Even if you take the parking lane away, the road is still not wide enough for two large vehicles to safely proceed down Bingham.  On top of that, Punahou Street, between Beretania and Wilder, gets so congested during certain times (Before and after school hours) of the day.  Adding an on ramp that can only be accessed via Bingham, will only add to that congestion.  If people have to wait 2-4 (Maybe more) traffic light cycles to make the right turn on Bingham, they'd be better off getting on the freeway at the UH or Humane Society on ramps.