The theft of thousands of dollars worth of traffic signs from roadwork sites around Whangarei has police worried it could lead to someone being killed.
Complaints  about signs and cones being stolen or tampered with has escalated in the past two months, with 30 signs worth between $3000 and $4000 taken in a week.
The signs belong to Integrated Traffic Solutions that work for Transit on State Highways.
Police have warned that anyone caught either stealing or tampering with road signs could be  charged with theft, endangering transport and disorderly behaviour.
Northland police road policing manager Inspector Clifford Paxton  said motorists ended up driving through the road works at speed or heading in the wrong direction.
 This could lead to a serious crash or a fatality, he said.
Mr Paxton said there was also a concern that motorists were speeding through sites even when the signs were up and in the right places. The speed at which some vehicles travelled through work sites caused road workers to fear for their safety from debris and the potential for vehicles to lose control on loose metal.
 Last year a speeding motorist died near Kaeo after losing control at a roadworks site and ramming into a parked roller.
"Over the next few weeks police will be focusing on safety around roadworks sites through enforcing the speed limits in these areas and making sure that signs are not removed or tempered with."
Integrated traffic solutions road supervisor Jim Anderson  said  police had returned stolen signs that were found in  raided home.

 Each road sign with its base and stand cost between $120 and $140.
"It has been an ongoing problem but probably got worse in the last two months," he said. "One week we had 30 signs missing and the next week their bases and stands ... it's never ending."