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41 CHAPTER 5 Evaluating Airport Curbside Operations This chapter presents measures of curbside roadway per- necessary to consider the operations of both the curbside lane formance, definitions of curbside roadway levels of service, and the through lanes concurrently because the capacity and and a hierarchy of analytical methods for estimating curb- level of service of an airport curbside roadway system is deter- side roadway capacities and levels of service. It also describes mined by the component that has the lowest capacity or pro- use of a macroscopic method, QATAR, for analysis of air- vides the poorest level of service. port curbside roadways, and explains the use of this method. The methods and data presented in this chapter represent Appendix G documents the queuing theory and assumptions the best available information concerning airport roadway used in QATAR. operations and the consensus of the research team, the Proj- In evaluating airport curbside roadway operations, analy- ect Panel, and other reviewers. It is suggested that additional ses of both the curbside lanes (where motorists stop to pick research be conducted to refine the estimated airport curb- up or drop off passengers) and the adjacent through lanes are side roadway maximum service rates (i.e., the maximum flow required. As described in Chapter 2, these analyses are neces- rates at each level of service). sary because double- or triple-parked vehicles impede or delay the flow of vehicles in the adjacent through lanes.* As a result, Performance Measures the capacity of the through lanes decreases as demand for curb- side space approaches or exceeds the capacity of a curbside Curbside utilization is the recommended performance mea- roadway segment, causing double or triple parking. sure for airport curbside roadways. Curbside utilization indi- As described in more detail later in this chapter, the capac- cates the ability of a roadway to accommodate existing or ity of curbside pickup and drop-off areas depends on the num- projected requirements for vehicles loading or unloading at ber of lanes airport management allows to be used for vehicles the curbside. It also indicates if spare capacity is available to to stop, load, or unload. For example, at airports where double serve additional demand and surges in demand. parking is prohibited, curbside capacity equals the effective Roadway and curbside capacities are typically analyzed for length of the lane next to the curb. At airports where double the peak hour or design hour of a facility. For airport road- parking is allowed, curbside capacity equals twice the length ways, it is suggested that the design hour be a typical busy hour of this lane. on the peak day of the week during the peak month. This sug- In this chapter, methods of estimating the volumes, capac- gestion is in contrast to planning for airfield and other airport ities, and levels of service of the curbside lanes and the through facilities, which often considers the peak hour of an average lanes are presented separately. However, when estimating air- day during the peak month. port curbside roadway capacities and levels of service, it is Typically, a utilization factor of 1.30 or less (65% of the capacity of the curbside loading/unloading lanes) is a desir- able planning target for new curbside roadways. A utilization *Throughout this chapter, the term "parked vehicle" refers to a vehicle that has factor of 1.70 (85% of the combined capacity of the inner and come to a complete stop and remains stopped to allow the loading or unloading second curbside lanes) is acceptable for existing facilities, rec- of passengers and their baggage. Vehicles on curbside roadways are not "parked" ognizing that during peak hours and days of the year, demand in the same sense as vehicles in a parking lot or an on-street parking space will exceed capacity. However, individual airport operator because these parked vehicles may not be left unattended on airport curbsides. Within the airport industry, vehicles stopped or standing at curbsides are com- policies regarding parking in multiple lanes may dictate differ- monly referred to as parked vehicles. ent utilization factor planning targets.