Two people were injured in a Macon County crash Thursday afternoon.  The Highway Patrol reports Shawn Robinson, 43, of Waukee, Iowa, was driving too fast for road conditions on Highway Z near New Cambria when he went off the side of the road and into a ditch.  Robinson was taken to University Hospital in Columbia with serious injuries.   His passenger, Kimberly Gaul, 11, of Ethel, Missouri, received minor injuries.