The Colorado Dept. of Transportation says that key early repairs made to the I-70 East viaduct between Brighton and Colorado boulevards in Denver are beginning to deteriorate. Several post tension rods, installed to reduce cracking along the viaduct, have corroded and separated from the bridge.

Initial signs of cracking and deterioration were first detected in 1981, triggering regular inspections and repairs to the structure. In 1997, CDOT installed tension rods to stop additional cracking. In 2005, loads on the bridge were reduced to prolong its life. A final series of major repairs, totaling over $30 million, were made in 2011.

A recent CDOT inspection found that two tension rods, part of the 1997 repair, had corroded and separated from the structure. The broken cables, which are easily visible from the side of the bridge, each have secondary cables that remain in place; and therefore, the bridge remains structurally sound.

“The recent deterioration of these repairs only highlights the degradation of this important structure and our need to replace it. CDOT has increased our inspection frequency on the bridge and we are developing repair plans should further components deteriorate. Safety of the public remains our primary focus,” said CDOT Chief Engineer Josh Laipply.

The I-70 East viaduct was constructed in 1964. Initially designed as a four-lane bridge, growth along I-70 triggered the need for an additional lane in each direction, which was added by narrowing shoulders and reducing lane widths along the bridge. Today, the 50-year old bridge is a critical piece of the state’s only east-west interstate, carrying more than 115,000 vehicles per day.

“This deterioration, while not a public safety concern, reminds us that we are working under a clock,” said Tony DeVito, CDOT’s I-70 East project director. “CDOT will continue to make the repairs we need to keep the bridge safe, but our ultimate goal remains to permanently address both this aging structure and growing congestion along this stretch of interstate. We are taking the final steps to bring major and long lasting safety and congestion improvements to I-70 East.”