Thousands of runners will descend on Madison Saturday morning for the second annual Madison Mini-Marathon, so motorists should be on the lookout for traffic delays at various times and in various locations. The race begins at 7 a.m. at the UW-Madison Memorial Union, winds around the Capitol Square, heads west to Lake Wingra and the UW-Madison Arboretum, then north to the campus and back to the union. A shorter 5K race also begins at 7 a.m. at the Union and ends at the Union, basically using campus streets for the route.