it is for the sake of killing duplication. And making it easier to reach W1,2 & NJT at GWB via . and link that area to the central park ave corridor via W21/20 & parts of Westchester via metro-north & W42 as bx16 crosses those lines. Also the gets to upper west side quicker than the from the Bronx depending on your origin. Those looking for & can continue taking bx34 service.