EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Confusion; Communication Breakdown; Time Pressure
Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Human Factors
Was coming into land on Runway 4L in BOS. A Gulfstream was ahead of me and was landing 4R.  While landing 4L; I noticed the Gulfstream approach my runway and I was expecting him to hold short of Runway 4L on Runway 33R per ATC instructions.  As I touched down on Runway 4L; I saw him taxi slightly onto my runway so I applied heavy brake pressure to stop quickly at the same time Boston Tower was ordering the Gulfstream to STOP!  I stopped around Taxiway Quebec short of the intersecting Runway 33L.  I exited Runway 4L on Runway 33L and then made a turn onto Taxiway November and taxied to the ramp via taxiway Bravo and Echo.  Taxi-in and parking was normal.
An ERJ-170 landed on BOS Runway 4L and braked aggressively as another aircraft exited Runway 4R and began to enter 4L after being told to hold short.