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26 next. The following system descriptive characteristics, to be supervision (ATS) system (control center computer system). reported on Form A, are defined in this section: Caution needs to be exercised so that miles performed in the non-passenger-carrying portions of the system or while Passenger Trips a vehicle is out of service are subtracted from totals that Vehicle Service Miles include such mileage. Vehicles Operated in Maximum Service Vehicles Available for Maximum Service 5.2.3Vehicles Operated in Maximum Service Headway in Maximum Service Vehicles Operated in Maximum Service is defined as the number of in-service vehicles operated at once in the system 5.2.1 Passenger Trips during the peak period of the day that maximum service is Passenger Trips is defined as the number of passenger trips provided during the reporting period, with a vehicle being in taken on the system during the reporting period, with a pas- service when located in the passenger-carrying portion of the senger trip being made by any individual that uses the APM system and when passengers are able to use it for transport. system to get from one station to another in the system. Vehicles staged as hot-standby or operational spares, regard- It is recognized that there is variability in how, and even if, less of location, are not included. passenger trips are quantified in airport APM systems. Some For example, if during maximum service an airport APM systems use automatic passenger counting systems, either system uses five in-service trains composed of three vehicles installed above train or platform doors or at a common location each and one train composed of two vehicles in standby at a where passengers enter and exit stations. Because of the open terminal station, the number of Vehicles Operated in Maxi- nature of airport APM systems, these automatic counting tech- mum Service is 15. nologies count global ins and outs and do not track individual Vehicles Operated in Maximum Service excludes vehicles used to address atypical, failure, or special-event service passenger movements like fare collection systems in closed during the reporting period. transit systems that use turnstiles and tickets. This makes these automatic counting technologies, although convenient, gener- ally less precise than those in closed transit systems. 5.2.4Vehicles Available for Maximum Service Other airport APM systems may not use automatic passen- Vehicles Available for Maximum Service is defined as the ger counting systems, but instead estimate APM passenger trips number of vehicles available to be in service at once in the sys- based on actual or forecast parking or airline passenger data. tem during the peak period of the day that maximum service Still other airport APM systems may quantify APM passen- is provided during the reporting period, with a vehicle being ger trips by physically counting passengers on a semi-regular available when it can be placed in service after no more than basis using employees or consultants posted on APM station a departure test, for example, and without first requiring any platforms. maintenance, cleaning, or other similar action. A vehicle is in It is recognized that airport APM systems may not be able service when located in the passenger-carrying portion of the to report the Passenger Trips service descriptive characteristic system and when passengers are able to use it for transport. or may not be able to report it accurately. For these systems, For example, if during maximum service an airport APM they are encouraged to report at least order-of-magnitude system has 29 vehicles in its total fleet, and: Passenger Trips where possible. 20 are in service; 5.2.2 Vehicle Service Miles One is in the maintenance shop but capable of being in service; Vehicle Service Miles is defined as the total miles traveled One is in the maintenance shop and being repaired due to by all in-service vehicles in the system during the reporting failure; period, with a vehicle being in service when located in the Three are coupled together on the vehicle storage tracks at passenger-carrying portion of the system and when passen- the maintenance and storage facility (M&SF), with one of gers are able to use it for transport. those three in failure; and For example, if an in-service train is composed of three Four are coupled together on the vehicle storage tracks at vehicles and the distance the train travels is 4 miles, then the the M&SF, with none of the four in failure; then the number number of Vehicle Service Miles is 12. of Vehicles Available for Maximum Service is 24. Vehicles Vehicle Service Miles performed during the reporting located in the maintenance shop, regardless of their status, period can be obtained directly from vehicle hub-o-meter as well as operable vehicles coupled to failed vehicles at the or odometer readings or possibly from the automatic train M&SF, are not considered available.