The 10,000m race at the Olympics starts along a curved line (see this video at 0:18). Once the gun goes off, runners can head directly toward the inner most lane. To get the shortest path, each runner should run along a line that is tangent to the path along the inner most lane. The shape of the curve is selected so that each person runs the same length (provided, of course, that no one is in the way). This curve is not a circle because each runner will reach the inner most lane at a different point.

In contrast, the 400m race at the olympics uses equally spaced starting lines. Runners are not allowed to leave their lanes. Because the track consists of two straight-aways and two semicircles, each lane is longer than its inward neighbor by 2 pi times the width of the lane. Hence, each lane's starting line should be this distance ahead of its neighbor's (like the staggered solid blue lines in the image above).

For directions on how to create this curved starting line, see Figure 2 on page 14 of the NCAA rules.