Do they have as much load space as an artic and are they cheaper to run.any info welcome. 
Dman:
Do they have as much load space as an artic and are they cheaper to run.any info welcome.
of course, they are longer if you use the 18.75m maximum allowed,
Depends what you mean by cheaper.
initial cost to buy, road tax, flexibility, replacement, driver retention, etc.
all of those.
Dman:
all of those.
If you buy a rigid with a drawbar and turn up at Bill Bloggs at 5.05 pm on a Friday, you wont get tipped, with an artic, you can drop the trailer and go do another paying job on Saturday morning 
With the rigid you are paying a driver to sit outside Bill Bloggs for 2 days
Didn’t think of that,good point.
with a WAG +DRAG you can load HAZ loads that have to be kept
separate, you can drop the demountable bodies off and pick up
new ones, allows you to enter areas where artics can not get to,
used by many firms over here as they allow pre-loading by others
to be done more effectively,
drawbacks you need to have a driver who is competent with such units
it takes time to become a GOOD wag+drag driver, where as a artic is
less strenuous,
brit pete:
with a WAG +DRAG you can load HAZ loads that have to be kept
separate, you can drop the demountable bodies off and pick up
new ones, allows you to enter areas where artics can not get to,
used by many firms over here as they allow pre-loading by others
to be done more effectively,drawbacks you need to have a driver who is competent with such units
it takes time to become a GOOD wag+drag driver, where as a artic is
less strenuous,
You can do all that if you spec the wag and drag with demountable equipment. How heavy is your rig though as opposed to a normal articulated rig. can you carry 28+ tonne?
Cost comes down to more than just money!
With the right combination and set up YES, and carry goods that
can not be carried in a artic set up, for example a fridge box on the front
and on the rear a liquid container or containers,
i used to have a 6 wheel truck and a tri axle trailer so plated at 44t plus was able to carry 30 uk size pallets compared to an artic which can cary 26.
personally though it’s hard work opening 4 curtains instead of 2 