Relax. This is a Michael Jackson-free zone.

This is Side Streets and we’re talking neighborhoods. Acutally, bridges in Colorado Springs.

Specifically, the bridge that carries Fillmore Street over Monument Creek just east of the interchange with Interstate 25.

Here’s a look from www.FlashEarth.com:

Here’s a photo of the bridge taken by Side Streets reader Jordan Strub:

In the photo, piers 2 and 3 are visible. And one of the tilting rocker bearing can be seen at the end of pier 3. The photo is looking south from the Pikes Peak Greenway trail.

Here’s a closer look at the pier and its rocker bearings:

 Here’s an even closer look:

There are 18 rocker bearings on the two piers and they are in various stages of tilting. The worst are at 10 degrees on pier 3 while those on pier 2 measure at 5 degrees.

Engineers with the Colorado Department of Transportation say the rocker bearings don’t need to be reset until the tilting reaches 15 degrees. Below is a view from the south.

Resetting them is not eash. The bridge must be jacked up and the rockers placed precisely between the pier and girder to safely transfer the weight of the bridge.

For you hard-core engineer-wanna-be types, here is a blueprint showing a rocker bearing on the right. This is from the CDOT Web site.

 CDOT bridge expert Jeff Anderson said the Fillmore Street bridge was built in 1961 and widened in 1971 and was known as bridge No. I-17-P. It was state-owned until 2007 when the city took ownership in a swap for Powers Boulevard.

While it was CDOT property, it was  inspected every two years — like every bridge in the state, Anderson said. In it’s last state inspection on Nov. 29, 2006, the bridge was given an 83 sufficiency rating on a scale of 0-100. The deck rated a 6. The superstructure a 7 on a 0-10 scale.

“That structure was still in good shape,” Anderson said, despite the tilting rocker bearings. Bridges must fall to a 50 sufficiency rating and be structurally deficient or functionally obsolete before they are replaced.

Anderson attributed the tilting rockers to natural movement in the bridge. He said it shifted east, flush against the abutment. And pier 3 moved west during a flood years ago.

Here’s a look at the east abutment. There is no gap. In fact, the railing above are smashed together.

Want to see what happens when rocker bearings fail?

Here’s a photo from July 2005 when a rocker bearing supporting a ramp on Interstate 787 in Albany, N.Y., failed.

The following is an excerpt from the August 3, 2005 edition of the Albany Times Union www.timesunion.com).

“A routine bridge inspection nearly two years ago found serious problems with the bearings supporting a section of elevated highway that ruptured and dropped 2 feet last week.

Yet, state transportation officials said they made no plans to fix the problems with the Empire State Plaza ramp before the next planned inspection this fall.

The overall rating on the 24-section ramp that links Interstate 787 northbound with the plaza was set at 5, or generally “good,” on a scale of 1 to 7 in the November 2003 inspection report. A set of bearings atop the concrete pier where the break occurred, however, received a rating of just 2.

“One of DOT’s top engineers said it’s now clear that the poorly rated rocker bearings, steel supports designed to accommodate weather-related expansions and contractions of bridge sections, could have been a factor.

“There were some low-rated bearing elements that may have had something to do with this,” said George Christian, the chief structural engineer for the state Department of Transportation.

“The set of poorly rated bearings was on the section of the ramp that remained atop the pier, sliding toward the section that tumbled from its bearings and nearly fell off. The group of bearings was rated so poorly because they were tipped at an unusually extreme angle, Christian said.

“It was tilted, definitely, more than we would have expected it to be tilted for the conditions at the time of the inspection,” he said.”

Ooops!

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