If you want to go to BNU, go to the north side of XinJieKouBeiDaJie and walk away from the ring road. This will bring you to the southeast corner of campus (you can either walk-about 18 minutes to campus or 26 to Lanhui; or take a bus). Ask the driver/ticket taker if the bus goes to BeiShiDa. Air conditioned buses are 2 kuai, non-air conditioned busses are 1 (and there's some variation on distance which is unclear to me at this point).
EAP China! Robert Klein