Lineto’s Typ1451 is close …

… and Optimo’s Gravostyle is even closer.

Then, they both are based on DIN. There’s a DIN 17 SB (Rounded) available from Elsner+Flake that would be a good match, too.
Or you wait until FontFont will release Albert-Jan Pool’s FF DIN Rounded … ;°)

Or you wait until FontFont will release Albert-Jan Pool’s FF DIN Rounded
No, wait … that one will have a two-storey ‘a’, at least according to this preview. Makes sense, as FF DIN has it, too.

Wow big help thanks a million Florian.
I'll sit down later and have a good look through those links and see which one will work the best.

Thanks

Bryant is another rounded sans with a single-story a (as an alternate):
http://processtypefoundry.com/typefaces/bryant2/index.html