These are what we use in Canada, where we have lane markings at least.

I'm not from UK but aren't they used for construction markings over there?

Yeah, think i`ve seen them at Dover also , good job its only a game otherwise they would be unrealistic :)

Port of Tyne and Port of Blyth both use yellow centre lines for in-port traffic... and those are the only places I've ever seen them :P

I think they're only yellow to make them stand out on the concrete too.

I haven`t seen them either, this was done as a request for someone.

I've never seen yellow central and stop lines in my life in the UK and I've been here and around a lot. Unrealistic.