A memo produced by an Empire State Development (ESD) consultant, and submitted to the Department of Transportation, which is holding the hearing, offers to answers: yes, and not much.
In other words, even if the effective sidewalk width--the width minus obstructions--is just 5.2 feet on the south side of Atlantic Avenue west of Sixth Avenue, it's OK, people will manage. That will be interesting to see tested in reality.
From the memo
The memo (below) from consultant HDR states:
In summary the effective sidewalk width as put forth in the FEIS is not met nor mitigated for the eastern segment of S6 (south side of Atlantic Av. between Ft. Greene Pl. & 6th Av.), and is not met for S7 (west side of 6th Av. between Atlantic Av. & Pacific St.) in the Arena opening condition. The primary reason for this is a change to the project implementation since the FEIS was finalized, specifically the delay in construction of Building 4.That "interim condition" could last for ten years or so.
The conclusion is that the Level of Service [LOS] would not be downgraded at all:
HDR took the results of the pedestrian sidewalk analysis from the FEIS and adjusted the calculations by utilizing the effective pedestrian widths that were calculated based on the Stantec construction documents. The tables on the preceding pages summarize the results of sidewalk LOS based on the FEIS and based on the effective sidewalk widths computed by HDR using the FEIS Phase 1 pedestrian volumes. In summary, although the narrowing of sidewalks at S6 and S7 does cause an increase in pedestrian density within the sidewalk, the original calculated values of LOS for these sidewalks were A, and even with a decrease in effective sidewalk width, LOS A still results for all peak hours.110927 ESDC HDR Atlantic Yards Sidewalk_Widths_Memo - FINAL
It should be noted, however, that the conditions analyzed in this memorandum are an interim construction condition; sidewalk widths upon completion of the buildings on the Arena block are not expected to be narrower than those described in the FEIS and 2009 Technical Memorandum.
==what about width of Dean Street?