GOLDEN, Colo. -- The collapsing girder that killed a family of three last weekend had been temporarily braced because workers ran out of time to finish the job, federal investigators said Wednesday.

Workers were sent to install two girders on May 11, but got behind schedule because the girder was first installed backward and had to be turned around. The highway had to be reopened at 5:30 a.m. the next morning, before any other girders were installed.

The girder was secured with five temporary lateral braces. The braces were not part of the original job order but were devised by the crew foreman and approved by the state transportation department, National Transportation Safety Board investigator Ken Suydam said.

Four of the five braces were found bent after the collapse. The ends of the girder were not fastened to the bridge.

Bad weather on Wednesday and Thursday kept workers from installing the second girder, which would have helped shore up the beam already installed, NTSB investigator Dan Walsh said.

The weather finally cleared Friday but the state does not allow highway closures on Fridays or Saturdays. The 40-ton girder collapsed Saturday morning, killing the Evergreen family as it sheared their SUV in half on eastbound Interstate 70.

The girder was manufactured in two sections, which were joined at the work site. One of the sections was incorrectly marked at the foundry, which led the workers to install it backward, said Dave Minshall, spokesman for Ridge Erection Co., the subcontractor which did the work.

Suydam said some of the 90 bolts used to install the girder had to be replaced, slowing down the work. Minshall disputed that, saying the only bolts that had to be replaced were five used in the temporary braces.

Minshall said the temporary fix was a "decision that was made at lots of levels." Transportation department spokeswoman Stacey Stegman said there was no documentation that the department signed off on the temporary solution.

The NTSB is trying to set up interviews with the construction workers and they plan to review the diary kept by the state inspector on the scene. Some of the workers want to have lawyers and union representatives present, which Suydam said was common.

Investigators are also looking at whether vibration from the road or changes in temperature caused the girder to shift and then fall. The girder was installed on a bridge carrying state highway C-470 over I-70.

The State Patrol has said one of its dispatchers received a call from a driver an hour before the accident warning that the girder looked like it had rolled two or three feet. The dispatcher told a state transportation crew to look for a downed sign instead.