OTTAWA - “Peak-to-Base” Ratio
On the chart above, the label “Increment - Maximum Peak Scheduled Fleet” refers to the difference between “Maximum Peak Scheduled Fleet” and “Midday Scheduled Fleet” (see table). 1972 data were included above to provide historic reference.
Adjustment for increased use of articulated vehicles would magnify the apparent increase from 1972 in fleet size and the number of buses scheduled.
1972
|
1982
|
1987
|
1992
|
1997
|
2002
|
|
|---|---|---|---|---|---|---|
Total Active Fleet
|
368
|
780
|
824
|
831
|
793
|
915
|
Index (1982 = 100)
|
47
|
100
|
106
|
107
|
102
|
117
|
Maximum Peak Scheduled Fleet
|
349
|
718
|
729
|
717
|
663
|
761
|
Index (1982 = 100)
|
49
|
100
|
102
|
100
|
92
|
106
|
Midday Scheduled Fleet
|
141
|
289
|
275
|
272
|
227
|
284
|
Index (1982 = 100)
|
49
|
100
|
95
|
94
|
79
|
98
|
Peak : Off-peak Scheduled Bus Ratio
|
2.475
|
2.484
|
2.651
|
2.636
|
2.921
|
2.680
|
The principal factor which determines bus transit system fixed (“overhead”) costs is vehicle fleet size. This in turn establishes factors such as operating base and maintenance facility size. The ratio of buses scheduled for peak service to buses scheduled for midday (“off-peak” or “base”) service is an important indicator of traffic patterns and cost efficiency. In general, a high “peak-to-base ratio” indicates that a relatively large share of total weekday traffic is carried during peak periods. Some of the vehicles, staff and facilities required for peak-period traffic are not needed at other times. Consequently, a high “peak-to-base” ratio also suggests relatively lower levels of cost efficiency than would occur if peak-hour was relatively less dominant. In the U.S., a “peak-to-base ratio” approaching 2.00 is considered “high.” A high peak-to-base ratio is a historic characteristic of Ottawa transit services.
Trends - Midday Scheduled Buses and Passengers;
Peak-Period Passengers and Buses Added for Peak Schedules
(1982 = 100)
On the chart above, “Increment - Peak Riders” refers to the difference between “ Weekday Peak Period Riders (a.m. & p.m)” and “ Weekday Riders.” “Increment - Peak Buses” refers to the difference between “Maximum Peak Scheduled Fleet” and “Midday Scheduled Fleet.” 1972 data were included to provide historic reference.
The increment of peak-period passengers increased significantly from 1982, continuing a trend visible from 1972 (at a somewhat lower rate than during 1972-1982). Midday ridership continued to increase after 1982, but at a much lower rate than during 1972-1982. Both indicators declined to 1997 but increased thereafter; the trends confirm that midday ridership increased at a higher rate during 1997-2002.
Adjustment for relative vehicle size (i.e. increased use of articulated vehicles after 1982) would magnify the apparent increase from 1972 in “Midday Buses” and “Increment - Peak Buses.” The authors believe that, if so adjusted, changes in “Midday Buses” would closely mirror changes in “Midday Riders.” The increase in the “Peak Rider” increment during 1982-1987 appears large enough to exceed the change in the “Peak Bus” increment, adjusted for relative vehicle size, although to what extent is not clear.
The number of “Midday Buses” operated by OC Transpo decreased significantly from 1982 to 1997 while the “Peak Bus” increment remained quite stable. This was reflected by a significant increase in the undertaking’s “peak-to-base ratio,” which in turn implies significant upward pressure on “overhead” cost per unit of service.