Race Circuit question

[Dr Steve]

I have been wondering this for a while, but never found an answer.

How is the length of a race circuit measured?

I could see several different methods that could be used:
1) Around a centre line of the circuit
2) Racing line (would this be different for different racing classes?)
3) Shortest route
4) Some other method?

Is the difference in the above significant?

[Mr_Thyroid]

I reckon the differences in distances for different categories is pretty negligible.

I'd imagine it's done approximately by centreline - either from a guy walking round with one of those wheels once the track is built but probably more likely by measuring it on a computer off the original plans before the circuit is built or in the case of a old circuit measuring off aerial photography or Ordnance Survey maps. There may therefore be various discrepancies - has the circuit been built exactly to plan? Has the curve of the earth been taken into account? Have hills been taken into account? Did the man with the wheel walk correctly on the centreline? Did the person who measured it on computer do it accurately?

It's probably up to the circuit to perform these measurements - and there may be a bit of cache in having a long circuit (in the case of indoor karting circuits there definitely is) there may therefore be a small amount of rounding-up going on.

[ma9mwah]

its #1 and it much easier than trying to to walk around the imaginary centre line of the circuit. Measure the inside line length, then the measure the outside length and then the average of the two is the centreline length.