§ 91.05 What do the estimation-related terms mean?

100% count.  A method of obtaining service-consumed data.  This term also often refers to the results of a 100% count.  For UPT, it involves counting passengers each time they board a transit vehicle in revenue service, such as through a registering farebox.  For PMT, it involves recording the distance traveled by all passengers.  A 100% count of PMT is typically only possible for systems that have only two stops, for rail systems that record entry and exit from the system, or for rail systems that rely upon destination-based tickets. 

Average passenger trip length (APTL).  The average distance traveled for an unlinked passenger trip. It is calculated as PMT divided by UPT.

Average route length.  The average length of a route actually traveled by vehicles in scheduled services.   It is calculated by dividing the annual vehicle revenue miles by the number of annual vehicle revenue one-way trips for that route. 

Expansion factor.  A measure of actual services operated or consumed during a given duration of time.  It is used to convert a sample average to the total of service-consumed data for that duration.  It varies with sampling plans.  The total number of one-way bus trips operated during an entire report year is an example of an expansion factor; when multiplied by the sample average PMT per one-way bus trip derived from annual NTD sample, it yields a measure of annual total PMT.

Passenger miles traveled (PMT).  The total distance traveled by all passengers during a given period.

Potential passenger miles traveled.  The maximum number of passenger miles that could have been traveled by all passengers along a given fixed route during a year (or some other time duration.)  It is calculated by multiplying a 100% count of UPT times the average route length of that route during that duration.

Sample average.  The sample total divided by the number of service units in the sample.  It may be calculated for the entire annual sample, or by the type of service day, or for specific weekday time periods.  For example, dividing the total PMT in an annual NTD sample by the total number of one-way bus trips in the annual NTD sample gives a sample average PMT.

Sample data.  The data collected from a sample of service units according to a sampling plan that meets FTA’s 95% confidence and 10% precision levels.

Sample ratio.  The ratio of the sample total for one measure of service-consumed over the sample total for another measure of service-consumed.  For example, the ratio of the sample data for PMT over the sample total for UPT gives the sample APTL.  It may be calculated for the entire annual sample, or by the type of service days, or for individual service group if your sampling plan is based on service grouping.

Sample total.  The sum total of all data across the service units in a random sample.  For example, if you are sampling for PMT, the PMT sample total is the sum of the PMT collected for each of the one-way bus trip in the sample.  It may be calculated for the entire annual sample, or by the type of service day, or for specific weekday time periods.

Service-consumed data.  Passenger miles traveled and unlinked passenger trips.

Type of service days.  Weekdays, Saturdays, or Sundays.  For scheduled services, service days in a report year are classified according to the schedule operated on that day.  If a weekday that is a holiday is served with a Sunday schedule, that weekday is considered to be a Sunday.  For non-scheduled services, service days are the actual days of a week regardless of whether they are a holiday or not.

Typical day.  For your scheduled services, it is a day on which you operate your normal, regular schedule and there are no anomalies such as extra service added for a special event or reduced service as a result of weather or interruption.  For your non-scheduled services, it is any day of operation.

Unlinked passenger trips (UPT).  The number of passengers who board transit vehicles in revenue service.  Passengers are counted each time they board a vehicle, no matter how many vehicles they use to travel from their origin to their destination.

Weekday time periods.  Weekday AM Peak, Weekday Midday, Weekday PM Peak, and Weekday Other.  The Reporting Manual instructs how you should define the start and end points of each period.