DURHAM, N.C. — The trained eye might figure it out right away; however, most people do not know what those strange silos are along two of the areas biggest road projects.

The devices -- movable, portable concrete plants -- could speed up road construction. One sits along the Durham Freeway at 15-501 and the other is on Interstate 40 near Highway 751.

The Department of Transportations says they are a big plus with concrete in short supply.

The I-40 and I-85 projects need tons and tons of concrete and they need most of it in the middle of the night.

The DOT decided to fix the perplexing problem by getting into the concrete business.

"Particularly, for these projects, for the volume of concrete we need, we need our own plant to control our production and increase our quality. We get a little better quality control when it's our plant versus a third party," DOT engineer Mitch Conner said.

The DOT says the concept is simple: putting the two close together is an attempt to save time and money.

"It should keep costs down and increase our production, which, in turn, gets the road done faster -- which everybody wants," Conner said.

"I doubt that. I don't see where it would save money or time," driver Barbara Black said. "It could cause an accident, but save time and money? I doubt it. They need to come up with something different."

Black drives the I-40 construction zone every day.

"I hate I-40. It's nerve racking," she said. "You're always thinking you're going have an accident and people are driving crazy, too!"

Many drivers will not be happy until the portable concrete plants are gone and the I-40 widening is done.

The portable concrete plants are still owned by McCarthy Contracting, but for the duration of the I-85 and I-40 projects, they are controlled by the DOT.