aldot aeronautics: greensboro municipal airport · greensboro municipal airport pavement...

ALDOT Aeronautics:Greensboro Municipal Airport

Pavement Maintenance Program

Pavement Maintenance Program General Plan Overview

ALDOT Aeronautics i December 2010

TABLE OF CONTENTS

General Plan Overview Page

Introduction………………………………………………………………..……… 1 Pavement Maintenance Classifications…………………………….……….…… 1 Airport Site Evaluations…………………………………………………….…….. 2 Airport Evaluation Analysis….…………………….………………….…….…… 3 Pavement Condition Index Diagram 3 Pavement Distress Chart 4 Distress Photographs 5-13 Standard PCI Rating Scale 14 PCI Deterioration & Maintenance Assumptions……………………………..….. 14 Asphalt Deterioration Curve & Rates 15 General Airport Recommendations…………………………………………….… 16 Conclusion…………………………………………………………………….…… 16 References…………………………………………………….……………….….. 17

Greensboro Municipal Airport Pavement Maintenance Program Page

Introduction………………………………………………………………..……… 18 Pavement History…………………………………………………….……….…… 18 PCI Inspection……………………………………………………………….…….. 18 Pavement Sketch 18a Extrapolated Distresses……………………………………………….……….…… 19 Photographs……………………………………………….…………………..…… 20 PCI Prediction……………………………………………….……….……………. 22 Recommended Maintenance Plan & Predictions……………………………..….. 23 PCI Prediction Charts 24a-d Summary………………………………………………………………………….… 25

Appendix A

Airfield Asphalt Pavement Condition Survey Data Sheet


ALDOT Aeronautics 1 December 2010

Introduction In 2008, the Alabama Department of Transportation – Aeronautics Bureau (ALDOT Aeronautics) embarked upon a plan to develop and implement pavement maintenance programs for the purpose of maximizing the lifespan of airfield pavements constructed of asphalt. ALDOT Aeronautics enlisted the services of Garver, LLC to assist in the development of these plans. This program was designed to create a five year pavement maintenance schedule for each subject airport. Pavement Maintenance Classifications As stated in FAA AC 150/5380-6B, while pavement deterioration from “usage and exposure to the environment cannot be completely prevented, a timely and effective pavement maintenance program can minimize this deterioration. Adequate and timely maintenance is the greatest single means of controlling pavement deterioration.” The pavement maintenance program proposed herein is designed to extend the life of the pavement by scheduling rehabilitation activities before the pavement deteriorates beyond the point at which the pavement will need global rehabilitation activities, such as an overlay or reconstruction. The reconstruction of existing pavements is estimated to be 4-5 times more expensive than rehabilitation. There are several types of maintenance activities which can enhance and increase the lifespan of airfield pavements; Localized Preventative Maintenance, Localized Stop-Gap Maintenance, and Global Preventative Maintenance. Localized Preventative Maintenance activities include maintenance in small, localized areas in an effort to prevent further deterioration. Localized Stop-Gap Maintenance activities include small, localized areas of maintenance intended not necessarily to improve the pavement, but to resolve safety issues. Global Preventative Maintenance activities include surface treatments applied to an entire pavement area in an effort to prevent and/or reverse deterioration, and thereby extend the life of the pavement The following pavement maintenance program (PMP) will consist of Localized Preventative Maintenance and Global Preventative Maintenance. The need for Localized Stop-Gap Maintenance will need to be evaluated, and if necessary, performed, by the airport on an as-needed basis. For the purpose of the PMP, pavement maintenance will be defined as proven, routine and low-cost procedures that are performed to extend the useful lifespan of asphalt pavements. Typical pavement maintenance procedures for this program include the following:

1. Localized crack and joint cleaning and sealing 2. Global asphalt rejuvenation 3. Global asphalt slurry-seal 4. Pavement marking application



Airport Site Evaluations Each distinct area of airfield pavement was evaluated separately. Only those taxiway(s), taxilane(s) and aircraft parking ramp(s) that are open to the public were evaluated. Taxiway(s) and/or parking ramp(s) that are used exclusively by an individual airport tenant and/or privately constructed were not subject to evaluation. Automobile parking areas and airport access or internal circulation roads were not included in the evaluation or recommendations. The PMP has been organized into a hierarchical structure as shown below:

1. The Airport, as a whole, is the “Network.” 2. Each Network is subdivided into “Branches”. Each Branch represents a distinct pavement area

on a particular airport in the ASPMP (e.g., primary runway, secondary runway, taxiway(s), aircraft parking ramp(s)).

3. “Sections” represent portions of the pavement area in a particular Branch (e.g., original runway construction, runway extensions, etc.).

4. Each Section includes smaller areas, roughly 5,000 (+/- 2,000) square feet each, called “Sample Units”.

Utilizing sketches and aerial photographs, approximately 10% of the sample units were randomly selected for evaluation before the inspection began. Additional sample units were added during the inspection if warranted. After evaluation, the distresses from each randomly selected Sample Unit were combined and extrapolated over the entire Section for overall results. Within a three-month period during the summer of 2009, Garver trained and sent inspectors to analyze the asphalt runways, taxiways, taxilanes and aprons at Airports across the state of Alabama. Garver’s pavement inspectors worked individually or in teams, depending on the size of the airfield. Some sites required less than a day to inspect, while others demanded two days of inspections. Each inspection included a pavement inventory to verify the pavement’s size and use; pavement history, complete with sponsor and patron interviews (if available); visual assessment and identification; and pertinent photographs.



Airport Evaluation Analysis In evaluating the pavements, Garver used the Pavement Condition Index (PCI) evaluation method developed by the U.S. Army Corps of Engineers. This method involves a non-destructive, visual inspection of the pavement areas. Garver also employed the Corps’ MicroPAVER 6.1 software to catalog and appraise pavements. The PCI method of evaluation of airport pavements concentrates on identifying certain standard asphalt deficiencies or failures that contribute to shortening a pavement’s lifespan. Such deficiencies or failures include, but are not necessarily limited to:

• Surface defects – raveling, flushing and/or polishing • Surface deformations – rutting, distortion, rippling, shoving, settling, and/or frost heave • Cracks – thermal cracks, reflection cracks, slippage cracks, joint/edge cracks, block cracks,

and/or alligator cracks. • Patches and potholes

There are three items which determine the Pavement Condition Index: the distress type, distress severity and distress quantity. The standard for categorizing airfield asphalt distresses is outlined in ASTM D 5340, Standard Test Method for Airport Pavement Condition Index Surveys. This standard is also recommended by the FAA in AC 150/5380-7A Airport Pavement Management Program and AC 150/5380-6B Guidelines and Procedures for Maintenance of Airport Pavements. See Appendix A for a sample Distress Data Sheet as utilized for the airfield evaluations. This form was obtained from the MicroPAVER 6.0 User Manual, Appendix E, page 134.

Distress Type

Pavement Condition

Index (PCI)Distress Severity

Distress Quantity



In performing a PCI inspection, random sample sections from each pavement area are visually inspected for distress types, severity and quantity. These distresses include the following:

Distress Quantity Severity Possible Cause

Alligator Cracking Sq. Ft. Low/Med/High Load. Fatigue failure of the asphalt surface under repeated traffic loading.

Bleeding Sq. Ft. N/A Excessive AC in the asphalt at the time of placement and/or low air-void content.

Block Cracking Sq. Ft. Low/Med/High Climate. Shrinkage of the asphalt and daily temperature cycling.

Corrugation Sq. Ft. Low/Med/High Traffic movements combined with an unstable pavement surface or base.

Depression Sq. Ft. Low/Med/High Settlement of the foundation soils or construction upon uneven base.

Jet Blast Sq. Ft. N/A Bituminous binder has been burned or carbonized by jet blast.

Joint Reflection/Cracking Ft. Low/Med/High Climate. Movement of a PCC slab under the asphalt caused by thermal and/or moisture changes.

Longitudinal and Transverse Cracking

Ft. Low/Med/High Shrinkage of the AC surface due to low temperatures or hardening of the asphalt; poorly constructed paving joints; or reflection of underlying cracks (including those caused by PCC which are not at joints).

Oil Spillage Sq. Ft. N/A Deterioration or softening of pavement surface caused by the spillage of oil, fuel or other solvents.

Patching Sq. Ft. Low/Med/High Utility cuts and patching, etc. Polished Aggregate Sq. Ft. N/A Repeated traffic applications. Weathering/Raveling Sq. Ft. Low/Med/High Climate. The wearing away of the pavement

surface caused by the dislodging of aggregate particles and loss of asphalt or tar binder.

Rutting Sq. Ft. Low/Med/High Load. Consolidation and/or lateral movement of materials due to traffic loading.

Shoving Sq. Ft. Low/Med/High Gradual opening of joints as they are filled with incompressible materials that prevent them from closing.

Slippage Cracking Sq. Ft. N/A Low-Strength surface mix and/or poor bond between the surface and the next layer of the pavement structure.

Swelling Sq. Ft. Low/Med/High Frost action in the subgrade or by swelling soil.



Below are photographs of some of the more common distresses encountered during the pavement inspections, though not necessarily at each airport. Alligator Cracking:



Block Cracking:



Depression:



Joint Reflection Cracking:



Longitudinal & Transverse Cracking:



Oil Spillage:



Patching:



Rutting:



Weathering:



After the evaluation of the airfield, the data was entered into MicroPAVER and each pavement area was rated on a PCI point scale of 0-100. Pavements assigned a PCI of 55 or greater were considered eligible for inclusion in the airfield’s pavement maintenance program. Any pavement ranking less than 55 was considered critical and was recommended for more serious reconstruction efforts. Once these pavements have undergone complete reconstruction or other appropriate rehabilitation, they may be re-evaluated and included in the airfield’s pavement maintenance program.

PCI Deterioration & Maintenance Assumptions In order to plan for future years of the pavement maintenance program, several assumptions were applied involving the effects of maintenance actions and the yearly deterioration of asphalt pavements. Asphalt pavements are generally estimated to have a design life of 20 years. During this 20 year design life, the asphalt pavements tend to deteriorate, losing their elasticity and durability. Traffic loadings and environmental conditions are the two main causes of asphalt deterioration. It is estimated that asphalt pavements deteriorate more with age, and in the absence of excessive traffic loading issues, this deterioration is estimated as follows.

10

0

100

85

70

55

Standard PCI Rating Scale

Very Poor

Serious

Failed

Good

Satisfactory

Fair

Poor40

25



Therefore, as a generalization, it was assumed that pavements within the following PCI ranges will deteriorate at the listed rates. Pavements with a PCI below 55 are not recommended for maintenance; therefore, the deterioration rate of these pavements was not taken into consideration.

The proposed maintenance actions recommended in the pavement maintenance program include crack cleaning & sealing followed by the global application of a rejuvenator or slurry-seal. It is estimated that these maintenance actions will add approximately 3 years of pavement life to the treated areas, which will result in a PCI increase of 4.5-12 points, depending on the age and condition of the pavement at the time of treatment. However, repeated applications of crack cleaning & sealing, rejuvenators and slurry-seals will not return the pavement to new condition These deterioration rates and maintenance assumptions were used to determine the initial schedule for subsequent years of the airfield’s pavement maintenance program; however, as these are just generalizations, it is recommended that all airfield pavements be re-evaluated every four years and the program re-aligned to meet the needs of the airfield.

0102030405060708090100

0 5 10 15 20 25 30

PCI

Asphalt Age (yrs)

Asphalt Deterioration Curve

AC Deterioration

Critical PCI

PCI Range PCI DeteriorationPer Year

100‐90 1.590‐80 2.580‐70 370‐60 3.560‐55 4



General Airport Recommendations Delays in performing pavement maintenance may allow minor distresses to progress into major failures, therefore, in addition to following the enclosed pavement maintenance program, it is also recommended that the airport perform internal pavement inspections on a regular basis and maintain a log of inspections. Routine repairs should be performed as soon as possible or deferred to regular cyclic repair schedules, as necessary. Emergency repairs should be performed immediately. Maintenance items that can and should be regularly addressed include patching, herbicide applications, and blading of pavement edges. It is recommended that the airport perform a daily general inspection of the airfield and that more detailed pavement inspections be conducted twice a year, at a minimum. It is also recommended that inspections be performed after severe storms or any other activities which may adversely affect the pavement, and that the Airport should solicit comments and reports from Airport patrons. The Airport should maintain a log of their pavement inspections and any maintenance performed, including each distress type, severity, location, probable causes, remedial actions and the results of follow-up inspections and maintenance. These files should also contain records of materials and equipment used to perform the maintenance activities for future reference. AC 150/5380-6B, Appendix A outlines a detailed Pavement Management Program that could be tailored to each individual Airport’s needs. Conclusion In Conclusion, the Alabama Department of Transportation – Aeronautics Bureau (ALDOT Aeronautics) has developed the enclosed Pavement Maintenance Program (PMP) for the purpose of maximizing the lifespan of airfield pavements constructed of asphalt. Every 5 years, the airfield should be re-evaluated in accordance with ASTM D 5340, Test Method for Airport Pavement Condition Surveys. This data can then be included in the appropriate MicroPAVER database to further analyze the airfield pavements and plan for future maintenance. It is also recommended that the Airport perform internal regular inspections and routine maintenance.



References ASTM Standard D5340, 2010, “Standard Test Method for Airport Pavement Condition Index Surveys,”

ASTM International, West Conshohocken, PA 2003, DOI:10.1520/D5340-10, www.astm.org.

Shahin, M. Pavement Management for Airports, Roads, and Parking Lots, Second Edition. New York,

NY. Springer, 2005.

Shahin, M. (2007). MicroPAVER 6.0 [computer software]. U.S. Army Corp of Engineers.

U.S. Depatrment of Transportation. Federal Aviation Administration. Advisory Circular 150/5380-6B,

Guidelines and Procedures for Maintenance of Airport Pavements, current edition.

U.S. Depatrment of Transportation. Federal Aviation Administration. Advisory Circular 150/5380-7A,

Airport Pavement Management Program, current edition.

Greensboro Municipal Airport

Pavement Maintenance Program

December 2010

Prepared by:

ALDOT Aeronautics Bureau &

Pavement Maintenance Program Greensboro Municipal Airport – Greensboro, AL


Introduction As part of the Alabama Department of Transportation’s Pavement Maintenance Program, Garver, LLC conducted a PCI Evaluation of the Greensboro Municipal Airport in Greensboro, Alabama. The purpose of this evaluation was to determine how best to extend the life of the airfield pavements. Using the available pavement history, PCI Inspection, and extrapolated distresses, both the current and predicted PCI’s were determined. The following is a summary of that inspection and a compilation/evaluation of the data obtained. Pavement History No pavement history records were available at the time of inspection. PCI Inspection Garver, LLC conducted the initial PCI Inspection of the Greensboro Municipal Airport on July 21, 2009. During the inspection, several types of asphalt deficiencies were identified, including: Alligator Cracking, Block Cracking, Depressions, Longitudinal & Transverse Cracking and Weathering. Please see the attached sketch to locate each Branch/Section of asphalt.



Extrapolated Distresses To calculate the extrapolated distresses, the average density of each distress per sample unit is determined, then that density is multiplied by the area of the entire branch. These extrapolated distresses are then used to calculate the PCI. Following is a listing of each distress type identified as it was extrapolated across the entire surface area of the associated branch at the Greensboro Municipal Airport.

Branch ID: RW

Distress Description SeverityExtrapolated

Quantity Units BLOCK CRACKING M 13,833.00 SqFt BLOCK CRACKING L 20,136.00 SqFt LONG & TRANS CRACKING M 1,208.00 Ft LONG & TRANS CRACKING L 11,463.00 Ft WEATH/RAVEL L 4,996.00 SqFt Branch ID: TW1 BLOCK CRACKING L 1,044.00 SqFt LONG & TRANS CRACKING M 27.00 Ft LONG & TRANS CRACKING L 303.00 Ft WEATH/RAVEL L 143.00 SqFt Branch ID: TW2 BLOCK CRACKING M 4,185.00 SqFt DEPRESSION H 15.00 SqFt LONG & TRANS CRACKING M 41.00 Ft LONG & TRANS CRACKING L 54.00 Ft Branch ID: AP ALLIGATOR CRACKING L 251.00 SqFt BLOCK CRACKING H 11,290.00 SqFt DEPRESSION M 335.00 SqFt LONG & TRANS CRACKING L 1,736.00 Ft WEATH/RAVEL L 9,784.00 SqFt



Photographs The following photographs were taken during the initial PCI inspection of the Greensboro Municipal Airport on July 21, 2009.

Runway 18-36. Southern End. Sample Unit RW-1.

Taxiway 1 (Southern Taxiway). Sample Unit TL-1.



Taxiway 2 (Northern Taxiway). Sample Unit TL-2.

Apron. Sample Unit AP-1.



PCI Prediction Based on the locations and quantities of these various asphalt distresses, the following Pavement Condition Index (PCI) has been calculated for each Branch.

Number of Sum Section Avg Section True Area PCI Weighted Branch ID Sections Length Width (SqFt) Use Average Standard Average

(Ft) (Ft) PCI Deviation PCI AP (Apron) 1 754.00 50.00 49,651.00 APRON 27.00 0.00 27.00RW (Runw ay 18-36) 1 3,513.00 79.00 277,527.00 RUNWAY 71.00 0.00 71.00TW1 (Taxiw ay 1) 1 127.00 35.00 6,843.00 TAXIWAY 66.00 0.00 66.00TW2 (Taxiw ay 2) 1 135.00 45.00 6,075.00 TAXIWAY 39.00 0.00 39.00

Pavement Database: Greensboro Network ID: Grensboro

As previously stated, pavements with a PCI lower than 55 are deemed beyond the scope of the maintenance program; such pavements will need to be repaired by other means in order to be eligible for the Pavement Maintenance Program in the future.

27.00

71.00

66.00

39.00

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

PCI

Branch ID

Branch Condition

Apron 1

Runway 18-36

Taxiway 1

Taxiway 2



Based on the pavement history and initial PCI Inspection of the Greensboro Municipal Airport on July 21, 2009, the following predictions were made for the airfield pavements. According to MicroPAVER’s prediction model, without additional maintenance, the runway will deteriorate to below the critical PCI of 55 by the year 2014, and the north connector taxiway, Taxiway 1, will deteriorate to below the critical PCI by 2012. The apron and Taxiway 2 were already past the critical PCI at the time of their inspection and are recommended for complete re-construction. Recommended Maintenance Plan & Predictions Based on the PCI Inspection and these extrapolated distresses, the following actions are recommended:

Branch MaintenanceGlobal

Preventative Maintenemce

Total Estimated Cost

Predicted Initial PCI

Predicted Final PCI

Runway 18-36 Preventative. Crack Sealing, etc. Rejuvenator $82,980.00 60.2 71.98Taxiway 1 Preventative. Crack Sealing, etc. Rejuvenator $2,243.00 54.44 67.05

Estimated Total $85,223.00

2012 Recommended Maintenance





Predicted Final PCI

Runway 18-36 Preventative. Crack Sealing, etc. None. $16,364.00 68.55 69.26Taxiway 1 Preventative. Crack Sealing, etc. None. $586.00 63.36 64.12







Predicted Final PCI










Predicted Final PCI








Predicted Final PCI

Runway 18-36 Preventative. Crack Sealing, etc. None. $31,892.00 59.58 60.38Taxiway 1 Preventative. Crack Sealing, etc. None. $1,010.00 53.78 54.63



As the inspected PCI of the apron and Taxiway 2 were below the critical PCI, these Branches will not be included in the recommended work plan. These Branches are recommended for global rehabilitation, as maintenance actions will not be sufficient to rehabilitate these pavements. Attached are copies of the predicted PCI charts. Each chart shows the predicted PCI value of the subject pavement assuming that no maintenance or repairs are performed, while also illustrating the predicted PCI should the above recommended maintenance items be performed.

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Summary The purpose of establishing a pavement maintenance program is to extend the useable life of the pavement. By evaluating the existing pavement and predicting the future condition, we can more accurately develop a plan that will effectively and economically increase the lifespan of airfield pavements.

Branch 5-year cost

Runway 18-36 $178,564.00Taxiway 1 $5,412.00 4

Additional Years of Pavement Life

4

In conclusion, by performing the recommended maintenance items as scheduled during the first 5 years of the plan, the Airport can expect to gain an additional 4 years of pavement life from the runway and Taxiway 1.

Appendix A

PID INSPECTORNAME

FROM BRANCHUSE

DATEINSPECTED

TO SECTION WIDTH SECTIONLENGTH

41. Alligator Cracking Sq Ft 45. Depression Sq Ft 49. Oil Spillage Sq Ft 53. Rutting Sq Ft

42. Bleeding Sq Ft 46. Jet Blast Sq Ft 50. Patching Sq Ft 54. Shoving from PCC Sq Ft

43. Block Cracking Sq Ft 47. Jt. Reflection (PCC) Ft 51. Polished Aggregate Sq Ft 55. Slippage Cracking Sq Ft

44. Corrugation Sq Ft 48. Long. & Trans. Cracking Ft 52. Raveling/Weathering Sq Ft 56. Swell Sq Ft

DISTRESSCODE L M H

SAMPLENUMBER

SAMPLEAREA

SAMPLENUMBER

SAMPLEAREA

DISTRESSCODE L M H DISTRESS CODE L M H

AIRFIELD ASPHALT PAVEMENT CONDITION SURVEY DATA SHEET

AC Surfaced Distress Codes

Sketch / CommentsSAMPLEAREA

SAMPLENUMBER

MicroPAVER 6.0 User ManualAppendix E - pg. 134

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