A Mobile Speed Camera. A talivan is a speed camera inside a police van, so that it can be moved from place to place, such as motorways or straight A-roads. They are revenue raising instruments that cause accidents (rather than prevent them as the operators claim)
That 'Davies Builders' van has parked right up against the talivan, so they've driven off in annoyance...
What the Taliban rides in.
We are the Taliban, we shoot bombs, and we ride in the Talivan! ALALALALALALALALLAALALALA