As I was driving north onto the 10 split to N51/E202 I saw the driver of this Chevy Silverado attempt to block a driver of a BMW X5 from merging into the E202 lane.  The driver of the BMW had turned his turn signal on, but the Driver of the Chevy sped up to block him even though there was plenty of room to merge. Then the driver of Silverado purposefully swerved into the BMW driver’s lane causing him to swerve into the adjacent lane all the while this aggressive person was gesticulating wildly and giving the driver of the BMW finger.  I was behind the driver of the Silverado from then until he went west on McDowell off of the N143 split.  He continued to drive aggressively and was a real danger to the rest of us.  Arizona plate XYG-106.