Referencing splits is easy in settled areas. Cross streets, mailboxes, front doors of numbered houses – there is no shortage of reference points. Out in farm country it is different. Endless cornfields, with nothing at the side of the road but telephone poles. These aren’t always numbered, either. I’ve often had points referenced as “172 feet east of the fourth pole east of Leppert Road on the north side” or such.
Rails-to-trails courses are even worse - they don't even have telephone poles.
You can’t do much about this, except to use the best mark you can find, even if it's far from the split. You can always put in a nail, but that’s hard to spot. I look at it like this – the race director will have a nicely painted course when I am done with it, and it will not be hard for him to find the marks. After the first race has been run, it’s his problem to stay current with the course.
There is a local 15 mile run that I measured a long time ago. I was called by the race director (fifth or sixth one since I measured) and asked to remeasure the course, although it had not changed. “Why?” I asked. “We can’t find the marks” was the answer. I grumpily agreed. I found out why they couldn’t find the marks – they had never repainted them in the decade since it was originally laid down.
In remeasuring I found that some of the reference points I’d used had vanished. If the race organization had done their job, they could have kept up with the changes – but it was easier to call me.
Once the measuring and certification is done, the owner is the race director. It’s not the measurer’s problem if they fail to maintain the course.