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Local Calibration of the MEPDG Using Pavement Management Systems
Chapter 7. Database Verification
Introduction
The overall success of this project is in large part linked to the successful completion of the verification process. Several forms of coordination were conducted with NCDOT to ensure data quality and applicability to MEPDG calibration. As NCDOT populated the MEPDG calibration database, the APTech team contacted the NCDOT staff to discuss progress approximately every two to three weeks. The APTech team worked with the NCDOT staff to verify that proper procedures were being followed for storing the data, ensuring that the framework was being tested and any problems with the framework were identified and adjusted. Specifically, the following details were confirmed with NCDOT:
- Are all the data items that were specified in the framework being collected or are plans in place for collecting any missing data?
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To minimize variability (e.g., construction, pavement performance, traffic loadings), pavement projects were selected from the North Carolina interstate and/or primary system.
- Climate stations currently contained within the MEPDG was used for all selected pavement sections.
- Pavement condition assessment is based on the NCDOT pavement condition definitions, which is not necessarily based on the LTPP Distress Identification Manual, as recommended in the MEPDG documentation. NCDOT pavement condition assessment is shown in table 33 and Appendix B (flexible survey manual) and Appendix C (rigid survey manual).
Table 33. NCDOT pavement distress types.
| Flexible Pavement |
Rigid Pavement |
| Alligator cracking |
Cracking |
| Transverse cracking |
Corner breaks |
| Rutting |
Joint seal damage |
| Raveling |
Spalling of joints |
| Bleeding |
Shoulder drop-off |
| Patching |
Patching |
| Oxidation |
|
- Have the data gone through the required quality control procedures to verify their correctness, accuracy, and reliability? If not, what procedures will be used to verify the accuracy of the data?
- NCDOT assured that all the data incorporated into the MEPDG calibration database had received the necessary quality control checks to ensure data accuracy.
- Does the data cover all the three typical pavement types, including both new design and rehabilitation activities? Are all distress types represented?
- Since the NCDOT highway network is comprised of primarily HMA pavements, with a lower percentage of portland cement concrete (PCC) pavements, only project data for these two pavement types was provided. In addition, the MEPDG calibration database contains several HMA pavements that have received an HMA overlay.
- Can the data from various sources be integrated in a single database so that performance data can be linked to material, traffic, construction, and climatic data and can the data be easily extracted for use in calibrating the models?
- NCDOT stated that all the necessary data was available, though not necessarily contained within one database or possibly in electronic format. NCDOT worked with other divisions (e.g., Materials, Construction, and Traffic) to obtain the necessary data. In addition, much of the available materials information was assembled into a database by the North Carolina State University (NCSU) as part of a NCDOT sponsored research project. NCDOT obtained the NCSU database and transferred the data into the MEPDG calibration database.
The final verification activity was conducted to ensure the data provided by the state appeared reasonable. Although it is difficult for the APTech team members to check the validity of the data, reasonableness checks were used to determine the overall soundness of the data. Distress data was compared to the construction data to verify that the level of deterioration was reasonable for the specific pavement design and age. Similarly, material test results were reviewed to check that they are within reasonable ranges of acceptance. From this review, the APTech team determined that the data provided by NCDOT appeared to be reasonable.
Project Selection
As previously described, NCDOT selected pavement sections for use in the calibration process based on representative pavement structural section, section uniformity (e.g., pavement type, pavement thickness, materials), and availability of traffic, material, and pavement performance data. As outlined in the NCHRP 1-40B report (NCHRP 2004) the minimum number of total pavement sections, by distress, that should be selected for performance prediction model calibration includes (see table 34): The research team recommended that NCDOT preferably select 20 to 30 pavement sections, for each pavement type, to be used in the calibration process. NCDOT stated that they would do their best to comply with this request, but also noted finding this number of sections, especially for the PCC pavement sections, may be challenging.
Table 34. Minimum sample size for MEPDG calibration.
| Distress |
Minimum number of roadway segments |
| Total rutting or faulting |
20 |
| Load related cracking |
30 |
| Non-load related cracking |
26 |
| Reflection cracking (HMA surfaces only) |
26 |
MEPDG Calibration Database
In March 2009, the APTech team delivered a preliminary MEPDG calibration database to NCDOT for data population. As part of this process, NCDOT was also asked to evaluate and comment on the application of the MEPDG calibration database to meet the data requirements. In addition, NCDOT was asked to provide any additional information that was needed for operation of the MEPDG calibration database by the APTech team. The following provides a summary of comments received from NCDOT on the MEPDG calibration database.
- The preliminary MEPDG calibration database was developed using MS Access 2003®; however, NCDOT is currently using MS Access 2007®. NCDOT updated the MEPDG calibration database to the newer version of MS Access.
- The MEPDG calibration database contains thirty-one NCDOT projects consisting of a mix of older asphalt, newer asphalt, rehabilitated/resurfaced asphalt, and JPCP. The listing of projects, according to pavement type, is shown in table 35.
Table 35. Projects by pavement type.
| Pavement Type |
No. of Projects |
| New asphalt (constructed in1993) |
9 |
| New asphalt (constructed in 1999) |
10 |
| Asphalt (thin layer thickness) |
3 |
| Asphalt (overlay projects) |
3 |
| Concrete |
6 |
- NCDOT developed and provided to the APTech team all of the MEPDG project files (*.DGP) for each project identified in table 34. These files allowed the project team the ability to verify or clarify the project input data as needed.
- NCDOT also provided the APTech team all climate files (*.HCD) for the state of North Carolina. The climatic files were generated for all identified projects based on the latitude and longitude of the projects midpoint location. Hourly climate data was unavailable and therefore excluded from the MEPDG calibration database.
- Upon review of the Highway Construction and Materials System (HiCAMS), it was discovered that much of the detailed construction and material data had been deleted three years after project completion for the majority of the projects; this is especially true for the concrete pavement projects. Though this data may be available in other NCDOT paper records, it was determined that it would require an unreasonable time commitment to obtain these files for this project.
- NCDOT determined that the MEPDG calibration database template originally provided by the APTech team was not conducive to data entry and did not adequately follow relational database design. All database fields were set to integer values, where many of the inputs also included text or decimal fields. Significant time was required to modify and improve the MEPDG calibration database to meet NCDOT data entry and relational database design requirements. The modified MEPDG calibration database by any means is not perfect; ideally NCDOT would like to have coded a few behaviors in that would have simplified the data entry and viewing process.
- NCDOT populated the MEPDG calibration database with the best available pavement condition data.
- Water table data is not available and therefore was not included in the MEPDG calibration database.
- Based on the work conducted for this project, NCDOT is discussing the possibilities of capturing additional materials data in the pavement management system. Currently, NCDOT only captures mix type and depth of each layer.
- Asphalt design files were obtained from NCSU. All information in the files had been entered by graduate students at the university as part of a separate NCDOT local calibration research project.
- Many of the values used are MEPDG defaults; however were applicable project specific traffic and material data has been included.
- Very little dynamic modulus (E *) data and no subgrade moduli (MR) data for asphalt projects was available.
- Material data is essentially non-existent for the NCDOT concrete pavement projects. This data was either filed in such a way as to be impossible to find or destroyed due to age. Therefore, the concrete design files were assembled with default values for nearly all inputs.
- AADTT counts for all projects was available; however, default traffic distributions were used on all projects.
- Soil type for each project was available from the pavement design files; however, all other soils data consisted of default values.
Review of NCDOT Data
Upon review of the NCDOT populated MEPDG calibration database, the APTech project team identified the following:
- The MEPDG calibration database was mainly populated with data to conduct calibration at Level 2 for asphalt and JPC pavements. This is a policy decision taken by NCDOT. Other SHAs may formulate similar decisions based on the common pavement types. It may be difficult for a SHA to obtain Level 1 project specific data prior to construction; however, other similar materials sources may be used by a SHA to obtain the data needed for Level 1 calibration.
- The MEPDG calibration database lacks data required for the calibration of CRCP and composite pavements (asphalt over JPCP or CRCP). Both of these pavement types are commonly in the United States (and abroad).
- The MEPDG calibration database contains information on new and rehabilitated asphalt pavements and only newly constructed JPCP (i.e., no JPCP rehabilitation projects).
- The MEPDG calibration database contains traffic data that includes AADT, truck count, and twenty year traffic projection. NCDOT is in the process of assembling MEPDG traffic data on newly constructed projects as part of a separate study.
- As noted previously, the NCDOT collected pavement performance data (i.e., pavement distresses) is not in accordance with the LTPP Distress Identification Manual(FHWA 2003).
MEPDG Calibration Database
The following describes the data contained in the MEPDG calibration database. Though this data is specific to the data definitions contained within the NCDOT pavement management system, it is believed to be applicable to other SHAs since it illustrates the level and amount of data needed for calibration of the MEPDG performance models.
Table 36 describes the data contained in the project reference information table. This table is replicated in all other database tables to ensure that a consistent referencing process is maintained for all data elements.
Table 36. Project reference information.
| Label |
Description |
| PRJCT_ID |
Unique number that identifies each project |
| SCTN_ID |
Unique number that identifies the section within each project |
| Latitude |
Latitude (degree, minute) of the mid-point of each project |
| Longitude |
Longitude (degree, minute) of the mid-point of each project |
| Elevation |
Elevation (ft) of the mid-point of each project |
| H20_Tbl_Dpth |
Depth to water table (ft) |
| Stationing_Type |
Describes the units of measure used for stationing (ft) |
| Stationing_Start |
Stationing of the project begin location (ft) |
| Stationing_End |
Stationing of the project end location (ft) |
| Design_Life |
Original pavement design life (years) |
| Construct_Date |
Date of original pavement construction |
| Overlay_Date |
Date of HMA overlay placement (where applicable) |
| Traffic_Date |
Date roadway was opened to traffic |
| Pavement Type |
Type of pavement (asphalt, JPCP, or CRCP) |
Based on discussion with NCDOT, it was determined that the climatic data contained within the MEPDG would be sufficient for use in the MEPDG calibration process. Therefore, the climatic data for North Carolina that is contained within the MEPDG *.hcd files was not repeated in the MEPDG calibration database. However, if a SHA was interested in adding additional climatic data, the needed data elements are described in table 37.
Table 37. Climatic input descriptions.
| Label |
Description |
| Year |
Year climate data was recorded |
| Month |
Month climate data was recorded |
| Day |
Day climate data was recorded |
| Hour |
Hour climate data was recorded |
| Temperature |
Mean hourly temperature (°F) |
| Wind_Speed |
Mean hourly wind speed (mph) |
| Percent_Sun |
Mean hourly percent sunshine |
| Precipitation |
Mean hourly precipitation (in) |
| Relative_Humidity |
Mean hourly relative humidity |
Table 38 includes a description of each AC material data element. Table 38. AC materials input descriptions.
Table 38. AC materials input descriptions.
| Name |
Description |
| LYR_NBR |
Layer number |
| Effctv_Bndr_Cntnt |
Effective binder content (by weight) |
| Poisson_Ratio |
Poisson’s ratio |
| Existing_Layer |
Existing layer as opposed to a new layer |
| Layer_Thickness |
Layer thickness (in) |
| Air_Voids |
Percent air voids |
| Thermal_Cndctvy |
Thermal conductivity. (BTU/hr-ft-°F) |
| Ref_Temp |
Reference temperature (°F) |
| Unit_Weight |
Total unit weight (pcf) |
| Heat_Capacity |
Heat capacity (BTU/lb-°F) |
| E* |
Dynamic modulus of asphalt mixture (Level 1) |
| Temperature |
Temperature (°F) |
| E*_0_1 |
Dynamic modulus (psi) at 0.1 Hz |
| E*_1 |
Dynamic modulus (psi) at 1 Hz |
| E*_10 |
Dynamic modulus (psi) at 10 Hz |
| E*_25 |
Dynamic modulus (psi) at 25 Hz |
| RTFO_SP |
Superpave binder test data (Level 1 and Level 2) |
| Temperature |
Temperature (°F) |
| G* |
Binder dynamic modulus (Pa) |
| Delta |
Phase angle |
| RTFO_Conv |
Conventional binder properties (Level 1 and Level 2) |
| Temp |
Temperature (°F) |
| Softening_Pnt |
Softening point (P) |
| Abslt_Vscsty |
Absolute viscosity (P) |
| Knmtc_Vscsty |
Kinematic viscosity (CS) |
| Spcfc_Grvty |
Specific gravity |
| Penetration |
Penetration |
| Brkfld_Vscsty |
Brookfield viscosity |
| Gradation |
Gradation properties of asphalt mixture (Level 2 and Level 3) |
| Retained_3/4 |
Cumulative percent retained on the ¾ in sieve. |
| Retained_3/8 |
Cumulative percent retained on the Ǫ in sieve. |
| Retained_ No_4 |
Cumulative percent retained on the #4 sieve. |
| Passing_No_200 |
Percent passing the No sieve. |
| Creep |
Creep compliance properties (thermal cracking). |
| Load_Time |
Loading time (sec). |
| Creep_-4F |
Low temperature (-4 °F). |
| Creep_-14F |
Mid temperature (14 °F). |
| Creep_-32F |
High temperature (32 °F). |
| Binder |
Asphalt binder properties (Level 3). |
| Binder_Type |
Binder Type |
| Binder_Grad |
Binder grade |
| Therm Crk |
Thermal cracking properties |
| Tnsl_Strngth |
Average tensile strength at 14 °F (psi) |
| VMA |
Mixture voids in mineral aggregate (%) |
| Aggrgt_CTC |
Aggregate coefficient of thermal contraction (in/in/°F) |
| Mix_CTC |
Mix coefficient of thermal contraction (in/in/°F) |
Table 39 includes descriptions of each PCC material data element. For much of the PCC materials inputs, NCDOT has limited data. As a result, much of the PCC material (JPCP, NCDOT did not provide any CRCP projects) inputs used the default values provide within the MEPDG.
Table 39. PCC materials input descriptions.
| Name |
Description |
| LYR_NBR |
Layer number |
| Layer_Thickness |
Layer thickness (in) |
| CTE |
Coefficient of thermal expansion (per °F x 10 -6) |
| Existing_Layer |
Existing layer as opposed to a new layer |
| Unit_Weight |
Unit weight (pcf) |
| Therm_Conduct |
Thermal conductivity (BTU/hr-ft-°F) |
| Poisson_Ratio |
Poisson’s ratio |
| Heat_Capacity |
Heat capacity (BTU/lb-°F) |
| Design |
Concrete pavement design features |
| Curl/Warp_Effective_ Temperature_Difference |
Permanent curl/warp effective temperature difference (°F) |
| Joint_Spacing |
Joint spacing (ft) |
| Sealant_Type |
Joint sealant type |
| Dowel_Diameter |
Dowel bar diameter (in) |
| Dowel_Spacing |
Dowel bar spacing (in) |
| Tied_PCC |
Identifies the presence of a tied concrete shoulder |
| Tied_LTE |
Load transfer efficiency of the tied concrete shoulder |
| Widened_Slab |
Identifies the presence of a widened lane |
| Slab_Width |
Width of the widened slab (ft) |
| PCC-Base_Interface |
Level of friction between the base and PCC |
| Base_Erodobility_Index |
Base erodobility index |
| Loss_of_Friction |
Loss of full friction (age in months) |
| Steel_Reinforcement |
Percent steel (%) |
| Reinforcement_Steel_Diameter |
Bar diameter (in) |
| Depth_of_Reinforcement |
Steel depth (in) |
| Base/Slab_Friction_Coefficient |
Base/slab friction coefficient |
| Crack_Spacing |
Mean crack spacing (in) |
| Mix |
Mix design properties |
| Cmnt_Typ |
Cement type |
| Cmntitious_Cntnt |
Cementitious content |
| W/C_Ratio |
Water-cement ratio |
| Ultimate_Shrinkage |
Ultimate shrinkage |
| Reverse_Shrink |
Reverse shrinkage |
| Curing_Type |
Curing type |
| Strength |
Strength properties |
| Age |
Age (yrs) |
| Elstc_Modulus |
Elastic modulus (psi) |
| Modulus_of_Rupture |
Modulus of rupture (psi) |
| Comp. Strength |
Compressive strength (psi) |
| Splt_Tnsle_Strngth |
Split tensile strength (psi) |
Table 40 includes a description of each PCC maintenance data element. Table 40. PCC maintenance input descriptions.
Table 40. PCC maintenance input descriptions.
| Name |
Description |
| Slabs_Transverse_Cracking_Before_Restoration |
Number of transverse cracks prior to restoration |
| Repaired_Slabs_After_Restoration |
Number of transverse cracks after restoration |
| CRCP_Existing_Punchouts |
Number of existing punchouts |
| Dynamic_Modulus_Subgrade_Reaction |
Dynamic modulus of subgrade reaction |
Table 41 includes a description of each unstabilized/stabilized material data element.
Table 41. Unstabilized/stabilized materials input descriptions.
| Name |
Description (and measure where applicable) |
| LYR_NBR |
Layer number |
| Layer_Thickness |
Layer thickness (in) |
| Layer_Type |
Layer type (aggregate base, bedrock, soil, or stabilized subgrade) |
| Last_Layer (semi-infinite) |
Identifies layer as the last layer of the pavement section |
| Bedrock |
Bedrock layer inputs |
| Type |
Soil type |
| Unit_Weight |
Unit weight (pcf) |
| Poisson_Ratio |
Poisson’s ratio |
| Resilient_Modulus |
Resilient modulus (psi) |
| Gradation(for each layer) |
Gradation inputs for each unstabilized/stabilized layer |
| Passing_3_5 |
Mean percent passing 3-½ in screen |
| Passing_3 |
Mean percent passing 3 in screen |
| Passing_2_5 |
Mean percent passing 2-½ in screen |
| Passing_2 |
Mean percent passing 2 in screen |
| Passing_1_5 |
Mean percent passing 1-½ in screen |
| Passing_1 |
Mean percent passing 1 in screen |
| Passing_3/4 |
Mean percent passing ¾ in screen |
| Passing_1/2 |
Mean percent passing ½ in screen |
| Passing_3/8 |
Mean percent passing Ǫ in screen |
| Passing_#4 |
Mean percent passing #4 screen |
| Passing_#8 |
Mean percent passing #8 screen |
| Passing_#10 |
Mean percent passing #10 screen |
| Passing_#16 |
Mean percent passing #16 screen |
| Passing_#20 |
Mean percent passing #20 screen |
| Passing_#30 |
Mean percent passing #30 screen |
| Passing_#40 |
Mean percent passing #40 screen |
| Passing_#50 |
Mean percent passing #50 screen |
| Passing_#60 |
Mean percent passing #60 screen |
| Passing_#80 |
Mean percent passing #80 screen |
| Passing_#100 |
Mean percent passing #100 screen |
| Passing_#200 |
Mean percent passing #200 screen |
| Passing_0_02mm |
Mean percent passing 0.020 mm screen |
| Passing_0_002mm |
Mean percent passing 0.002 mm screen |
| Passing_0_001mm |
Mean percent passing 0.001 mm screen |
| PI |
Plasticity index |
| LL |
Liquid limit |
| Compacted_Layer |
Compacted layer |
| Stabilized |
Inputs for stabilized layer |
| Unit_Wght |
Unit weight (pcf |
| Poisson_Ratio |
Poisson’s ratio |
| Elastic/Resilient_Mod |
Elastic/resilient modulus (psi) |
| Minimum_Mod |
Minimum elastic/resilient modulus (psi) |
| Mod_of_Rupture |
Modulus of rupture (psi) |
| Therm_Cndctvty |
Thermal conductivity (BTU/hr-ft-°F) |
| Heat_Capacity |
Heat capacity (BTU/lb-°F) |
| Strength (for each layer) |
Strength inputs for each unstabilized/stabilized layer |
| k1 |
Regression constants (used for Level 1 calculation of MR) |
| k2 |
Regression constants (used for Level 1 calculation of MR) |
| k3 |
Regression constants (used for Level 1 calculation of MR) |
| Poisson_Ratio |
Poisson’s ratio |
| Ltrl_Pressure |
Lateral pressure |
| Modulus |
Resilient modulus (psi) |
| CBR |
California Bearing Ratio |
| R_Val |
R-Value |
| Lyr_Coefnt |
AASHTO layer coefficient |
| DCP |
Dynamic Cone Penetrometer (mm/blow) |
Table 42 includes a description of the pavement performance data elements for HMA pavements and table 43 includes the PCC pavement performance data elements.
Table 42. Pavement performance input descriptions – HMA.
| Name |
Description |
| HMA Analysis |
Analysis parameters for flexible pavement |
| IRI_Limit |
Terminal IRI limit (in/mi) |
| IRI_Reliability |
Terminal IRI reliability (%) |
| Surface_Down_Limit |
Surface down longitudinal cracking limit (ft/mi) |
| Surface_Down_Reliability |
Surface down longitudinal cracking reliability (%) |
| Bottom_Up_Limit |
Bottom up alligator cracking limit (%) |
| Bottom_Up_Reliability |
Bottom up alligator cracking reliability (%) |
| Thermal_Fracutre_Limit |
Thermal fracture limit (ft/mi) |
| Thermal_Fracture_Reliability |
Thermal fracture reliability (%) |
| Stabilized_Fatigue_Limit |
Chemically stabilized layer fatigue fracture limit (%) |
| Stabilized_Fatigue_Reliability |
Chemically stabilized layer fatigue fracture reliability (%) |
| Total_Deformation_Limit |
Permanent deformation – total pavement limit (in) |
| Total_Deformation_Reliability |
Permanent deformation – total pavement reliability (%) |
| AC_Deformation_Limit |
Permanent deformation – AC only limit (in) |
| AC_Deformation_Reliability |
Permanent deformation – AC only reliability (%) |
Table 43. Pavement performance input descriptions – PCC.
| Name |
Description |
| PCC Analysis |
Analysis parameters for rigid pavements |
| IRI_Limit |
Terminal IRI limit (in/mi) |
| IRI_Reliability |
Terminal IRI reliability (%) |
| Transverse_Crack_Limit |
Transverse cracking limit (% slabs cracked) |
| Transverse_Crack_Reliability |
Transverse cracking reliability (%) |
| Joint_Fault_Limit |
Mean joint faulting limit (in) |
| Joint_Fault_Reliability |
Mean joint faulting reliability (%) |
| Punchouts_Limit |
CRCP existing punchout limit (number of punchouts) |
| Punchouts_Reliability |
CRCP existing punchout reliability (%) |
| Crack_Width_Limit |
Maximum CRCP crack width (in) |
| Crack_LTE_Limit |
Minimum crack load transfer efficiency (%) |
| Min_Crack_Spacing_Limit |
Minimum crack spacing (ft) |
| Max_Crack_Spacing_Limit |
Maximum crack spacing (ft) |
| Maintenance |
Rigid rehabilitation |
| Transverse_Crack_Before |
Before restoration, percent of slabs with transverse cracks plus percent of previously repaired/replaced slabs (%) |
| Transverse_Crack_After |
After restoration, total percent repaired/replaced slabs (%) |
| CRCP_Punchouts |
Number of existing punchouts (per mile) |
| Subgrade_Dynamic_Modulus |
Dynamic modulus of subgrade reaction (psi/in) |
| |
Month modulus of subgrade reaction measured |
Table 44 includes a description of each traffic data element. NCDOT has recommended the use the MEPDG default values for the monthly adjustments factors; therefore, this information is not shown in table 44.
Table 44. Traffic input descriptions.
| Name |
Description |
| AADTT |
Initial two-way average annual daily truck traffic |
| Direction |
Direction of traffic |
| No_Design_Lane |
Number of lanes in the design direction |
| %_Trcks_Dsgn_Dir |
Percent of trucks in the design direction (%) |
| %_Trcks_Dsgn_Lane |
Percent of trucks in design lane (%) |
| Speed |
Operational speed (mph) |
| Growth_Rate |
Traffic growth rate (%) |
| General Traffic Inputs |
|
| Wheel_Location |
Mean wheel location (inches from the lane marking) |
| Trffc_Wander_Stdev |
Traffic wander standard deviation (in) |
| Design_Lane_Width |
Design lane width (ft) |
| Axle Configuration |
|
| Avg_Axle_Width |
Average axle width (edge-to-edge), outside dimension (ft) |
| Dual_Tire_Spacing |
Dual tire spacing (in) |
| Tire_Pressure |
Tire pressure (psi) |
| Axle_Spcing_Tandem |
Tandem axle spacing (in) |
| Axle_Spcing_Tridem |
Tridem axle spacing (in) |
| Name |
Description |
| Axle_Spcing_Quad |
Quad axle spacing (in) |
| Wheelbase |
| Wheelbase_Short |
Average short axle spacing (ft) |
| % Trucks_Short |
Percent of trucks – short axle spacing (%) |
| Wheelbase_Medium |
Average medium axle spacing (ft) |
| % Trucks_Medium |
Percent of trucks – medium axle spacing (%) |
| Wheelbase_Long |
Average long axle spacing (ft) |
| % Trucks_Long |
Percent of trucks – long axle spacing (%) |
| Axle/Truck |
Number of axles/truck |
| Class |
FHWA truck class 4 – 13 |
| Single |
Average number of single axles per truck class |
| Tandem |
Average number of tandem axles per truck class |
| Tridem |
Average number of tridem axles per truck class |
| Quad |
Average number of quad axles per truck class |
| Traffic Volume Adjustment Factors |
| Hour Distrib |
Hourly distribution |
| Midnight – 11:00 PM |
Hourly truck traffic distribution by hour (%) |
| Total |
Sum of hourly distribution (must total 100%) |
| Monthly Adjust |
Monthly adjustments |
| Month |
Month of the year (January – December) |
| Class_1 – Class_13 |
Monthly adjustment factor for each FHWA truck class 1 – 13 |
| Vehicle Distrib |
Vehicle class distribution |
| Class_1 – Class_13 |
AADTT distribution by vehicle class (%) |
| Total |
Sum of AADTT distribution (must total 100%) |
| Axle Load Distribution Factors |
| Single |
Single axle |
| Month |
Month of the year (January – December) |
| Class |
FHWA truck class 1 – 13 |
| Total |
Sum of axle load distribution factors (must total 100%) |
| 3000 – 41000 |
Percent of axles in each load interval (1000 lb increments) |
| Tandem |
Tandem axle |
| Month |
Month of the year (January – December) |
| Class |
FHWA truck class 1 – 13 |
| Total |
Sum of axle load distribution factors (must total 100%) |
| 6000 – 82000 |
Percent of axles in each load interval (2000 lb increments) |
| Tridem |
Tridem axle |
| Month |
Month of the year (January – December) |
| Class |
FHWA truck class 1 – 13 |
| Total |
Sum of axle load distribution factors (must total 100%) |
| 12000 – 102000 |
Percent of axles in each load interval (3000 lb increments) |
| Quad |
Quad axle |
| Month |
Month of the year (January – December) |
| Class |
FHWA truck class 1 – 13 |
| Total |
Sum of axle load distribution factors (must total 100%) |
| 12000 – 102000 |
Percent of axles in each load interval (3000 lb increments) |
Table 45 through table 47 includes a description of each agency data element (HMA, JCP, and CRC, respectively).
Table 45. Agency data input descriptions – HMA.
| Name |
Description (and measure where applicable) |
| CNTY_NBR |
NCDOT county number – value ranges from 1-100 and is based on the alphabetical order of counties |
| RTE_NBR |
NCDOT eight digit route number |
| DIR |
Direction |
| BGN_MLPST_NBR |
Begin milepost number |
| BGN_DES |
Begin description |
| SCTN_LEN |
Length of the survey section |
| END_MLPST_NBR |
End milepost number |
| END_DES |
End description |
| SRVY_YR_NBR |
Survey year number (condition data year) |
| ALGTR_NONE_PCT |
Percent of route with no alligator cracking – stored number is percent/10 |
| ALGTR_LOW_PCT |
Percent of route with no low severity alligator cracking – stored number is percent/10 Measure– Hairline cracks about ⅛" wide |
| ALGTR_MDRT_PCT |
Percent of route with moderate severity alligator cracking – stored number is percent/10 Measure– May be slightly spalled, about ¼" wide |
| ALGTR_HGH_PCT |
Percent of route with no high severity alligator cracking – stored number is percent/10 Measure– Pieces appear loose, severely spalled, about ⅜" to ½" wide |
| TRNSVRS_CD |
Transverse cracking distress level – (N)one, (L)ight, (M)oderate, (S)evere Measure– L = ¼" wide, no spalling; M = may be spalled, ¼ to ½" wide, 5 to 20 ft apart; S = may be severely spalled, > ½" wide, 1 to 2 ft apart |
| RUT_CD |
Rutting distress level – (N)one, (L)ight, (M)oderate, (S)evere Measure– L = ¼" to < ½" deep; M = ½" to < 1" deep; S = > 1" deep |
| RVL_CD |
Raveling distress level – (N)one, (L)ight, (M)oderate, (S)evere Measure– L = small amounts of stripping, aggregate starting to wear away; M = some stripping is evident and in small areas or aggregate broken away; S = stripping very evident, aggregate accumulation |
| OXDTN_CD |
Transverse cracking level – (N)one, (S)evere Measure– N = not present; S = present |
| BLD_CD |
Bleeding distress level – (N)one, (L)ight, (M)oderate, (S)evere Measure– L = present on 10 to 25% of section; M = present on 26 to 50% of section; S = present on > 50% of section |
| PTCH_CD |
Patching distress level – (N)one, (L)ight, (M)oderate, (S)evere Measure– L = present on 6 to 15% of section; M = present on 16 to 30% of section; S = present on greater than 30% of section |
| Name |
Description (and measure where applicable) |
| RIDE_CD |
Ride distress level – (N)one, (L)ight, (M)oderate, (S)evere Measure– L = minimum tire noise, isolated bumps/dips (up to ¼ of the section); M = ¼ to ½ of section is uneven with bumps/dips/ruts; S = more than ½ section is uneven and bumpy |
| ADT_NBR |
Average daily traffic for the section |
| FAS_CD |
Federal aid status (largely a deprecated field) |
| RTG_NBR |
NCDOT composite rating number – calculated from the above distress fields |
| SYS_CD |
Route type |
| RSRFC_YR_NBR |
Last known resurface year (not used for interstates) |
| RSRF_THCKNS_NBR |
Last known resurface thickness (not used for interstates) |
| SBDVSN_RRL_CD |
Subdivision or rural route CD |
| SCTN_CST_AMT |
Estimate treatment cost to repair section based on current distresses |
| LANE_MILE_CST_AMT |
Estimated treatment cost per lane mile to repair section based on current distresses |
| PVMT_TYP_CD |
Pavement type code Measure– P = plant mix, B = bituminous surface treatment, S = slurry seal |
| PVMT_WID |
Pavement width |
| LANE_NBR |
Number of lanes |
| SHLDR_CD |
Shoulder type Measure– P = plant mix, B = bituminous surface treatment, S = slurry seal, U = unpaved |
| SHLDR_WID |
Shoulder width |
| CURB_GTR_CD |
Curb and gutter indicator Measure– Y = on both sides; N = on one side only |
| MIN_IRI_NBR |
Minimum IRI number in the section |
| MAX_IRI_NBR |
Maximum IRI number in the section |
| AVG_IRI_NBR |
Average IRI number in the section |
| IRI_YR_NBR |
Year IRI data was collected |
Table 46. Agency data input descriptions – JCP.
| Name |
Description (and measure where applicable) |
| CNTY_NBR |
NCDOT county number – value ranges from 1-100 and is based on the alphabetical order of counties |
| RTE_NBR |
5 digit route number |
| DIR |
Cardinal direction |
| BGN_MLPST_NBR |
Begin milepost number |
| END_MLPST_NBR |
End milepost number |
| SRVY_YR_NBR |
Survey year number (condition data year) |
| BGN_DES |
Begin description |
| END_DES |
End description |
| LANE_NBR |
Number of lanes |
| CURB_GTR_CD |
Curb and gutter indicator Measure– Y = on both sides; N = on one side only |
| JNT_SPCG_NBR |
Joint spacing (ft) |
| SLAB_NBR |
Number of slabs surveyed |
| PVD_SHLDR_CD |
Paved shoulder type Measure– P = plant mix, B = bituminous surface treatment, S = slurry seal |
| PVD_SHLDR_WID |
Paved shoulder width |
| PVD_SHLDR_CNDTN_CD |
Paved shoulder condition Code (N, L, M, S) Measure– Asphalt: L = good condition; M = acceptable condition, some cracking ¼" to ½" wide; S = unacceptable condition, cracking > ¼" wide, edge breaking away Concrete: L = good condition; M = Cracks < ⅛" wide, light to moderate spalling; S = cracks over ⅛" wide, unstable material, faulting > ¼" |
| UNPVD_SHLDR_WID |
Unpaved shoulder width (ft) |
| SRFC_WEAR_NONE_PCT |
Percent of pavement with no detectable surface wear |
| SRFC_WEAR_LGHT_PCT |
Percent of pavement with low levels of detectable surface wear Measure– Texture worn away with < 25% visible aggregate, small popouts may be visible |
| SRFC_WEAR_MDRT_PCT |
Percent of pavement with moderate levels of detectable surface wear Measure– Texture worn away with 25 to 50% visible aggregate, small extensive popouts may be present |
| SRFC_WEAR_SVR_PCT |
Percent of pavement with high levels of detectable surface wear Measure– Texture worn away with > 50% visible aggregate, large extensive popouts may be present |
| PMPG_NBR |
Number of joints exhibiting pumping |
| LNGTDNL_LGHT_NBR |
Number of slabs with low severity longitudinal cracking Measure– Crack widths < ⅛", no spalling or faulting |
| LNGTDNL_MDRT_NBR |
Number of slabs with moderate severity longitudinal cracking Measure– Crack widths ⅛" to ½", spalling less than 3", or faulting up to ½", may be sealed |
| LNGTDNL_SVR_NBR |
Number of slabs with high severity longitudinal cracking Measure– Crack widths > ½", spalling greater than 3", or faulting greater than ½" |
| CRNR_LGHT_NBR |
Number of slabs with low severity corner breaks Measure– Cracks well sealed or hairline, no faulting, spalling or break-up |
| CRNR_MDRT_NBR |
Number of slabs with moderate severity corner breaks Measure– Low to medium severity spalling, faulting < ½", no pieces broken |
| CRNR_SVR_NBR |
Number of slabs with high severity corner breaks Measure– Moderate to severe spalling, faulting > ½", broken into two or more pieces |
| SPLL_LGHT_NBR |
Number of slabs with low severity spalls Measure– Spalls < 3" wide |
| SPLL_MDRT_NBR |
Number of slabs with moderate severity spalls Measure– Spalls 3" to 6" wide |
| SPLL_SVR_NBR |
Number of slabs with high severity spalls Measure– Spalls > 6" wide |
| TRNSVRS_LGHT_NBR |
Number of slabs with low severity transverse cracking Measure– Crack widths < ⅛", no spalling or faulting |
| TRNSVRS_MDRT_NBR |
Number of slabs with moderate severity transverse cracking Measure– Crack widths ⅛" to ½", spalling less than 3", or faulting up to ½", may be sealed |
| TRNSVRS_SVR_NBR |
Number of slabs with high severity transverse cracking Measure– Crack widths > ½", spalling greater than 3", or faulting greater than ½" |
| SEAL_LGHT_NBR |
Number of seals exhibiting light deterioration Measure– Exists on < 10% of joint |
| SEAL_MDRT_NBR |
Number of seals exhibiting moderate deterioration Measure– Exists on 10 to 50% of joint |
| SEAL_SVR_NBR |
Number of seals exhibiting severe deterioration Measure– Exists on > 50% of joint |
| FALT_NBR |
Average faulting in the survey section |
| ADT_NBR |
Average daily traffic for the section |
| RTG_NBR |
NCDOT composite rating number – calculated from the above distress fields |
| RIDE_CD |
Ride distress level – (N)one, (L)ight, (M)oderate, (S)evere Measure– L = few bumps and dips, joints are fairly smooth; M = some joints appear faulted, joints or cracks cause bumps and unevenness; S = most joints severely faulted, cracks cause unevenness and surface may be broken, cracked or worn away |
| MIN_IRI_NBR |
Minimum IRI number in the section |
| MAX_IRI_NBR |
Maximum IRI number in the section |
| AVG_IRI_NBR |
Average IRI number in the section |
| IRI_YR_NBR |
Year IRI data was collected |
Table 47. Agency data input descriptions – CRC.
| Name |
Description |
| SRVY_YR_NBR |
Survey year number (condition data year) |
| CNTY_NBR |
NCDOT county number. Value ranges from 1-100 and is based on the alphabetical order of counties |
| RTE_NBR |
5 digit route number |
| DIR |
Cardinal direction |
| BGN_MLPST_NBR |
Begin milepost number |
| BGN_DES |
Begin description |
| END_MLPST_NBR |
End milepost number |
| END_DES |
End description |
| LANE_NBR |
Number of lanes |
| CURB_GTR_CD |
Curb and gutter indicator |
| PVD_SHLDR_CD |
Paved shoulder type Measure– P = plant mix, B = bituminous surface treatment, S = slurry seal. |
| PVD_SHLDR_WID |
Paved shoulder width |
| PVD_SHLDR_CNDTN_CD |
Paved shoulder condition code (N, L, M, S) |
| UNPVD_SHLDR_WID |
Unpaved shoulder width |
| UNPVD_SHLDR_CNDTN_CD |
Unpaved shoulder condition code (N, L, M, S) |
| SHLDR_DRPOFF_CD |
Shoulder drop-off severity (N, L, M, S) |
| SHLDR_LANE_JNT_CD |
Shoulder and travel lane joint condition (N, L, M, S) |
| CNCRT_PTCH_GOOD_NBR |
Number of good quality concrete patches in the survey section |
| CNCRT_PTCH_FAIR_NBR |
Number of fair quality concrete patches in the survey section |
| CNCRT_PTCH_POOR_NBR |
Number of poor quality concrete patches in the survey section |
| ASPHLT_PTCH_NBR |
Number of asphalt patches |
| SRFC_WEAR_NONE_PCT |
Percent of pavement with no detectable surface wear |
| SRFC_WEAR_LGHT_PCT |
Percent of pavement with low levels of detectable surface wear |
| SRFC_WEAR_MDRT_PCT |
Percent of pavement with moderate levels of detectable surface wear |
| SRFC_WEAR_SVR_PCT |
Percent of pavement with high levels of detectable surface wear |
| PMPG_NBR |
Number of joints exhibiting pumping |
| RIDE_GOOD_PCT |
Percent of pavement with good ride quality |
| RIDE_FAIR_PCT |
Percent of pavement with fair ride quality |
| RIDE_POOR_PCT |
Percent of pavement with poor ride quality |
| LNGTDNL_LGHT_LEN |
Total length of low severity longitudinal cracking in the survey section |
| LNGTDNL_MDRT_LEN |
Total length of moderate severity longitudinal cracking in the survey section |
| LNGTDNL_SVR_LEN |
Total length of high severity longitudinal cracking in the survey section |
| TRNSVRS_MDRT_NBR |
Number of moderate severity transverse cracks |
| TRNSVRS_SVR_NBR |
Number of high severity transverse cracks |
| PNCH_LGHT_NBR |
Number of low severity punch-outs |
| PNCH_MDRT_NBR |
Number of moderate severity punch-outs |
| PNCH_SVR_NBR |
Number of high severity punch-outs |
| NRW_CRCK_NBR |
Total length of narrow cracks in the survey section |
| Y_CRCK_NBR |
Total length of y-cracks in the survey section |
| ADT_NBR |
Average daily traffic for the section |
| RTG_NBR |
Not calculated for CRC pavements |
| MIN_IRI_NBR |
Minimum IRI number in the section |
| MAX_IRI_NBR |
Maximum IRI number in the section |
| AVG_IRI_NBR |
Average IRI number in the section |
| IRI_YR_NBR |
Year IRI data was collected |
Summary
The development of a MEPDG calibration database is essential for the calibration and validation of the MEPDG performance models using pavement management data. This is necessary not only for the initial calibration/validation process, but will be critical for future updates and modifications.
A preliminary MEPDG calibration database was provided to NCDOT by the APTech research team that contained all of the data elements identified in the preliminary framework. The NCDOT pavement management group reviewed the preliminary MEPDG calibration database and determined that a number of changes (e.g., storage of input values, addition of NCDOT specific data, database structure) would be necessary to adequately address the various data collection/storage needs of the NCDOT. Based on discussion with the APTech research team, it was determined that it would be more efficient for the NCDOT pavement management group to modify the MEPDG calibration database to meet the data and formatting needs of the NCDOT.
This chapter has documented the verification of input and pavement performance data for NCDOT pavement sections to be used in the MEPDG calibration process. A total of thirty-one projects, consisting of nineteen new asphalt pavement sections, three thin asphalt pavement sections, three asphalt overlay sections, and six new JPCP sections, have been entered into the MEPDG calibration database. In addition, NCDOT has populated the MEPDG calibration database with all available project, materials, construction, and traffic data. NCDOT has also determined that the climatic files contained within the MEPDG are sufficient for the calibration process.
The APTech team has reviewed the MEPDG calibration database and found that it meets the framework for this project.
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