Lets run through a little excersise:
Given that the acceleration/deceleration rate of a train is 1.34 m/s/s, and that the maximum speed of the train is held to 22.22 m/s (80 K/h) then how long does it take the train to leave one station and stop at the next?
At the rate of 1.34 m/s/s, it takes 368.5 m to reach 22.22 m/s, thus for any spacing wider than about 370x2 m the train will reach its top speed.
LeBreton to DT-west:
835m means the train will accelerate for 370 m, cruise for 95 m and then decelerate for 370 m.
16.6s accel + 4.3s cruise + 16.6s decel = 37.5 seconds
DT-west to DT-east:
670m means accelerating then decelerating for 335 metres each.
15.8s accel + 15.8s decel = 31.6 seconds
DT-east to Rideau:
545m means acceleration then deceleration for 272.5 metres each.
14.3s accel + 14.3s decel = 28.5 seconds
Rideau to Campus:
1180m means acceleration for 370m, cruise for 440m, then deceleration for 370m.
16.6s accel + 19.8s cruise + 16.6s decel = 53.0 seconds
If I assume a worst case station dwell time of 15 seconds for each of DT-west, DT-east, and Rideau, the total travel time from leaving LeBreton to arriving at Campus is 195.6 seconds. Three and a quarter minutes. This does not concider any slowing of the train due to the curves.
Lets say that a layout like the following were used:
This configuration has an extra station downdown and provides access at Mackenzie-King and Waller. Centre to centre station spacing are:
LeBreton (not shown) - Bay = 780m
Bay - Bank = 550m
Bank - Confusion Square = 560m
Confederation Square - Mackenzie-King = 540m
Mackenzie-King to Campus = 705m
Using the same assumptions above of an acceleration/deceleration rate of 1.34m/s/s, max speed of 22.22 m/s, and dwell times of 15 seconds, the travel time from departure of LeBreton to the arrival at Campus is 213.3 seconds.
My route takes 17.7 seconds longer but has an extra station downtown. This time difference is almost entirely due to the dwell at the new station. Only 2.7 seconds are due to the shorter average distance between stations. Given this small time difference, and the fact that downtown is THE destination for most people, is there really an argument that the system will no longer be rapid if an extra station is added?