The list of poor and structurally deficient Colorado highway bridges keeps growing, a yearly state survey shows.
This year’s total: 128 poor bridges, up from 116 in two years. Three of Colorado’s 64 counties — Denver, Adams and Pueblo — host nearly one-third of those bridges. Of the 25 worst-rated bridges, nearly half are in those three counties.
The Colorado Department of Transportation hopes to trim the list of poor bridges as ramped-up auto registration fees and other transportation fee increases bring in a projected $225 million in three years for bridge repairs.
But there is no replacement plan in sight for the biggest budget-buster on the bad-bridge list.
At last estimate, it would cost $800 million to replace more than a mile of the deteriorating I-70 bridge west of Colorado Boulevard. The state is spending $20 million just to repair its expansion joints, a two-year project that is closing portions of the roads below.
This year a new problem appeared: fatigue cracks spreading across steel spans supporting the bridge, which caused its overall rating to drop from 44 to 27 in one year. Anything below 50 is considered poor.
Holes have been drilled to arrest the cracks, and that should improve the bridge’s structural rating next year.
But “for the life of the bridge, we’ll have to monitor it,” state bridge engineer Mark Leonard said. “There’s a good chance we’ll have to get in there and drill these cracks again. It’s a sign of age with steel.”
Transportation officials have been studying what to do about this crowded, aging bridge for a decade. The alternatives have ranged from a double-decker highway above a residential area to relocating a stretch of the interstate.
In the meantime, “we have to get at least 10 more years out of this bridge, and potentially more,” Leonard said.
Deficient bridges have gained scrutiny nationwide since an Interstate 35W bridge collapsed in Minnesota, killing 13 people and injuring 145.
Colorado’s transportation department has spent little of the money it received from this year’s federal stimulus bill to fix bad bridges. That’s because it will get money devoted to bridge repairs from the new state fee increases: about $50 million this year, $75 million next year and $100 million thereafter.
This year’s money alone will more than double the department’s budget for bridge repairs.
In three years, the new money should bring “a temporary decrease of the number of poor bridges,” Leonard said. “In the long term, it will not be enough.”
Colorado’s transportation commission will discuss what to do with this year’s bridge-repair money at a workshop Wednesday.
Many of Colorado’s poor-rated highway bridges are small and could be replaced inexpensively. But more people depend on the big-ticket bridges.
Of the 25 worst-rated bridges in Colorado, four carry as many as 200,000 cars a day on Interstates 25 and 70 through Denver.
Given $50 million, “do you take that whole allocation and put it on one bridge? Or do you spread it around the state?” department spokeswoman Stacey Stegman asked. “That’s what the commission has been wrestling with.”
