(a) Table 67.05 shows an example of sample data for a oneway trip where PMT is based on calculated leaving loads. The first row of Table 67.07 shows the vehicle trip length, UPT, PMT, APTL, and the ratio of PMT/PPMT for this trip.
(b) It has the following errors:
(1) Vehicle trip length > route length.
(2) APTL > route length.
(3) Total boardings in column (10) < total alightings in column (11).
(4) The load at the end stop < 0.
(c) Error (b)(1) clearly indicates errors in the predetermined betweenstop distances. If you check what you have entered in column (9), you would notice the 7 miles from stop 3 to stop 4. Correct the dataentry error by replacing 7 by 0.7. After this change,
(1) vehicle trip length matches the route length,
(2) APTL becomes smaller than the route length, and
(3) PMT is reduced to 34.7 with an APTL of 1.58 miles.
(d) To identify the source of error (3), compare the calculated loads with the observed loads. You may notice that the calculated load is lower by 2 at the first stop. It appears that the ride checker did not include the number of passengers from the previous trip in the number of boardings at the first stop. With this correction,
(1) Boardings become greater than alightings.
(2) PMT is increased to 42.7 miles with an APTL of 1.78 miles.
Table 67.05. Example of Correcting Data Errors
Stop Sequence 
Distance to Next Stop 
No. of Pass. Boarded 
No. of Pass. Alighted 
Observed Leaving Load 
No. of Pass. from Previous Trip (Stop 1 only) 
No. of Pass. Continuing to Next Trip (Last Stop only) 
Calculated Leaving Load 
PMT 
(7) 
(9) 
(10) 
(11) 
(12) 
(13) 
(14) 
(15) 
(16) 
1 
0.0 
18 
0 
20 
2 

18 
0.0 
2 
0.3 
2 
1 
21 


19 
5.7 
3 
7.0 
0 
2 
19 


17 
119.0 
4 
0.6 
1 
3 
17 


15 
9.0 
5 
0.3 
1 
9 
8 


7 
2.1 
6 
0.5 
0 
2 
6 


5 
2.5 
7 
0.8 
0 
1 
5 


4 
3.2 
8 
0.2 
0 
2 
3 


2 
0.4 
9 
0.1 
0 
2 
1 


0 
0.0 
10 
0.1 
0 
0 
1 


0 
0.0 
11 
0.3 
0 
0 
1 


0 
0.0 
12 
0.1 
0 
1 
1 

1 
1 
0.1 
Total 
10.3 
22 
23 

2 
1 
N/A 
141.8 
(e) To identify why boardings are still larger than alightings, compare the recalculated loads with the observed loads again. You may notice that the recalculated load starts deviating from the observed load at stop 5. Since the calculated load is one passenger too big, increase the number of alighted passengers at stop 5 by 1 from 9 to 10. With this correction,
(1) Boardings equal alightings,
(2) The leaving load at the end stop is 0, and
(3) PMT is further reduced to 40.3 with an APTL of 1.68 miles.
(f) You should also check the consistency between betweenstop distances and the calculated loads. Column (9) is based on the distance from the previous stop, but the calculated load is the leaving load. Correcting this error leads to a final PMT of 47.8 with an APTL of 1.99 miles.
(g) Table 67.07 also shows vehicle trip distance, UPT, PMT, APTL, and ratio PMT/PPMT for the cumulative corrections in (c), (d), (e), and (f).
Table 67.07. Impacts of Correcting Errors
Error Corrections 
Vehicle Trip Length 
PMT 
UPT 
APTL 
PMT/PPMT 
No corrections 
10.3 
141.8 
22 
6.45 
0.63 
§69.13 (c) 
4.0 
34.7 
22 
1.58 
0.39 
§69.13 (c) + (d) 
4.0 
42.7 
24 
1.78 
0.44 
§69.13 (c) + (d) + (e) 
4.0 
40.3 
24 
1.68 
0.42 
§69.13 (c) + (d) + (e) + (f) 
4.0 
47.8 
24 
1.99 
0.50 