They?re the ones responsible for keeping road work zones safe...and now they're under investigation by the Delta County Sheriff's Office.

KJCT News 8 has learned of some serious allegations of worker misconduct by traffic flaggers--including drug abuse on the job.

?You?re working with somebody who?s not sober enough to do your job with,? says one Alert Traffic Control worker who came forward to us.

She says everything from smoking marijuana to hard drug use happens on the job site.

?It?s a concern of safety,? she says. ?It?s become an enormous issue.?

She claims supervisors are no help.

?I told my supervisors, you know these claims have been made several times and you?ve never, ever investigated it.?

We spoke with two other workers who didn?t want to go on the record for fear of losing their jobs. But they tell the same story.

?It?s not just one job site,? one says. ?It?s all over, every job site. It?s an understood thing it?s going to be happening.?

The job sites in question are contracted out by the Colorado Department of Transportation. Alert Traffic Control is a sub-contractor on several of them.

CDOT says it?s aware of the allegations.

?We received a report from an individual,? says CDOT?s West Program Engineer Pete Mertes, ?and in that report there were allegations of drug use and alcohol use on the project.?

So why hasn?t drug testing been done? It?s because Alert is not under direct contract with CDOT.

?The traffic control company is a subcontractor on this project,? Mertes says, ?and our contract is with the prime contractor. Any business dealings with the traffic control company are done between the prime contractor and them.?

We took a look at Alert?s policy. Their procedures manual clearly states ?...the unlawful possession or use of a controlled substance or alcohol is prohibited.?

It also tells employees ?...there shall be no reprisals against you for voicing your concerns.? But employees say that?s just not the case.

?You become the bad guy,? one worker says. ?You get threatened. How do you fight that??

CDOT says the drug testing question is out of its hands.

?We have our own internal policies, each of the contractors has their own policies,? Mertes says. ?We can?t force them to do drug testing.?

Workers worry by the time action is taken on the situation, it may be too late.

?I don?t want to see anyone hurt,? our source says. ?I?m concerned because, who has to die in this situation??

We tried to contact Alert Traffic Control several times for comment, but our calls went unreturned.

Stay with KJCT News 8 and kjct8.com for the latest on this developing story.