New details were released last week about a decades-old fire that destroyed the Bay Area's first bay crossing -- the Dumbarton Rail Bridge.

The bridge opened in 1910 and was used to transport freight from the Peninsula to the East Bay. It shaved 26 miles off the journey on land, and at the time it was the costliest bridge in the state.

Freight transport across the rail bridge ceased in 1982, the same year the Dumbarton Automotive Bridge opened less than a mile north.

When the San Mateo County Transportation Authority bought the defunct bridge in 1994, it was considering plans to use it for commuter transport. But the $120 million needed for the project was nowhere to be found, and the bridge sat unused.

Four years later a significant portion of it burned in a fire that took three days to fully extinguish -- and to this day remains a mystery.

In recognition of the 20th anniversary of the fire, Menlo Park fire officials released a more detailed story of what happened, as well as never-before-seen photos.

The Night the Old Bridge Burned

Just before 7 p.m. on Jan. 3, 1998, the Menlo Park Fire Department received a report of a fire at the edge of Palo Alto, near an abandoned gun club. Because it was pouring rain, firefighters expected to find the fire in one of the abandoned buildings. Homeless people were often seen in the area.

But when Menlo Engine Two arrived, firefighters saw thick black smoke emanating not from the old gun club, but billowing from a spot farther down toward the water.

Menlo Park Fire Chief Harold Schapelhouman, then acting battalion chief, made his way toward the orange glow. He was surprised to find nearly a third of a mile of the Dumbarton Rail Bridge trestle being devoured by flames.

"I'm talking about the supports down to the waterline and the rail deck itself," Schapelhouman said. "I mean, it was on fire literally from one end to the other end and I thought, how could this be?"

The railroad ties had been treated with a highly flammable and toxic product called creosote.

The first thing firefighters did was shut down the adjacent Dumbarton Automotive Bridge to protect drivers from the smoke blowing onto the roadway. They also warned nearby communities. Still, complaints of respiratory issues came from as far away as Oakland -- 30 miles from the fire.

Crews then faced the challenge of figuring out how to fight the blaze.

With limited road access to the edge of the bay, it was difficult to get firetrucks anywhere near the bridge. They started rolling out firehoses from as close as they could get -- and that wasn't exactly close. From the nearest water truck, crews had to attach 4,000 feet of line to get to the water's edge.

The depth of the water around the rail trestle wouldn't allow for a conventional fire or Coast Guard boat to get close. Fan boats were brought in, and firefighters used floating pumps and bay water to try and put out the flames.

Crews stayed out there all night doing what they could, but most of the bridge burned. After the tide went out, timbers engulfed in flames fell from the bridge onto the muddy bay floor.

"When the tide came back," says Schapelhouman, "all the timbers that had collapsed out on the mud lifted up and ... on fire, started floating down the bay. It was like something out of a Viking movie."

The size and intensity of the flames, the necessity of fighting it on land and sea, and the difficulty fire crews had even getting close enough to fight the fire make the experience stand out in Schapelhouman's mind.

"It was probably one of the more frustrating events I've ever had to deal with," he says.

The morning after the fire started, crews were able to get a water truck closer to the edge of the bay by loading it onto a special railcar. At that point, the flames had died down, but the underground wooden pilings were still burning. They had to be dug out and the embers extinguished. It was three days until the last smoldering hot spots were put out.

Photos of the event had not previously been released because it was being investigated as a potential arson. But a lack of evidence led the fire department to rule the incident as suspicious in the end.

So what now for the half-burned bridge?

Two year ago, Facebook donated $1 million to fund a study looking at ways to reduce traffic, including creating a Caltrain connection between the Peninsula and BART on the other side of the bay. Turning the bridge into a pedestrian or bike path has also been floated, but no plans are currently in place.