JACKSONVILLE, Fla. – After a 19-hour traffic nightmare, motorists got good news Friday morning: The Florida Highway Patrol reopened southbound lanes of Interstate 95 to traffic about 10:30 a.m. Friday and the northbound lanes less than 30 minutes later.

One northbound lane just north of Pecan Park Road remains closed for the safety of fire personnel working in the area. Traffic was below the speed limit, but flowing freely.

Dozens of Florida Forest Service and Jacksonville Fire-Rescue personnel spend the day battling the blaze, which had blackened 600 acres by Friday afternoon and, at one point, burned within 25 feet of the highway. Two helicopters made continuous water drops on the hot spots and 14 dozers were reinforcing fire lines, although the northern boundary was marsh, and not accessible with heavy equipment.

​​The Jacksonville Fire and Rescue Department said 12 team members were assigned to the wildfire on Friday. JFRD had three brush trucks, two tankers, one engine, one rescue vehicle, one command center and one district chief assigned.

An FFS spokesperson said it could take several days, even a week before the fire is completely out. On Friday night, the Forest Service said crews made good progress throughout the day, and the fire was 55% contained.

"I think the conditions are in our favor," FFS spokesman Terrell Drew said. "As long as the smoke stays up and we have a good dispersion to stay off the roads, I think we'll be OK."

SPECIAL SECTION: News4Jax.com/wildfires

VIEW: Interactive traffic map and DOT cams

MORE ONLINE: FL511.com

IMAGES: Wildfire burning near Nassau-Duval County line

FFS Operations Manager Mike Work said Friday's conditions had drastically improved from the conditions Thursday.

“On the northern edge of the fire, out in the marsh, all of that is cold out. It either hit an interior creek coming off the main marsh or the helicopter has put it out with no smoke at all and no flare-ups," Work said. “Coming down 95, the crews got a lot of good mop-up. (There's) not as much smoke today and the road is open and it’s still staying clear.”

Although the roadway reopened, northbound traffic still moved slowly because a 2-mile stretch of the interstate was down to two lanes, giving fire crews enough room to battle fires that were still burning close to the roadway. Those crews were also battling the heat.

“For the firefighters, the heat for the next three or four days, upper 90s, possibly 100-degree temperatures, that’s a huge safety issue for our guys," Work said. "So, they have to stay hydrated on the job and off the job.”

With many traveling over the Memorial Day weekend, News4Jax asked Work what's the likelihood that I-95 could potentially be shut down again.

“What I’ve seen out there currently, in the amount of smoke that is still actively hot, I’m hoping FHP doesn’t have to go through that again, or the citizens or the Florida Forest Service," he said, adding that weather conditions affecting the wildfire will dictate whether the interstate remains open through the weekend.

No one lives in the immediate area that's burning, but tens of thousands of motorists were inconvenienced when I-95 was shut down from Thursday afternoon to Friday morning.

As frustrating as the closure was, those News4Jax spoke with know the firefighters are doing the best they can.

"These guys have done an absolutely wonderful job," Bud Payne said.

Interstate closing becomes national news

Just after 3 p.m. Thursday afternoon, the interstate was closed in both directions from State Road 200 in Yulee to I-295 in North Jacksonville because of the 600-acre Yellow Bluff Fire, and visibility was reduced to just 40 yards because of the smoke, according to FHP spokesman Sgt. Dylan Bryan.

"This morning at 5 a.m., the smoke laid in so thick, it was fortunate the highway was closed," Annaleasa Winter, a spokeswoman for Florida Forest Service, told News4Jax on Friday morning.

Visual representation of what a difference a few hours could be. As we prepare to open I-95, please use caution in the area. Crews will be on scene continuing to work the #YellowBluffFire. Please be advised that the road can be closed again if conditions worsen. pic.twitter.com/XEheI7oEQ2 — FHPJacksonville (@FHPJacksonville) May 24, 2019

Motorists were still asked to exercise caution because of firefighters and their equipment in the area. The Jacksonville Sheriff's Office and FHP advised they had people monitoring visibility and the highway would close again if conditions worsen.

Gov. Ron DeSantis tweeted Friday morning he was in constant contact with FHP about the fire and highway closure situation.

"I encourage everyone impacted to remain vigilant and heed all instructions from law enforcement," DeSantis said.

Schools affected

Yulee Middle School officials told News4Jax that they are expecting a lot of late students and school buses Friday.

Nassau Emergency Management tweeted Friday that because of severe traffic in the Yulee area, buses serving U.S. 17 and adjoining streets will experience up to one-hour delays in bus pickup times.

Tardies will be excused for the day, the last day of the school year in Nassau County.

Traffic woes

Southbound traffic on I-95 early Friday morning began to back up between the Florida-Georgia border and U.S. 17. There were more backups at the S.R. 200 exit.

Drivers reported traffic backups on the primary detour route -- U.S. 17 -- were slow even before Friday's rush hour began. News4Jax reporters, both covering the story and commuting to work Friday, reported stop-and-go traffic.

“Usually I get to work in 20 minutes, but it’s like a line down the street trying to get out of here," driver Jermel Rollins said.

Drivers said it took them three hours to move 5 miles, and many drivers feared they would run out of gas. Some said they saw people getting out of their cars to walk their dogs.

"My wife had to go to work. She works up in Amelia Island and she’s probably still stuck in this mess," driver Jim Flanagan said. "I’m not going to even try to attempt this. I’ll go down and go around.”

AAA says late afternoon Friday will be the worst time to drive because commuters leave work early and then mix with holiday travelers.

If I-95 were to close again...

The detours used Thursday night would be implemented:

I-95 northbound: exit I-295 exit 362. At I-295, drivers can go either east or west.

I-95 southbound: east on S.R. 200, south on U.S. 17

There are two other ways to get into and out of Nassau County:

Heckscher Drive to the Buccaneer Trail over the Nassau Sound Bridge and west on S.R. 200

Interstate 10 to U.S. 301 into Callahan and then east on S.R. 200

VIEW: Interactive Traffic Map and live DOT cams

Smoke concerns

The FHP continues to monitor conditions in the area and warned drivers that visibility may deteriorate quickly due to fog and smoke-type conditions. Drivers are urged to slow down, use caution and turn on low-beam headlights.

"If you come into an area of low visibility -- whether it’s fog, smoke or something like that -- the rules of the road still apply. You’ve got to maintain proper control of your vehicle, be observant while driving, reduce your speed and utilize your headlights and just drive as safe as possible," Bryan said. "Absolutely (turn your headlights on) because visibility is reduced. Not only can you see a little bit better, everybody else can see you, as well. With that being said, we use low-beam headlights. We don’t use emergency flashers when the vehicle is in motion. So utilize low-beam headlights and drive cautiously through the area."

Not only is the smoke a concern for drivers, but it's also a concern for those who live near the area where the wildfire started.

The National Weather Service Jacksonville said Friday that a dense smoke advisory remained in effect around the Yellow Bluff Fire. Smoke can hurt your eyes, irritate your respiratory system, and worsen chronic heart and lung diseases, NWS Jacksonville said.

A dense smoke advisory continues this morning around the #YellowBluffFire near I-95 in northern Duval and western Nassau Counties. Smoke can hurt your eyes, irritate your

respiratory system, and worsen chronic heart and lung diseases. #flwx #gawx #jaxwx @JaxReady pic.twitter.com/OP7zf16woU — NWS Jacksonville (@NWSJacksonville) May 24, 2019

What we know about the Yellow Bluff Fire

The Yellow Bluff Fire began as two separate fires on Wednesday afternoon, and spot-overs increased the size of the fire as it moved west toward I-95 and jumped the highway. West of the highway is more wilderness area -- the Seton Creek Preserve and the Four Creeks Wildlife Management Area. Though most of it is considered to be marsh and swamplands, it's not wet enough to keep from catching fire.

“What was holding water two months ago is not holding water on the surface, so those surface fuels are now exposed. They have been curing under the sun -- the hot, dry sun. Low humidity cures it all," Work said. "Then once you get fire to it, it burns across the top.”

According to Forestry Service's Winter, the fires appeared to have started Wednesday afternoon near the train tracks that run parallel to Main Street, but it was too early to determine whether the fires were started by sparks from a moving train.

"It could have been something thrown out of the train. It could have been exhaust. Sometimes, it is the catalytic converter. Sometimes it’s the friction from the brakes," Winter said. "This time of year, we are going to see more human-caused fires, but people need to be very careful."

The Florida Department of Agriculture is assisting the Forest Service with the investigation into the cause.