As Simon pointed out, the cars in your image appear to be towing airport barriers, which are used to visually mark areas on the aerodrome that are temporarily not available for air traffic.
They are typically used during construction work on or near runways and taxiways at an aerodrome, like in this image:
Although air crews are notified of such construction work through other means, such as NOTAM's and information from the air traffic control, the visible barriers are there to add another level of safety to prevent traffic from entering such areas. There has been a number of incidents and accidents where aircraft have entered closed areas, in spite of the fact that information of the closures was published correctly. See more here: http://www.skybrary.aero/index.php/Runway/Taxiway_Construction_Risks
I do not know how recent your image is. If it is recent, it may very well be related to some of the below NOTAMs, which announce closures of different areas at Prague airport:
Q) LKAA/QMXLC/IV/M /A /000/999/5006N01416E A) LKPR B) 16/09/11 09:35 C) 16/09/11 13:00 E)
TAXILANE BTN TWY 'R' AND TWY 'P' CLSD. DAY MARKING
Q) LKAA/QMXLC/IV/NBO /A /000/999/5006N01416E
B) 16/09/08 06:00 C) 16/09/30 12:00
E) TAXILANE FOR EXIT FROM STAND S55 AND S56 CLSD FOR ACFT TAXIING. DAY AND NIGHT MARKING.
Q) LKAA/QMXLC/IV/M /A /000/999/5006N01416E
B) 16/09/08 06:00 C) 16/09/15 10:00
E) TWY R BTN TWY L AND ENTRY TO STAND S54 CLSD. TWY RR CLSD.DAY AND NIGHT MARKING