A group of principal taxiways at Nashville International Airport recently discovered the aviatic Fountain of Youth and have unveiled their rejuvenated pavement.
Garver designed the reconstruction of four taxiways in 2005 which are crucial to the airport's busy, growing enterprise—Fiscal Year 2007 witnessed peak numbers, more than 217,500 operations moving 9.8 million passengers and 75,000 tons of cargo. The passenger count set a new record, surpassing the previous pinnacle of 9.5 million recorded in Fiscal Year 2006. With more improvements proposed for the airport—a fifth runway, new terminals, additional parking—officials expect more records to broken in the years to come.
To continue to meet its level of service, Nashville International officials recognized that four taxiways needed attention. The taxiways were functioning below minimum service levels, and pavement deterioration and cracking were allowing water to penetrate the base and weaken the sections.
"These are all very heavily trafficked taxiways next to the main terminal," said Ryan Sisemore, Garver's project leader. "The trick to maintaining pavement is to prevent water from penetrating the surface and weakening the base. Water causes the base to segregate, heave with freeze and thaw, and eventually lead to the severe degradation of the pavement"
Taxiway T2 had a successful bid process in 2006 and was restored during the summer of 2006. Taxiways Lima and Juliet were bid in April 2007 and were completed in the summer and fall of 2007. Taxiway T6 has been incorporated into a separate project.
The design work for each taxiway included aspects pertaining to excavation, drainage, pavement, electrical systems and lighting, pavement marking and erosion control. To limit the impact on airport operations, the work was broken into separate phases with particular attention paid to the construction sequence and safety plan.
"Any time you're working at an airport of this size there's a massive effort directed toward safety," said Sisemore. "We're reconstructing taxiways for very large aircraft such as the Boeing 727 and 737."
The taxiway rehabilitation process included analyzing existing data for the pavement and determining the proper reconstruction method—surface treatment, structural overlay or full-depth replacement.
"We examined every taxiway and designed the fix that fit that age and condition of each pavement," Sisemore said. "Design emphasis also included symmetrical widening for pilot oversteering and coordination with other ongoing airfield projects."
The entire length of taxiway T2 received attention. The taxiway connects the terminal apron to taxiway Bravo, which provides aircraft ground movement to and from runway 2L-20R. The rutted and cracked taxiway had a vertical sag curve near the center, which was raised to provide better surface drainage and comply with FAA slope criteria.
The $1.6 million construction project was finished substantially under budget and on day 81 of a 120-day allotted construction period.
Parallel taxiways Lima and Juliet support runway 13-31 and also were finished under their $2 million budget and were on schedule..
"Designing that phase was a little more complex," said Robert Ramsey, director of design with the Metropolitan Nashville Airport Authority. "That is one of the busiest parts of the airport coming off our ‘C' concourse. We had to make sure we kept access open to the runways during reconstruction.
"Repairs to these taxiways means it will be safer, easier for aircraft to travel, reduce downtime, improve traffic flow and hopefully reduce delays," said Ramsey.