As with other features that we dont see much of these days like blind shots, I dont mind crossing holes, as it all adds to the character of a course, and harks back to the old layouts that did this. Its clearly safer on a course that isnt busy and if there arent any trees for people to suddenly appear from behind then all the better. I'd be more than happy to see one added to a modern course, but can understand why that might not be possible from a H&S point of view? I would also imagine a crossing pair of par 3s such as the two on the Eden at St Andrews is safer than longer holes crossing, as its more likley everyone is playing from the tee to the green and not some random part of the hole?
I recall Whittington Heath having a few examples, even if it was teeing off over the previous green, rather than a real crossover?
Clyde lists a few courses in the Highlands that have them, and I'd add Gairloch to that, which has them on 1/2, 5/8, 8/9. One of those, you walk off the 4th green, leave your bag, cross the 8th fairway to hit your tee shot on the 5th back across where you just came from. I dont know the history of the layout but suspect originally there wasnt a crossover here, but one was created to lengthen one of the holes.
However this got me thinking about crossover between holes and not as part of the holes, not playing shots just walking? For example at Brancaster where you walk off the 5th green, across the 7th fairway, to get to the 6th tee. The previously mentioned Erewash Valley here in Derbyshire has a similar example where after the crossing holes in the quarry, you have to walk over the 15th fairway to get to the 6th tee (golfers popping out from the trees ahead of you on 15 when you arent expecting it and they are in their own world means many a person has had to stand back from their tee shot!)
Perhaps these walkover holes, or crossovers out of sequence are more dangerous as the people playing the hole you cross wont always know who is playing, and therefore crossing, a hole several away from them in the routing?
Cheers,
James