Analysis of 29 Dufferin for March 2012 — Part I: Headway Reliability

[Apologies to those of you who are pining for even more articles on the Queen car.  They will show up in due course.  I have been diverted onto Dufferin by recent events.]

Service on the 29 Dufferin bus has been a burning issue for decades.  Buses run in packs, they arrive full of passengers, and the advertised service bears little resemblance to what riders see  on the street.

Recently, this was the subject of an article in The Grid by David Topping.  In it, the TTC’s Brad Ross trots out many of the usual explanations of why service is unreliable.  In deference to Brad (who is really a nice guy), I don’t want to spend an article eviscerating his comments line by line.  I will leave readers to contemplate information in this and following articles and make up their minds.

What riders see is “headways”, the time between vehicles, as well as the degree of variation in that time.  If the TTC says a bus will appear every 5 minutes, and the service manages to achieve this, more or less, most of the time, then a rider will consider this “reliable”.  Even on a wider advertised headway, if buses appear at roughly the expected interval, riders know what to expect.

However, if the headways vary widely from the scheduled value, this makes a service unreliable and riders must, at a minimum, build in additional travel time to account for the possibility of a long wait.  Moreover, at the end of the wait, they may be faced with a jammed bus they cannot board.  There might be another one (or two) right behind, but that makes no difference to the length of the wait, and those buses might not be going to the rider’s destination.  Providing frequent service “on average” is not what riders want to see.

In this article, I will review the actual headways provided by the Dufferin bus at various locations during the month of March 2012.  Although this is technically “winter” (most of it), 2012 was a balmy year and the route operated without the kind of severe weather delays we have seen in 2013.

In future articles I will turn to running times and the effects of congestion on the route’s ability to maintain regular service.  I will also look at a few days’ operation in detail to see exactly what was going on.

The information used for this analysis comes from the TTC’s GPS-based vehicle tracking system which reports the position of every vehicle every 20 seconds allowing fine-grained resolution of movements at any location.

Continue reading