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21 CHAPTER 2. TRENDS AND CHANGES IN AUTO AND AIR MARKETS OVER TWO DECADES 2(A) INTRODUCTION AND STRUCTURE INTRODUCTION The past two decades have seen major changes in the role of shorter-distance air service, and this is correlated with a major increase in the role of the private automobile in providing parallel services. While metropolitan auto trip making is either flat or down (depending on the specific years being examined), the portion of auto travel being devoted to the occasional long-distance trip is increasing, resulting in total vehicle miles of travel (VMT) rates that are rebounding back after their dramatic declines after the recession of 2008. While the rate of air trips per person is only modestly higher over the past twenty years, the average length of the air trip has grown considerably: more air services are now offered for longer distances, with less air service for shorter distances. STRUCTURE Chapter 1 has presented a summary of the results of the overarching scenario testing process undertaken in the research project: the five possible future scenarios explored futures at a very high level of abstraction, emphasizing the range of possible futures being faced. Chapter 2 now explores in far more detail how the separate factors and travel behaviors have evolved over the past two decades, and where the major corridors of competition are located. Then, Chapter 3 will examine the roles of the various influencing factors in the present timeframe, and how those separate factors interact with trip distance in influencing the choice of long-distance mode. 2(B) UNDERSTANDING MARKET TRENDS FOR AIR TRAVEL Descriptions of air travel behavior are the most accurate and the most readily available to researchers because of the federal agenciesâ interest in and oversight of air travel. Federal Aviation Administration (FAA) publishes its update of the Terminal Area Forecast (TAF) Summary annually, which âprovides aviation data users with summary historical and forecast statistics on passenger demand and aviation activity at U.S. airports. The summary level forecasts are based on individual airport projections.2â HISTORICAL TRENDS IN ENPLANEMENT Airport activity data for the period between 1995 and 2017 is summarized in Figure 2-1, taken from TAF 2017â2045. 2 Quote from TAF 2015-2040
22 FIGURE 2-1. HISTORY OF GROWTH IN AIRPORT ENPLANEMENT (1995â2017) Source: Federal Aviation Administration, TAF Summaries The enplanement data illustrates the effects of two periods of economic upheaval. In the aviation sector (but not in the highway sector) there was a sharp decline between 2000 and 2002, which includes the passenger market reaction to September 11, 2001. Equally dramatic is the response of the market between 2003 and 2007, where the previous levels were regained and increased upon substantially. The volumes at airports in the summer of 2007 were at an all-time high, with significant congestion occurring at busy airports like JFK. From 2008 to 2009, during the depths of the Great Recession, the graph shows a sharp decline like that experienced in 2002. The industry rebounded with enplanement levels finally rising above those of 2007 by the end of 2015. In sum, there was about a 48% increase in total enplanements between 1995 and 2017. In the study of modal choice between the auto and the air services, it is particularly important to look at per-capita patterns of transportation behavior, in this case change in per-capita rates of enplanement. A chart of enplanements per capita is presented as Figure 2-2, which shows a relatively linear pattern of increase between the base year of 1995 and 2000, followed by a more volatile period after September 11, and the declines around 2008. The per-capita rate then bounces back around 2014, resulting in a net increase of about 19% in the per capita rate between 1995 and 2017. Â 350 Â 450 Â 550 Â 650 Â 750 Â 850 Â 950 19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 En pl an em en ts ,Â i nÂ M ill io ns Year GrowthÂ inÂ Enplanements,Â 1995Â â2017
23 FIGURE 2-2. ENPLANEMENTS PER CAPITA, 1995 TO 2017 Sources: TAF Summaries, US Census 2(C) UNDERSTANDING THE SERVICES PROVIDED BY THE AIRLINES The distributions of air travel services by distance between 2008 and 2011 were examined in "Aviation Industry Performance: A Review of the Aviation Industry 2008-2011" from the Office of Inspector General, US DOT. The chart taken from that report (Figure 2-3) illustrates the decrease in airline service as a function of distance of the flight segment. The figure shows this decrease in airline services between 2008 and 2011 occurred most strongly for flight segments under 500 miles and almost entirely for flights under 1,000 miles. This chart is presented to emphasize the fact that fewer flight segments are offered, affecting the combined frequency of flights from any given airport. In the evolution of services that occurred, airline resources were reallocated away from shorter-distance segments to longer-distance segments. This chapter will explore the parallel conclusion that the role of the automobile in the shorter portion of the long- distance trip market has increased significantly over the past 20 years and is markedly different from the role indicated by the 1995 data. The decline in air trip segments of under 500 miles has been well documented in the literature. In an article entitled âWhat caused the short haul traffic decline in the US?â 3a market analyst from Bombardier (a major supplier of shorter distance aircraft) reviews several possible explanations for the decline. Miller (2018) writes, âAs the total market has grown about 30%, short-haul traffic under 500 miles has declined by the same amount, almost 30%.â Reviewed by trip length, 3 Miller, C. âWhat Caused the Short Haul Traffic Decline in the US? â the $34b Questionâ August 2017; linkedin.com/pulse/what-caused-short-haul-traffic-decline-us-34b-question-miller 0.00 0.50 1.00 1.50 2.00 2.50 3.00 19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 En pl an em en tÂ p er Â C ap ita Year GrowthÂ inÂ EnplanementÂ perÂ Capita,Â 1995â2017Â Â
24 between 2000 and 2017 his analysis shows a 51% drop in O-D trips in the distance band between 100 and 200 miles; 39% between 200 and 300; and 14% between 300 and 400 miles. Air trip FIGURE 2-3. DECREASE IN AIRLINE SERVICE BY DISTANCE OF FLIGHT SEGMENT (2007â2012) Source: Office of Inspector General (2012). "US DOT Aviation Industry Performance: A Review of the Aviation Industry 2008-2011â Reproduced from Figure 26, page 29. making in O-D markets of longer than 400 miles show and gradual increase with increasing distance, resulting in a total market increase of 30%. While the airports reporting such short distance declines are well distributed around the country, notable exceptions can be traced to Jet- Blue in JFK and Long Beach, with Virgin American influencing an increase in traffic under 500 miles at SFO, and increased utilization at Washington National. Miller provides a valuable review of possible causes for the loss, including airline consolidation, raised prices on shorter segments, and the âhassle factorâ of airport security after 9/11. Examining the reasons for a 40% decline in air passengers between Dallas and Houston, he downplays the role of consolidation, accepts the logic of higher prices, and focuses squarely on the extra hour of âhassleâ associated with security as tipping the door-to-door time comparison in favor of the auto. CHANGE IN THE COMPOSITION OF AIR FLIGHT SEGMENTS 1995-2016 In what the FAA TAF managers describe to as â¦ âthe shift in the U.S. airline industry emphasis on market share to boosting returns on invested capital,4â airline managers have stopped asking 4 Quote from TAF document, âReview of 2017,â page 3
25 the question about beating their competitors in weak markets, and ask instead âwhich routes and services are profitable?â This means that the industry supplies less seats when there is less profit predicted. Holding the growth in the US population aside, we can observe the change in seats offered per capita. Comparing the year 2017 with the year 2000 -- for trip distances under 500 miles in length, it is now down by 34%; for distances between 500 and 1500 miles, it is essentially the same as two decades ago; and for longer trips up by 7%. Thus, the airlines have increased the portion of seats for longer trips and decreased the portion of seats for shorter trip segments, based on this comparison of T-100 trip segment descriptions from the FAA and BTS. This, then, results in the average air trip segment getting longer on a rather consistent basis, as shown in Figure 2-4. FIGURE 2-4 INCREASE IN THE LENGTH OF AIR SEGMENT, 1995-2015 Source: BTS. https://www.bts.gov/content/average-length-haul-domestic-freight-and-passenger-modes-miles The Bureau of Transportation Statistics computes the average trip length by dividing reported air passenger revenue miles by reported revenue enplanements5, revealing the growth in air segment distance over time graphed in Figure 2-4. The examination of change in segment length is mirrored in the data about full trips taken. Looking at O-D air trips taken, 1995, 20% of trips by air were under 400 miles in length, according to the ATS: by 2011 only about 11% of air trips were under 400 miles. CHANGES IN AIR TRAVEL, 1995 AND 2016 Table 2-1 presents a quick summary of key changes in air travel between 1995 and 2016. The latest estimate for 2016 from the FAA TAF reports shows nearly 818,000,000 enplanements by 5 https://www.bts.gov/content/average-length-haul-domestic-freight-and-passenger-modes-miles 720 740 760 780 800 820 840 860 880 900 920 M ile s AverageÂ LengthÂ ofÂ AirÂ Segment,Â 1995Â toÂ 2015Â Â AirÂ carrier,Â domestic,Â scheduled
26 commercial carriers at airports with FAA presence. This represents a 18 % growth (or a ratio of 1.18 to 1) in the per capita rate of enplanement since the base year. Phrased differently, the average American is boarding planes about 18% more than he/she was in 1995; about 1.4 segments are taken per full trip from airport of origin to airport of destination. Over the study period, the number of round trips per capita taken by air has increased from about .77 trips to .90 trips. TABLE 2-1. KEY CHANGES IN AIR TRIP MAKING RATES, 1995 VS 2016 1995Â 2016Â INCREASEÂ 2016/1995Â Enplanements6 565,235,549 817,964,902 45% Enplanement per capita 2.2 2.5 18% Trips at 1.4 segments per trip 403,739,678 584,260,644 45% Round trips 201,869,839 292,130,322 45% Round Trips per Capita 0.77 0.90 18% 2(D) UNDERSTANDING MARKET TRENDS FOR THE AUTOMOBILE HISTORICAL TRENDS IN VMT PER CAPITA BETWEEN 1995 AND 2015 All in all, the trends in auto use over the past few decades can be described as less volatile than those in the aviation sector. The recent history of automobile travel includes a pattern of yearly increase in vehicle travel per person, plateauing around 2004 or 2005, as shown in Figure 2-5. At this point, VMT no longer consistently increases, with a pattern of decline to about 2013. Interestingly, the 2005 flattening occurred several years prior to the Great Recession, which also significantly affected aviation trip volumes. When the per capita rate for all (not just long 6 FAA, TAF Summary 2017-2046, and historical data from TAF Summary 2024- 2040
27 FIGURE 2-5. VEHICLE MILES OF TRAVEL PER CAPITA (1995â2017) Source: Federal Highway Administration; Year 2017 estimated from first quarter results by research team. distance) VMT for 2017 is compared with the base year of 1995, the rate of VMT generation per capita has increased by about 7% (or a factor of 1.07 to 1), whilst still lower than in its peak years. VMT AS A FUNCTION OF ECONOMIC GROWTH The timing of the flattening of the growth in VMT at the turn of the century is reflected the examination of the relationship between VMT growth and gross domestic product (GDP) economic growth. The BTSâs Passenger Travel Facts and Figures report includes a graph (Figure 2-6) that charts GDP and VMT patterns between 1990 and 2014. The slope of the VMT line parallels the slope of the GDP between 1990 and 2005. The slope of the GDP line continued upward until the Great Recession, at which point it also declined. In short, the decoupling of VMT from the GDP pattern occurs somewhere around 2005 and continues downward until flattening at the end of the Great Recession. Figure 2-6 supports the argument that the alteration in the pattern of perpetual growth in automobile VMT cannot solely be attributed to larger economic patterns. VMT growth trailed the economic recovery until it reached prerecession levels by 2015. Thus, the national VMT levels have returned to historic heights, while VMT per person rates have not. 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 VMTÂ perÂ Capita,Â 1995â 2017Â
28 FIGURE 2-6. COMPARISON OF GDP AND VMT PATTERNS (1990â2014) Source: Bureau of Transportation Statistics. Reproduced from Figure 4-2, Passenger Travel Facts and Figures, 2016 2(E) AIR AND AUTOMOBILE TRAVEL TOGETHER This research project examined the relationship between highway travel and air travel and the growth in the two modes. The comparative volatility of the two modal trends can be seen in Figure 2-7, where the pattern of fluctuation in air travel is more pronounced than that in the highway data. That figure presents both automobile travel and air travel growth lines in the form of an index of growth from 1991. This uses absolute growth in VMT (not VMT per capita, as applied in Figure 2.4) to compare with absolute growth in enplanements; thus, part of the growth in each travel mode is attributable to an increase in the national population over this period. The relative volatility of the aviation enplanements compared with the automobile mileage is pronounced. Specifically, the sharp fall in aviation travel between 2000 and 2002 is not mirrored in the VMT data, which show nearly linear growth between 1992 and 2005. In short, the 2001 decrease in air travel was not mirrored in the highway use data. Both air travel and automobile travel were affected by the Great Recession. However, air travel experienced a steeper decline than travel by automobile. (N.B., the base volume of the VMT number is vastly larger than that of the aviation number, making relative change more difficult.) More recent data shows a strong rebound in both air travel and travel by automobile between 2013 and 2017.
29 FIGURE 2-7. GROWTH INDEX FROM BASE YEAR OF 2001, FOR AIR ENPLANEMENTS AND AUTO VMT MODE SHARE, BY DISTANCE (1995 VS. 2002) Changes in the role of air and automobile by 2002 Interpretations from 2001. National long-distance data that systematically includes travel by both automobile and air is provided in only two surveys: the ATS of 1995 and the National Household Travel Survey (NHTS) of 2001. The latter attempted to monitor both local and long- distance trips in one survey, with mixed results. An early review of the 1995 and 2001 data suggested that the role of the automobile in trips under 1,000 miles was significantly higher in the difficult period after the events of 9-11.7 Research team member Nancy McGuckin compared air/automobile mode shares in the 1995 survey to those in the (smaller) 2001/2002 survey. Accepting her caution that the two surveys are not perfectly parallel, the results showed that the relative role of the auto in the lower end of the long-distance trip distance range had grown compared to the 1995 base year. Later in this chapter, the results of the project 2017 long- distance travel survey will be applied to this question, which tend to confirm the hypothesis of increased auto reliance, but not to the degree observed in the volatile 2001-2002 data collection period. 2(F) PRESENT LONG-DISTANCE TRAVEL BEHAVIOR COMPARED WITH 1995 COMPARISON WITH EARLIER MODE SHARE DATA Our examination of the 2017 project survey results reveals a considerable level of stability in American long-distance travel patterns when compared with the 1995 base-year data. The preliminary results suggest that Americansâ long-distance trip-making by car has increased demonstrably in parallel to the growth of domestic enplanements. The analysis of the direct output of the 2017 survey data (i.e., not modified through simulation) shows an auto mode share 7 The analysis of change undertaken with 2001-2002 NHTS data is presented in the Technical Appendix. 0% 10% 20% 30% 40% 50% 60% Air Auto
30 of 51% for trips exceeding 300 miles, which is somewhat higher than a directly comparable mode share of 46% from the 1995 American Travel Survey data. Auto mode share is shown as a function of trip distance from this comparison in Figure 2-8. Comparing with 2017 direct survey results Important differences exist between the content of the 1995 ATS and the recent 2017 project survey. First, the surveys were undertaken for different purposes. The 1995 ATS sought to understand all long-distance travel in the United States. This research projectâs survey sought to understand the travel from only four market survey areasâareas chosen to improve the understanding of the choice between smaller airports and larger airports in major markets. By contrast, the 1995 ATS was undertaken in all areas. FIGURE 2-8. EFFECT OF DISTANCE ON AUTO MODE SHARE, 1995 VS 2017 SURVEY RESULTS Source: Results from the 2017 Project Survey (not simulated data) To undertake this comparison, the 1995 ATS results were reexamined for trips beginning in the four US Census districts covered the 2017 survey: New England, South Atlantic, East North Central, and Mountain. Comparisons were made between 1995 curve for all regions and the curves for just these four geographic areas, resulting in the conclusion that there were no significant differences among them. Thus, to maximize the sample size, the curve based on the entire 1995 sample was used in the analysis. The research team restructured the 1995 ATS data to reflect only trips by air and auto to facilitate comparison with the data collected in the 2017 survey, which only modeled those two modes. Thus, the âauto mode shareâ in all cases represents the ratio of auto trips to auto-plus-air trips. A significant increase in the mode share of auto between 1995 and 2017 is evident from Figure 2-8 for all but the shortest distance bands. 0% 10% 20% 30% 40% 50% 60% 70% 80% 300-700 700-1100 1100-1500 1500-1900 1900-2300 above 2300 A ut o M od e S ha re One-way Trip distance, in Miles Auto Mode Share, by Trip Distance 2017 Survey Compared with 1995 Full Sample 2017 1995 All
31 Using the projectâs simulated data As described in Chapter 6, this ACRP project has created a new analysis method to simulate (among other things) the mode choice of all long-distance trips in lower 48 states. That national trip dataset was used in the creation of Figure 2-9 based on the simulation of millions of trips between 200 and 3200 miles in length. FIGURE 2-9. CHANGE IN AUTO SHARE, 1995 VS 2011 SIMULATION Source: ACRP Scenario Testing Model DOES AN INCREASE IN CAR USE MAKE SENSE? The overall pattern from multiple data sources is that auto travel has become more important for the long-distance trip in general, with particular growth from trips under 1,000-mile range. This strong increase for these distance bands is generally consistent with the national trend, in which the national per-capita VMT is about 7% higher in 2017 than it was in 1995. Thus, compared to our base year of 1995, overall driving is up modestly, using data that combines local and longer distance trips together. Changes in gas prices The higher rate of auto travel has occurred even though the price of gas has increased significantly. Gas prices at the pump were higher (adjusting for inflation) at the time of project 2017 survey than at the time of the 1995 ATS survey: we estimate that -- adjusted for inflation -- gas in 2017 survey was about 34% higher than in 1995.8 This reinforces the well-documented 8 Source: FHWA 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 200â400 400â600 600â800 800â1000 1000â1200 1200â1400 1400â1600 1600â3200 Au to Â a sÂ % Â o fÂ A ut oÂ +Â Ai r OneÂ WayÂ TripÂ Distance AutoÂ ModeÂ Share,Â byÂ DistanceÂ 1995Â vsÂ 2011 WithÂ 2011Â SimulationÂ 1995 2011
32 observation that changes in gas prices do not predict changes in car use well. In sum, while the gas price rose by approximately one-third, the travel rate rose by approximately 7%. FIGURE 2-10. COST OF AIRLINE TICKETS AND GAS OVER TIME Changes in air fares The relationship between frequency of air travel and the price of air travel is more intuitive. Reviewing several sources9 of data produces multiple estimates of how much the cost of air has decreased on a per/mile basis, but the latest updates from the airline industry suggest that compared to the estimates for the 1995 base year, the cost has dropped by more than half.10 2(G) A MAJOR FINDING: AN OVERALL CHANGE IN COMPOSITION OF VMT? Based on the results of the analysis so far, we can conclude that the role of the auto for long- distance trips has increased significantly over the past two decades. The national simulation model created for this project supports the ability to undertake more precise analyses of national data. Table 2-2 shows the auto share of the auto-plus-air market for trips, for comparison with 1995 values, for all distance bands above 200 miles. Utilizing several different data sources concerning present auto use, between 1995 and the present there is a consistent pattern of increase in auto share for most distance bands. The projectâs simulation modeling supports the finding of a major increase in the present role of the auto in the long-distance trip. The parallel trip making patterns for air are also clear, based on the empirically observed decrease in both flights (seats) and passenger enplanements for the 9 Several sources were reviewed. Those in Figure 16 came from http://www.planetickets.com/airfare.html. Gas prices over time in Figure 16 came from www.randomuseless.info/gasprice/gasprice.html 10 https://www.theatlantic.com/business/archive/2013/02/how-airline-ticket-prices-fell-50-in-30-years-and-why- nobody-noticed/273506/ 0 0.1 0.2 0.3 0.4 0.5 0.6 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 C os t p er m ile (d ol la rs ) Air (ticket price only) Auto (gas price only)
33 shorter air trips. Thus, the lowest row in Table 2-2 shows that two decades ago the air system carried about 40% market for trips above 200 miles and is now carrying about 23% of that market. TABLE 2-2. AUTO MODE SHARE OF LONG-DISTANCE TRIPS BY DISTANCE, 1995 VS 2011. Source: ATS, 1995; FHWA National Model, 2011 AUTO SHARE OF AUTO+AIR Distance Band, in miles 1995 2011 200-400 86% 95% 400-600 68% 83% 600-800 47% 72% 800-1000 37% 59% 1000-1200 30% 45% 1200-1400 22% 36% 1400-1600 19% 28% 1600-3200 9% 16% Total above 200 miles 60% 77% This chapter has noted that both the air and VMT volumes change on a year by year basis, so the 23% figure should be seen as indicative of a value within a reasonable range, plus or minus. Further, the reader is reminded again that the auto volumes for 1995 came from an actual nationwide survey, while the auto volumes used in the calibration process for our model came from modeling and estimate procedures used by FHWA. However, the overall pattern of a decrease in the role of the air system for trips âshorterâ trips, and an increase of the auto for such trips is supported by a wide variety of analyses undertaken in this project. Long-distance auto travel as a portion of total auto travel Under most definitions, the long-distance trip is considered to be anything above 100 miles in length. Looking this time at the total long-distance market (including trips between 100 and 200 miles), we estimate that the auto mode share was 77% in 1995 and rose to 85% in the 2011 calibration year. Seen as auto miles per capita, this translates to approximately 2,700 VMT per capita of long-distance travel, a significant component of the 9,400 total VMT per capita reported in that year. In this 2011 travel pattern, auto trips over 100 miles for whatever purpose would account for 29% of vehicle miles taken in the year. These values represent a larger role for the long-distance trip than is often used in the composition of component elements of VMT and should be subject of further research. By way of comparison, in 1995 trips over 100 miles in length represented about 17% of total VMT per capita, using the same set of assumptions as used above.
34 2(H) WHERE THE COMPETIVE MARKETS ARE LOCATED CORRIDORS UNDER 800 MILES IN DISTANCE There are only a finite number of corridors (or city pairs) were the auto and the air services actually compete. Even within the lower 48 states, the propensity of a given corridor (or city pair) to offer travel options that are really competitive varies widely. A trip from Seattle to Key West is not competitive by car; a 400-mile trip from Hartford to Buffalo NY is presently almost illogical by plane. Chapter 2 now examines the top inter-city markets where air travel and the automobile realistically compete. Our work program was designed to allow the examination of one-day auto trips separately from trips that would require an overnight stay. The research team has defined the top âone-dayâ markets, using trip tables originally developed to explore the possible role of buses in corridors. That study11 reviewed all candidate city pairs of over 100-mile distance between them and assumed that corridors with no reported bus service should not be included in the top 200 markets. This ACRP project further narrowed that list by including only those city-pairs with an air mode share over 2%. Figure 2-11 shows all the market corridors between 100 and 800 miles that meet this definition, resulting in only 68 of such city pairs where air is a reasonable competitor to the automobile. Here, they are rank-ordered by total travel by all modes. Number of annual trips by all modes in study corridors Most of the corridors have under two million annual trips by the two modes together. Figure 2-11 shows that there are only 18 city pairs in this list that generate more than 2 million long- distance trips per corridor in the base year of 2008. Another 32 city pairs are included on the list with travel volumes between one million and two million annual trips. An additional 18 city-pair markets are shown with volumes of one million and under. Relatively small variations in definitions could change the number of city pairs listed in Figure 2-11. The Great Circle Route distance from New Yorkâs City Hall to Philadelphiaâs City Hall is 81 Miles. Actual routing distance between the two cities (derived from Google Maps) by I-95 is about 98 milesâmaking it a potential candidate for consideration in a study of distances around 100 miles. 11 Federal Highway Administration, 2015. Developing Refined Estimates of Intercity Bus Ridership: Final Report.
35 FIGURE 2-11. ONE-DAY DRIVE CORRIDORS RANKED, BY TOTAL TRAFFIC VOLUME Source: Research team, based data from Federal Highway Administration Bus Study.
36 New York City/Philadelphia (NYC/PHL) would emerge as the single largest intercity pair corridor in the United States with a slightly different set of definitions. If it had been included, the NYC/PHL volume would comprise approximately 19 million interregional trips, with an air share of 3%. At a 90-mile distance, LA/San Diego would show approximately 21 million interregional trips, but with insignificant O-D air share reported and thus not a candidate by this criterion either. AIR MODE SHARE, BY DISTANCEâCHART FORMAT The relationship between trip distance and air mode share for the city pairs included in Figure 2-11 can be depicted in graph format, as shown in Figure 2-12. FIGURE 2-12. AIR MODE SHARE AS FUNCTION OF DISTANCE, FOR THE âONE-DAY DRIVEâ CITY PAIRS Source: Data from Figure 2-11. Mode share data available in the Technical Appendix. EXAMPLES OF THE SCALE OF TRIP-MAKING OVER 800 MILES The longest distances included in this section include trips that might be made by automobile in one (very long) day, including descriptions of distances for Chicago/New York and Chicago/Dallas that are over 700 miles, both with air mode shares around 90%. As noted above, not many drivers go more than 800 miles in a single daily driving segment. However, a sense of scale for the longer trips can also be gained by examining a small set of long-distance air volumes, which are empirically reported. Project modeling has been undertaken by the research team for the study of airport choice in multiairport settings, whichâ as an exampleâsupports the examination of air volumes from all the airports in the Los Angeles area to all the airports in the New York area12. Examples of such metro region-to-metro region air passenger flows include: NYC/LA, at 4.4 million air passengers; NYC/Bay Area, at 3.1 air passengers; LA/Chicago, at 2.7 million air passengers; and Chicago to all the airports competing with Boston/Logan, at 2.3 million air passengers. Current data suggest that each of these air 12 This analysis of choice between dominant airports and smaller airports is included in the Technical Appendix. 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 100 200 300 400 500 600 700 800 A ir M od e S ha re Distance (Great Circle)
37 volumes is associated with automobile volume that result in automobile mode shares between 3% and 5%.