It notices the existence of conditional tags but it doesn’t parse them (there is unfortunately no parser for the infamously complex opening hours grammar in the Lua language that c.t’s routing engine uses). It’ll show “restricted cycling hours” for any route using that section. 

Oh, this question is interesting. There's a set of byways in Suffolk — actually part of the Wolf Way, amongst other routes — that have been closed all year. I'd gone to OSM hoping to tag it as such, but couldn't work out how to mark a temporary closure. That is, I couldn't find a standard notation. Is that @-labelling generally accepted? If so, I would at least add the metadata.

Of course, my motivation is to avoid being caught out when I've not properly checked a route (for example, if I'm out on a ride and I change my plans). From the descriptions I've seen of the routing algorithm, I suspect a request like "don't use this road" is rather difficult to accomodate unless it's encoded in the source data.

I'd argue it's ok to set access=no with a note if something is closed for that long. You can always undo the change when they reopen.

Maybe, yes. It’s slightly complicated because it was just closed for six months, then extended later.

I did look into editing OSM at the time, though, but couldn’t find any guidelines. Actually I was hoping for some “closed until” syntax, like that described in this thread, but couldn’t find anything.

I realise I should be asking this on an OSM forum somewhere.

> infamously complex opening hours grammar

Richard, is it this one? If so, I could have a go. However, I’m not sure how this interacts with pre-calculated routes. I think I saw you mention that they’re generated weekly, in which case short closures are probably best ignored.

It is – there are libraries in PHP, Java, Kotlin, JavaScript, TypeScript, Python, Rust, but not Lua. But given that c.t doesn’t know about different times of day, and the routing graph is updated roughly monthly, I wouldn’t worry unduly – I think dan200’s suggestion of a simple access tag is probably going to be best in 90% of cases.