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SATS Transportation Systems Analysis Overview Virginia SATS Alliance TSAA Group Meeting October 29-30, 2002
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Task Objectives Quantify current U.S. National travel patterns as a prelude to model SATS as a feasible transportation system (the baseline for this analysis is the year 2000 ) Develop a suitable framework and algorithms to study SATS as a feasible mode of transportation Relate the effect of four SATS technical capabilities and how they would contribute to make SATS a feasible mode of transportation
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Participants in the Integrated Transportation Systems Analysis Study Virginia Tech: –Dr. Hojong Baik –Mr. Howard Swingle –Mr. Senanu Ashiabor –Dr. Antonio Trani LMI (Logistics Management Institute) –Mr. Earl Wingrove –Dr. Dou Long George Mason University –Dr. George Donohue –Mr. Arash Yousefi –Mr. Khurram Qureshi Transportation Systems Analysis Report TransportationNetworkAnalysis (Enroute Study)
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Transportation Systems FrameworkMetrics Travel time Economic benefits Noise Traffic densities Energy use Low Landing Minima Single Pilot Safety High Volume Operations EnrouteOperations
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Implementation Scheme (Systems Dynamics) Time = Base Year Time = 1 Time = 2 Time = Horizon Year National Mobility Metrics Policies (Op. Capability Deployment)
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Scenario Definition
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Distribution of Airports Considered 3343 Airports
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Runway Length Distribution Runway Length > 3,000 Serves 95% of Aircraft Population < 12,500 lb. Per FAA AC 5325-5 3343 Airports
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Baseline Itinerant Operations (TAF) 3343 Airports 14 operations/day 28 operations/day 56 operations/day 7 operations/day 83 operations/day
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Number of Aircraft Based at 3343 Airports
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2,221 Runways vs. FAR Part 77 Design Criteria
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Approach Lights at 2,221 Airports
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Runway Operations Saturation Capacity Envelopes
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Where do People Live around Airports? Towered Airports (474) Hub Airports (135) Census 1990 and 2000 Data with 61,224 tracts in NAS 3346 Airports Large Hub Airports (30)
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Distribution of Income in the U.S. Household Income ($) Percent of Population Census 2000 Data
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Travel Studies
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The American Travel Survey One-Way Trip Distance (miles) Household Income (10 5 $) Percent Travelers by Air (%) 540,000 person trips 80,000 households
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Trip Rates are Influenced by Income and Trip Purpose Data: ATS 1995 High Income Medium Income Low Income One-Way Trip Distance (miles) Percent Travelers by Air (%) Data: ATS 1995
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Transportation Systems Modeling
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Some Details of the Methods Employed All methods have been coded in MATLAB at the county level
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Trip Generation
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Trip Demand Generation Given: Socio-economic characteristics for each county (for all states) Predict: a) Number of trips produced per household/year for various income levels b) Trips attracted to a county Use: Trip rate tables Annual Household Income ($) Years After High School Person-trips Per Year (per Household)
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Trip Generation Flowchart
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Model Results (after Calibration) Business Trips and MSA
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Trip Generation Results
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Trip Distribution
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Trip Distribution Analysis Given: Trips produced from and attracted to each county Predict: a) Number of person-trips from each origin to every destination (county to county) Use: Gravity Model
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Trip Distribution Analysis Calibration of Fij factors (impedence function) for business trips
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Observed vs Predicted Trip Interchanges Good correlation is shown between observed and predicted trip interchanges (business trips)
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Modal Split Analysis
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Transportation Modal Split Given: Trips from each origin to each destination Predict: a) Number of person-trips for every mode of transportation available Use: Nested Multinomial Logit Model and Diversion Curves Key variables: travel cost, access time, travel time, safety
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Mode Diversion Curves (derived from ATS) Distance (nm) Ground Transportation Commercial Aircraft Weibull Model Provide a picture on how people travel across modes (shown are diversion curves for business trips and high income)
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Mode Diversion Curves (cont.) Distance (nm) Ground Transportation General and Corporate Aviation Weibull Model Provide a picture on how people travel across modes (shown are diversion curves for business trips and high income)
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Diversion Curves Represent Incomplete Information Lack of understanding why traveler’s selected a mode No information on mode attributes (i.e., cost, convenience, perceived safety, etc.) used by decision makers No information on mode availability (i.e. who owns an aircraft or pilot capabilities - for GA trips) Data set for GA and corporate travelers is small (as expected from the ATS sample size)
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Recommended Next Steps (Modal Split Model) Formulate a model split model that captures mode- specific attributes and relates them to decision- maker’s view in selecting a mode (Volpe is designing the experiment) Calibrate the modal split model to include SATS as a feasible mode of transportation The modal split model will be an unbiased model
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Mode Split Model Development
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Sample MNLM Mathematical Representation Utility Function Probability of Selecting a Mode ’s = are model parameters IVT = in-vehicle time ACC = access time C/I = cost/income ratio WT = intermodal waiting time
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Sample Use of the MNLM Results for a hypothetical 200 nm trip
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Aircraft Cost Model Quantifies all the operating costs of GA vehicles including future SATS aircraft (over the life cycle of the vehicle) Critical sub-model in modal split analysis Uses Business and Commercial Aviation Week database (Operations Planning Guide) Use of regression analysis to derive various DOC and IOC factors
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Aircraft Cost Model (Cost Categories Considered) Variable costs (fuel, maintenance hrs., parts, miscellaneous) Fixed costs (hull insurance, liability, software, miscellaneous) Periodic costs (engine overhaul, paint, interiors, flight deck upgrades) Personnel costs (captain and first officer - if applicable) Training costs (crew training and recurrent training, maintenance training) Facilities costs (hangar space, office lease, miscellaneous) Depreciation cost (amortization of aircraft value)
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Small Aircraft Cost Model Uses real-data bases collected by Business and Commercial Aviation and ARG/US Employs regression models to derive realistic operation costs for Piston, Turboprop and Jet-engine powered aircraft 600 hours / year Jet Aircraft
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Comparison of Jet-Aircraft Costs (Air Taxi Operation) Jet > 20,000 lb Jet > 10,000 lb Jet < 10,000 lb
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New Generation Ultra-light Business Jet Aircraft (Eclipse 500) Total Operating Cost ($/seat-mile) Fuel Cost ($2.8/gal.) Professional Pilot Four seats
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Summary of Total Aircraft Costs Corporate turboprop aircraft –25-50 cents per Available Seat-Mile (ASM) Corporate Jet aircraft –45-95 cents ASM Regional turboprop aircraft (EMB-120, ATR-72, Saab 340) –9.2 to 11.5 cents per ASM Regional jets (Bombardier CRJ-200, Embraer 145) – 9.5 to14.0 cents per ASM Transport aircraft (Boeing 737-800, Airbus A321) – 6.1 to 8.2 cents per ASM
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Airport Choice Modeling The goal is to distribute trip interchanges across all selected airports Currently we modeled 3,343 GA and hub airports
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Airport Choice Model (Attractiveness Parameters)
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Airport Choice Model
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Airport Choice Model (cont.)
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Airport Choice Model (Intermediate Airport Selection) Intermediate airport attractiveness is a function of airport services and airport operations
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Sample Trip with an Intermediate Stop Cessna Citation II (C550) with 60% load factor Candidate Airports Aircraft Performance Data: BADA 3.0 OriginAirport DestinationAirport
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GA Data Used in the Model Utilization factors for GA aircraft are used as part of the trip assignment and airport choice modeling processes GAATA data has been criticized in some GA circles so we adjusted the occupancy factors based on anecdotal experience
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Transportation Model Outputs Percentage of Hours Flown
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Transportation Model Outputs
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GA Trips Predicted by the Model
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Transportation Network Analysis
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Network Scenario Analysis Used fast-time simulation models –TAAM –LMI SATS Net –Flight explorer 29,815 aircraft modeled in TAAM (single day operations at 5 ARTCC Centers) –Included all airline traffic –Included all GA traffic (estimated from our transportation systems analysis method) Derived precursor metrics of workload and sector delays
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Methodology Used in Traffic Flow Modeling
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ARTCC ZDC Analysis (GMU Study Reported by the Alliance)
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Baseline Traffic Flows (George Mason University Analysis)
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Enroute Parametric Results
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Enroute Conflict Analysis (Baik et al., 2002) Number of Daily Flights (all types) Number of Daily Conflicts Region of Interest = Size of ZDC ARTCC
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LMI SATS Net Model Analysis Uses a broader definition of sectors in NAS
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Baseline Cumulative Traffic Flows (Airline + GA)
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Animation of Baseline NAS Flows
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Baseline Transportation Analysis Conclusions The number of trip-persons using GA as mode in the year 2000 amounted to 13 million. This equates to about 9-10 billion Transported Passenger Miles (TPM) via GA in 2000. Based on our study of various transportation data sets, the amount of GA travel in the U.S constitutes a small fraction (<1.2%) of the total trip-persons done in the year 2000. SATS has good potential, but the economic (i.e., cost) and performance variables have to be very competitive for the system to thrive in the presence of other modes of transportation
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Conclusions (cont.) A nested multinomial Logit model has been postulated to estimate modal splits when SATS becomes a feasible model of transportation. This model obviously requires suitable calibration (one of our recommendations). A credible demand estimation for SATS is necessary because many of the SATS concepts of operation generated by all participating alliances depend on metrics and analyses derived from the transportation systems analysis presented here
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Final Remarks All the analyses presented in this report have been integrated into a standard numerical computing environment called MATLAB. MATLAB is an off-the-shelf computer environment suitable to handle the large matrices and complex manipulations of the data presented in this report The algorithms for trip demand, trip distribution and mode split (including the airport choice model) can be executed in less than one hour at the country-to- county level of detail
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Proposed Follow-up Diagram for SATS Transportation Studies Volpe/VT VT ERAU
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