Hi all,
I'm designing a concrete floodway/causeway over a box culvert. At the moment there is no guardrail on the culvert or approaches. Where can I find the exact guardrail requirement in this situation ? The site is in Queensland .
I would advise you check out your local roadside safety manual. For roads, it's a combination of the severity of the sideslopes, vehicle speed, etc.
This won't be physically useful to you since it won't match your locales requirements, but the State of Illinois details how to design guardrail lengths in this manual: