Updated July 4, 2013 at 7:50pm: Observations of actual operations at the intersection for one hour today have been added. These reveal that the level of service actually operated on all routes (except 508 Lake Shore) is less than advertised. Although traffic congestion causes some backlogs of westbound cars, the number of movements, especially the west-to-north turn, is low enough to fit within the available traffic signal cycles. This would not be the case if 100% of the service were operated.
See the end of the article for details.
Updated June 28, 2013 at 6:30pm: Information on traffic signal timings has been added to this article.
The original article follows the break below.
Starting June 29 and continuing until July 15 (or whenever the street re-opens), 501 Queen cars will divert around construction at York Street via Church, King and Spadina. Problems at King & Spadina have already been discussed on this site, and one big issue is the number of cars that can physically get through the intersection per hour.
Currently, the peak hour transit vehicle movements include:
- Eastbound 504 King and 508 Lake Shore cars (about 33 between the two routes in the AM, about 24 in the PM)
- 510 Spadina cars turning west to north (24 AM, 30 PM) and the same number turning south to west out of Charlotte Street and merging into the King Street traffic
There are already long traffic and streetcar queues extending east on King from Spadina thanks to the volume of auto and transit traffic, and interference from pedestrians. They both board streetcars at the westbound stop and cross the north side of the King & Spadina intersection where there is no transit priority phase for the turning streetcars.
To this will be added:
- Westbound 501 Queen cars on diversion turning north on Spadina (about 12/hour in both peak periods)
- Eastbound 501 Queen cars on diversion turning south to east from Spadina to King (same volume)
The 501 cars will increase the volume of westbound turns by over 1/3. The south-to-east turns are a net new movement at this location. Although there is a transit priority signal, it is unlikely to be activated because the electric switch controlling it is out of service. Bulling their way around the corner, a 501 car could consume a good deal of green time that otherwise would be used by northbound traffic (already badly congested) on Spadina.
Signalled intersections impose certain limits on the number of cars per hour, especially if only one can pass through per direction per cycle (not unusual if they all stop to handle passengers and/or wait for a clear path to turn). Typical city traffic signals operate at or near an 80 second cycle which gives only 45 cycles per hour.
At King & Spadina, the AM peak cycle (as of June 27) is 100 seconds divided 60/40 between Spadina and King. The PM peak cycle (as of June 28) is 90 seconds divided 50/40 between Spadina and King, and including a 15 second northbound only phase for left turns. This gives 36 cycles/hour in the AM, and 40 cycles/hour in the PM.
That is less than the peak scheduled frequency westbound on King without the addition of the Queen cars.
In some cases, two cars can get through on one cycle but this depends on low interference from pedestrians crossing east-west on the north side of the intersection and/or on westbound cars serving the stop wherever they happen to be during the red phase for King rather than pulling right up to the stop. This is a general problem where TTC official practices cause transit vehicles to consume one green phase just to reach their stop, and another to finally cross an intersection.
[End of Update]
One possible alternative would be to send the Queen cars south to King via Shaw rather than Spadina both to get them out of the more congested section of Queen Street, and to shift the turning moves away from Spadina. This will not lessen the number of cars approaching the intersection from the east, but will reduce the number which attempt to turn.
We will not see full peak service including the diversion operated until July 2. It will be intriguing to watch a combined headway of less than 60 seconds, if only for one block.
Update 2: Observations from July 4, 2013
Between 5:00 and 6:00 pm, I clocked the actual operation of streetcar service through the King & Spadina intersection. The attached chart shows which movements occurred on which portions of the traffic signal cycles during the hour.
The full cycle takes 90 seconds, and so there is a fresh “green” for King 40 times per hour. Westbound streetcar traffic is the heaviest with the combined service of 504, 508, 501 and 510 lines all coming through the intersection.
If all of the scheduled service operated, there would be a total of 67 cars in the hour westbound, of which 42 would be turning west to north. This would require one car to turn on every cycle, an unlikely event given traffic and pedestrian congestion at the location.
In fact, only 85% of the King service, 77% of the Spadina service and 51% of the Queen service actually appeared during my observations. This reduced the total movements westbound to 51 of which 29 were turning.
During the hour, no service alerts were issued by the TTC for any route.
It should be noted that some Queen cars are being turned back westbound from McCaul Loop, and possibly eastbound from points downtown. Until I see route monitoring data from the TTC for this period, I won’t know exactly how the complete service on Queen was being managed. All I know is that only half as much as scheduled actually appeared where I was watching it.
In the table linked below, the time period is broken up into 90-second blocks based on when the signal for King turned green. In those cases when an eastbound Queen car appeared, I have included the time for the Spadina green phase. This includes a north-to-west advanced green for autos, but does not include a south-to-east transit-only phase for streetcars which must bull their way through traffic and pedestrians to make the turn. In some cases, they don’t make it on the first attempt. Each “X” in the chart represents one car.
There was a paid duty officer managing the intersection until shortly after 5:00pm. He was doing a good job keeping pedestrians and autos clear of turning streetcars, and preventing the intersection from locking up with (mainly) southbound traffic that could not clear on the green. Shortly after I arrived, he left, and the service was left to its own devices with a noticeable increase in the time needed for cars to get through. Had all of the scheduled service actually operated, this would have been a severe problem because getting it all through depends on multiple cars clearing the intersection on most east-west cycles.
This will all be over, or at least reduced with the Queen cars back on their home turf on or about July 15. However, this shows how there is more to operating a diversion through busy streets than posting notices on stops. The quality of service on affected routes, even on King which is simply sideswiped with the extra streetcar traffic, touches riders, the customers we hear so much about from the TTC. Those who are on surface routes are just as important and long-suffering as those on the subway.