Inroads had encountered significant shotgun damage to signs in the No2, Mangatoi and Mountain Rd area, plus damage to a sign at the more public SH2 and SH33 turnoff to Whakatane.
"Much of the damage appears to be deliberately running down signs with vehicles, or just smashing them, pulling out of ground etc," Ms Michel said.
About two weeks ago, a right-of-way sign and a give-way sign were badly torn apart in Ohauiti Rd by someone with a shotgun.
"Someone has stood there and fired a lot of shots into that. At first I just thought someone had put the shots into it and then taken to it with a sledge hammer.
"[Now] the feeling from our end was that they've just put so many shots through it, it eventually just gave in," Ms Michel said.
Not all damage to road signs was intentional.
Ms Michel said some signs were knocked over by large trucks, the drivers of which might not notice.
However, wanton vandalism appeared to be responsible for most call-outs to repair or replace signs.
"If a sign disappears or gets damaged, it's generally vandalism," she said.
Within the Tauranga City Council boundary, $280,000 was spent on maintaining and fixing road signs - but the council could not provide details of how much was spent repairing damage from vandalism.
Martin Parkes, transport operations manager for the council, said there were about 12,500 road signs around the city.
Western Bay of Plenty head of road policing Senior Sergeant Ian Campion said police were not aware of recent attacks on Ohauiti road signs but incidents involving anyone intentionally damaging signs were worrying.
"It's just mindless that people would deface or vandalise road signs when they are there to keep them and other motorists and pedestrians safe," Mr Campion said.
"It is certainly a concern for us as police. Not only can they (vandals) be charged with wilful damage, which carries a maximum term of imprisonment of three months, but they actually make the area less safe for the road users."