South Spadina Headways: What the Riders See

The matter of service on Spadina south of King has been before the TTC on two previous occasions, most recently in March 2011.

In brief, local riders and their Councillor, Adam Vaughan, complain that service is poor and riders are packed into streetcars.  TTC staff reply that the average load on a streetcar south of King is 29, and therefore additional service is not justified.  This matter was held down in March in order to get updated riding counts on the route.

The problem with the TTC’s analysis is that it looks at overall averages, not at the specifics of actual experience on the route.  Most importantly, if a service that is supposed to run every 7’30” is badly disrupted and unreliable, then wide headways will be common.  Because more riders accumulate waiting for long gaps than short ones, the “average” rider’s experience will be a long wait followed by an overcrowded car.  This situation exists on many TTC routes, but it is particularly troubling if that is the case on a short route with an entirely private right-of-way.

First, let’s have a look at how well behaved headways are in this area.  Before you even open the file, I will warn you that it’s a real mess.  The intention is to show the mess before attempting an analysis.

South of King Northbound Headways February 2010

Those of you familiar with my previous analyses of TTC’s vehicle monitoring data will recognize this chart as a scatter diagram of headways by time of day.  Each dot represents one car.  The vertical position on the chart is the headway as seen just south of King Street northbound, and the horizontal position is the time of day.

If the service were well-behaved, these points should be clustered on either side of the scheduled headway through the day.  However, the points appear as a cloud with little discernible concentration.  This means that the actual headways seen by customers are essentially random, and they are spread over a wide range.  Many cars run close together, and gaps over 10 minutes are common.

My next step was to break down this information based on the TTC’s standard that service ±3 minutes of schedule is considered to be “on time”.  Of course riders don’t care about the schedule, only the headway, and it is the headway that determines the wait time and average load on a car.  For the purpose of this analysis, I subdivided the information about each car into three categories:

  • Early (headway less than 4.5 minutes on a 7.5 minute schedule)
  • Late (headway greater than 10.5 minutes on a 7.5 minute schedule)
  • On time (headways between 4.5 and 10.5 minutes)

It’s worth noting that, assuming a uniform arrival rate for passengers, that a car carrying a 10.5 minute headway will have over twice the passengers than one carrying 4.5 minutes.

Headway Distribution ±3 minutes South Of King Northbound February 2010

There are four pages for this chart, one for each half-hour interval from 0700 to 0900.  The vertical bars represent each weekday, and the rightmost bar averages the values over the month.

The dark red portion of each bar shows how many cars were “on time”.  The cream and blue portions are the “early” and “late” cars respectively.

On a 7’30” headway, there should be 4 cars in each half hour, although minor variations may give us 3 or 5 where a car expected in one period actually arrived in an adjacent one.

Between 0700 and 0730, things are fairly well behaved, but the service becomes less reliable as the AM peak continues.  At least half of the service fails the TTC’s own “on time” test, even averaged over the entire month.  For some periods and days, most of the headways lie outside of the acceptable range.  This means that a large proportion of the riders on the south end of Spadina receive far worse service than is advertised, or even what is considered acceptable by the TTC’s own standards.

If we considered a tighter standard allowing only ±2 minutes, the situation is even worse.

Headway Distribution ±2 minutes South of King Northbound February 2010

When the TTC reports its riding counts, it does not include any information about the reliability of service.  Moreover, if short turn trips are mixed in, these may be counted and dilute the average even though they are not of use to all riders.

In the case of northbound service at King, this isn’t an issue.  However, short turns southbound do affect the quality of service on Queen’s Quay eastbound to Union Station, as well as westbound for riders wishing to travel northwest to locations on Spadina.  During the AM peak, almost all of the scheduled service reaches Union Station, albeit on an erratic headway.  However, starting about 9am, short turning at Queen’s Quay Loop becomes fairly common and disrupts service reliability on Queen’s Quay.

York Eastbound Headways February 2010

This chart contains five pages.  The first is the monthly headway scatter diagram similar to the one shown above for service northbound at King.  Once again we see a cloud of data points spread over a wide range of values.  It is worth mentioning what the scheduled headway is supposed to be here:

  • AM peak: 7’30”
  • Midday: 5’40”
  • PM peak:  6’00”
  • Early evening:  6’00”
  • Late evening:  6’00”

The next four pages of the chart break down the cloud of data into individual weeks and add trend lines for each day.  These lines show how the typical headways are, overall, higher than the scheduled value.  This is due to short turns at Queen’s Quay Loop.  The variation in headways with many values well over 9 minutes (the high end of the “on time” standard for a 6 minute headway) shows just how far actual service quality is from what the TTC advertises.

Soon, the bus network will switch over completely to GPS-based vehicle tracking, and the data stream is supposed to be made public.  Whether this actually happens depends in part on the success of TTC managers, who prefer to hide information about service quality, in convincing the new Commission of the need for this secrecy.  In our new era of “Customer Service” and “Transparency”, there will be no excuse, and we may finally start to see just how bad service is on the system as a whole.

Meanwhile on Spadina, TTC staff will again claim that there is lots of service.  The problem is that it does not run reliably.  Capacity could be provided out of thin air simply by spacing cars regularly so that wait times were predictable and loads accumulated more evenly.  However, that would require the TTC actually do something about its service rather than gripe about the cost of more service, the lack of equipment or traffic congestion.