Memphis Rapid Rebuild

Guard shacks and continuous sweeping operations kept three intersections open at all times for crossing aircraft. (Memphis International Airport)

Carroll McCormick explains how bonuses have inspired contractors to meet a nine-month deadline for the Memphis runway rebuild in Tennessee.

Guard shacks and continuous sweeping operations kept three intersections open at all times for crossing aircraft. (Memphis International Airport)

When the 2004 resurfacing of its Runway 9/27 turned out to have a shorter working life than expected, the Memphis-Shelby County Airport Authority decided to completely reconstruct the 8,946-ft (2,727m) strip in 2009.  Rather than follow a more typical two-season schedule, it prepared a fast-track project that would have runway 9/27 back in service in time for FedEx’s post-Thanksgiving peak cargo season.
Home to the FedEx Memphis World Hub, the Memphis International Airport has been the world’s top-ranked cargo airport for many years.  In 2008, it moved 3,695,438 tonnes, edging out the number two global freight mover, the Hong Kong International Airport, by 34,537 tonnes. Memphis ranked 40th for passenger traffic, with 10,949,481, in North America in 2008.
“FedEx is a major portion of our airfield landed weight.  We did not feel that the impact on their peak season would be a viable option.  It is also more efficient and less expensive to do such a project in a single season, compared to completing it over two seasons,” explains John Greaud.  He is Vice President of Operations at the Memphis airport and is responsible for the maintenance, development and operations divisions.
Built in the 1920s, 9/27 had been extended and rehabilitated over the years, but never rebuilt.  In 1989 crews dug out the keel section of the runway − where aircraft main landing gear travel on it − and filled it with a very lean concrete called econocrete as a base material.
The pavement surface and structural top portion of the runway was asphalt.  There were less than five years between that project and the 2009 reconstruction, and Greaud says: “We expected to get a lot more life out of it than we did.”
In the years leading up to the reconstruction, the runway developed rutting and some sections started to depress.  Still, the demands on the other runways at the airport precluded limiting the weight of aircraft using 9/27.  “It really cripples us to limit the weight,” Greaud says.
The US$49 million reconstruction project was launched March 1, 2009, after a fairly short planning period.  The engineering and land planning firm Kimley-Horn & Associates, headquartered in Raleigh, North Carolina, was the lead design firm for the project.  (Its Memphis office was also responsible for the design for the rebuilding of runway 18R/36L, which was completed in 2002).  The general contractor was Ajax Paving Industries, Inc.
Runway 9/27 is now concrete, like the other three runways at Memphis. (Memphis International Airport)

“Water was the main problem with the subsurface failures.  Some of the subsurface material was clay, which tends to grab onto moisture and not release it.  One thing we did was ensure that we had a solid surface before we started paving,” Greaud says.
To achieve this, the contractors removed the old runway at least 52 inches (132cm) down, except for a 1,500-ft (457.2m) sag on the east end of the runway.  “When the runway was extended years before, it was constructed that way.  That sag didn’t meet the current Federal Aviation Administration criteria.  We had to raise it three feet.” Greaud explains.
The subcontractor that milled off the asphalt retained it to recycle into other asphalt projects.  The old econocrete was removed, crushed and reused as a base under the asphalt shoulders.
To help motivate Ajax to compete the project within the nine-month window, the airport authority included a bonus system in the contract; this was the second time it had used such an incentive to help ensure the completion of a time-sensitive runway rebuild.  “While we rebuilt the west runway [18R/36L] we lost some capacity.  We initiated a bonus system with the contractor to get it back in service as soon as possible,” Greaud says.
The bonus for the 9/27 project came in two purses: Ajax would earn the first purse if the runway was ready for a flight check by November 9; Ajax would earn the second purse if the runway was ready for use by December 1.  The contractor made both of these dates.  The two bonuses were worth $2.5 million.
Joe Polk, the airport’s manager of construction administration, feels strongly about the usefulness of bonuses.  “I am an advocate of date-and-time-certain bonuses.  They should be used much more than they are, in my opinion.  Contractors will move heaven and earth to get them.”
Polk was also confident his team could deliver the planning, design and construction by December.  His team is made up of continuously assigned staff from the Memphis-based engineering firm Allen & Hoshall.  Team members can, with this project under their belts, lay claim to having been involved in four permanent runway construction projects and one temporary runway.  “We have built new 90% of the pavement that existed at Memphis in the last 14 years,” Polk says.
A veteran construction administration team and US$2.5 million in contractor bonuses sped this runway’s reconstruction to completion in nine-month. (Via Memphis International Airport)

“One thing we are very proud of is the team we have worked with for a long time on runway reconstruction projects,” Greaud says.  “The team that Joe Polk heads up includes consultants and staff who are responsible for much of the success of this project.  They understand construction standards and construction sequences. They ensure that we get a superior end product.”
There was much more to the challenge than the physical task of reconstructing 9/27 by December 1.  “Nine months is not that short a time frame to reconstruct a runway when the construction site is completely turned over to the contractor,” Greaud says.  But there was no such luxury with this project: The contractors had to keep the three taxiway crossings for the three parallel north-south runways open at all times for hundreds of FedEx aircraft every day and night.
Safely controlling the truck and aircraft traffic in the intersections greatly complicated matters.  “We had two guard shacks at each intersection and had hand-operated semaphores, like they have at railway crossings.  We partnered closely with all the airlines,” Greaud explains.
A unique example of the cooperation between the airlines and the airport authority was the loan of a Sensis Advanced Surface Movement Guidance and Control System (A-SMGCS) by FedEx to the airport authority.  A-SMEGCS provides a comprehensive surveillance picture of the airport surface. “This gave us additional flight data on each aircraft. With it the guards could see which gates the planes were going to taxi to, so they knew which intersections they were going to cross,” Greaud says.
Home to the FedEx Memphis World Hub, the Memphis International Airport has been the world’s top-ranked cargo airport for many years. (Duncan Cubitt - www.duncancubitt.com)

“The equipment and control of traffic at the runway intersections helped achieve an accident and incursion-free project,” Greaud reports.  “I’m very pleased with our safety record.”
The contractors were allowed to work around the clock.  Typically though, they worked 16-hour days because reduced visibility and odd shift schedules for crews would have made night-time paving more challenging.  More importantly though, was the ongoing traffic to and from the Memphis World Hub: FedEx runs about 300 night time operations in under five hours, but “only” 200 in a ten-hour timeframe during the day.  Generally, the contractors would start very early in the morning, after the FedEx night launch, and pave all day.
The contractor used a slip form paver, which leaves 20inches (51cm) of concrete behind as it moves along. Contraction joints had to be sawn in the concrete at just the right time − the pavement cannot be too soft or too hard.  To do this, workers sometimes sawed the curing concrete at night.
The rebuilt runway has four layers. From the top down they are: 20inches of one-half inch (12.7mm) slump concrete, which is very, very stiff.  It has 650 psi flexural strength, which correlates to about 5,000 psi compressive strength; four inches (10.2cm) of porous asphalt, which has relatively large stones without the fines.  It is put down like regular asphalt, but water will penetrate it and flow into the new under-drain installed beneath the cement-treated base; eight inches (20.3cm) of cement-treated base, which is a mixture of Portland cement and aggregate that is very dense in rock proximity; and 20inches (51cm) of soil cement.  Contractors make soil cement by churning Portland cement into the soil and rolling it in place to firm it up.  It adds strength and also gives the contractors an all-weather surface to work on.
Contractors also installed replacement halogen edge lighting and a set of centreline lights − a first for 9/27 − manufactured by Siemens.  The project specified cast aluminum fixtures for the centerline lights: the airport authority had learned from using them elsewhere that they don’t rust and dissipate heat better than ductile iron and prolong bulb life.  Contractors also installed a Land and Hold Short Operations (LAHSO) lighting system just east of the November taxiway crossing of 9/27.
The LAHSO allows aircraft to continuously cross 9/27 and proceed to the sort facility without the delay that would otherwise be incurred.  The new procedure will benefit FedEx approximately 125 times a day.  It is expected to reduce aircraft operating costs by approximately $23 million over the next 20 years.
The runway reconstruction work is expected to have a service life of at least 20 years.