They are the signs that no motorists like to see, those orange diamond-shaped signs that foretell of road construction that can serve up everything from pavement hazards to lane closures to reduced speeds to the dreaded detour.

Officially they are called traffic control devices, and their purpose is to warn motorists of an upcoming condition and give them time to take appropriate action, said Tiffany Dagon, a metro pavement engineer for the Minnesota Department of Transportation (MnDOT). They also are meant to guide motorists through a work zone safely and keep those who fix the roads out of harm's way.

Failure to comply with those wonderful signs can be expensive. Drivers caught speeding through a work zone or disobeying a flagger's orders can be slapped with a $300 fine under a new state law that took effect Aug. 1.

It can also be deadly. In 2013, there were 1,740 crashes in work zones and eight deaths, according to MnDOT figures.

Just last week, a Minnesota man died when he sped through a construction zone on a North Dakota freeway, lost control and rolled his vehicle several times.

While most drivers respect construction zone rules, especially when workers are present, perhaps nothing is more irksome than to see signs warning of danger when a hazard can't be seen.

On Dowling Avenue in north Minneapolis, where a week after a seal-coating project was cleaned up this month, signs still warned motorists to beware of loose gravel and adjust their speed. Last Thursday, signs on along County Road B2 between Victoria and Dale Street in Roseville alerted drivers to flaggers, yet there were none when the Drive passed by.

Changing signs important

When signs don't convey accurate information, "people will get complacent and not to pay attention to them," said Michael Sherber, road and bridge supervisor for Hennepin County.

He said it's the county's goal to turn signs "out of service" when they are not applicable to a project, such as when a flagger is present during the day but not at night.

Cities, counties and MnDOT follow rules spelled out in the Minnesota Manual on Uniform Traffic Control Devices. The manual includes rules for where signs can be placed, the language to be used and the duration they can be up.

By and large, contractors are responsible for putting up and taking down signs. At this time of year, they are busy moving them from site to site and it's possible a sign may get left behind, Dagon said.

That is likely what happened on Dowling Avenue, said Mike Kennedy, the transportation maintenance director for Minneapolis. The signs were picked up a week after the project was complete.

In some cases, it might look to the public that a project is finished, but it's not. The signs are still up because workers are simply off in another area and will be back a few days later. Sometimes signs are moved by the public and appear in places they should not be.

Kennedy said it's important that signs convey correct information. "It does give a false impression," he said. "People's lives are at risk. It's important to get it done right. We don't want the signs being ignored or to lose credibility."

Still, he said, "It's better to have the sign and not the condition than the reverse."