With the shift to the larger low-floor streetcars, the TTC will begin schedule changes on Sunday October 13 (Thanksgiving weekend) for route 506 Carlton. In many periods of operation, the headways will widen in recognition of the capacity of the new cars, although the change will also bring a capacity increase.

The schedules are designed on the basis that most service will be provided by Flexitys, especially in the off-peak period. This could lead to problems such as those seen on other routes where CLRVs operate on headways designed for larger cars and are badly overloaded as a result. A lot depends on there being enough new cars to fully populate the route.

On the schedules, the only CLRVs remaining in operation will be the 506 Carlton trippers and 511 Bathurst (which is planned to start conversion late in 2019).

The TTC Service Standards set design capacities for vehicles which in theory dictate the level of service a route received. The standard is more generous for off-peak than for peak service.

Peak Off-Peak CLRV 74 42 Flexity 130 70 Ratio Flexity:CLRV 1.76 1.67 Ratio CLRV:Flexity 0.57 0.60

If service were replaced purely on the basis of scheduled capacity, then there would be about 60% as many Flexitys/hour as on a schedule for CLRVs.

The new service design (click to enlarge, or retrieve PDF version) is shown below.

The change in AM peak and midday headways is from 5’40” (340 seconds, 10.6 cars/hour) to 7’50” (470 seconds, 7.7 cars/hour), a decrease in cars per hour to 72% of current service. This will be partly offset by the larger capacity of the new cars plus the benefit of trippers scheduled during the height of the peak period.

The change in PM peak headways is from 6’00” (360 seconds, 10 cars/hour) to 8’30” (510 seconds, 7.1 cars/hour), a decrease in cars/hour of to 71% of current service.

This change comes on top of wider headways introduced in August in an attempt to improve route reliability by giving streetcars more running time and longer terminal layovers in a bid to cut down on short turns.

The capacity goes up, but the service frequency worsens. This will almost certainly be compounded by the TTC’s inability to maintain even spacing of vehicles as they move across the route. Even though they might leave their terminals somewhat “on time”, this situation quickly deteriorates into bunches and gaps.

There is always a challenge when the TTC substitutes larger vehicles on a route and widens the headway. Laissez-faire route management that might work tolerably on shorter headways falls apart when headways are wider. If two vehicles nominally ten minutes apart actually operate as a pair, then there is a twenty minute gap and the service might as well not exist at all. Equally, the short-turn stats might look wonderful because both cars have time to reach their terminal, but riders see the same gap they would have if one of the cars short-turned.

The TTC has a huge challenge in this regard, but shows little sign of trying to fix the problem preferring to assume that more running time and longer layovers will do the trick.

The charts below show the evolution of mid-August 2019 service at various points along the route. (The AM peak bus trippers are not included in these charts.)

Here is the service leaving Main Station. The headway values are clustered around the trend lines, although there are a number of gaps over 10 minutes.

By the time service reaches Coxwell, it looks like this. Even though this is only a few kilometres from the terminal, the headway values have started to spread out.

By Yonge Street, the situation is even worse with more cars in the 10-15 minute band, and correspondingly more on headways of only a few minutes.

When the service gets to Dufferin, the spread of headways continues with several at 1 minute or less.

Finally, we arrive at Parkside (High Park Loop), and the headway chart does not look good at all.

For the eastbound trip, the service leaving High Park is somewhat better organized than what arrived there westbound (the previous chart). This is due in part to the recovery time built into schedules so that some of the gapping/bunching seen above can be smoothed out. Note, however, there there are still many cars on very short and long headways.

When this service reaches Dufferin eastbound, the evolution of bunching is clear with more headways in the 0-3 minute range compared to what left High Park Loop.

By Yonge Street, the situation is roughly the same.

When the service gets to Coxwell, there is a wide range of headways, many well away from the trend line (which roughly matches the scheduled headway).

Finally, the service arriving at Main Station. The range of headways bears no relationship to the schedule and, as is typical for the outer ends of routes all over the system, wide gaps and bunching are common.