The five worst highway bridges in Denver
By Kevin Flynn 
| August 24, 2009 | 7:01 AM
The bridge carrying Federal Boulevard over Lakewood Gulch in Denver has the lowest sufficiency rating of all state bridges in the metro area. The concrete arch structure was built in 1922. (RMI photo by Kevin Flynn)
Most are big, one is small, some are old, and some are very old.
They all need replacement, but there isn’t enough money right now to complete the work.
They are the five worst state highway bridges in metro Denver, at the top of a list of 128 bridges that would be repaired or replaced with some of the money from Colorado’s controversial new hikes in auto registration fees.
Even though those fees have just started to roll in, the Colorado Department of Transportation has already moved to get some of the bridges off the list. It has put together part of its annual funding from gas taxes along with a helping of President Obama’s stimulus money to start construction on a few projects that already were close to shovel-ready.
The projects include a bridge so low-profile, a motorist could miss seeing it while crossing it. Another is very hard to miss as it carries traffic high over Santa Fe Drive. Yet another is practically invisible to speeding drivers who might not even realize they’re crossing a bridge, even though it’s 10 lanes wide.
The increased auto registration fees come from the FASTER bill — Funding Advancements for Surface Transportation and Economic Recovery — which provides a dedicated fund for road surface and bridge repairs. When it was working its way through the legislative process this year, CDOT’s list of bridges in poor condition had 126 structures on it.
Since the new fiscal year started July 1, the list has seen a net increase of two, to 128. Of them, 51 are in the seven-county Denver area.
This is a look at the five worst of those: where they are and what’s being done about them.
These five bridges, ranked by their sufficiency rating on a scale of 0 to 100, are in various stages of the replacement process. Construction already has started on two; one is being designed for bidding next year; the other two are headed to design, but there’s no money on the horizon to build them.
The FASTER money will ramp up this year and next and eventually will bring in $100 million a year. Not enough has come in yet to fund any big projects, although the state Transportation Commission has drawn up a list of 17 bridges that FASTER will fund next year. Neither of the two bridges on the five-worst list that don’t yet have funding are among those 17, mainly because their replacements are part of larger corridor improvements that require substantially more funding than is available.
When all five are done, the state’s most massive bridge replacement project — currently a category-killer sitting in the sixth-worst spot — will move to the top of the metro list. It’s the 1.2-mile Interstate 70 viaduct through Denver’s Swansea and Elyria neighborhoods, built in 1964. It has a rating of 27.0 on the scale of 100.
Its estimated $800 million replacement cost can’t be absorbed in CDOT’s budget for now and would eat up all the FASTER funding for nearly a decade. In the meantime, the state is spending $20 million on repairs during the next few years to keep the viaduct in service until it can find a solution. One proposal is to reroute I-70 to the north and tear down the viaduct entirely.
Here is the status of the five worst state highway bridges in metro Denver:
1. Federal Boulevard Bridge over Lakewood Gulch, Denver. Replacement in progress.
At the top — or bottom, if you prefer — of the list is the graceful but crumbling concrete arch built in 1922 to carry Federal Boulevard over Lakewood Gulch, a quarter-mile south of Colfax Avenue. With a rating of 15.5 on a scale of 100, this graffiti-covered grand lady of the state highway system has long been targeted for replacement, and it is finally under way for $6 million, all of it regular CDOT funds.
The 121-foot bridge was widened in 1960 and carries about 36,000 vehicles a day. It has a lane imbalance — three lanes go south, while only two go north — but eventually will be part of widening Federal to six lanes.
The deck itself is in fair condition, but the superstructure — the portion atop the foundation that contains the paving — is in poor condition. Worse, the substructure that holds the whole thing up is in serious condition. Significant portions of the concrete supports have fallen away and exposed the steel reinforcing bars inside. Nearly three years ago, CDOT bridge inspectors listed it as “intolerable requiring high-priority corrective action.”
The bridge work has been coordinated with a completely different project — RTD’s West Corridor FasTracks light rail. The Federal bridge spans not only the gulch, but the old pathway of the Denver Lakewood and Golden Railway built in 1890 by Golden entrepreneur and Lakewood founder William A.H. Loveland. The track that went under the bridge led to the railway’s maintenance yard across the South Platte River, next to the Xcel Zuni power plant. Light rail will follow that path. Because the tracks will be a bit higher on the hillside, additional clearance is needed under the new bridge to ensure that the rails are out of the flood plain there.
With light-rail construction under way, so is the Federal bridge replacement. Concrete abutments for the widened structure already have been placed on the hilltops above the gulch just to the west of the existing bridge. Soon girders will be placed and decked so that traffic can be moved to the new half. Then, the old bridge will be demolished and the second half of the new bridge built and joined to the first half.
2. Interstate 25 northbound and southbound over Santa Fe Drive, Denver. Design in progress, no money to construct.
This is a set of two bridges, both built in 1958 as part of the original Valley Highway freeway project. The northbound structure, at 337 feet long, is rated at 20.2 out of 100 for structural deficiency, while the southbound span, 242 feet long, rates at 22.8. Each bridge carries nearly 100,000 vehicles a day, with about 6 percent of that being heavy trucks, which do exponentially more damage to structures and roadways than passenger vehicles.
These riveted plate steel girder bridges have some support columns set outside the bridges’ footprints, like outriggers, because of the skewed angle at which I-25 diverges.
CDOT has plans to replace these bridges and reconfigure the entire interchange. Plans. But not money.
The Valley Highway, which became the central corridor of Interstate 25 through Denver, was built in phases starting in 1949 with the Mousetrap interchange. Santa Fe is where the highway left the “valley” of the South Platte River and curved east through south Denver along the old Colorado & Southern Railroad freight tracks.
While modern for its time, the Santa Fe interchange is woefully out of compliance with current safety standards. Both on-ramps from Santa Fe enter the left lanes of I-25, which violates current design standards. Headed southbound, entering traffic is forced to merge into the left lane of the high-speed freeway.
The replacements will include a large flyover ramp from northbound Santa Fe to enter I-25 northbound’s right lane. The work has been cleared by the federal government after the Valley Highway Environmental Impact Statement was approved. Design work is under way. The bridge replacements come in phases II and III.
But when the design is finished next year, CDOT will stick the plans on a shelf until it can find the funds to build them. It is too far behind the curve to qualify right now for federal stimulus funds, which are focused on ready-to-build projects.
The estimated cost for the work is $33 million out of the total $61 million for those two phases. The non-bridge work includes widening I-25 to eight through lanes and eliminating the short bottleneck there, where it narrows to six lanes for 1,000 feet. That causes morning and evening rush-hour backups between Alameda Avenue and Broadway.
3. U.S. 85 over draw, 1.2 miles north of Louviers, Douglas County. Design starting soon, no money to construct.
The smallest bridge in this list, this 42-foot concrete-on-rolled-steel I-beam structure is crumbling, structurally deficient and rated 23.3. It was built in 1934 as part of the original great north-south highway along the Colorado Front Range, from Trinidad to Wellington, which started as State Highway 1 and was designated U.S. 85 when the federal aid for highways program began in 1956. People traveling to Denver from the south almost always took this route, now replaced by I-25.
CDOT has reinforced this bridge with supporting steel beams below each side while it studies how and when to replace it. The entire U.S. 85 corridor from Littleton to Castle Rock is being upgraded to four lanes, and the improvements have reached just north of this point to the new grade-separated overpass at Titan Road.
With the growth in Highlands Ranch and the Sedalia area, plus traffic taking this route up from Castle Rock, the segment handles about 18,300 vehicles a day. But pushing the upgrades farther south is a matter of funding.
CDOT will begin design work in a few months on the segment including this bridge and another bridge three-tenths of a mile south of here. Design work will take about 18 months. Because it involves realigning the roadway, CDOT is spending about $5.5 million for the necessary right-of-way, which involves buying and relocating many businesses along the roadway.
The replacement for this deficient bridge will be on the new alignment and also will provide an underpass for wildlife to cross.
But once again, funding is a problem. It is estimated that the segment will cost $20 million. CDOT doesn’t yet know where that money will come from.
4. Interstate 25 over the South Platte River, Denver. Design under way, construction next year.
Another original Valley Highway bridge, this large steel arch structure carries 10 lanes of I-25 over the river as well as the ramps from the 17th Avenue exit that take northbound freeway traffic to Invesco Field. A freight railroad track also goes under the bridge. Broncos fans are familiar with it from walking next to it as they cross the river from the Auraria parking lots to the stadium on game days.
The bridge was built in 1951, when the first segments of the Valley Highway stretched from 49th Avenue on the north to 11th Avenue at Zuni Street on the south. It is 384 feet long end to end and is rated structurally deficient at 24.5. Inspectors say it needs high-priority corrective action.
A replacement is in the design stages, and CDOT expects that it will be advertised for construction bids next March. The estimated cost is $22 million, and funding is programmed through CDOT’s regular allocations.
5. Interstate 76 northbound and southbound over the Union Pacific Railroad Boulder Branch, Adams County. Construction under way.
This is another two-bridge set, and they won’t be on the five-worst list for long. Work crews already are drilling caissons and forming new abutments for the replacement structures, thanks to stimulus funding from the American Recovery and Reinvestment Act.
Built in 1967, the eastbound bridge is two lanes and 157 feet long. It is rated at 22.8 and structurally deficient with a high priority for corrective action. The westbound structure, rated at 25.4, was built the same year. They carry a combined 70,000 vehicles a day.
These welded continuous girder structures cross over the single railroad track on a very high berm, and each is supported by two sets of very high steel columns, five to a set, braced by a crossbeam.
SEMA Construction is building the replacements. The total cost is $11 million, all but $200,000 of it covered by the stimulus funds. It is scheduled for completion in January 2011.
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