It's About Brine: Keeping Ice off the Roads
The Waco District has a new line of defense in the fight against icy roadways—and it could save the district a lot of money.
In addition to the sand and crushed-rock mixture — called ice chat — that provides traction once ice has formed, the Waco District has begun supplementing that tried-and-true method with a new pre-treatment process, potentially safer than other, current pre-treatment solutions to help prevent ice forming in the first place.
|Using the brine method, TxDOT can help prevent ice ever forming on the roadway — and for 90 percent less than using ice chat would cost.|
"This is a different approach than what we are used to," says Rick Swinson, TxDOT maintenance section supervisor in McLennan County. "We are being proactive instead of reactive, and so far, from everything we are learning about it, we're impressed."
Swinson is talking about a liquid pre-treatment that is simply salt mixed with water. The brine solution is applied with the use of herbicide trucks, 24 to 48 hours in advance of a storm. The trucks are able to spray two lanes of roadway in one pass. The 23 percent salt water solution forms a barrier on the road surface, lowering the temperature when water freezes.
"The salt prevents ice from forming, unless it gets down to 15 degrees. If ice does form, the solution makes it much easier for us to remove it," Swinson explains.
The brine was used in the Waco District during the holidays, when the first ice-threat of the year occurred. "We brined the entire interstate before the temperatures fell. We had no reports of ice forming, but it also did not get as cold as forecasted. I'm sure we will soon have other opportunities to see just how well it works." Swinson says the Waco District gets an average of three ice events each winter. The brining method has already been used in North and East Texas, with good results.
|Here you see a section of US-2 in northern Wisconsin near the Michigan border, with the brine pre-treatment solution applied. Photo courtesy of Michigan LTAP, Michigan Tech University.|
Each of the eight counties in the Waco District has one herbicide truck that will be used to apply the brine. The trucks carry 1,200 gallons of pre-treatment, which is good for about 20 miles of a two-lane roadway. "I-35 is our priority, so we will brine it first, before we expand to the other major roadways in the counties," says Swinson.
Swinson says ice chat will still be used about 75 percent of the time, but likes the idea of being able to fight ice before it accumulates. He says there are several advantages to using brine (it's easier to apply, easier to store and it's not as messy), but the biggest plus is the price.
"Brine is just a fraction of what ice chat combined with traditional deicer materials, like magnesium chloride, cost— about 90 percent less. The savings could be substantial, and it will allow us to take on other maintenance projects that we just could not afford otherwise."
A disadvantage of using saltwater is the potential harm to bridges and overpasses.
"We know that salt could eventually damage concrete, so we're working on a plan to neutralize the salt solution after the storm has passed, probably with some kind of spray wash," Swinson explains. "It would take 10 to 20 years for any damage to occur, but we need to eliminate that possibility."
In the meantime, Swinson is checking the weather forecasts, looking at the radar and listening to the news for any hint that a winter storm is approaching. He knows it's not if, it's when. "And we'll be ready," he says.