The cost-benefit ratio conservatively forecast for CABR of 2.6x is extremely strong for a public transit project. It compares with a high end cost benefit ratio for the Green Line of 0.60x. Large scale public transit investments in Canada are routinely made at cost benefit ratios as low as 0.30x.
It may seem to make no sense to invest in a project which returns fewer benefits than the costs. In part this is due to limitations of the cost-benefit methodology where construction cost benefits are not included and benefits of a network may not be fully attributable to a first stage.
CABR is an integrated project on a manageable scale which delvers diverse benefits, resulting in a much higher ratio of benefits compared to costs than typical.
Economists also like to take into account the losers from an investment as well as the winners. If a train replaces bus service then only the incremental riders or travel time savings are taken into account. CABR in contrast provides a lot of incremental economic benefits which would otherwise simply not exist.