No second chances

Case Studies
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On April 29, a tanker truck crashed through a guardrail on northern California’s major interchange between I-580 and I-80 and exploded into flames. Intense fire melted the steel underbelly of the elevated roadway and caused it to collapse onto the roadway below. Reports warned that the mangled section of roadway—known as Oakland’s MacArthur Maze—would be unusable for six weeks to several months, with a shortage of steel adding to the challenge of the massive reconstruction effort.

A mere 25 days later, however, the roadway was reopened. Thanks to the efforts of C.C. Myers (CCM), survey subcontractor Andregg Geomatics and the Trimble S6 Total Station , motorists were able to use the roadway a full month earlier than the California Department of Transportation’s deadline.

The high-profile, 165-ft roadway reconstruction project required 200 cu yd of concrete road deck, 96 hours of curing time and 12 steel girders.

Within two hours of CCM’s call, Andregg’s survey team was providing as-built measurements of the remaining bridge using the Trimble S6 Total Station ; they computed the lengths for fabricating new steel girders to 1/4-in. tolerances.

Crews also laid out for the concrete bent cap girder so workers could accurately position it on top of the existing columns. When the steel girders arrived, they had to fit in between the bent caps.

Due to the bridge curve, the 12 girders required varying lengths. Andregg performed the field survey from noon to midnight on May 8, and then continued in the office until 5a.m. to deliver the results, successfully meeting the girder manufacturer’s deadline at 6 a.m. May 9.

"We used [the survey equipment chosen] because of its high accuracy and its ability to measure reflectorless on impossible-to-reach dark surfaces," said Andregg’s Project Manager Tom Holmberg, PLS.

"In addition, a good portion of the survey took place during the night and the built-in laser pointer was very useful in pinpointing where the shot was taken.

"The [survey equipment] was the main tool for this job and instrumental in getting the job done to the necessary accuracy. Due to the prefab, measurements couldn’t be off by any amount: There were no second chances."

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