TAOS — As the Río Grande Gorge Bridge nears its 50th anniversary, the New Mexico Department of Transportation has begun initial work on a $2.4 million project to repair and restore the graceful steel span 650 feet above the Rio Grande.

But project manager Glen Baker says that doesn't mean the bridge will be closed this fall when main construction begins. Crews already have begun climbing down zip lines and building scaffolding beneath the bridge.

"My intention is to keep that bridge open to one lane with temporary signal lights," Baker said last week. "We'll have to limit truck weight to 80,000 pounds, and they won't be able to go faster than 5 miles per hour over the bridge."

The plan, which Baker says has been in the works for roughly five years, is to replace five 6-inch-by-50-inch steel bearings that sit between the steel piers of the bridge and the concrete columns. Yearly inspections have shown the bearings in only one of the piers need replacement.

So how do you replace five 1,200-pound bearings that are nestled between thousands of pounds of steel and concrete? Two really powerful hydraulic jacks will be placed under plates at the base of the pier and lifted just 1 inch, giving workers room to get the five bearings out and install new ones.

To make things a bit more interesting, the operation will have to be completed at night, Baker says, when workers will benefit from steady temperatures on the steel.

The entire project is expected to last through October, or about a month. Baker says the new bearings are being made in California and are expected to arrive in Taos in September. While they're at it, workers also will repair the concrete column, repaint the handrail, take measures to prevent erosion around the column and add access ramps that comply with the Americans with Disabilities Act.

Using a process called hydrodemolition, workers also will make 2-inch-deep cuts into the bridge's surface pavement using highly pressurized water in order to completely repave the bridge using what's called "polyester" concrete.

"We just want that bridge to last longer, and the polyester concrete is a better wearing surface," Baker said.

What won't go away, Baker says, is the telltale shiver the bridge has when traffic drives over it — movement that Baker says is necessary and that the bearings provide.

"That movement is called a moment. It keeps the bridge stable and from tearing itself apart," Baker said.

The project's funding comes from what Baker called "bridge monies," which the state and the Federal Highway Administration has set aside for this kind of maintenance and repairs. The contract for the project went to Moriarty's Ryman Corp. Southwest.

Baker says the project became more urgent when a major bridge collapse in Minnesota in 2007 raised public questions about the state of U.S. infrastructure.

"It's like when you take in your car and you replace your brakes," Baker said. "Most of us will do it way before the brakes run out."