deano wrote:

Anyone know where I can find such material?

Thanks,
deano.

Thanks again to all for the suggestions and links.

Having done some phoning around, the most cost-effective route for me
to proceed would be to aquire 13 lengths of 'profiled' crash barrier,
as it comes off the production line (or second hand if I can get it)
and then paint it up on site.

Anytthing with a 'closed' cross section such as box or tubular steel,
or timber, is a problem as I only have one central fixing hole on each
post. Therefore I need something that can overlap, allowing left rail,
right rail and post to be secured using one bolt (there are actually
two holes in each post but they are one above the other and not
horizontal).

Having followed up all the links posted, these products are part of a
"system" and come with posts, rails, bolts end-caps etc, and as such
are very pricey and would leave me with stuff not used.

Even if the 'rolled steel' crash barrier might appear unsightly on its
own, having had another look at the site, I don't think it would be too
out of place. The most important criteria here is function over form
and the heavy-duty look of motorway barrier would dissuade drivers from
actually contacting it with their cars, thus giving it an even longer
shelf-life... especially when I've painted it bright yellow

So, I now have a couple of contacts, hopefully coming back to me with a
price for 260m of second-hand crash barrier, profiled steel.

d.