Click for next page ( 8


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 7
7 different curbside roadway). Compared to access roadways, Operating Characteristics of Airport circulation roadways typically operate at lower speeds and Terminal Area Roadways allow for multiple decision points. The above roadways--access roadways, curbside road- The operating characteristics of airport terminal area road- ways, and circulation roadways--are considered "curbside ways differ from those of other public roads. This section and terminal area" roadways and are the focus of this Guide. describes the distinguishing operating characteristics of airport Other airport roads include service and access roads, as terminal area roadways, weaving sections, and curbside areas. described below. What Makes Airport Roadway Service Roads Operations Unique Service roads link the airport access roadways with on- The main differences between the operating characteristics airport hotels, employee parking areas, and employment of airport terminal area access and circulation roadways and centers (e.g., aircraft maintenance facilities or hangars), air nonairport roadways include cargo/air freight buildings and overnight parcel delivery services, loading docks/trash pickup areas, post offices, fixed- A high proportion of unfamiliar motorists. Because most base operators (FBOs) or general aviation areas, airport airline passengers fly infrequently (e.g., fewer than four maintenance buildings and garages, military bases, and other times per year), they (and the drivers who are dropping nonsecure portions of the airport that generate little airline them off/picking them up) are not familiar with the road- passenger traffic. ways at their local airport(s), much less the roadways at their The traffic generated by these land uses differs from that gen- destination airport(s). Unlike commuters, who rarely need erated by the passenger terminal building in several respects. to refer to roadway signs, airline passengers rely upon signs First, the traffic on service roads includes a higher proportion (or other visual cues) to guide them into and out of an air- of trucks, semi-trailers, and other heavy vehicles than the traf- port and to/from their destinations on the airport. Picking fic on curbside and terminal area roadways, which rarely serve up passengers may be particularly challenging for unfamil- trucks or delivery vehicles. Second, most drivers on the service iar motorists, who must follow the appropriate signs, be roads (e.g., employees and drivers of cargo vehicles) use these aware of all the traffic and pedestrian activity at the curbside roads frequently and are familiar with the roads and their des- areas, and also be able to identify their party among crowds tinations, unlike drivers using the curbside and terminal area of other passengers waiting to be picked up. roadways. Large number of complex directional signs. Directional For purposes of operational analyses, the service roads are signs on airports often provide more information (i.e., more similar to those found in an industrial park. Typically, they lines of text) than those on public roadways governed by the consist of two- to four-lane roads with generous provision for Manual of Uniform Traffic Control Devices (published by the turning paths of large trucks and semi-trailers and for FHWA) because of the number of terminals, separation of entering and exiting vehicles, including separate or exclusive departures and arrivals level roadways, airlines, parking turning lanes. options, and rental car companies that must be provided to motorists (see Figure 2-3). For example, the general policy at U.S. airports is to display the name of every airline serving Airfield Roads an airport, even those operating only a few times a week. The A separate network of roads located within the aircraft signs often include colors, fonts, symbols, and messages not operating area or the airfield is used by ground service equip- used on other public roadway signs. ment, including vehicles servicing aircraft, towing aircraft, or Because of the number, size, and complexity of these towing baggage carts and vehicles used for runway mainte- signs, motorists may not see regulatory or warning signs nance or emergency response. Often these vehicles are not concerning height restrictions, parking rates, security reg- licensed to operate on public streets. Only drivers with air- ulations, use restrictions (e.g., authorized vehicles only), field licenses are permitted to operate vehicles with aero- and other messages. These signs may result in an overload drome permits in secure or restricted areas. The design and of information and cause motorists to decelerate while operation of these roads is addressed in guidelines issued by attempting to read the signs. the FAA Series 150 Advisory Circulars Stressful conditions. Motorists operating on airport The remainder of this Guide addresses curbside and termi- roadways are under more stress than typical motorists. nal area roadways only. This stress results from the knowledge that minor delays or

OCR for page 7
8 bus, find a parking place, find a passenger ("Where is Aunt Meg?"), find the correct place to drop off or pick up a pas- senger, locate the taxicab, courtesy vehicle, or city bus stop, and so forth. Passengers realize the importance of making correct decisions in an environment that is more compli- cated and anxiety-filled than a typical roadway situation so that they do not miss their flights or rides. Each action on an airport is part of a chain of events, any one of which can go wrong and disrupt or delay a vacation, business meet- ing, or other important event. High proportion of large vehicles. More than 10 types of ground transportation services operate on airport road- ways. The characteristics of each service, the needs of the customers using the services, and the operating character- istics of the vehicles used to provide these services must be considered when developing physical and operational plans for airport curbside and terminal area roadways. Courtesy vehicles, door-to-door vans, scheduled buses, and other large vehicles may represent 10% to 20% of the traffic volume on a terminal area roadway. On a typical pub- lic street, less than 10% of the traffic consists of large vehi- cles. Standard Highway Capacity Manual (HCM) capacity calculation procedures reduce the capacity of a public high- way with a high percentage of truck, bus, and other large vehicle traffic to account for the slower acceleration/ deceleration characteristics of these vehicles. However, the use of a capacity adjustment factor may not be necessary on airport terminal area roadways because courtesy vehicles, vans, and buses operating on those road- ways do not interfere with the flow of other traffic to the extent that they do on public highways. On airport termi- nal area roadways, these large vehicles can operate at the range of prevailing speeds typically found on airport road- ways (i.e., 25 miles per hour [mph] to 45 mph) and have sufficient power to accelerate and decelerate at rates that are comparable to those of private vehicles--and do so unless they are transporting standing passengers--because most airport roadways are level or have gentle vertical slopes. Additionally, large vehicles such as courtesy vans or shuttle buses may obstruct motorists' views of wayfinding signs and may interfere with the operation of passing vehicles as Source: LeighFisher. they enter or exit curbside areas. Mix of experienced and inexperienced drivers. Although Figure 2-3. Complex airport roadway signs. most private vehicle drivers use an airport infrequently, 20% to 30% of the vehicles on airport roadways are oper- wrong turns may cause a person to arrive too late to check ated by professional drivers who are thoroughly famil- baggage, claim a pre-reserved seat, or greet an arriving pas- iar with the on-airport roadways because they use them senger, or in an extreme case, miss a flight entirely. Con- frequently--perhaps several times each day. This difference gested airport roadways, closely spaced decision points, contributes to vehicles operating at a range of speeds on the and complex signs can add to this stress and discomfort. same roadway segment--slow-moving vehicles (e.g., un- Factors adding to passenger stress at an airport include familiar drivers of private vehicles attempting to read signs the need to connect from a car to a plane, from a car to a or complete required turns and maneuvers) and faster vehi-

OCR for page 7
9 cles (e.g., taxicabs and limousines operated by professional ramp, while vehicles from the on-ramp move from the aux- drivers familiar with the airport roadways and who may iliary lane onto the freeway. ignore posted speed limits). The operation of weaving and merging areas on airport Recirculating traffic. Traffic officers often require motorists roadways differs from the operation on nonairport roadways to exit the terminal area if they are not actively loading or primarily because these operations occur at slower speeds on unloading passengers, unable to find an empty curbside airport roadways than they do on freeways and arterial streets. space, or waiting for an arriving passenger who is not yet at Weaving analyses generally are conducted for freeways and the curbside. Motorists exiting the curbside area may either arterial streets on which vehicles operate at higher speeds than wait in a cell phone lot until the passenger arrives (which is those on most airport roadways. At high speeds, drivers require encouraged by airport operators) or recirculate around the large gaps between successive vehicles in order to merge airport and back to the curbside. Table 2-1 indicates the per- into, or weave across, a traffic stream. In the 2000 HCM, it was centage of roadway traffic that recirculates past the terminal assumed that a free-flow speed of 35 mph on a weaving section more than once. represents level of service (LOS) E (i.e., operations at or near a roadway's capacity--the HCM chapters on weaving and merg- These recirculating vehicles contribute to roadway conges- ing were prepared for freeways). Thus, the metrics used in the tion and represent unnecessary traffic volumes. Factors con- HCM to establish satisfactory weaving conditions are not suit- tributing to recirculating roadway traffic include (1) stricter able for analysis of airport roadways, which operate at lower enforcement procedures required by current security regula- speeds than freeways. Chapter 4 of this Guide presents alterna- tions, (2) motorists who may not understand the difference tive metrics and analysis methods for use on airport roadways. between the published flight arrival time and the time when Upon entering an airport, motorists typically encounter a a passenger arrives at the curbside, (3) motorists waiting for series of exits or turns leading to nonterminal areas (e.g., econ- passengers whose flights have been delayed, and (4) drivers omy parking, air cargo, general aviation), close-in parking of commercial vehicles who, in violation of airport regula- (hourly, daily, or valet) and rental car return (by company), and tions, are improperly soliciting customers along the curbside ticketing/departures vs. baggage claim/arrivals curbside areas. roadway. Upon exiting the airport, motorists may encounter a similar series of exits as well as roads leading back to the terminal and alternative regional destinations. What Makes Airport Roadway Weaving Often, the distance between successive decision points is Section Operations Unique much less than that suggested by highway design standards Weaving is defined as the crossing of two or more traffic established for limited access highways because of the relatively streams traveling in the same direction along a length of short distances available between an airport entrance and the highway without the aid of a traffic signal or other control terminal area. Unlike a regional highway where decision points device. A weaving maneuver occurs when vehicles enter a may be separated by a mile or more, successive decision points roadway segment from one side and exit the segment on the on an airport may be separated by 500 feet or less. Even though other while other vehicles do the opposite at the same time. motorists on airport roadways are traveling at speeds (e.g., The most common example of weaving occurs on freeways 35 mph or less) that are slower than those on freeways or arte- where an on-ramp is followed by an off-ramp a short dis- rial roadways, the limited distances between decision points tance later, and those two ramps are connected by an auxil- compromise the ability of motorists to recognize, read, and iary lane. The weaving movement occurs when vehicles on react to roadway guide signs, or do not allow adequate time to the freeway move into the auxiliary lane to exit via the off- complete required merging and weaving maneuvers. Table 2-1. Percentage of private vehicles What Makes Airport Curbside recirculating to the arrivals curbside. Operations Unique Recirculating As noted in Chapter 1, curbside roadways consist of the Airport (%) inner curbside lane(s) where vehicles stop or stand typically in Baltimore/Washington International Thurgood Marshall Airport 50% a nose-to-tail arrangement while passengers board and alight, San Francisco International Airport 43% an adjacent maneuvering lane that vehicles may occupy while Seattle-Tacoma International Airport 30% decelerating or accelerating to enter or exit the curbside lane, Dallas Love Field 26% and one or more "through" or bypass lanes. The operating Reagan Washington National Airport 15% characteristics of airport terminal curbsides differ significantly Source: Based on data provided by Ricondo & Associates, Inc., June 2009. from those of most other roadways because of the interactions

OCR for page 7
10 between vehicles maneuvering into and out of curbside spaces Maneuvering traffic and parking preferences. Unlike and vehicles traveling in the through or bypass lanes. motorists on city streets, motorists parallel parking at air- The capacity of a curbside roadway is defined both by the ports rarely back into a curbside space. Motorists frequently number of vehicles that can be accommodated while stopping stop with their vehicles askew to the travel lanes or sidewalk to pick up or drop off passengers and the number that can be areas rather than maneuvering their vehicles into positions accommodated while traveling past the curbside in the through parallel to the curbside. By doing so, they may block or lanes. The capacity of the through lanes is restricted by vehicles interfere with the flow of traffic in other lanes. Motorists that are double parked (which is often tolerated on airport leave space between successive vehicles to assure that they curbside roadways) or triple parked. These capacity restric- are not blocked and to allow access to the trunk or baggage tions can cause traffic delays and the formation of queues that storage area. block vehicles trying to maneuver around stopped vehicles or Motorists using airport curbside roadways may stop in attempting to enter and exit curbside spaces. (Additional infor- the second lane even if there is an empty space in the curb- mation on the operating characteristics of curbside roadways side lane to avoid being blocked in by other motorists and to is presented in Chapter 5.) reduce the walking distances of passengers being dropped The length (or capacity) of a curbside area must be in bal- off (e.g., stop near a desired door or skycap position) or ance with the capacity of the through lanes drivers use to being picked up (e.g., stop at a point near where the person enter and exit the curbside area. For example, a mile-long is standing). Thus, motorists frequently stop in the second curbside served by only two lanes (one curbside lane and one lane in front of the door serving the desired airline even through lane) would be imbalanced because, even though the though there may be an empty curbside space located down- curb length could accommodate a large number of vehicles, stream. The propensity to avoid inner lanes and double park traffic flow in the single through lane would be delayed every reflects local driver behavior or courtesy. time a vehicle maneuvers into and out of a curbside space or Capacity of adjacent through lanes. Through-lane capacity double parks waiting for an empty space. The reverse imbal- is reduced by traffic entering and exiting curbside spaces, ance would occur with a very short curbside area and multi- high proportions of vehicles double and triple parking, the ple through lanes. use of the maneuver lanes, and other factors. As such, the Other operating characteristics of airport curbside road- capacity analysis procedures presented in the 2000 HCM are ways that differ from public roads, as further described in not applicable. Chapter 5 of this Guide presents suggested Chapter 5, include the following: methods for calculating the capacities of curbside lanes and through lanes at airports. Dwell times. The length of time a vehicle remains stopped Uneven distribution of demand. Curbside demand is not at the curbside area is referred to as "dwell time." Generally, uniformly distributed during peak periods, reflecting (1) air- vehicles transporting a large number of passengers and bag- line schedules and (2) the uneven distribution of the times gage require a long dwell time. The number of vehicles that passengers arrive at the enplaning curbside prior to their can be accommodated along a given curbside length is scheduled departures (lead time) or the times passengers determined by the size of the vehicles (i.e., the length of the arrive at the deplaning curbside after their flights have landed stall each vehicle occupies, including maneuvering space in (lag times). Furthermore, stopped vehicles are not uniformly front of and behind the vehicle) and the amount of time distributed along the length of a curbside area, reflecting each vehicle remains at the curbside (i.e., the dwell time). motorist preferences for spaces near specific doors and sky- Dwell times at a particular airport are affected by enforce- cap positions and their aversion to spaces near columns or ment policies (i.e., strict enforcement leads to shorter dwell without weather protection, if weather-protected spaces times) and local driver behavior (e.g., do drivers double park are available. in a way that allows other motorists to easily enter and exit An aerial view of a busy terminal curbside area would the lane adjacent to the terminal?). show vehicles stopped adjacent to the door(s) serving Motorists dropping off passengers typically have shorter major airlines. When a new terminal is opened, the airline dwell times than those picking up passengers (unless with the largest market share frequently gets the first choice motorists are prohibited from waiting for the arrival of a of ticket counter and baggage claim area locations. Often, deplaning passenger). Thus, since airports generally have this airline selects the most prominent location, which gen- equivalent volumes of originating and terminating airline erally is the area nearest the entrance to the curbside area. passengers (and associated traffic volumes), the required Thus, curbside demand is often heaviest at the entrance to capacity or length of an arrivals (pickup) curbside area is the curbside area, causing double-parked vehicles and typically greater than that of the departures (drop-off) congestion in this area, while downstream areas remain curbside area. unoccupied.

OCR for page 7
11 Allocation of space for commercial vehicles and other uses. At most airports, curb space is allocated to commercial vehicles on the pickup curbside area. In the allocation of commercial vehicle curb space, multiple factors must be considered in addition to calculated space requirements, such as customer service, operational needs, airport poli- cies, revenues, and perceived or actual competition among ground transportation services. Curb space may also be allo- cated for disabled parking, police vehicles, airport vehicles, valet parking drop-off/pickup, tow trucks, and other users. Allocation of traffic on inner and outer curbside areas. At airports having inner and outer curbside areas, one curbside area is generally allocated for private vehicles and the other curbside area(s) is (are) allocated for commercial vehicles. It may be difficult to direct private motorists--especially those unfamiliar with the airport--to multiple curbsides (or sup- Source: LeighFisher. plemental curbsides) and, as such, supplemental curbsides Figure 2-4. Double-wide curbside lane at are rarely used. Conversely, it is fairly common to direct Washington Dulles International Airport. commercial vehicles to multiple curbside areas. Crosswalk location, frequency, and controls. Crosswalks provide for the safe movement of pedestrians between the terminal building and center island curbside areas or a park- availability of cell phone or call-and-wait lots can reduce ing facility located opposite the terminal. The use of cross- curbside roadway traffic volumes. walks can be encouraged and jaywalking discouraged by Multiterminal airports. Large airports may have multiple providing numerous crosswalks at convenient (i.e., closely terminals, each with separate curbside areas, or continuous spaced) locations and/or fences or other barriers to pedes- curbsides that extend between terminal buildings. Curbside trians along the outer island. operations at each terminal may differ, reflecting the char- However, providing multiple crosswalks adversely affects acteristics of the dominant passenger groups and airlines the flow of through traffic. Motorists are often required to (e.g., international vs. domestic passengers, or legacy vs. low stop at more than one crosswalk because traffic controls at cost carriers). the crosswalks (whether traffic officers or signals) are rarely Recirculating or bypass traffic. At many airports, there is coordinated in such a way as to allow a continuous flow of a significant proportion of nonstopping or bypass traffic on through vehicles, such as commonly occurs on an urban the terminal curbsides. This bypass traffic includes (1) recir- street. Multiple crosswalks also reduce the available length culating traffic that, because of police enforcement or of curb space. A single crosswalk has less impact on through other reasons, passes the terminal curbside (particularly the traffic and available curb length than multiple, unsignal- deplaning curbside) more than once, (2) curbside traffic ized crosswalks, although multiple crosswalks are more destined for another terminal or adjacent curbside section, convenient. which must bypass the curbside in question, and (3) non- Curbside lane widths. At most airports, curbside roadway curbside traffic traveling past the curbside (e.g., cut-through lane widths are the same as those on public streets (e.g., 10 vehicles, employee vehicles, or airport service or mainte- to 12 feet). Recognizing the tendency of drivers to double nance vehicles). park, some airport operators have elected to delineate one Nonstandard curbside configurations. Although most air- double-wide (e.g., 20 to 24 feet) curbside lane rather than ports have linear curbsides where vehicles stop bumper to two adjacent 10- to 12-foot lanes. (See Figure 2-4.) bumper or nose to tail, a few airports have nonstandard Availability of short-duration parking. Curbside demand curbside configurations. can be influenced by the availability and price of conve- Pull-through private vehicle spaces. As shown on Fig- niently located, short-duration (e.g., hourly) parking. If such ure 2-5, the curbside areas at some U.S. airports (e.g., parking is readily available and reasonably priced, fewer Lambert-St. Louis International, Nashville International, motorists may choose to use the curbsides. Conversely, the and Little Rock National Airports), as well as many over- perceived lack or high cost of available short-duration park- seas, have (or had) pull-through spaces arranged at ing spaces can discourage motorists from parking and 45-degree angles that allow motorists to pull through, instead lead to increased curbside demand. Similarly, the similar to the way they would at a drive-through window.

OCR for page 7
12 Source: LeighFisher. Source: LeighFisher. Figure 2-5. Pull-through curbside lanes at Brussels Figure 2-7. Pay for curbside use at Paris Charles Airport. de Gaulle International Airport. Angled commercial vehicle spaces. The commercial motorists can use for a fee. These areas can be configured vehicle curbside areas at the airports serving Atlanta, parallel to the curbside (see Figure 2-7) or in a traditional Newark, and Orlando, among others, have angled spaces parking lot adjacent to the terminal building (see Fig- that require vehicles to back up to exit. ure 2-8). In Europe, unattended vehicles are permitted Driver-side loading. As shown on Figure 2-6, at a few air- in these zones, but in the United States, current security ports (e.g., Bush Intercontinental Airport/Houston and regulations prohibit unattended vehicles at the terminal Mineta San Jose International Airport), the deplaning curbsides. curbsides are located on the driver's side of the vehicle, Supplemental curbsides. Some airports provide sup- requiring private vehicle passengers to open the door and plemental curbsides in or near parking structures or at enter or exit the vehicle on the side away from the termi- remotely located sites. Examples of airports with curb- nal building while standing in a traffic lane. Driver-side side areas within parking structures include those at the loading is used at some airports for taxicabs because pas- airports serving New York (LaGuardia), St. Louis, and sengers may enter the cab from either side of the vehicle. Salt Lake City (see Figure 2-9). Brief parking zones--pay for curbside use. Some Euro- pean airports do not provide free curb space, but instead provide parking areas adjacent to the terminals that Source: LeighFisher. Source: LeighFisher. Figure 2-6. Driver-side loading at Mineta San Jose Figure 2-8. Brief parking curbside zone at Munich International Airport. Airport.