Long line of Kennedy

Paving Article April 13, 2010
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At 14,572 ft long, Runway 13R-31L is the longest runway at John F. Kennedy International Airport (JFK) and the second-longest commercial runway in North America.

The runway’s original construction consisted of 12 in. of portland cement concrete (PCC) on 6 in. of stone screenings placed 200 ft wide and 10,000 ft long. The runway was placed into service in 1947. Two separate contracts in 1958 extended the runway to its current length using 12 in. of PCC on 6 in. of stone screenings placed 150 ft wide. Subsequent contracts strengthened the runway for the arrival of the Boeing 747 by paving a hot-mix asphalt (HMA) overlay on the existing PCC surface.

The last major rehabilitation of Runway 13R-31L was in 1993. The existing HMA surface was milled and overlaid with an HMA surface course, and the runway centerline and leadoff lights were adjusted to final grade after the paving. Nightly runway closures were used to accomplish the construction, with the runway returning to service each day. With average annual operations exceeding 120,000 departures and 21,000 arrivals, the expected service life for this rehabilitation was 10 to 12 years. This is consistent with other HMA runways at JFK.

The JFK Airport Pavement Management System (MicroPAVER) predicted a pavement condition index rating of “poor” for 2004. During biannual visual inspections, pavement engineers observed longitudinal and transverse cracks, raveling and oxidation, consistent with the “poor” predicted pavement condition index, and a pavement rehabilitation contract was required.

Since the next scheduled rehabilitation was postponed while a long-term plan for the runway and the associated taxiway system was being developed, an interim repair was performed in 2004. This repair consisted of milling and overlaying with HMA approximately 2,500 ft of the runway’s 50-ft keel section in the touchdown zone and crack sealing the open joints.

In anticipation of the next major repaving contract, and the need for JFK to maximize the efficiency of its runway and taxiway system, a multiyear study was initiated and completed in 2007. This study, titled “Design Options and Functional Program Development for Rehabilitation of Runway 13R-31L at John F. Kennedy International Airport and Cost/Benefit Analysis for Planned Fillet Modifications at Selected Taxiway Intersections,” developed a new conceptual plan for the runway and associated taxiways to maximize capacity and minimize delays.

In general, the conceptual plan included widening the runway from 150 ft to 200 ft to conform to the Federal Aviation Administration (FAA) Design Group VI standards, construction of 40-ft-wide shoulders and 40-ft-wide jet-blast erosion pavements, improved taxiway fillets, the relocation of the 13R threshold and the incorporation of new taxiways into the construction. These improvements will increase runway operational efficiencies, reduce taxiway delays and allow the runway to accommodate the A380 jumbo jet and future Group VI aircraft without operational restrictions.

In addition, the runway would receive a new storm drainage system compliant with the new New York state storm-water regulations and a new electrical infrastructure including the infrastructure for future runway status lights. Approximately 100 acres of grass within the runway’s safety area would be regraded, positively drained and seeded to mitigate bird hazards. Approximately 7.5 acres of artificial turf would be placed in areas subject to high jet blast.

Portland authority

Using the conceptual plan as a base, a constructability study was initiated and completed by the Port Authority of New York and New Jersey during the summer of 2007. This study investigated traditional HMA rehabilitation as well as the placement of a PCC overlay on top of the existing HMA surface. Both options included the construction of HMA shoulders and jet-blast erosion pavements. The main focus of this study included the initial construction cost, the life-cycle cost, construction staging and the construction duration for both options.

The constructability study revealed that while the initial construction cost of a typical mill and HMA overlay was approximately 28% less than paving with PCC, the 40-year life-cycle savings was approximately 17% if using PCC. Using nightly runway closures and returning the runway to daily service, it was determined that the HMA rehabilitation and widening would take approximately 30 months. The nightly closure option was deemed not practicable for use with PCC construction. The only feasible method for paving with PCC was to implement an extended runway closure.

The PCC staging options included a four-stage plan where the entire runway would be closed for 120 days. At the end of the first stage, 10,700 ft on the western portion of the runway would be returned to service, enough length to accommodate all aircraft serving JFK, including the Airbus A380. This section would remain open during the subsequent stages. The second stage would close the perpendicular runway, 4L-22R, for 14 days to complete the intersection of these two runways. The third stage would complete the remaining 1,900 ft of the runway.

To minimize the amount of construction required during the runway closures, both the HMA and PCC options placed the construction of large portions of the drainage and electrical systems in the fourth stage. This stage is located outside of the runway safety area, thereby allowing construction before and after the runway closures. Also, all long-lead items necessary for the construction within the runway safety area were required to be onsite before the runway would be closed.

At the completion of the constructability study a series of briefings were held with the airlines and the FAA to present the study’s findings and to get their buy-in to the final plan. The major concern expressed during these briefings dealt with the uncertainty of getting the runway placed back into daily service if the nightly closure option was chosen. A delay in the runway’s return to service causes airline delays. Based upon the feedback from these sessions, the life-cycle costs and the fact the PCC option would, in essence, be a new runway with minimal maintenance, the PCC option was chosen.

View from a FAAR

As with any major construction project, there were literally hundreds of details, design solutions and logistics that needed to be investigated and designed. Focusing on the concrete pavement, using the FAA design program FAARFIELD, the final design for the runway is to place 18 in. of PCC on the milled runway surface and 20 in. of PCC on an open-graded HMA base for the concrete taxiways. Approximately 192,000 cu yd of PCC, 198,000 tons of HMA and 2,400 lights will be used on the runway and associated taxiways.

The runway will be milled 6 in. to limit the increase in elevation of the runway edge line after the placement of 18 in. of PCC. Preliminary profiles indicated that by limiting the edge-line elevation increase to 12 in. allowed for the transition to the existing parallel taxiways’ elevation to occur within the cross taxiways, minimizing the impact on operations. The milled surface specified has stringent grade tolerance and texture criteria. The contract specified that the milled surface be whitewashed to allow the PCC slabs to move freely on the surface and to cool the HMA before PCC placement during hot weather.

The slab size is 25 ft × 25 ft. The slabs are doweled in both directions using 11?2-in. dowels, 20 in. long, spaced at 18 in. on center. Premolded joint sealer was chosen for the joints due to their durability and proven performance at JFK. The contract was designed to allow the PCC to be placed either by slipforming or by side forms. The option was left to the contractor to permit flexibility during construction to meet the contract’s schedule requirements.

Of particular interest to a PCC runway project is the concrete mix itself. The contract required that the PCC paving be supplied from an onsite plant to provide a continuous supply of concrete as well as to reduce the amount of trucking required on the public roadway system. The contractor opted for a twin-barrel central mix plant. A contingency plan is in place, which incorporates an additional onsite batch plant and a local ready-mix supplier. The mix consists of 550 lb total cementitious materials, including blended type I-S cement. The blend is 58% portland cement, 319 lb; and 42%, 231 lb, of ground-granulated blast furnace slag. The introduction of slag to the mix has the added benefit of reducing the PCC’s carbon footprint.

The fine aggregate content is 1,190 lb, and the coarse aggregate is a blend of ASTM C-33 No. 3, No. 57 and No. 8 stone. The combination of fine and coarse aggregate makes up 71% of the overall mix volume. Provisions are included in the contract for barging the aggregates to the work site. To control shrinkage cracking, the contract documents specified that the PCC mix is required to have an absolute drying shrinkage of less than 0.04% at 28 days when tested in accordance with ASTM C-157. The result obtained for this mix was 0.021%.

This mix will be used for both the slipform and side-form operations with water and a high-range water reducer used to adjust workability. The Port Authorities Materials Engineering Unit will perform the quality acceptance testing. Results will be evaluated on a lot/sublot basis.

Payments, incentives and penalties will be calculated and evaluated using a statistical pay-for-performance specification. The primary criterion for payment is flexural strength of 700 psi, which must obtain a minimum of 95% within limits. Other properties that are evaluated for incentive payment consideration are air, water/cement ratio (microwave oven drying AASHTO T 318) and coulombs permeability (AASHTO T 277). Cylinders for compressive strength, slump, unit weight and temperature also will be tested and monitored on an ongoing basis but are not part of the payment calculation.

Taking the test

One of the most important elements of this project was the construction of a test section. The test section was designed to test the materials specified, construction methods and schedule.

The test section chosen for this project was the new taxiway KC. This taxiway is a 1,000-ft-long and 100-ft-wide PCC surface with 40-ft-wide HMA shoulders and jet-blast pavements. The test section included excavation, milling, grooving, pavement markings, joint sealing and relocation of a patrol road, the taxiway safety area grading, seeding and drainage. In addition, the electrical items included the installation and testing of centerline lights, guidance signs and electrical infrastructure.

The test section construction was completed in November 2009 and was instrumental in getting everyone on the team familiar with acceptable construction methods, quality control and assurance methods and testing, safety and security requirements, and operating in an airport environment.

Thirteen of the 14 lots tested achieved an incentive payment of 6% in accordance with all statistical performance specifications. The 14th was paid at full price.

All the flexural strengths met the required minimum of 95% within limit. To qualify for an incentive payment, the air, water and permeability also were tested and evaluated. The average results were as follows:

Flexural strength @ 28 days: 1,072 psi (7,370 psi compressive strength);

Air content: 4.7%; and

Coulomb permeability: 798 (cored from beams cured seven days @ 73°F and 21 days at 100°F).

A series of lessons-learned meetings were held after the completion of the test section through January 2010, with participation from Port Authority of NY & NJ’s Engineering Design, Construction and Materials divisions’ staff, JFK operations staff and contractor representatives. Some of these sessions were moderated by an outside consultant and covered design, operational and construction issues that arose during the test section and project startup.

The schedule allowed for 31?2 months of time between the completion of the test section and the start of the 120-day closure. All parties agreed that the construction of a large, fully functional test section and the 3½-month preparation period was essential to moving forward. In addition, the expectations from both the contractor and the Port Authority of NY & NJ on how the remaining portion of this contract was to be executed were worked out during these meetings.

June, September, November

The next major milestone occurs on June 28, 2010, when the western-most 10,700 ft of the runway will be returned to service. The paving of the intersection of the two runways is scheduled for a 14-day continuous closure in September 2010. Between these two milestone dates, and until the contract closeout in November 2011, the construction outside the runway safety area and the portions of the runway east of runway 4L-22R will be completed.

This project signifies a new approach to runway design. Participation, commitment and the buy-in of all critical elements by all stakeholders were key to the advancement of this project. Airlines needed to trim schedules, JFK hired additional inspection, scheduling and operational personnel, a joint trailer compound was built to house both the contractor and Port Authority of NY & NJ staff and a project website was established to keep all parties informed of progress. This unprecedented cooperation is making this project a reality.

About the author: 
Zummo is a senior consulting engineer with the Port Authority of New York & New Jersey. Marsano is an engineer of materials with the Port Authority of NY & NJ.
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