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During overnight work July 9, giant telescoping
cranes sitting on Cimarron Street (Highway 24) just west of I-25 lift a 120-foot
girder that will make up part of the new southbound interstate bridge. It was the
15th of 30 being placed for the new bridge between July 5 and 11, with Cimarron
being closed those nights at the I-25 interchange from 9 p.m. to 5 a.m. Photo
looks south. The far end of the girder is being placed on a temporary metal
structure called a "falsework," which will later be replaced (in a slightly different
location) by a permanent pier of concrete and rebar.
Girders placed in overnight work on new Cimarron/I-25 southbound bridge
The same girder is shown a few seconds earlier
July 9, in more of a wide-angle shot that gives an idea of the height of the cranes.
The workmen standing on the opposite structure wait for their end to come down.
The red blocks on the cranes' rear areas are counterweights (roughly 50 tons for
each crane) that keep them from toppling over while lifting the girder.
Westside Pioneer photo
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About 90 tons in weight, the prefabricated units of concrete and steel were lined up in three sets of 10, forming an overall span of approximately 350 feet over Cimarron Street (Highway 24).
According to Eric Norwood, construction manager for project consultant Wilson & Company, the northern-set girders are 120 feet long, those in the middle 80 feet and the southern set 150 feet.
Abutments will eventually be finalized at either end of the span, with a pier in the middle just north of the future alignment of Cimarron Street, he said. For now, a temporary metal structure, nicknamed a "falsework" by those in the trade, is serving as the pier.
Kraemer North America, the main contractor on the $113 million project to replace the Cimarron/I-25 interchange, is coordinating with Rocky Mountain Cranes of Denver on the placement of the girders. The units were fabricated by EnCon Colorado, also of Denver.
The placement process required the synchronization of the operators of two giant telescoping cranes, along with specialized workers at either end who make sure that each girder nestles into its pre-measured spot.
The girders are to be tied together by multiple steel cables going through them, as well as by concrete with rebar poured over and around them. Also, a concrete deck will be poured on top to turn the surface into a roadway.
For the work, Cimarron was closed in both directions each night from 9 p.m. to 5 a.m.
Initially, the girder job was only going to last through Saturday, July 9, but a computer malfunction in one of the cranes kept work from occurring that night and the night before, Norwood said.
The new interstate bridge is being constructed about 75 feet west of the current one (built in 1960), as part of an interchange that will take up a bigger footprint in general.
It will be the end of the year before the bridge can open to southbound traffic, based on the Kraemer schedule. After that, traffic in both directions will be temporarily redirected from the old bridge to the new one to allow construction to start on the northbound side, plans show. Technically, the girder work comprises not only the southbound bridge but part of what will be the new northbound bridge, CDOT officials have noted.
Overall project completion is expected in late 2017.
The photos on this page were shot by the Westside Pioneer the nights of July 7 and 9 and in the daytime July 13 (after the girders were in), as noted in the cutlines.
Westside Pioneer article
(Posted 7/10/16, updated 7/13/16;
Transportation:Cimarron/I-25)
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Construction workers weld a section of iron to
temporarily secure a just-placed girder July 9 (the same one shown in the photos
above). It is now one of the northern set of 10 girders in the 350-foot bridge span,
as explained in the story. To its left, fading into the less illuminated background,
can be seen some of the other, previously laid girders in the set. Eventually, a steel
"pre-tensioning" cable will be strung through the lengthwise holes (the four gray,
symetrically aligned cylinders extending from the back of each girder), to connect
the sets of girders. After that, concrete with rebar will be poured around the
girders (including where the workers are standing) to further secure the structure
and make a flat surface for the bridge deck.
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Weighing about 90 tons, each girder had to be
transported to the Cimarron/I-25 worksite on a separate semi tractor-trailer. This
view of a girder on a trailer was photographed the night of July 7 - one of the
nights Cimarron Street was shut off both ways for the girder placements (although
a crane's computer malfunction prevented any such activity that night and the
next). The view here is to the west, with the lights of businesses around Eighth
Street visible in the background.
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This was the view July 13, driving eastbound on
Cimarron Street under the future I-25 southbbound bridge, two days after the last
girders were placed. The "falsework," shown in the background of the top two
photos on this page, is in the foreground here.
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