A4.2.2  Parking Facilities  APPENDIX A4$_{ }$ Parking emissions are a compound function of how many vehicles are entering and exiting  airport parking facilities (i.e., garages and surface lots) , the distance they travel to access and  egress the parking area, and any idling time incurred as the vehicles queue either in waiting for a  space or to enter or exit. The travel-based component of the parking emissions can be estimated  by applying  Equation A4-1  ( Total Pollutant Emissions from Travelling Motor Vehicles ). The  idling-based component of the parking emissions may be quantified by applying  Equation A4-2  ( Total Pollutant Emissions from Motor Vehicles Idling ). Emissions should be estimated for each  on-site and/or off-site parking facility associated with the airport. A typical idle time is 1.5  minutes and a typical travel distance is equivalent to twice the diagonal of the parking area.  Emissions from the terminal curbside areas are based on the number of vehicles traveling to  these areas, the distance of the curbside area and the amount of  idling time incurred as these  vehicles pickup and drop-off passengers. The approaches discussed previously for roadways and  parking facilities may be applied to estimate motor vehicle emissions from terminal curbside  areas. Therefore, the travel- and idling-based components of these emissions may be quantified  by applying  Equation A4-1  ( Total Pollutant Emissions from Traveling Motor Vehicles ) and  Equation A4-2  ( Total Pollutant Emissions from Motor Vehicles Idling ), respectively. A typical  idle time ranges from 1.5 to 6.0 minutes depending on vehicle type and a typical travel distance  is equivalent to length of the terminal curbside holding area.  Total emissions from roadway, parking and curbside motor vehicle activities may be obtained by  summing the travel emissions based on VMT and the idling emissions based on hours operation, as shown by  Equation A4-3  ( Total Pollutant Emissions from Motor Vehicles ).  Equation A4-2. Total Pollutant Emissions from Motor Vehicles Idling  Where:  E$_{Idling }$ = total idling motor vehicle emissions of pollutant (i.e., CO, SO$_{2}$, PM$_{10}$, PM$_{2.5}$, NO$_{x}$, or  VOC), for a given time period, expressed in pounds.  CF = factor to convert grams to pounds (i.e., 0.0022046)  AADT$_{j }$= average annual daily traffic counts by vehicle type j for the parking facility.  IT$_{j }$= idling time, expressed in minutes per vehicle type j.  ER$_{j }$ = emissions rate of pollutant from idling considering speed of vehicle type j, expressed in  grams per minute.  j = vehicle type (e.g., Honda Civic).  𝑬 𝑻𝑰𝑻𝒊𝑰𝑰 =  𝑪𝑭 ×  ෍ൣ𝑨𝑨𝑨𝑳 𝒊 ×  𝑻𝑳 𝒊 ×  𝑬𝑬 𝒊 ൧ 𝒊 19$_{ }$