the M-E PDG. We really have little experience with the actual design guide. If another state is interested in discussing what Illinois has one/is pursuing, I would be the logical contact.) Bibliography of M-E PDG reports WISCONSIN www.whrp.org has many related reports MINNESOTA none at this time ILLINOIS Publications relating to IDOT's current mechanistic-empirical design work can be accessed on-line at http://www.ict.uiuc.edu/Publications.asp Reports of interest include: TES-119 IHR-R32 Construction of Extended Life Continuously Reinforced Concrete Pavements at ATREL <http://www.ict.uiuc.edu/Publications/report%20files/TES-119.pdf> Erwin Kohler, Genevieve Long, Jeff Roesler Dec-02 TES-141 IHR-R32 ACCELERATED PAVEMENT TESTING OF EXTENDED LIFE CONTINUOUSLY REINFORCED CONCRETE PAVEMENT SECTIONS <http://www.ict.uiuc.edu/Publications/report%20files/TES-141.pdf> Erwin Kohler, Jeffery Roesler Dec-06 NOTE: These two reports are from IHR-32, "Accelerated Pavement Testing of Extended Life Continuously Reinforced Concrete Pavement Sections", and deal with the construction, instrumentation, and accelerated testing of CRCP sections. Information on crack width, crack spacing, punchouts/failure modes can also be found. FHWA-ICT-07-005 IHR-R39 HMA Dynamic Modulus Predictive Models: A Review <http://www.ict.uiuc.edu/Publications/report%20files/FHWA-ICT-07-005.pdf Gabriel Garcia, Marshall R. Thompson Jan-07 FHWA-ICT-07-006 ICT/IHR R39 HMA Dynamic Modulus: Temperature Relations <http://www.ict.uiuc.edu/Publications/report%20files/FHWA-ICT-07-006.pdf Gabriel Garcia, Marshall R. Thompson Jun-07 FHWA-ICT-07-007 ICT-R39 FATIGUE PERFORMANCE OF IDOT MIXTURES <http://www.ict.uiuc.edu/Publications/report%20files/FHWA-ICT-07-007.pdf S.H. Carpenter Jul-2006 FHWA-ICT-07-008 ICT R-39 DYNAMIC MODULUS PERFORMANCE OF IDOT MIXTURES <http://www.ict.uiuc.edu/Publications/report%20files/FHWA-ICT-07-008.pdf S.H. Carpenter Dec-2007 NOTE: These reports are from study IHR-39-1, "Validation of Extended Life HMA Pavement Design Concepts". There was a lab portion where HMA samples were tested for dynamic modulus and fatigue, and a field portion where sections were constructed, instrumented, and tested under accelerated loading and responses collected and checked against prediction models.

http://www.whrp.org/


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State Implementation Plans & Sensitivity Studies NEBRASKA NE will not have sensitivity study or implementation plan finalized until later this summer. IOWA Sensitivity Study of Iowa Flexible Pavements Using Mechanistic-Empirical Pavement Design Guide, Poster Session 522, TRB 2006 S. Kim, H. Ceylan, K. Gopalakrishnan, M. Heitzman

Development of Mechanistic-Empirical Structural Design Program for Hot-Mix Asphalt Overlaid Rubblized Portland Cement Concrete Pavements, Poster Session 522, TRB 2006 H. Ceylan, K. Gopalakrishnan, B. Coree, T. Kota, R. Mathews

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Proceedings of the North-Central States M-E PDG User Group ... · Proceedings of the . North-Central States . M-E PDG User Group Meeting . This document captures the information shared