This installment completes Chapter 3 of the study with the evaluation of alternative signalling strategies. The recommented alternative is Automatic Train Control, no surprise there, based on the premise that it provides the maximum benefit versus the expenditure. Underlying this, however, is the goal of a 90-second headway and the increasing challenges to subway operations as the headway drops. ATC is treated as a means to achieve this dubious goal rather than a worthwhile move in its own right.
Chapter 3.4 Evaluation and Recommendations starts with a set of charts attempting to show a “cost effectiveness” value for the various options.
Exhibits 3.3.8 and 3.3.9 show the minimum headway and increased capacity for each option. These are, of course, an inverse relationship because shorter headways mean more capacity.
Exhibits 3.3.10 and 3.3.11 show the estimated capital cost and implementation periods for the four options. Note that the costs include neither include either the additional vehicles nor the station modifications needed at Bloor-Yonge or Finch to support the schemes that depend on reduced dwell time at this location. (See footnote 8 in the text.)
Exhibits 3.3.12 and 3.3.13 purport to show the “cost effectiveness” and “productivity” of the options.
Exhibit 3.3.14 summarizes the information for the four options. Note that this is a $708-million project in 1988 dollars before we even start on the infrastructure changes needed to make short headways possible.
Exhibits 3.3.15 details the operating implications of each option both while under construction and after implementation.
Cost effectiveness is measured as a ratio between the capacity increase and capital cost, but the absence of infrastructure and vehicle costs renders 3.3.12 questionable at best. The dip in the line for option 1C, extensive changes to the existing signal system, is cited in the text as showing that it should not be pursued because the “cost effectiveness” value does not go up as much as with the other options. Alas, we do not have a chart showing the same ratios with missing components included.
Productivity is measured as a ratio between total capacity and fleet size. Again option 1C fares relatively badly because it requires slower line operation and a larger fleet to provide a given capacity. In effect, this chart is a measure of line speed because speed determines the fleet size needed for a given capacity. Common to all options is a drop in line speed because trains are so close together.
The “cost effectiveness” ratios, were they recalculated with the fleets included, would be:
- 1A: $15.4-million per thousand increase in capacity
- 1B: $27.7-million
- 1C: $53.3-million
- 2: $49.2-million
In the text, we also learn that the increased revenues through riding may not cover the increase operating costs, although a change to one-man train operation could offset some of this. No specifics are given, and I caution readers that the cost of maintaining vehicles is a considerable part of total operating costs, and for subways in general the train crews account for less than one quarter of that total.
The text also cautions about the impact on customer satisfaction both during and after completion of the project. A vital paragraph warns:
The ability to consistently sustain the desired headway must also be considered during the evaluation process. For example, in order to guarantee that 112 second headway can be consistently sustained under all operating conditions, Bloor Station should be reconstructed to achieve 30 second dwells, and the Finch terminal should be modified as indicated under Option IB herein. (However, apart from the high capital cost of reconstructing Finch terminal and the small reduction in headway gained, productivity would be reduced due to train turnaround behind the terminal stations, and a fleet increase would be required. This would suggest that subway extensions to new terminals should be considered as an alternative.) With regard to 90 second headway operation, the fact that several worldwide transit systems which are designed for 90 second headway operation are not actually operated at 90 second headways, suggests that the headway objective under Option 2 may not be sustained under all operating conditions.
This should have been a red flag to everyone. If there is even the possibility that the 90 second headway could not actually be sustained, this calls out for a review of the basic assumption. Notwithstanding the concern, the report goes on to recommend approval in principle of a 90 second design guideline.