EVERETT — Thirty-thousand cars drive over the Broadway Bridge daily.

Yet it was built when people in Everett got around on horses.

The bridge turns 100 next year, and the city hopes to tear it down and replace it in 2013.

Most people probably don’t even notice the bridge, which looks like a big bump in the road. It’s just north of the intersection of Hewitt Avenue and Broadway.

For a century, it’s spanned railroad tracks that bisect downtown Everett. Now, it’s reached the end of its life and will cost an estimated $9 million to replace, said city engineer Ryan Sass.

It was one of a series of bridges and a tunnel built over tracks by the railroad in the early part of the last century. Bridges on Hewitt, Lombard and Oakes avenues were all replaced in the 1980s.

Now the Broadway Bridge badly needs replacement. It’s one of two bridges in the city deemed “structurally insufficient” by the federal government. The other is over the Union Slough on State Route 529.

The National Bridge Inventory describes the Broadway Bridge’s substructure as in “serious condition” and in a structural evaluation says that the bridge is “basically intolerable” and requires “high priority of replacement.”

In 2008, concerns about the substructure of the bridge led the city to ban parking along the bridge and place load restrictions on trucks. With those measures in place, it’s safe for cars to use at the moment, Sass said.

Still, the bridge shows its age. A few hunks of concrete have fallen away on the top of the span. The real concern is what the casual passerby can’t see: The steel underpinnings are corroding.

“It’s not like it’s just one trouble spot,” Sass said.

Replacing the bridge will be a challenge. The current bridge rises up like a camel’s hump and drops steeply down to the intersection of Hewitt and Broadway.

Those limited sight lines make it difficult for drivers traveling south on Broadway to see what’s coming at the intersection. The city would like to correct that, but they also want to work with the railroad, which has its own needs.

Sass said Burlington Northern Sante Fe has told the city that they’d like the bridge to be higher so trains have more clearance. To meet that request, the city would have to move the apex of the bridge north, which could complicate access to nearby buildings.

Perhaps the biggest challenge is who will pay for it.

The federal government has committed $8 million and the city might have to pay $1 million — though the city believes the railroad owns the bridge.

That belief stems back to a 110-year-old franchise agreement that allowed the railroad to build and operate through town.

In 1902, the St. Paul, Minneapolis &Manitoba Railway Co. signed a contract with the city promising to build several bridges, including the Broadway Bridge, and maintain them forever. The city, in turn, is supposed to keep the surface decks in good repair. That contract includes a stipulation that any successors of the original railroad would be responsible.

In the 1980s, the city struggled to get the railroad to help pay for replacing three other bridges spanning railroad tracks. Mayor Bill Moore became so frustrated with the railroad at one point that he threatened to bulldoze the railroad tracks or halt train traffic by parking police cars and fire trucks on the tracks. That threat got the railroad to the negotiating table.

The city is again trying to negotiate with the railroad to share some of that cost of replacing the bridge.

A spokesman for Burlington Northern Sante Fe said the railroad was reviewing the situation and would comment later.

The replacement project would take around a year. During construction, one lane in each direction would remain open, Sass said.

Debra Smith: 425-339-3197; dsmith@heraldnet.com.