Sidewalk plaque at 17th and Stout streets, the heart of downtown Denver. commemorates the 58-year-old all-walk phase known as the Barnes Dance. Inside Lane photo.

By Kevin Flynn
Inside-Lane.com

Save the last dance for me!

Denver, the city that popularized the pedestrian-friendly all-walk diagonal-crossing Barnes Dance, is considering phasing it out of the busy downtown grid as part of a larger evaluation of signal timing within the central business district.

Another Denver institution on the ropes? Could they leave the Barnes Dance, the cheeseburger and the ice cream soda in their native town and instead eliminate the Denver Boot?

“We have preliminary data from our consultant and we’re talking to stakeholders,” said Matt Wager, director of operations for traffic engineering services at Denver Public Works. “It’s a complex discussion.”

Pedestrians would still get “Walk” signals, but not the all-red diagonal crossing.

Wager said a decision is likely six months out. The “All Pedestrian Phase Study” is being done by Jacobs Engineering, while a larger retiming study of the downtown signal system, called the Downtown Denver Traffic Signal Retiming Study, is being done by Navjoy Consulting Services.
“We are taking a look at signal timing downtown and are evaluating not only pedestrians but bicycles, autos and transit,” Wager said. “We’re always evaluating signal timing downtown.”

In part, the retiming study is a response to RTD’s anticipated introduction of four-car light rail trains along Stout and California streets. The longer train consists – RTD now operates two- and three-car consists on the Central Corridor downtown – will require more all-red clearance at cross streets.

The so-called Barnes Dance refers to the inclusion of an all-red phase within the traffic signal cycle that stops vehicles on all approaches and allows pedestrians to freely cross, including diagonally. It’s called the Barnes Dance because it was brought to Denver by the city’s visionary first traffic engineer, Henry Barnes. He did not come up with it, but was the first to apply it in an entire downtown zone when it went live in 1952.

Henry Barnes, left, in Baltimore with traffic signal inventor Charles Adler, center, installing a plaque at the 1928 location of Adler's first signal. Photo from Signalfan.com

In his autobiography, “The Man with the Red and Green Eyes,” Barnes said he came up with the notion for the all-walk phase while dropping his daughter off at school and watching her try to cross the street with her friends. People trying to cross the street during breaks in traffic were playing games of chicken. In a presentation in Los Angeles to a meeting of the Institute of Traffic Engineers, Barnes told them:

“As things stood now, a downtown shopper needed a four-leaf clover, a voodoo charm, and a St. Christopher’s medal to make it in one piece from one curbstone to the other. As far as I was concerned – a traffic engineer with Methodist leanings – I didn’t think that the Almighty should be bothered with problems which we, ourselves, were capable of solving. Therefore, I was going to aid and abet prayers and benedictions with a practical scheme: Henceforth, the pedestrian – as far as Denver was concerned – was going to be blessed with a complete interval in the traffic signal cycle all his own. First of all, there would be the usual red and green signals for vehicular traffic. Let the cars have their way, moving straight through or making right turns. Then a red light for all vehicles while the pedestrians were given their own signal. In this interim, the street crossers could move directly or diagonally to their objectives, having free access to all four corners while all cars waited for a change of lights.”

Barnes acknowledged there were such intersections already using such a signal by the 1940s in Kansas City, Vancouver and a few other places. But Denver was where Barnes had them installed throughout the business district, where for the most part they remain in use today.

But downtown Denver has changed.

The 1982 debut of the 16th Street Mall into the traffic flow presented signal timing issues. To accommodate the transit shuttles, 16th was converted to two-way traffic from its former one-way function in the downtown grid. Engineers had to integrate efficient timing for RTD’s shuttle business going in both directions into a total 75-second cycle from green to green. Also, since the original Denver grid is platted on a 45-degree diagonal to north-south-east-west, the connections to East Denver and Golden Triangle streets east of Broadway and south of Colfax Avenue present timing issues.

Wager said Denver uses the mall shuttle movement as the starting point for setting all the other timings.

The diagonal crossing was dubbed the “Barnes Dance” after Denver Post city hall reporter John Buchanan wrote that, despite citizen and official apprehension in advance of its introduction, the innovative all-walk phase had pedestrians “dancing in the street.”

Barnes also oversaw the demise of the Denver Tramway’s 1950 conversion of the city’s extensive but aging streetcar lines to buses – having been quoted as saying he had no objection to streetcars except that they ran in the street.

Barnes departed Denver a year after introducing his dance and became traffic engineer in Baltimore, where he introduced computerized signal controls. He was hired to be New York City’s traffic commissioner in 1962 by Mayor Robert Wagner. Barnes used the all-walk phase in Manhattan, although only a few locations remain in use today.

He died of a heart attack on the job in New York in 1968, at the age of 61.

On a personal note, my own subconscious awareness of the Barnes Dance and downtown signal timing nearly got me whacked by a car when Denver altered signal timing with little fanfare years ago. While working at the Rocky Mountain News, I was in the habit of taking reading material with me when walking to appointments or lunch. The timing patterns had been inculcated into my brain for years: Named streets got the green light first, then the numbered streets, followed by the all-walk Barnes Dance.

One day, walking back to 400 W. Colfax from the Brown Palace, I stepped to the curb at Tremont Place and 17th Street, my nose in a book, looking to cross west toward 16th. When the last of the traffic zoomed past me on 17th, I started out into the street still reading, confident Henry Barnes had my back.

But I heard cars starting out from Tremont, including some making a left turn right into my path. I looked up to see a bumper coming at me, and jumped back.

I found out Denver traffic engineers had flipped the order of the signal phases east the mall. Numbered streets now went first, named streets second.

Denver's design shows the new bridge, in green, with a traditional diamond-type interchange on I-70 and a set of braided ramps, in purple, on the west side connecting to I-270.

By Kevin Flynn
Inside-Lane.com

Where jetliners used to cross Interstate 70, Denver soon will be building a new $50.6 million interchange project that will reunite the south side of the old Stapleton airfield with the north side.

But this time, it’s not 747s or DC-10s that will go over top of I-70 traffic, but Stapleton neighborhood residents, regional shoppers and other highway travelers.

The new interchange will carry the Stapleton neighborhood’s Central Park Boulevard over I-70 to Northfield Boulevard in the growing commercial area where Stapleton’s two old north-south runways used to be.

The project is being done by SEMA Construction and Wilson and Company under a design-build contract with Denver. In January, SEMA was given the Notice to Proceed, and the design phase is at 40 percent completion, according to Steven Coggins, Denver’s project manager. Construction is expected to start in June with completion anticipated by October 2011.

A TWA jet is on take-off from Stapleton's old Runway 35 crossing I-70. Several years later, a second north-south runway was added north of I-70 and a second tunnel-bridge was built next to this one for the access taxiway. Photo at Matt Salek's Milepost 61 blog.

The project is using a mix of funding sources including the city’s Better Denver bond program, which is providing up to $30 million.

It is also using $12 million in federal stimulus funds through the American Recovery and Reinvestment Act competitive grants program, channeled through the Denver Regional Council of Governments; and $8 million in other federal transportation funding.

And this week, the Colorado Transportation Commission is expected to approve an application for $1 million in earmarked Interstate Maintenance funds from the Federal Highway Administration to add the replacement of 800 feet of dilapidated concrete on the ramp from westbound I-70 to Interstate 270 to the project. The new ramps tied into this segment but initially it was going to be left as-is.

The Colorado Department of Transportation, which controls I-70, is providing oversight.

Rendering from Denver's interchange study shows the conceptual layout of the wide bridge planned for Central Park Boulevard over I-70. Ramps from and to I-270 straddle I-70 under the bridge.

The “spaghetti” of ramps will allow drivers direct access into both sides of Stapleton via a new Central Park Boulevard bridge, which will cross I-70 just to the east of the existing airport cargo bridge. That is the only bridge over the highway left from Stapleton’s airport days, but it was not adequate for re-use. Central Park Boulevard’s bridge will be between the cargo bridge and the spot where old Runway 17R-35L used to cross over on a long bridge that formed a tunnel carrying I-70. Just to the east of that spot, there used to be a second I-70 tunnel over which a taxiway to Runway 17L-35R was located.

While development of the Stapleton neighborhood has pretty much erased traces of the old runways south of I-70, there are still vestiges of them remaining on the north side.

The Stapleton developer, Forest City Enterprises, will spend an additional amount up to $20 million to construct the extension of Central Park Boulevard from 36th Avenue to Northfield Boulevard.

The design includes two “braided” style ramps, which allow traffic to and from I-270 to cross over entrance and exit ramps from I-70 to Central Park Boulevard. Braided ramps lift one flow of traffic over another to let them change sides without conflict.

While more expensive to build, braided ramps are much safer than old-style “weave lanes” in which traffic trying to merge left onto a freeway had to compete with traffic merging right to get off. Recently constructed examples are at southbound Interstate 25 and Speer Boulevard, and northbound I-25 at Belleview Avenue/Interstate 225.

Old CDOT photo shows then-new I-70 tunnel going under Stapleton Airport's Runway 17-35. Later, a second tunnel was built for the highway, closer to front of photo, for a taxiway to a new runway on the north airfield.

A rush of workers and equipment helps Concrete Works of Colorado get a one-block section of new sidewalk along South Broadway done in one day. Inside Lane photo.

By Kevin Flynn
Inside-Lane.com

One block of South Broadway in Denver on Thursday turned into what Joe Schwartz, Concrete Works of Colorado superintendent, calls an ant hill.

That’s when all hands are on deck in a colony of activity for a contractor to get in quickly, get a job done and get out by the end of the work day.

For the city of Denver’s ambitious South Broadway reconstruction, a project funded by the voter-approved Better Denver bond program, that meant getting the new sidewalks poured in one day on the east side of the 1500 block south.

“The ant hill – that’s what we call it,” Schwartz said while roaming the block to choreograph the work and make sure everyone is sequenced on time – that’s how to ensure each crew is ready to move on to the next task.

Making a big push to do the work in one area so quickly is a huge help to businesses on the block, whose access is temporarily disrupted by the construction.

“Our aim is to get this done as quickly as possible,” said Ann Leggett, spokeswoman for Concrete Works of Colorado. “We made a commitment to the people here to get this done today.”

Bill Wieder, left, stands in front of his South Broadway properties watching the work. He grew up on the block and believes the improvements will be a boost to investment in the neighborhood. Inside Lane photo.

“I think it’s going to be very much of a stimulant to Broadway because it will look so much better,” said Wieder, whose mother bought property on the block in 1948. Wieder grew up here and is landlord to several of the businesses on the east side. He can remember when neighboring Herman’s Hideaway was Cunningham’s Supper Club, and can rattle off where the grocery store and doughnut shop used to be.

He said he’s reduced their rents during the project to help them weather the construction period and come out the other side.

Concrete Works is helping with that too by allowing parking along its new concrete curbs when work permits, and by putting out numerous signs along other curbside areas for shopper parking.

When the project is finished – and this is only the first of three segments that will reconstruct Broadway in concrete all the way to the Englewood line – both the city and the property owners expect that the improved transportation infrastructure will boost the economy of the neighborhood.

You can view a slideshow of the work. The photos were taken on Thursday.

To expand to full screen and read the captions, first click on the “play” button and then click on the box that will appear at the lower right corner — with the four little arrows pointing outward. When the full screen appears, click on “Show Info” at the menu bar on the top right.

Perhaps the best aspect of the work is lowering the grade on the street itself. Frequent drivers of the area around Broadway and Iowa Avenue know how hail storms and summer downpours can result in flooding there. Over the years, the street surface has built up to where it is higher than the sidewalks. As traffic made it through the water, it pushed waves of runoff onto the sidewalks and into the fronts doors of the businesses. Many owners have sandbags at the ready to keep the water out.

New drainage patterns on the street will resolve that problem.

The work also includes Denver Water’s replacement of a 100-year-old water line, a late addition that held up work for a bit, but this portion of the job will still be done in June, says Augie Maestas, the city’s inspector following the work.

The South Broadway project represents a major investment in the popular commercial strip that houses the metro area’s Antique Row, among other businesses. The plan includes a raised landscaped median similar to that in Englewood, with a mix of trees, antique-style streetlamps, sidewalk planting areas and colored concrete in the median.

Rendering shows what the 1500 block of South Broadway will look like when the project is completed. City of Denver rendering.

One of the first items of work was to remove old Denver Tramway trolley tracks that were still embedded under the asphalt.

It’s getting through the pain of construction to get to that gain of revitalization. The ant-hill approach, sort of a construction SWAT team, helps.

Schwartz had 45 crew members at work up and down the block, including company owner Marc Lenart, who was operating a loader. Each with their own tasks, the crews moved from framing and preparing each site to tamping down fill dirt for an even surface to pouring and spreading the concrete and, finally, to finishing and smoothing it.

The city divided the entire 17-block project into three pieces. Schwartz said the four-block section now under construction between Iowa and Arizona avenues will be done in June. It includes new traffic signals at Iowa, Arkansas and Louisiana avenues. It is a $6.8 million contract. Next month, the southern segment from the Englewood line at Yale Avenue to Wesley Avenue will go out to bid. The middle and largest segment, Wesley to Iowa, will be last.

Mike Roth, co-owner of the popular Herman’s Hideaway, watched the crew pour the first new sidewalk slab right at his doorway – as he pondered whether to put his initials in the wet batch once the crew moved up the way.

Mike Roth, right, co-owner of Herman's Hideaway, watches the crew finish the slab in front of the popular club. Inside Lane photo.

His grandfather was Herman, who started at Cunningham’s in 1962. He bought the place, changed the name and began booking musical acts into the place in 1982 and it has become a prime destination on South Broadway since then. The place helped launch Big Head Todd and the Monsters and Opie Gone Bad. It has fostered local talent as well as featuring such bands as Faith No More, 311, The Fray, Dave Matthews Band, Widespread Panic and Phish.

Roth said he prepared for the construction period by realizing that he’d lose some of the impulse customers who might drive by and otherwise come in but for seeing all the dirt and equipment.

“I saw this coming a mile away and started booking real strong acts,” Roth said. That would help ensure his regulars and those destination customers would come regardless of having to park a bit farther away.

“We’ll put it in our ads when the work is done,” Roth said. “Because to see something like this happen on South Broadway is exciting.”

The preferred alternative Gold Line alignment is pictured in the Final Environmental Impact Statement.

RTD is holding two public hearings in the coming weeks on the FasTracks Gold Line Final Environmental Impact Statement, and anticipates getting federal approval for the project in the fall.

The Gold Line is an 11.2-mile heavy-rail commuter corridor that connect Denver Union Station with Wheat Ridge at Ward Road, while preserving a future extension corridor from there into Golden.

Public hearings are set for Wednesday, Sept. 9, in the Arvada Center, 6901 Wadsworth Blvd., and on Thursday, Sept. 17, in the Highlands Masonic Center, 3550 Federal Blvd. Both hearings start at 6 p.m.

Under the EIS findings, it would run north along the east side of the Burlington Northern Santa Fe Railways/Union Pacific Railroad tracks that parallel Inca Street, then curve west at Utah Junction near 56th Avenue and Pecos Street along the BNSF “Beer Line” track that serves the Coors Brewery and facilities in Golden.

It would have seven stations along the way in addition to Union Station: 41st Avenue and Fox Street in north Denver; Pecos Street near 62nd Avenue; Federal Boulevard at 61st Avenue; Sheridan Boulevard at 60th Avenue; Olde Town Arvada at Wadsworth Boulevard and 56th Avenue; Arvada Ridge at Ridge Road and Miller Street; and the end-of-line Ward Road station, east of Ward at 50th Place near Van Gordon Street.

Conceptual design of the Olde Town Arvada station platform structures uses Craftsman style, one of four styles proposed for the seven stations.

The EIS is available for viewing online at the FasTracks Gold Line web page, and at Arvada Library, 7525 W. 57th Ave.; Perl Mack Library, 7611 Hilltop Circle; Red Rocks Community College, Arvada Campus, 5420 Miller St.; Regis University Library, 3333 Regis Blvd.; Smiley Library, 4501 W. 46th Ave.; Standley Lake Library, Kipling Street; Westminster Public Library, 7392 Irving St., and the Wheat Ridge Library on , West 32nd Avenue.

The public can also submit comments regarding the EIS online at the project web site, or by direct email to the EIS staff at comments@rtdgoldline.com.

The deadline for public comments is Monday, Sept. 21. A newsletter about the process can be viewed here.

The Gold Line has been packaged into a single initiative called Eagle P3, a planned Public-Private Partnership, with the East Corridor commuter rail project to Denver International Airport and construction of a rail yard and maintenance facility for all four FasTracks commuter rail corridors.

RTD had difficulty siting the maintenance facility, which has undergone at least four revisions at three selected sites. It ended up north of 48th Avenue and Fox Street, but was scaled back from the original size to avoid forcing relocation of the Owens Corning Fiberglass roofing shingle plant at the north end. Workers were concerned that the company would close the plant and lose its 100 jobs if it were forced to move.

One company impacted by the site is Rocla Concrete Tie Inc., which has sold RTD the railroad ties used in three out of four of its previous light rail corridors.

If successful, a consortium of designers, contractors, transit operators and financiers will take over the two corridors and other associated work, finance it privately, design it and build it, and then operate it for at least 40 years, under a contract with RTD.

The upside for RTD is that, by converting projects it would have to pay entirely upfront through borrowing and grants into a long-term concession contract for which it would make annual payments to the operators, it could build some financial breathing room into the beleaguered FasTracks plan of finance.

Currently, there is a $2.2 billion gap between what RTD now believes FasTracks will cost to build – $6.9 billion – and the amount of money it projects the current economy will allow it to leverage through the 2017 target completion date – $4.7 billion.

The Eagle P3 project financing also figures on receiving two Federal Transit Administration New Starts grants totaling $1 billion. While that seems like a reasonable figure based on RTD’s experience of receiving three previous New Starts grants for the light rail lines to Littleton, T-REX and the under-construction FasTracks West Corridor, the New Starts program itself is expiring at the end of this month with the six-year federal transportation funding authorization bill. Every indication is that Congress will keep the program in some form but there is no guarantee that the rules and regulations will be the same.

RTD is preparing for flexibility with the Eagle P3 package by telling the three consortiums interested in bidding on it that it may break it into phases. In that case, the airport line would begin first, and RTD would reserve the start of the Gold Line until as late as the end of 2011, when the financial situation should be much clearer.

The corridor is scheduled for completion in 2015 or 2016.

The make-up of the three consortiums interested in the Eagle P3 project.

Denver is installing flashing yellow lights to on school zones to warn drivers of reduced speed limits.

Generally, traffic fines are doubled in school zones.

The flashing beacons are being installed by Denver Public Works Department’s Traffic Engineering Services Division. Bill Vidal, manager of public works, will inaugurate the set outside Steele Elementary School, 320 S. Marion St. Parkway, on Tuesday at 2 p.m.

The other completed installations are:

• Columbian/St. Catherine’s, Federal Blvd/W. 41st Ave
• Cheltenham, W. Colfax Ave/Irving St.
• Colfax, W. Colfax Ave/Tennyson St.
• Southmoor, S. Monaco Pkwy/S. Magnolia Way
• Phillips, Monaco Pkwy/Montview Blvd.
• Valverde, W. Alameda Ave/S. Tejon St.
• Goldrick, W. Mississippi Ave/S. Zuni St.
• Asbury , Evans Ave/Lafayette St.
• Ebert-Polaris, Park Ave West/Tremont St.

The other 21 planned locations are:

• Johnson, W. Jewell Ave/S. Irving St.
• Force , W. Florida Ave/S. Wolff St.
• Dennison, W. Jewell Ave/S. Yates St.
• Gust, W. Yale Ave/S. Irving St.
• Barnum, W. 1st Ave/Irving St.
• Ashley, Montview Blvd/Syracuse St.
• Hillel Academy, Holly St./Dakota Ave.
• Christ the King, 8th Ave/Glencoe St.
• Paddington/St. James, 13th Ave/Quebec St. -Oneida St.
• McMeen, S. Holly St/Tennessee Ave.
• McKinley/Thatcher, S. Logan St/Louisiana Ave.
• Montessori/Cole, MLK Jr. Blvd/Franklin St.
• Whittier, Downing St/24th Ave.
• Blessed Sacrament, Montview Blvd/Elm St.
• Gilpin, Stout St/31st St.
• Valdez, W. 29th Ave/Bryant St.
• Swansea, 46th Ave/Columbine St.
• Greenlee, Kalamath St./W.11th Ave.
• Moore, 8th Ave/Downing St.
• Good Shepherd, 6th Ave/Elizabeth St.
• Bromwell, Josephine St/4th Ave.
• Greenwood, Gateway Blvd/Dearborn St.

Eastbound traffic exits the work zone on the Sixth Avenue Viaduct, where concrete deck repairs are to be completed this month.

Denver’s Sixth Avenue Viaduct got a facelift for its 50th birthday, and taxpayers got a lesson in cost-effectiveness.

It’s a lesson based on Ben Franklin’s maxim that “an ounce of prevention is worth a pound of cure.”

Replacing support piers and bearings under the westbound bridge last year and rehabbing the concrete decking atop the eastbound structure this year for a total cost of $6 million will add 25 years to the useful life of the “twin” bridges.

Without it, Denver Public Works’ chief infrastructure engineer Jim Barwick estimated the aging structures eventually would have cost $30 million to replace.

“If we hadn’t done this, we would have had to replace it in 10 years,” Barwick said.

View Larger Map
The repair work involved the two bridges that make up the viaduct’s eastbound and westbound lanes from Kalamath to Osage streets.

What that means is that, by incurring a cost that averages $240,000 for each year of life – or $400,000 a year for the 15 net new years of life it bought, Denver is saving drivers up to $260,000 a year by not having to replace the bridges.

While many bridges will have to be replaced at some future point, timely projects to upgrade and maintain them can extend that useful lifetime.

The two bridges are “fraternal” twins rather than identical. While they look similar from above, underneath they are two different structures. The westbound bridge uses single-column reinforced concrete support piers; the eastbound one uses steel-framed supports.

View a slideshow of the viaduct’s substructure and repairs:

To expand to full screen and read the captions, first start the show. Then click on the expand box that will appear at the lower right corner of the screen. When the full-screen version begins, click on “Show Info” at the menu bar on the top right.

Motorists who used the Sixth Avenue Freeway to get in and out of central Denver up through the mid-1990s remember well the roller coaster ride they used to get from driving over the hubcap-jarring expansion joints on the viaduct. They were placed every 75 feet to allow for contraction and expansion of the 1,250-foot structures. In 1998, the joints were taken out and the replaced at either end.

But the results weren’t all good. While the ride was smoothed out, the now-continuous superstructure of the bridge experienced more contraction and expansion with weather extremes and it failed to slide properly along the new bearing pads. During the winter of 1999-2000, this resulted in visible damage underneath. The city commissioned a study to gauge the viaduct’s safety on the short term and the impact on its long-term lifespan. While measurements of pier movement showed it was safe, the city needed to make changes to ensure the viaduct’s long-term health.

“The bridge became fixed in the middle but it could expand and contract toward the ends, where we put the new large expansion joints,” Barwick said. “But the problem we found was that when it moved, it didn’t slide over the columns. It was dragging them.”

In the center of the span, this wasn’t a big problem. But the effect was more pronounced at the two ends.

“There was one concrete pier at the end where when we took the load off that sucker, it moved three and a half inches to the east,” Barwick recalled. “It had been pushed to the west. We literally saw it move back.”

New reinforced concrete support piers replaced the ones that moved with the deck expansion on the westbound viaduct.

The city put together additional savings in the project by applying some innovative techniques and choices, such as using temporary piers to shore up the westbound bridge while reinforced concrete piers were torn out and replaced with new ones. As a result, the city didn’t need extensive traffic closures and saved about $150,000 in traffic control costs.

Instead, it used short 10 to 20-minute stoppages during off-peak traffic times when each of the 18 piers was taken offline one at a time and 18 more when the viaduct was rested down on each new one. The viaduct carries a combined 60,000 vehicles a day and is a key commuting route to and from Interstate 25, Lakewood and Golden. Lengthy closures would require difficult detours.

URS Corp. was the engineering firm that headed up the project. Barwick said the city had several bottom-line requirements that URS had to work with, including safe removal of lead-based paint from the underneath structure.

URS addressed all of the points, and found a way to include some of the temporary shoring pilings into the foundations for the new reinforced concrete piers, saving some more money, Barwick said.

Denver also saved several hundred thousand dollars when project inspector Bill Cusack suggested removing the lead-based paint with a system that is used to contain residue of contaminated paint in nuclear power plants. It captures virtually all the material and can be operated by workers without heavy protective hazmat suits. The hazardous material goes directly into a barrel for shipment to a disposal facility.

After some research, the city bought the system and its net cost was lower even after taking the purchase into account.

Edward Kraemer and Sons won the contract and work started in February 2008 on the westbound structure, where the piers were replaced. That was finished early this year, and the rehabilitation of poor concrete area on the eastbound structure started soon after and will be completed by the end of this month.

In the midst of all the modern technology used on design today, the eastbound bridge’s repair spots were determined in a decidedly old-fashioned way.

Denver hired engineering interns to get up on lifts and sound the underside of the eastbound bridge concrete deck for hollow spots that were to be repaired.

He compared it to dental assistants probing for cavities in teeth. Using lifts, the workers got up to the underside of the concrete and started hammering on it. Hollow spots sound different. They were marked, and then the locations were mapped on the topside.

Barwick said the other old fashioned way to “sound” the deck would have been to shut down all traffic, mill off the asphalt and drag chains across the top surface. But the hammering could go on while traffic was still moving on top.

“The interns got some practical real-world engineering work and we got the locations we needed.”

Traffic was reduced to two lanes, first on the north side and then on the south, so Kraemer’s workers could drill out the bad concrete from around the steel rebar – again, like dental work preparing to fill a cavity. It left a hole in the deck except for the steel grid.

“You have to get all the concrete out without affecting the reinforcing steel,” Barwick said.

New concrete was then placed into the opening.

In the official Colorado state highway map of 1946, there is no Valley Highway, and no Sixth Avenue east of Federal. Traffic entered town via the Eighth Avenue Viaduct.

The two bridges making up the viaduct were part of Denver’s first big freeway building boom in the 1950s. The Valley Highway, now Interstate 25, had pushed south to Zuni Street near Eighth Avenue. There, a rickety old viaduct carried east-west traffic over the Denver & Rio Grande Western’s Burnham Yard to Federal Boulevard. Across Federal, motorists could swing southwest along the hillside and connect with Sixth Avenue, which was going to be developed into a freeway in part to serve the Denver Federal Center.

The Sixth Avenue Viaduct was conceived as a straight-on connector from that future freeway into town, and the interchange with the Valley

The 1960 state highway map showed the new Valley Highway, labeled as 185 rather than I-25, and the Sixth Avenue connector. But Eighth was reduced to a tiny line.

It is a vital high-speed traffic corridor on the west side of the metro area.