The 2020 Vision of Air Transportation: Emerging Issues and Innovative Solutions

Existing airport pavement evaluation and design methodologies are primarily oriented toward heavy, air carrier size aircraft, and often do not adequately address the lighter loading conditions at General Aviation (GA) airports. Although GA pavements generally serve light aircraft, many GA airports need to accommodate heavier corporate or military aircraft on an occasional or periodic basis. Existing GA design methods cannot handle mixed traffic, or overload operations. To address these shortcomings and to augment its formal strength rating program, the North Carolina Division of Aviation (NCDOA) conducted a two year study during 1997–1999 to develop standardized procedures for nondestructive testing (NDT) and evaluation of GA airport pavements and analytical software based on layered elastic design theory for evaluating pavement strength and "overload" operations. This study focused on flexible pavements and consisted of the following four primary elements: 1) Field Testing — Nondestructive and conventional tests were performed on one runway at each of six North Carolina (NC) GA airports. 2) Data Analysis — Back-calculated NDT subgrade moduli were correlated with California Bearing Ratio (CBR) and laboratory resilient modulus test data for development of failure algorithms and to allow direct input of back-calculated Falling Weight Deflectometer (FWD) subgrade modulus into the evaluation procedure. 3) Subgrade Strain Criteria — The results of a literature search and design of Federal Aviation Administration (FAA) compliant pavements over a broad range of subgrade and traffic inputs formed the basis for a new subgrade strain failure criterion. 4) Development of Analytical Software — Layered elastic evaluation and design software was developed using the FAA's LEDFAA software for air carrier pavement as a model. The new software, termed LEDGA for Layered Elastic Design — General Aviation, incorporates the new subgrade strain criterion and permits multiple aircraft analysis and evaluation of "overload" operations based on cumulative damage concepts.

Federal Aviation Administration (FAA) projects at Denver International Airport (DIA) and at the National Airport Pavement Test Facility (NAPTF), William J. Hughes Technical Center, Atlantic City International Airport, New Jersey, have yielded significant new data on load transfer behavior of rigid pavement joints. Using the results of previous finite element studies, load transfer efficiencies were predicted for doweled joints that agree reasonably well with the measured values from heavy-weight deflectometer tests.

This paper focuses on the analyses of jointed concrete slabs under the simultaneous temperature gradient and Boeing 777 aircraft gear loadings. Using the results from the ILLI-SLAB finite element program, a comprehensive artificial neural network (ANN) model was trained for the different conditions of aircraft loading only, temperature loading only, and the simultaneous aircraft and temperature loading cases. Special consideration has been given to the loading of a typical jointed slab assembly under the tri-tandem type gear of the B-777 aircraft. In addition to various slab load locations (interior, corners, and two mid-span slab edges) and joint load transfer efficiencies, a wide range of realistic airfield slab thicknesses and subgrade supports have been considered as ANN input conditions. More than 5,600 ILLI-SLAB analyses have provided the design parameters and the pavement responses as inputs for training the ANN model. Comparing the ANN predictions to the ILLI-SLAB solutions validated the performance of the ANN model. The trained ANN model gave maximum bending stresses and maximum vertical deflections within an average absolute error of 1.4 percent of those obtained directly from the ILLI-SLAB analyses. A typical ANN run is about 0.3 million times faster than the ILLI-SLAB finite element solution. The use of an ANN-based design tool is deemed to be very effective for studying hundreds or thousands of "what if" scenarios for including the temperature effects in pavement design. A sample design is presented to illustrate how such an ANN-based design methodology can easily be applied in the pavement design process.

Nondestructive deflection testing is used to assess the adequacy of airfield pavements and strengthening design for future operations of heavier aircraft. Deflection testing by a falling weight deflectometer (FWD) device is widely used for pavement nondestructive evaluation. The Pavement Evaluation Based on Dynamic Deflections (PEDD) microcomputer program is used to backcalculate reasonably accurate modulus values in the case studies presented in this paper. Nonlinear moduli of granular layers and soils associated with main gear load configurations used in large modern aircraft can reduce to one half of the backcalculated moduli. It is shown that the use of one set of design moduli and simplified load equivalency concepts, such as the ESWL concept for airfields, may be inadequate to assess pavement damage due to mixed aircraft traffic. Effects of temperature and moisture on seasonal nonlinear moduli and fatigue/rutting damage can be significant. This is shown by the results of the newly developed Pavement Design System for New and Existing Asphalt Pavements (PADAP) program for mechanistic pavement designs and simulations. This paper also demonstrates the use of advanced three dimensional-finite element (3D-FE) pavement analysis procedures for correctly simulating pavements subjected to dynamic loads. Good agreement is shown between simulated and measured FWD deflection time histories for asphalt pavements using the moduli backcalculated from the PEDD program.

The rapid growth of both domestic and international flights at Newark International Airport has resulted in record aircraft operations, straining airfield capacity. To improve capacity and reduce delays, Runway 4L-22R, the primary departure runway, needed to be extended from 2,500 to 3,350 meters (8,200 to 11,000 feet). During 1998, The Port Authority of New York and New Jersey, the airport operator, launched an ambitious program consisting of extending Runway 4L-22R (completed in 1999), resurfacing Runway 11–29, and construction of associated taxiways and aprons. While under construction, Runway 4L-22R remained in operation accommodating up to 700 aircraft daily. The program design included special requirements to facilitate construction and ensure satisfactory, long-term performance of the constructed product including the following elements: 1) Dividing the program into smaller projects to expedite design and construction 2) Pavement design using the FAA's layered elastic design procedure 3) Complicated staging to minimize the impact of construction on operations 4) Swales lined with stone designed to reduced suspended solids from entering the drainage system 5) Uniformly graded aggregate in the Portland cement concrete 6) Stone-rich asphalt concrete mixes containing performance graded binders 7) Open-graded, asphalt-stabilized base under the Portland cement concrete pavement 8) Portland cement concrete air content and water/cement ratio criteria that must be met to qualify for payment incentives for quality concrete 9) Smoothness correction criteria These design enhancements resulted in a high-quality constructed product, which was completed on schedule and will provide excellent, long-term performance.

The existing Runway 15R-33L at the Bush Intercontinental Airport/Houston (BLAH), Texas is 1,840-m. (6,038-ft.) long and 30.5-m. (100-ft.) wide and is constructed of 38-cm. (15-in.) full depth asphalt on 15-cm. (6-in.) of lime stabilized subgrade. It was designed for a DC-9 aircraft with a weight of 54,886-kgs. (121,000-lbs.). The proposed runway upgrade will include a lengthening to 3,048-m. (10,000-ft.) and widening to 45.7-m. (150-ft.), to accommodate Boeing 747 and similar aircraft with weights upwards of 396,900-kgs. (875,000-lbs.). The proposed improvements will be in the form of a whitetopping with a 48-cm. (19-in.) concrete overlay after milling 20-cm. (8-in.) of asphalt in the keel section to cater to existing adjacent taxiway and proposed taxiway elevations. A new parallel taxiway will be constructed with a 36-cm. (14-in.) concrete pavement on a 1.9-cm. (3/4-in.) Stress Absorbing Membrane Interlayer (SAMI), 46-cm. (18-in.) lime/cement/fly ash crushed concrete stabilized base (LCF), and 20-cm. (8-in.) lime, lime/fly ash stabilized subgrade. This $100 million project will include the largest whitetopping project on a runway among the airports in the U.S.A. This will also be the first time in the world that an LCF base is used under a portland cement concrete (PCC) surface.

This paper discusses the construction and 5-year performance trends of two innovative portland cement concrete (PCC) pavement test sections at the Greater Rockford Airport (Rockford, Illinois). The results of this study reveal the importance of continued airport pavement research, as well as some design factors that may improve pavement performance. This information will be useful to airport managers, safety coordinators, maintenance personnel, and consulting engineers.

The Smyrna Airport (Smyrna), located 17.7 km (11 miles) south of Nashville, TN, was recently approached by a European shipping company that was looking to locate a hub airport somewhere in the central United States. The shipper anticipated using DC10, L1011, and B747 aircraft on a nearly daily basis within 2 years of starting operations. It was uncertain how the existing pavements at Smyrna would perform with this dramatic change in anticipated aircraft fleet mix. A standard pavement management system (PMS) implementation, which would normally be able to predict future pavement deterioration rates, would fall short in this scenario because changes in the fleet mix would alter the rate of structural deterioration. Therefore, a pavement evaluation was performed on the airside pavements at Smyrna to determine: 1) Current condition of the pavements at the network level. 2) Structural capacity of selected pavements at the project level. 3) Remaining life of selected pavements based on the proposed aircraft fleet. This paper presents the processes that were developed for Smyrna.

At the San Francisco International Airport, asphalt-concrete mixes in full compliance with the current FAA mix design criteria exhibited rutting on major taxiways subjected to heavy aircraft-wheel loadings during the period August 1995 through June 1996. Because of the high air traffic volumes at the airport, the heavy departing aircraft are subjected to slow moving, or "stop-and-go" traffic condition. To mitigate the problem, enhancements were introduced to the current FAA mix design criteria providing for a High Stability mix, which is performing satisfactorily. This provided an opportunity to use shear test equipment developed during the Strategic Highway Research Program (SHRP) for mix evaluations for airfields. The mix evaluation procedure using this equipment defines the propensity of a mix to rutting by means of a repeated simple shear test at constant height (RSST-CH). This procedure, and results of shear tests on cores obtained from the rutted sections and sections constructed with the High Stability mix are summarized in the paper. The results demonstrate that the shear test can be used to differentiate between the mixes that have shoved and rutted under the heavy aircraft wheel loadings and the High Stability mix, which has performed satisfactorily. This latter observation is supported by laser profilometer measurements as well as by visual observation. Based on the results of these tests as well as other experience with the RSST-CH, a mix design methodology is proposed for asphalt-concrete mixes to be used for asphalt pavements subjected to heavy aircraft wheel loadings.

The Integrated Climatic Model (ICM) is used to evaluate the behavior of Denver International Airport (DIA) concrete pavements due to climatic loading. Pavement surface temperatures are highly influenced by local climatic factors like air temperature, amount of sunshine, wind, and radiation, and less influenced by material properties like heat capacity and thermal conductivity of the concrete. Only the temperatures near the pavement surface showed significant variation between the measured and calculated values. Changes in the average pavement temperature also led to significant changes in joint opening, and consequently to the effectiveness in load transfer across joints, which do not have dowels or other load transfer devices. Through the use of historical weather data and the ICM, it should be possible to accurately predict the load transfer efficiency across most joints over time for any particular region of the country.

It has been estimated that the Ground Service Equipment (GSE) accounts for approximately sixty percent of the total emissions at McCarran International Airport in the Las Vegas (Nevada) metropolitan area. Factors affecting emissions from GSE include the length (time) of operation, ambient environmental conditions, fuel used, etc. One key factor affecting the length of operation of GSEs is aircraft size. This paper presents the results of a preliminary survey conducted of the actual operational times of GSE for various types of aircraft at McCarran International Airport in Las Vegas, Nevada. Further, the paper compares these results with the current default GSE input parameters of the Emissions and Dispersion Modeling System (EDMS). The surveys at McCarran International Airport show that several of the observed engine running times of the GSE do not correspond with the default input values of the EDMS Model. The default values used by EDMS are significantly higher than those observed in the field. Therefore, the use of default data would lead to erroneously high results from the emissions model. Although these results are based only on observations in Las Vegas, the significance of this finding is that the use of default input data in the EDMS for GSE operations results in higher than actual estimates of emissions. Thus, individual airports may wish to conduct an analysis of the actual times of operation of the GSE used at their airports for use as inputs to the EDMS and for other air quality studies.

Airport curbside roadways serve to provide (a) loading and unloading areas for vehicles and (b) circulation lanes for vehicles approaching, departing, and traveling adjacent to the curbside areas. This dual-purpose travel/parking characteristic is not usually considered in standard traffic simulations. Leigh Fisher Associates has developed the Leigh Fisher Associates' Curbside Traffic Simulation (LFACTS) Model to specifically address this issue. This paper discusses the theory and assumptions driving LFACTS and provides examples of how it has been applied at select airports.

Most major airports in the US and worldwide are experiencing a strong growth in passenger demand and worsening of traffic congestion. This paper presents a simulation model that is specifically developed for the analysis of airport terminal roadway and curbside parking operations. Model validation results as well as model applications are presented in this paper.

Aviation simulation tools help planners make informed decisions. This paper discusses the role of simulation in aviation planning and the types of simulation tools used today. The FAA's airport and airspace simulation, SIMMOD, is described, and several SIMMOD applications are detailed.

San Jose International Airport (SJIA) is in the process of implementing a $1 billion Master Plan Development Program. One of the key components of the Master Plan is an Automated People Mover (APM), which will link several key activity centers at the Airport. The use of an APM will provide a high level of service to passengers and employees and enhance landside operational efficiency. The APM system is one of many elements of the Master Plan that have to be balanced in terms of level of service and capacity. This paper provides insights into the key planning considerations associated with the development of the APM at SJIA. Of particular interest is the development of an APM at a mid-sized airport (15–20 Millions of Annual Passengers [MAP]). Typically larger airport's e.g., Chicago, Newark, San Francisco (25 –50 MAP) have implemented landside APMs to increase their landside capacity and level of service. The specific needs and requirements of SJIA will be explored, and the applicability of these needs and requirements to other mid-sized airports will be discussed.

The advent of the New Large Aircraft (NLA) will impose a series of problems on airports. Most existing airports were not designed to accommodate aircraft larger than the Boeing 747, and new airports will have to be designed so as to cope with NLA. The location of NLA gate positions in the passenger terminal is of importance to landside operations. Two of the most important parameters of terminal design efficiency — passenger walking and baggage transfer distances — will be directly affected by the location of the NLA gates. This paper will provide a discussion on the location of NLA gates in the passenger terminal. Based on the proportions of hub transfer passengers, a mathematical formulation is derived for pier terminals to help in the choice of the specific location of NLA gates that will minimize passenger walking distance. Two basic cases of pier terminals are considered: access to the main building through the pier base; and access to the main building via the middle of the pier.

Like many large, urban airports, the Los Angeles International Airport faces increasing capacity demands coupled with a site severely constrained by existing development. The Southern Runway Complex is built over a 1950's era tunnel that allows Sepulveda Boulevard, California State Route 1, to pass under the airfield. The tunnel was strengthened in the 1970's and 80's to accommodate larger and heavier aircraft, but the existing structure was not long enough to accommodate the dual taxiway system on the north side of the south runways. As a result, there is currently substandard separation between Taxiway "C" and Taxiway "B" at the tunnel. In addition, Taxiway C is intersected by the airport's busiest vehicle service road on both sides of the tunnel, restricting its use to small commuter and towed aircraft, and creating a bottleneck to efficient operations. At its core, this paper discusses a relatively simple realignment of the taxiway and service road to improve airport operations. The engineering challenge lies in imposing a simple solution on a complicated, congested site, and designing the elements of the total solution based on the impacts to existing facilities. These elements include construction of a taxiway bridge over a busy state highway, several facility modifications, utility relocations, and an extensive upgrade of the 45 year old tunnel ventilation and lighting systems, all with minimum interruptions to both aircraft and vehicular traffic, and in coordination with federal, state and local authorities. This project presents a prime example of the difficulties involved in designing major infrastructure improvements at a congested, existing site. Through careful investigation, analysis, and design, this project will meet the primary goal: to increase efficiency while minimizing disruptions to the public and to the existing operations.

The Greater Toronto Airports Authority (GTAA) is redeveloping the Lester B. Pearson International Airport (LBPIA) in Toronto, Ontario, Canada. The hub of the groundside redevelopment is the new parking garage. This garage is the subject of this paper.

The car rental industry at Dallas/Fort Worth (DFW) International Airport received a giant boost on May 26, 2000, when the new Consolidated Rent-A-Car (RAC) Facility opened for public operations. The four rental car companies previously operating from on-airport facilities and six additional companies servicing the airport from off-airport facilities were consolidated into a single facility that sprawls across approximately 97 hectares (240 acres) of airport property southeast of the central terminal area (Figure 1 next page). At DFW Airport the rental car industry is currently growing at a rate of over 6% annually and during the first year of operation in this new facility over two million car rental transactions are anticipated.

This paper describes the development of the access and circulation roadways serving the new International Terminal Building and other master plan projects (e.g., the consolidated rental car and employee parking structures) at San Francisco International Airport. Developing the roadway concept was particularly challenging due to (1) the proximity of the International Terminal Building to the adjacent freeway (U.S. Highway 101) and the resulting constraints on inbound and outbound passenger wayfinding/decision-making, and (2) the requirement to maintain access to the existing terminal buildings and central parking garage during construction of the roadway network. The paper describes the process used to estimate future roadway traffic requirements and to translate these requirements into roadway concepts. Over time, the concepts evolved from those originally presented in the master plan, and incorporated improvements in traffic operations, passenger wayfinding, and roadway capacity. The concepts responded to changing objectives concerning vistas provided approaching motorists, circulation and geometric constraints, and construction costs and challenges. The City and County of San Francisco Airport Commission used the results of the study to guide the detailed design and construction of the roadways serving the new International and domestic terminals, two parking structures, and three interchanges on the freeway serving the Airport.

Final planning is currently underway for the development of the north end of the Seattle-Tacoma Internationa] Airport. The initial impetus for moving the airport expansion planning process forward was the initiative that is underway to connect the first phase of the regional light rail system to the airport. A major focus of the planning process is to plan a connection that would best serve the existing and future airport facilities and minimize the impacts to the existing airport operations and infrastructure. The airport expansion planning includes programming and siting for new airport facilities including; 1) a terminal, 2) an intermodal center, 3) a consolidated rental car facility, 4) development of new access roadways, 5) an on-airport Automated People Mover (APM) to connect the existing and planned facilities, and 6) the on-airport portion of the alignment and station location for the regional light rail system (LRT). This paper provides a discussion of the issues encountered by the Port of Seattle and its consultants while working with local, regional, federal agencies, and the airlines in planning the expansion of the terminal facilities. The discussion includes the initial difficulties in attempting to integrate the regional rail into the existing terminal and the opportunities found in connecting the regional rail into the planned expansion of the terminal complex. The planning process used by Sea-Tac planners is highlighted as an example of how early cooperation and collaboration between agencies and airlines can build consensus and support for the plan.

This paper examines the influence of airport capacity constraints on airline fleet mix, and the potential for an increase in average aircraft size to allow an airport to serve more passengers with the same number of aircraft movements. It has been common for airport traffic forecasts to assume a continuing increase in average aircraft size in the future. However, in order to understand the likely future trends in average aircraft size, as well as strategies that the airport might pursue to encourage favorable trends, it is necessary to understand the competitive dynamics of the various markets served by the airport, and the factors that determine the size of equipment that airlines will use in those markets. The paper addresses this issue by analyzing recent trends in different markets at a major U.S. West Coast airport and presents the results of an empirical study of the influence of airport delays on the average size of aircraft used in domestic U.S. markets. The paper concludes by discussing the prospects for airport capacity constraints to influence airlines to make use of larger aircraft.

When airport owners and operators embark on a capital improvement program, they often assume the planning decisions have been made and no further involvement is needed by the planners. But completion of a master plan marks only the first chapter, not the end of an airport planner's participation in a capital improvement program. There will be planning of one sort or another from the time the first design workscope is prepared to the time the ribbon is cut on the final facility in the program. Rather than end, a planner's role metamorphoses as acapital improvement program moves forward. Emphasis is placed less on visionary thinking and more on coordination and facilitation. In addition, planning is a continuing process affected by sometimes abrupt shifts in marketing strategies or regulatory changes that often will not conveniently wait for a capital improvement program to be completed. A planner must anticipate problems and propose and implement solutions. In any capital improvement program, somebody does the planning. The responsibility may fall to the owner (or airport authority), the program manager, or in the case of improvement programs with separate design and construction management teams, either the design manager or construction manager. In Washington, D.C., where the Capital Development Program(CDP) for both Reagan National and Washington Dulles International Airports has entered its twelfth year and provided almost $2 billion in new facilities, both the Metropolitan Washington Airports Authority (the Authority) and the Parsons Management Consultants(PMC) team have planning staffs whose involvement began with the development of the program and has continued throughout design, construction and start of operations.

This paper provides a summary overview of the current emerging issues that have been identified by the aviation community in the areas of airport environmental planning, and in related design and planning areas. The process used to identify these major issues is outlined and how this information is being used is discussed. This includes a brief overview of the Peer Review process.

Fatigue in concrete is very difficult to analytically quantify owing to the intricacies of several factors that affect concrete performance. As a result, it has been a subject of much experimental research. Fatigue effects have been incorporated into concrete design procedures including airport pavement design. This research effort studied the factors that affect concrete fatigue life in relation to an airport pavement scenario. Analysis of preliminary test results from the National Airport Pavement Test Facility (NAPTF) test site reveal that pavements experience more stress reversals and more load cycles than anticipated when a dual tandem or a tridem gear is used for loading. Stress patterns were observed at the longitudinal edge, a critical location for pavement response. Test results were supported with finite element simulations. The NAPTF was a scaled model and hence effects of gear type on stress ranges were analytically simulated for an actual airport pavement at the Denver International Airport (DIA) with B777 loads. It is concluded that the NAPTF sections are subjected to more severe loads than anticipated and might fail earlier than expected. It is recommended that effects of axle spacing be accounted for when results from these tests are related to real life airport pavements.

This paper presents the background on the development of the design and construction requirements for the Federal Aviation Administration's (FAA) National Airport Pavement Test Facility (NAPTF) pavement test items and provides an overview of the properties of the subgrade and pavement materials that were incorporated into the construction. The paper specifically addresses: 1) analysis of the effect of boundary conditions on computed pavement responses; 2) development of the geometric requirements for pavements and subgrade; 3) properties of soils used for subgrade construction; 4) development of requirements for test pavement construction; and 5) overview of materials properties.

Runway 9–27 was constructed and commissioned into operation in July 1987. Runway 9–27 and its associated taxiways (the south complex) were constructed using an innovative Lime Cement Fly Ash Stabilized Base (LCF Base) with an asphalt surface. This pavement was designed by Dr. Nai Yang. In comparison with concrete pavement alternate, the savings was $10 million for the entire south complex. This south complex is shown in Exhibit No. 1. The compressive strength gain of this LCF Base demonstrated a long, slow rate of pozzolonic reaction with the potential to minimize shrinkage cracking potential and maximize long-term autogeneous healing. From an average of 1200-psi compressive strength in six months, it rose to 2,200 psi in six years and average of 3,000 psi to 3,200-psi compressive strength in ten years. The modulus of elasticity of the LCF Base was approximately 2,000,000 psi in ten years. It was projected during the design phase that rehabilitation would be needed in approximately ten years. The condition of the existing asphalt surface in 1997 at ten years showed widespread reflective cracking. This was due to the shrinkage cracking of the LCF Base. However, the asphalt was deemed to be moderately susceptible to permanent deformation under normal traffic and rut-susceptible under demanding traffic conditions, such as braking and high speed turning. However, potential rutting problems within the existing asphalt are of no practical concern under normal traffic after the application of the recommended overlay. The rehabilitation of Runway 9–27 was performed costing approximately $15 million. Obviously, a task of this magnitude required excellent planning, work at a tumultuous pace, and superb teamwork. In addition, it required a great deal of coordination with the airlines and others.

The paper describes the development and case study of an innovative solution, called the High Stability mix, for airfield pavement design. The High Stability mix provides improved resistance to permanent deformation of asphalt concrete pavements under heavy aircraft wheel loads. Development of the High Stability mix began in 1995 in response to permanent deformation and distortion in the surface layer of asphalt concrete taxiways at San Francisco International Airport (SFIA). Asphalt mixes on these taxiways fully met the Federal Aviation Administration (FAA) P-401 specifications for conventional mixes. However, stationary, stop-and-go, and slow movement of Boeing 747-400 wheel loads caused "dimples" on the pavement surface as well as ruts from turning movements on the taxiways. Mix design, construction, pavement loading history and results of laboratory studies showing deficiencies of the then-existing asphalt concrete mix is described. The development of enhancements to the FAA P-401 specification, evaluation of job mix formulas and recommended additional laboratory tests are discussed. The paper describes attributes of the High Stability mix, including the use of a stiffer binder, crushed aggregates, and increased air void content. Subsequent to construction of High Stability mix on the taxiways, pavement surface profile measurements and condition evaluations were recorded over a two-year period and are described in the paper. Results show superior long-term performance compared with previously used asphalt concrete mixes.