§ 85.01 – What expansion factor should I use for the PPMT option?

(a)    You must use your 100% count of PPMT as the expansion factor.

(b)   For estimating annual total PMT:

(1)   Use annual total PPMT if your sampling plan is not based on grouping.

(2)   Use annual total PPMT by group if your sampling plan is based on grouping.

(c)    For estimating average daily PMT by type of service days, use annual total PPMT by type of service days.

§ 85.03 – How do I determine annual total PPMT?

(a)    Suppose that:

(1)   Your unit of sampling and measurement is one-way bus trips, and

(2)   You are going to estimate annual total PMT.

(b)   You should do the following for each route:

(1)   Determine the annual number of vehicle revenue miles for the report year.

(2)   Determine the annual number of vehicle revenue one-way trips for the report year.

(3)   Divide the annual number of vehicle revenue miles by the annual number of vehicle revenue one-way trips to get the average route length.

(4)   Multiply your route-level 100% counts of UPT with the calculated average route length to get route-level PPMT.

(c)    You should sum the calculated route-level PPMT across all routes to get your annual PPMT for all routes.

(d)   Table 85.01 illustrates how you may accomplish (b) and (c).

Table 85.01.  Calculating Annual Total PPMT for All Operating Routes

Route Number

Route Name

Annual Revenue Trips

Annual Revenue Miles

Average

Route Length

100% UPT

100% PPMT

90

Blue Line

3,869

9,975

2.58

22,866

58,952

50

Red Line

3,286

10,310

3.14

23,634

74,148

14

Prospect

1,643

10,690

6.51

24,506

159,446

12

Beechcrest

1,643

11,835

7.20

27,131

195,435

17

College

3,286

30,666

9.33

70,298

656,036

37

Park 100

1,325

22,733

17.16

52,112

894,068

8

Washington

3,392

61,077

18.01

140,012

2,521,072

19

Castleton

1,696

32,916

19.41

75,457

1,464,491

26

Keystone

1,378

28,505

20.69

65,344

1,351,666

10

10th St.

3,339

69,897

20.93

160,231

3,354,198

Total

10,729,514

(e)    If your sampling plan is based on service grouping, you must also determine PPMT for each group.  Suppose, for example, that you have grouped your short routes into one group and your longer routes into another.  Table 85.03 illustrates how you may use route-level information on annual revenue miles, annual revenue trips, and annual UPT to determine PPMT for each group.

Table 85.03.  Calculating Annual Total PPMT by Route Group

Route Group

Route Number

Annual Revenue Trips

Annual Revenue Miles

Average

Route Length

100% UPT

100% PPMT

Short Routes

90

3,869

9,975

2.58

22,866

58,952

50

3,286

10,310

3.14

23,634

74,148

14

1,643

10,690

6.51

24,506

159,446

12

1,643

11,835

7.20

27,131

195,435

17

3,286

30,666

9.33

70,298

656,036

Total

1,144,018

Long Routes

37

1,325

22,733

17.16

52,112

894,068

8

3,392

61,077

18.01

140,012

2,521,072

19

1,696

32,916

19.41

75,457

1,464,491

26

1,378

28,505

20.69

65,344

1,351,666

10

3,339

69,897

20.93

160,231

3,354,198

Total

9,585,496

§ 85.05 – How should I get the sample total of PPMT for each service unit?

(a)    You should follow the guidance for question § 85.03 to determine the average route length for each route.

(b)   Identify the route for each one-way trip in your service units in the sample.

(c)    Multiply the sample UPT by the average route length for each one-way trip to get sample PPMT for each one-way trip.

(d)   Sum the trip-level PPMT for all one-way trips in a service unit to get sample PPMT for each service unit. 

§ 85.07 – What sample ratio should I use for the PPMT option?

(a)    You must use the ratio of sample total PMT over sample total PPMT as the sample ratio.

(b)   For estimating annual total PMT:

(1)   Use sample PMT/PPMT ratio for the entire sample if you do not group your service.

(2)   Use sample PMT/PPMT for each group if your sampling plan is based on grouping.

(c)    For estimating average daily PMT by type of service days, use the sample PMT/PPMT ratio by type of service days.

§ 85.09 – How should I determine the PMT/PPMT ratio for a sample?

(a)    You must determine the sample PMT/PPMT ratio for a given sample as the ratio of sample total PMT over sample total PPMT.

(b)   You must not determine the sample ratio as the average of the PMT/PPMT ratio for individual service units in the sample.

§ 85.11 – How should I estimate annual total PMT for the PPMT option?

(a)    You should multiply your sample PMT/PPMT ratio for the entire annual sample with the annual total of your PPMT to get an estimate of the annual total PMT if your  sampling plan is not based on service grouping, or

(b)   You should take a two-step approach if your sampling plan is based on service grouping:

(1)   Multiply your sample PMT/PPMT ratio with your corresponding annual total PPMT for each group, and

(2)   Sum the above products across all groups to get your annual total PMT.

§ 85.13 – How should I estimate average daily PMT by type of service days?

(a)    If you operate your service only on weekdays, all you need to do is to divide your estimated annual total PMT by the number of typical weekday days of service.

(b)   If you operate your service on Saturdays, Sundays, or both as well, you should take the following two steps:

(1)   Multiply your sample PMT/PPMT ratio for each type of service days with the corresponding annual total PPMT to get the annual total PMT for each type of service days.

(2)   Divide the annual total PMT for each type of service days by the corresponding number of typical days for each type of service days.