Taxiway Upgrades at George Bush Intercontinental Airport: Full Depth Reclamation (FDR)—Pavement Competitive, Increased Capacity, Optimum Efficiency, & 20+ Years Lifespan
Flatiron Construction crews are making steady progress on the Houston Airports System (HAS)‘s George Bush Intercontinental Airport (IAH) in Houston, Texas, USA—part of the HAS‘s move towards its “5-star future”. The $58.9-million rehabilitation of Taxiway WB, designed by RS&H Inc., began in early February 2020 with a delivery date slated for early 2022. The goal of the project is to ensure the efficiency and value of the IAH taxiway; extend its lifespan by a minimum of 20 years; and greatly increase safety for planes taking off and landing.
2020 was the fifth year in a row that HAS received a “4-star rating” and the third straight year IAH received the same distinction from Skytrax, a leading global air transport rating organization. Mario Diaz, Director-HAS explained, “Beyond the present crisis, these 4-star ratings are indicative of the consistency and sustained excellence that each Houston Airports’ employee is committed to. Despite the COVID 19 crisis, we will use this time to continue to make improvements that will help us reach our vision of establishing HAS as a “5-star global air service gateway” where the magic of flight is celebrated!”
PROJECT SCOPE & KEY BENEFITS:
The scale and scope of the Taxiway WB initiative is considerable, including the amounts of materials to be brought in for the phased construction:
• Full-depth reconstruction, including associated pavements to facilitate a fully functioning taxiway system
• Storm water underdrains beneath the taxiway
• LED centerline lights—Furnishing and installing new that will upgrade aircraft guidance
• Signage—Furnishing and installing new that will upgrade aircraft guidance
• New markings to improve movement of pilots—better visibility to the airfield
• Intersections & paving—vast improvements
• Reduced maintenance costs = minimal impacts to airport operations
• Larger aircraft moved to the north end is allowed by changing some of the radiuses and associated happenings
Barker said, “We fully recognize that significant infrastructure needs have to be properly addressed in order for us to remain competitive in the global marketplace. We are actively working to ensure that our facilities not only meet, but exceed demands for increased capacity and optimum efficiency.”
“Right now the team is focused on demolition—must demolish up to three separate layers of pavement, all the way down through the subgrade. We are demolishing roughly 45 inches of total thickness and we will build it back to the HAS current standards. The next steps will be to stabilize the subgrade, then return with embankment fill and build it back up to the paving. IAH originally undertook a rehabilitation project several years’ back for Taxiways WA and WB, along with several connector taxiways and multiple connector taxilanes to one of the western complex’ runways [west side of IAH],” said McGhee.
In working with Johnathan Limb, HAS Construction Manager, Robert Vinson, Resident Engineer, and Jeff Cruser, Airfield Operations Construction Coordinator, McGhee noted, “Close coordination is always important as we are also about to undertake the Sanitary Sewer Rehabilitation Project, which will certainly overlap with this taxiway rehabilitation.”
Taking on both taxiway projects has ensured more efficient construction. “This allowed us to start work on WB more quickly. My experience [entails] 4 decades of working with several different airport authorities that has allowed me to bring [my] experiences here—put in some of the best construction practices terms of specifications; the client’s [desires]; and field operations assistance from a high level—to ensure our team is successful,” said Michael Zanella, Manager-Flatiron Houston.
SAFETY:
Zanella added, “We have numerous safety protocols in place:
• Maintaining proper distances between the taxiway and the runway—extremely important for planes when coming in and out of our work zones or to other operational taxiways
• All flags and lighting are identifiable
• We are very visible to Airport operations
• Right personnel in place, including subcontractors who play a very big and important role in our work
• Trials and tribulations have given us a better understanding of the extremely important sequencing, operations, and maintaining schedules
• Stronger work plans due to all earlier work
• Communication is key—Relations with HAS and airport operations staff have been excellent.”
“Working with HAS assistant director has ensured we have been able to meet all the terms of the contract. [As there are] always site differences and things[/issues] that are not in the plans that we have to work through. This partnering allows us to get through issues we run into,” said Zanella.
CHALLENGES, ISSUES, and OPERATIONS:
Elizabeth McNew, Traffic Control Foreman-Flatiron, stressed how heavy rains have been a challenge. She said, “We work 24/7 with day and night shifts. [But], it [has rained] pretty hard causing [work] to be out for a good 4 or 5 days, so we work whenever we can and pick up wherever we can. I learned how to handle the gate and airport regulations and rules, and the concerns of airport operations:
• Supplies—if we’re low, we’ll bring them in rapidly
• Safety is a constant concern—Alex Castellanos, Safety Manager, is on top of things at all times
• Flaggers clear the area when planes pass
• Hangers—some have scheduled times for when planes come out, and we have to stop all traffic at those times”
McNew said, “Whenever problems arise the Field Superintendent and Engineers all work together; Everyone is working hard to meet the schedule; It’s evident teamwork has developed; They look after each other … they want to get the job done; WB is going smoothly.”
Tim Gee, Project Manager–Flatiron, said, “We have a mechanic who works with our concrete paving group and he’ll be there to deal with a hose break or any other issue. He also helps with sizing the pan to get the width we need and pre-check the machine before we start the pour to make sure it is in good and operating condition. The key to maintaining the equipment is daily inspections. When we see an issue, it’s brought up with our equipment department or vendor; we locate high wear and tear items like cutting edges and teeth on buckets, and when they get low, we have to replace them before it’s too late. If we have a downed piece of equipment, they get out here as soon as they can to either fix it or replace it Fostering good relationships with the dealerships [is crucial, and so far we have been successful].”
SOIL and UTILITY issues are being dealt with as they arise. Flatiron has dirt work/excavation, pipe installation and paving crews working simultaneously. Gee said, “We are always dealing with storm water issues.”
McNew said, “If there are issues, they usually work together on them. The construction yard is convenient to the service road and is pretty big. We have plenty of room the for concrete batch plant, storing of materials, and offices.”
DEMOLITION, RECONSTRUCTION, & FUTURE PHASES:
The demolition and reconstruction of WB is being done in phases, having started at the north end and proceeding to the south end. Currently three phases of WB. The plan of attack for the demolition, for which 20% has been done, depends on the type of pavement being encountered.
Gee said, “We’re pre-planning for future phases. A phase is 1,600 ft. long and takes about 1.5 weeks to demolish. We’ve got some very different pavement sections—up to 39-inch deep—using hydraulic hammers to break it up because we can’t use a guillotine piece of equipment to break it up and load it out. It’s hard on the equipment. We have two Cat 336 excavators with 15,000-pound hammers running double shifts.
Several different layers of pavement have been poured:
• Top unreinforced 8-inch layer
• Below, 24 inches of reinforced concrete
• Below that, another unreinforced section underneath that”
Trimble Total Station robots are being used to meet specifications for the new taxiway. Gee added, “The tolerances are tight in regards to specifications and the robots’ level of accuracy is down to the 32nd of an inch rather than a one-half inch with GPS. The only times we’re going to use GPS is when we have machine controls on a motor grader for grade and subgrade on the shoulders.”
The Erie wet batch plant at the yard is expected to produce 78,000 cu. yds. of concrete.
The excavated material is removed a few days later after being broken up to let crews push ahead. Gee added, “… we have 2 options:
• Subcontractor—[Take] it 8 miles away, to be crushed and turned into P2 219, our base material and P304, a cement stabilized base
• Stockpiling it—recently started [taking] the material to our yard. An on-site machine crushes so we can make our P2 219 and P304″
Gee pointed out that light traffic is generally permitted on the new concrete after 3 days, and complete curing takes about 7 days.
FULL-DEPTH RECLAMATION Taxiway:
The new taxiway is based on these 4 layers, and before paving, the subgrade has to be stabilized:
• 5-in. P2 219 base
• 8 in. cement treated base
• 1-in. thick asphalt bond breaker
• 18 in. thick concrete top
Gee said, “We use a cement slurry. We’ll dump some cement on the subgrade, mix it up and let it cure. Any time we demolish a section of taxiway, we have to take extreme caution so we don’t cause spalling or damage the pavement that is proposed to be left in place. With each new phase, we look at and learn from what happened in the last one. We’ll step two feet away from an edge that remained in place, put in a relief cut—full depth to the bottom and then work our way back to the relief cut so were not putting any pressure on the pavement that stays. The key is to not put too much pressure on it.”
Gee said, “We are always dealing with storm water issues.” For the storm water underdrains, the pipe crews are installing perforated PVC pipe wrapped with ¾-inch rock and filter fabric around it. “They are installed prior to the concrete pours and placed on the shoulders of the taxiway,” said Gee.
Personnel—Peak days have personnel of nearly 60 Flatiron and 9 main subcontractors on-site for each shift
Excavated materials—Concrete, rebar and asphalt—will only be tabulated towards the end of the project
Machines—Excavators, one with a hammer; dozer; loader; roller; a box blade; boomlifts, forklifts, buggies and light plants; sweepers; air compressors; backhoes; and a water truck
AIRPORT BACKGROUND:
IAH is among the busiest airports in the United States. In 2019, it served almost 45.3 million passengers, a 3.3% increase from 2018. The taxiway upgrades are part of the plan to improve customer service as the number of passengers continues to increase. “Houston Airports is actively working to ensure that our facilities not only meet but exceed demands for increased capacity and optimum efficiency,” said Robert Barker, Chief Infrastructure Officer–HAS.
“The work requires considerable coordination because of its impact to cargo carriers, tenants and others,” said Chad McGhee, Construction Manager-HAS. “The [construction] has been carefully phased, with some phases of work being performed exclusively at night and other phases during the day since the entire taxiway cannot be shut down during construction. As always, we’ll seek to minimize operational impacts during construction.”
The WB reconstruction was added to the project as substantial completion on WA was approaching, which began on Oct. 19, 2018, was substantially completed on Oct. 10, 2019, and reopened the same month. McGhee stressed that improving airfield conditions are critical and go together with improving the customer experience.
“Houston Airports has more than $1 billion of airside civil work — either in planning, design or under construction,” he said, “and that just strongly illustrates its ongoing commitment to safety, to service, and to state-of-the-art infrastructure.”
For many more details, including dollar amounts, numbers, names of engineers, constructions personnel, airport personnel, contractor and subcontractor names, names of machinery companies, and more in the Construction Equipment Guide Online Magazine online article titled “Flatiron Upgrades Taxiway at George Bush Intercontinental Airport”, please go to: www.constructionequipmentguide.com/flatiron-upgrades-taxiway-at-george-bush-intercontinental-airport/49988