Ook wrote:

In that case, it should be 4" wider than a wheelbarrow,
and you should build an arch over the opening.


The arch doesn't sound bad. Is there any reason for it other then
aesthetics?

Yes it will make the gate posts stronger and less likely to move. The
gate posts are subject to more stress than the other posts because the
swinging gate puts lateral stress -- and especially if you have a
spring on there, the post that it bangs into gets stressed. So the
arch is a good idea; you may need longer posts for that to give enough
headroom. Even better, structure wise, is to use some more posts and
make it into a little arbor.

How deep you put the posts depends in part on your climate, you need to
get below the freeze line. I had to set mine about 3 feet deep
(Chicago area) and so I had to get 10-foot posts, which irritatingly
cost about 50% more than 8-footers, and then cut a foot off the top of
them, but I didn't want to risk having them not deep enough.

-- H