§ 41.07 – What sampling options are available?

(a)    The available sampling options vary in:

(1)   the unit of sampling and measurement,

(2)   sampling structure,

(3)   efficiency options, and

(4)   sampling frequency.

(b)   The particular unit of sampling and measurement used in these ready-to-use sampling plans varies by mode and whether the service is scheduled (Table 41.01).

(1)   For non-scheduled services, the unit is in vehicle days.

(2)   For bus services (MB, CB, RB, and TB), separate sampling plans are available with units in one-way trips and in round trips.

(3)   For commuter rail, the unit is in one-way car trips.

(4)   For other rail modes, separate sampling plans are available in units of one-way car trips and one-way train trips.

Table 41.01.  Options for Unit of Sampling and Measurement

Service

Mode

Units of Sampling and Measurement

Non-Scheduled

Demand Response (DR, DT)

Vehicle days

Commuter Vanpool

Vehicle days

Scheduled

Bus (MB, CB, RB, TB)

One-way trips, round trips

Commuter Rail (CR)

One-way car trips

Other Rail Modes

One-way car trips, one-way train trips

(c)    Two options are provided for sampling structure—period-based and interval-based.  Interval-based sampling plans are available for bus services only.

(d)   Three efficiency options are provided:

(1)   Base Option – you must estimate both UPT and PMT through random sampling.

(2)   APTL Option – you must report a 100% count of UPT, estimate the average passenger trip length (APTL) through random sampling, and obtain annual PMT by multiplying the 100% UPT with the estimated APTL.

(3)   Grouping Option – you must divide your bus routes into two groups by route length.  The grouping option is available for period-based sampling plans only.

(e)    Three frequency options are provided for period-based sampling plans—quarterly, monthly, or weekly.  You may choose whichever of these options is best suited for your agency.  One factor to consider is that the annual realized sample size may be larger at a lower sampling frequency due to rounding.  Another factor is that a lower sampling frequency means a larger annual number of acts for random sampling.

(f)    Up to six frequency options are provided for interval-based sampling plans—every day, every 2nd day, every 3rd day, every 4th day, every 5th day, and every 6th day.  Three sets of these sampling plans are available for 7-day weekly service, 6-day weekly service, and 5-day weekly service, respectively.  The sampling plans for 7-day weekly service and the base option are similar to those in Circular 2710.1A.

§ 41.05 – For what modes are ready-to-use sampling plans available?

(a)    For non-scheduled services, they are available for demand response services (DR and DT) and commuter vanpool.  You should not use the ready-to-use sampling plans for commuter vanpool if your vanpool service does not serve commuters exclusively.

(b)   For scheduled services, they are available for bus services (bus (MB), commuter bus (CB), bus rapid transit (RB), and trolleybus (TB)), commuter rail (CR), and other rail modes. 

§ 41.03 – If I am using a ready-to-use sampling plan this year, may I use it again for my next report year?

(a)    You should not use it again if your next report year is your mandatory sampling year.  After you have collected the sample data from this year, you should develop a template sampling plan with that sample data for your next report year.

(b)   You may use it again for the next report year if that year is not your mandatory sampling year.

(c)    You may use it while you operate no more than 30 vehicles operated in maximum service for all modes combined.

§ 41.01 – Under what conditions may I use ready-to-use sampling plans?

(a)    Small Systems – If you operate no more than 30 vehicles operated in maximum service for all modes combined and if you choose to sample for determining your annual service-consumed data for any of the modes you operate. 

(b)   New Mode – If you will be sampling and reporting for the first time this current report year for a particular mode that you do not already operate.  For example, you would meet this condition if you will add light rail (LR) service this year, but you have not operated this service previously, or

(c)    New Type of Service – If you will be sampling and reporting this current report year for a particular type of service for the first time.  For example, you would meet this condition if you previously directly operated all of your bus (MB) service, but will contract out part or all of that service to a private entity for this year, or

(d)   Major Changes of Service – You have made major changes to your service since your last sampling year, or

(e)    No Sample Data – If you have reported your service to the NTD before through random sampling, but no longer have the original sample data, or

(f)    Sample Data Not Reliable – If you have reported your service to the NTD before through random sampling, but the sample data are found to be not reliable, or

(g)   Sample Data Not Enough – if you have reported your service to the NTD before through random sampling, but the sample size is smaller than 50 service units.

§ 10.03 – What procedures does this Sampling Manual cover?

(a)    Development of sampling plans with two options:

(1)   Section 40 on ready-to-use sampling plans.

(2)   Section 50 on agency-developed template sampling plans with agency sample data.

(b)   Collection of sample data in Section 60.

(c)    Estimation of annual service-consumed data with two options:

(1)   Both UPT and PMT if you do not report 100% counts of UPT.

(2)   PMT if you report 100% counts of UPT.

(d)   Section 30 specifies several requirements for alternative sampling plans that template sampling plans must also meet. 

(e)    Figure 10.01 shows how these procedures and options relate to each other.

 Figure 10.01. Flow Chart of Procedures and Options

Flow Chart

§ 10.01 – What is the purpose of this Sampling Manual?

(a)    It suggests procedures for obtaining annual data on unlinked passenger trips (UPT) and passenger miles traveled (PMT) for the National Transit Database (NTD) through random sampling according to the requirements in the NTD Reporting Manual.

(b)   In the event of a conflict between the requirements in the Reporting Manual and this Sampling Manual, the requirements of the Reporting Manual are definitive.

(c)    When it is possible to obtain annual UPT and PMT data according to the requirements in the Reporting Manual by using other methods not specified in this Sampling Manual, then you may do so.