B737-800
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict Ground Conflict; Critical
Flight Crew Took Evasive Action
Human Factors; Procedure
After landing on Runway 30 late at night we were cleared to taxi W5 - W - U to the gate and instructed to remain on tower freq.  I read back the clearance and added our assigned gate for completeness.  On W; as we approached taxiway U; I saw the lights of another aircraft separate from the lights around the terminal area.  It was difficult to see from the angle; similar aircraft parked in the remote ramp (parallel to TXY U); and illumination of the ramp area versus the darkness of the U/W taxi area.  I abruptly alerted 'STOP!' which the Captain quickly acted on. We stopped short; and allowed the other aircraft to pass in front of us on their taxi to the runway.  There wasn't enough time to query the controller or the aircraft before they had passed.  No incursion occurred; and the aircraft passed safely.  Upon debriefing at the gate; we thought that the nature of this event warranted a report.I believe the cause to have been mainly attributed to the possibility of only one ATC controller multi-tasking.  The controller was working multiple frequencies and instructed us to remain on the tower frequency for taxi-in.  The other aircraft taxiing out may have been on the ground frequency - as we never heard a word from or about them.  Keeping us on a split frequency prevented us from hearing anyone else's taxi instructions or intentions. Another minor issue to the cause is using a taxiway as a bi-directional and giving two aircraft instructions to taxi on it.  In OAK; with limited ATC personnel; it may be a safer option to use taxiways as single-direction during certain times of the day to mitigate this.  Landing 30; make W-V-T the standard taxi-in; while T-U-W is the taxi-out.
B737-800 First Officer experiences a late night ground conflict during taxi to the gate via Taxiways W and U on Tower frequency. A departing aircraft had been cleared to taxi via U and W on ground frequency and the two aircraft met at the intersection with the inbound crew yielding.