Don't make that replacement.
For one thing, it would then read: Health and safety rules are ignored as a rule on the building site.
If nothing else, it's very awkward to talk about rules being ignored as a rule.
The better reason is that "as a rule" doesn't mean "it's a rule (an instruction) to do something" it means "If you guess, you will probably be right if you guess this way."
If you really wanted to use that phrase, you could say something like "As a rule, you'll be able to see plenty of health and safety violations at this site."
It means "I think it's likely you'll see this."