News 5 Investigates

Nov 7, 2013 10:54 PM by Andy Koen

News 5 Investigates: Structurally deficient bridges

COLORADO SPRINGS - Dozens of bridges we drive on everyday are in poor condition. The official term is structurally deficient and means a bridge has deteriorated to a point that inspectors think it should be fixed or replaced soon. It can also mean the bridge is inadequately designed to handle modern traffic flows.

News 5 Investigates searched the National Bridge Inventory database to find inspection reports for the structurally deficient bridges in El Paso, Pueblo, Teller and Fremont Counties. Those bridges are plotted out on the map below.

Structural engineer Gary Griffith of Matrix Design Group in Colorado Springs also served recently as a bridge inspector for the State of Colorado. He says many structurally deficient bridges are capable of safely carrying passenger traffic, but those in more critical need may have weight restrictions in place to keep heavy trucks from crossing.

"Any bridge that is structurally deficient, it is aged," Griffith explained. "It's under stress or it was never designed for the current highway load."

We asked Griffith to show us warning signs he looks for when inspecting a bridge. He explained that bridges are evaluated across their three major components: the deck, superstructure and substructure.

Based on the condition of the materials, each component is given a score on a scale of 9 to 1. If any component receives a score of four or less the bridge is deemed structurally deficient.

Crumbling concrete and flaking steel can indicate weakness in the bridge deck. If a bridge crosses a waterway, Griffith said the stream should flow in the center of the channel to limit the risk of scouring. Scouring happens when the flow of water washes out the earth below the substructure.

"Bridges that are scoured, they can get scoured right through and you can have a failure there," Griffith warned.

Many problems areas for bridges are related to age. For example, salt used to melt ice can leach through the asphalt or concrete creating weaknesses in the deck and superstructure.

More than half of the structurally deficient bridges mapped for this report are at least 75 years old.

"Historically the bridge engineer would design a bridge for 50 years; recently a 75 year lifespan," Griffith said. "Of course we try to make them last as long as we can."

Out of all 640 bridges in El Paso County, 5.8 percent are structurally deficient. In Pueblo County, 7.3 percent are deficient; the state average is 6.6 percent.

"Safety of the public is our primary concern and being good stewards with the funding that we have," said Aaron Egbert, a civil engineer for the City of Colorado Springs.

He says the 14 deficient bridges owned by the city will soon be fixed.

"All of those bridges should be either replaced or we'll have a plan for their replacement within the next seven and half to eight years."

The most expensive bridges on the list are ones that carry Circle Drive across Fountain Creek, Las Vegas Street, Hancock Avenue and the Denver Rio Grand Railroad. El Paso County voters made funding available to completely replace those bridges by passing the extension of the Pikes Peak Rural Transportation Authority tax.


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