HOUSTON - The Texas Department of Transportation scattered spotters around Houston to help break any ice forming before the morning rush hour Thursday.

All HOV lanes remained closed for the morning commute. As of 10 a.m. there were just nine (down from more than 130) remaining reports of ice on Houston's freeways, overpasses and ramps, so conditions are improving.

ROAD CONDITIONS: List of icy freeways & highways

LATEST FORECAST: View the latest weather info

Early Thursday, KHOU 11's Brandi Smith came across one crash that appeared to be caused by ice.

"The driver of this pickup hit a patch in the I-45 NB feeder near Crosstimbers. It shot the truck onto the guardrail for the main lanes. Scene cleared now. Ice still there," smith tweeted.

Later in the morning crews had to block the left lane of the Southwest Freeway inbound at the Spur 527 due to ice.

After 24 hours of winter gridlock, most of the ice had melted away by Wednesday afternoon on Houston-area highways and surface streets. So how do TxDOT, the toll road agencies, and law enforcement make sure the roads are safe enough to re-open?

Sgt. Martinez with the Harris County Precinct 5 Constable’s Office told KHOU 11 that authorities won’t make the final call on whether to re-open toll roads for the Harris County Toll Road Authority until patrol units or incident management teams have driven the road themselves, sometimes after already treating it several times, to make sure it’s safe.

While sand provided traction on roads, afternoon temperatures above freezing and sunlight evaporated melted ice on the Pierce elevated and other roads. Still, KHOU 11 News found sheets of ice on Will Clayton Parkway near Bush Intercontinental Airport.

Deidrea George, a spokesperson for TxDOT’s Houston office, says the agency has 30 to 40 crews spread across six counties, working 12-hour shifts constantly looking, treating, and re-treating.

“We are constantly scouting those locations,” said George. “So, it’s not one of those things where you treat once and then that’s it. You have to go back and constantly make sure. (Workers are) out of the vehicles as well checking to make sure that it’s safe for vehicles.”

George says overpasses and busy traffic spots get priority, followed by surface streets. She says TxDOT listens to reports from the public on where they are seeing icy spots.

TxDOT also keeps in close contact with law enforcement officers, who George says have the final say on whether or not to lift the barricades.

“We actually go out there, walk it, drive it slowly ourselves to make sure it’s safe for the public,” said Chief Art Acevedo of the Houston Police Department. “Chief (Troy) Finner and Chief (Matt) Slinkard just helped open up the 527 spur…. We actually got out momentarily and we actually drove It, did some braking maneuvers to see if it was slick or not, determined it was safe, and we reopened it.”