Southbound Interstate 29 is closed near the Platte/Buchanan County line due to a fatal accident.  The Missouri State Highway Patrol said a semi-truck driver veered off the roadway at about 8:45 a.m. Friday near Dearborn.  The driver was reportedly pronounced dead at the scene.  No other vehicles were involved.  Traffic is being diverted at Faucett, which is exit 35.  Authorities expect to clear the scene around noon.