Pavement Condition Survey, Testing & Evaluation of DFW International Airport Cargo Ramp: Conducted by The Transtec Group A testing and evaluation plan for the Evergreen cargo ramp at the Dallas-Fort Worth (DFW) International Airport was developed by The Transtec Group Pavement Engineering Firm. Based on their evaluation, the DFW Airport can determine whether the existing pavement is suitable for the airport’s needs based on the departure capacity of the ramp or if some structural improvements may be required.
Working with RS&H, Transtec developed a testing and evaluation plan that included a pavement condition survey by RS&H, as well as geotechnical testing and non-destructive deflection testing provided by other firms. Transtec reviewed the data collected and performed engineering calculations to determine the feasibility of using the existing ramp to support loading from Boeing 747-8 aircraft. The results of this pavement analysis were submitted to the DFW Airport to assist in their evaluation of the feasibility of the proposed project. The findings were primarily used to determine whether the existing pavement is suitable to support the anticipated aircraft operations on the ramp.
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Geotechnical Investigation Testing and Results After evaluating core data from the existing ramp pavement, Transtec found that the ramp pavement is broken up into two primary pavement sections—
1—NORTHERN PORTION (yellow in the figure above)
2—SOUTHERN PORTION (green & red in the figure above)
NORTHERN PORTION composed of:
Approximately 12 to 13 inches of concrete on 8 to 13 inches of cement treated base
Thinner than the southern portion of the pavement—most likely due to the limited anticipated loading from the aircraft in this location
SOUTHERN PORTION composed of:
16 to 17 inches of concrete on 8 to 10 inches of cement treated base
Dynamic cone penetrometer (DCP) tests were used to evaluate the general consistency of the subbase and subgrade. The DCP testing generally suggested a variable subbase layer (lime treated subgrade) with varying thickness ranging from 6 to 8 inches, when present. However, the stiffer subbase layer was not found in all tested locations, indicating that the layer was either impacted by moisture or not present at all. This data was further validated with the non-destructive testing.
Non-Destructive Testing and Results Transtec developed a Heavy Weight Deflectometer (HWD) testing plan based on the guidance of Federal Aviation Administration (FAA) Advisory Circular AC 150/5370-11B and Transtec’s past experience with similar projects. HWD testing was conducted:
• At 172 discrete test locations throughout the ramp
• To evaluate the pavement response to loading
• To test the pavement response by dropping a weight onto a loading plate and measuring the deflection of the pavement structure both under the plate and at several locations away from the plate. The measured deflection allows for characterization and analysis of the current structural performance of the existing pavement
• To better understand the ability of the pavement to sustain the proposed airplane load
• To document potential weaker or problem areas
• Mid-panel testing was done to determine the modulus values of the different pavement layers
• Joint testing was done to determine the load transfer efficiency (LTE)
RS&H conducted a visual pavement condition survey to supplement the other testing and get a better understanding of how the pavement has performed to date. The survey consisted of:
• Dividing the cargo ramp into a grid of 25 sample units
• Conducting a visual survey of the 424 slabs
• Tabulating the frequency and severity of observable pavement distress across the ramp
• Evaluating structural pavement performance from results of this survey used in conjunction with the HWD testing
Conclusion Transtec analyzed the data gathered from the geotechnical survey, non-destructive testing, and pavement evaluation. Transtec conducted backcalculation and load transfer efficiency analysis of the deflection data using FAA’s BAKFAA software along with the procedures outlined in FAA Advisory Circular AC 150/5370-11B. The results from the backcalculation were then combined with the results of the pavement condition survey to evaluate the potential for the pavement to support the anticipated aircraft loading. FAA’s FAARFIELD software was used for this analysis.
The three sections of pavement—the northern, eastern, and western portions—were considered separately in the analysis due to differences in pavement thickness and deflection data. Since the actual number of future operations is unknown, the evaluation was done for multiple scenarios to determine the feasibility of supporting fully loaded 747-8 aircraft.
Based on the evaluation completed by Transtec, the DFW Airport can now determine whether the existing pavement is suitable for their needs based on the departure capacity of the ramp, or if some structural improvements may be required.
For more information, please go to: www.thetranstecgroup.com/the-transtec-group-conducts-dfw-international-airport-cargo-ramp-evaluation/?utm_medium=email&utm_campaign=April%20Newsletter&utm_content=April%20Newsletter+Version+B+CID_be43d547216c45e93c334fe35ae7be64&utm_source=Email%20Campaign%20Monitor&utm_term=Learn%20More