An Olympic 400 m track has staggered start lines. Why? Because the outer lanes are longer — runners in lane 8 would run further than lane 1 if they started level.
Only the curves matter
The two straights are the same length in every lane — runners go parallel down them. It's the bends that bite: a wider arc with the same angle is a longer arc. Each lane out adds about 2π × 1.22 ≈ 7.66 m per lap, so the staggered start lines cancel it exactly.
That's why a '400 m' race is only 400 m for the runner who hugs the inside line of lane 1. Everyone else's stagger is doing geometry on their behalf.
Lanes are 1.22 m apart. Roughly how much further than lane 1 does a lane-4 runner travel per lap, if start lines weren't staggered?
Do the maths
Each lane is 1.22 m wider than the inside of the next. The extra distance per lap is roughly 2π × 1.22 ≈ 7.66 m per lane. Stagger fixes that exactly.
On a curve, going wider means a longer arc — even if it 'looks' the same length. Geometry gets you fair.