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9 chapter three Complexities AssoCiAted with developing truCk trip generAtion rAtes for Air CArgo fACilities The increased importance of trucks in transportation planning and traffic engineering has contributed to a need for trip generation data that can be used to estimate truck traffic volumes. As noted earlier, the robustness of trip generation data for trucks associated with air cargo facilities has not received as much study or attention as more general truck traffic. This chapter discusses the determinants and complexities associated with air cargo-related truck behavior and provides context for the subsequent chapters on the state of the practice and further research needs. determinAnts of Air CArgo truCk trips dynamic Cargo types and volumes Air cargo moving to, from, and within the United States and Canada accounts for 9.1% of the worldâs air cargo traffic in terms of ton-miles and 14.1% in terms of tonnage alone. In 2015, total US air tonnage cargo enplaned was about 23.6 million tons (Bureau of Transportation Statistics 2016). The U.S. domestic market has remained relatively flat in recent years, except during the global economic downturn, which resulted in a drop of 12.4% in 2009. Traffic continued a slow recovery in 2014 and 2015, growing 2.9% and 2.5%, respectively. Figure 3 provides an overview of trends in U.S. air cargo volumes since 1999, measured in revenue ton kilometers (RTK) (Boeing 2016). facility types The size and form of cargo facilities in an airport vary substantially. Cargo type, characteristics of trucks serving the facility, materials handling, and degree of mechanization make cargo facilities different and hence different truck trips may be generated from those facilities. reduced Air Cargo Capacity and shifts to truck Rationalization of the size of the passenger fleet, the predominance of narrow-body airplanes on domes- tic routes, and the decline of scheduled domestic air freight airlines has reduced North American domestic air cargo capacity, measured in available ton-miles. Continuing the trend of past years, combination carriers continue to rely on trucks to offset the loss of domestic air capacity that has resulted from reduced fleet size and the shift of widebody airplanes from domestic to interna- tional markets. Consequently, most cargo between airports in the U.S. today travels by road on trucks. These road feeder services (RFS) allow combination carriers to offer service comparable to that of pure cargo carriers. Rising fuel costs have magnified the inherent cost advantages of ground transport over air transport (Boeing 2016). In addition, freight forwarders prefer to avoid deal- ing with the more onerous air cargo security regulations of the post-9/11 world and use road services whenever possible (Air Cargo World 2015). Complexities pace and nature of Change in the Air Cargo industry The emergence and continued growth of e-commerce, the mobile Internet, and a global consumer class has led to an environment in which businesses and purchasers depend on freight and goods
10 being shipped and delivered wherever and whenever they are desired. This relatively new âpull economy,â in which consumers and users of commodities and products drive the production and shipping activities, differs significantly from the historical âpush economy,â in which manufac- turing cycles and processes generally dictated when and where commodities would be needed and products would be available to consumers. Further, as new product shelf life decreased, such as for consumer electronics, and as the value of goods shipped has increased, the demand for expedi- tious transport and control, as well as transparency, has correspondingly increased (Plumeau 2016). Domestic air cargo in the United States also experienced shifts, particularly as fuel costs increased in recent years and integrated express carriers developed deferred delivery business models, reducing the demand for overnight delivery by aircraft and relying increasingly on truck networks. Since the late 2000s, however, the rate of growth of air cargo volumes, both worldwide and in North America, has generally fallen short of forecasts or stakeholder expectations. For example, air cargo tonnage was about 11% lower in 2015 at North American airports than had been forecast in 2011 (Muscatello 2016). As much as 20% of the freight moving through an air cargo facility can be truck-to-truck. Thus, even though it is shipped with an air bill, it never actually gets on an aircraft. It therefore remains unreported to the airport and can complicate the planning process if it is not anticipated in the plan- ning (Muscatello 2016). 0 10,000 20,000 30,000 40,000 50,000 60,000 RT K (m ill io ns ) 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 Scheduled freight (inc. express carriers) Charter freight Mail FIGURE 3 U.S. air cargo volumes, 1999â2015 (Source: Boeing World Air Cargo Forecast 2016â2017).
11 The trends of major significance to the future of air cargo include: â¢ Increasing focus of shipping activities on major gateway airports â¢ Rationalization of belly cargo capacity â¢ Modal shifts, new markets emerging (primarily international) â¢ Dynamic and changing distribution systems â¢ Imbalances in freight flows between key countries and gateway airports â¢ E-commerce (e.g., Amazon) (Muscatello 2016). These trends create change in freight logistics, freight volumes, and freight transportation routes, not analyzed in this report. data sources and Access The principal data required for estimating air cargo truck trip generation rates come from surveys or interviews. However, gate surveys or cargo business interviews are costly and typically have low response rates. In addition, most air cargo carriers are not willing to share truck movements data in an effort to keep their customerâs information confidential. Traffic counting data collection surveys, which employ pneumatic tubes in the roadway attached to an automated counter, are potentially more useful. However, they are also more complex, as there are significant non-cargo movements to/from cargo facilities that the traffic counting tubes will typi- cally not be able to discriminate from cargo traffic without additional significant effort to manually break out traffic types in the resulting count database. Collecting data through observation could be another option; however, this can be expensive because a field surveyor will need to be in position to collect the data for a designated time period. Video counting systems, which automatically count vehicles entering and exiting a facility, may also hold promise for counting air cargo truck trips, but similarly can be costly.