Towers for the Hoover Dam bypass bridge can be seen in the bottom left of a photo taken Wednesday downstream from the dam on the border of Nevada and Arizona. Photo by John Locher.

Engineers took baby steps this week in resuming work on a Hoover Dam bypass bridge, but they're still months away from fully ramping up construction after a mid-September crane collapse at the site.

Work that has restarted involves bridge construction segments that have no need for two pairs of 280-foot towers that made up a pulley-type "high line" crane system knocked down by high winds Sept. 18.

No one was hurt in the collapse about a quarter-mile south of the dam in Black Canyon. Project leaders hope to wrap up an investigation into the incident and have a new construction timeline in place by year's end.

The project could see a delay of around six months, pushing back an opening date to around mid-2009.

"It's going to take a significant effort and replanning. The bottom line, the job is progressing in a significant way in the very near future," Dave Zanetell, a Federal Highway Administration engineer overseeing the construction project, said this week.

"There's a significant amount of work that can be accomplished without a high line" crane, Zanetell said. "The job is advancing. It's back on its feet. The job is going to get done."

Zanetell could not offer a precise new target completion date. "It will be moved significantly" from an original target of the end of 2008, he said.

The project's work force of approximately 50 workers at any given time is roughly divided between crane cleanup work and new construction activities, according to Zanetell.

"We're in the final phases of securing the site and cleaning up," Zanetell said.

Cleanup work is expected to take "several weeks more" to finish, Zanetell said.

Although engineers are confident wind gusts clocked at up to 51 mph in the Las Vegas Valley that day contributed significantly to the collapse, an inquiry has yet to determine precisely why heavy winds took down the crane system and 2,300-foot strands of steel cable between the tower pairs on either end of the gorge.

Work had been suspended the day of the collapse due to high winds. Only a skeleton crew was on hand at the time to keep an eye on the work area.

Current work phases involve setting concrete columns that will support bridge approach roads, and other work on the approach structures on either end of the canyon.

Engineers have yet to determine whether to rebuild the high line crane or use some other type of crane system, and when those new cranes may be in place.

Such considerations will impact a final new work schedule, as some sort of cranes will be needed as the bridge takes shape over the Colorado River.

"We're hoping to have a pretty definitive schedule by the end of the year," Zanetell said.

The high line cranes were used to tote up to 50 tons of materials and workers about 1,100 feet over the river.

It is not yet clear whether the delays will add to the bridge's $234 million price tag, or who would be responsible for any collapse-related overruns.

The project has been contracted to a partnership of multinational construction firms, Obayashi/Mitsubishi PSM.

The project was about halfway done before last month's setback. Planners originally hoped to start extending the bridge deck over the river this month.

When finished, the 1,905-foot span 890 feet over the river will carry U.S. Highway 93 traffic that now crosses the dam.

The bridge itself is designed to withstand winds of up to 100 mph. From the project's outset, wind was expected to be a major challenge in erecting the span.

U.S. 93 at the dam was closed just after the collapse, and traffic restrictions were in place for weeks afterward.

U.S. 93 was fully open at the dam Wednesday, but drivers were asked to check roadside message boards for any future traffic restrictions to allow cleanup work.