Complaints about them make up the highest number of calls to the district council's roading team.
So the council has purchased a $25,000 rough-o-meter to find out just how rough those unsealed roads are - the second local authority in the country to do so as far as they are aware.
Wired into a vehicle and its axle, the device has been travelling some of the district's gravel roads for the last couple of months.
The information it has collected had been downloaded into a council database with the aim of objectively determining where grading work needed to be done, council roading manager Julie Muir said.
She said a reduction in funding from the New Zealand Transport Agency meant they had to find a way to "work smarter".
Last year the council spent $645,000 on maintaining gravel roads but the agency has set funding of $621,000 for the same thing for each of the coming three years.
"So when people complain, we can say 'yes, OK' and we can change the grading times, or we can say 'no, you want a higher level of service than we are funded for'."
So far the device has covered the Cromwell and Earnscleugh areas and has just started in the Teviot Valley and Manuherikia areas.
Ms Muir said it would also be used on any road that came up in the diary to be graded so the council could determine whether that road actually needed the amount of work scheduled.
Over the last year the council has already changed the way the graders worked, cutting the roads deeper before gravelling, for example, which Ms Muir said was thought to have been responsible for a dramatic decrease in complaints.
She said from April to June there had been a 77% reduction in calls compared with the previous three years.
A long-term aim is to have all the information collected by the rough-o-meter available to the public online, she said.
