SACRAMENTO (CBS13) — An investigation is underway into an accident that injured three workers during the Fix 50 project as construction continues into its second day.

The California Division of Occupational Safety and Health joined construction crews on the Fix 50 job site after three workers were injured by a piece of wood sent flying by a big rig.

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“One we did speak to didn’t even see it coming,” said Dennis Keaton with Caltrans.

The semi hit a 20-foot 2-by-4 piece of lumber a worker was putting in place on the west end of the project to fix the span stretching between W and X streets in Sacramento.

“As he picked it up and turned, part of the board went over the guardrail, protruding into the traffic lane,” said California Highway Patrol Officer Michael Bradley.

On Wednesday night, it was like the accident never happened. Traffic on eastbound Highway 50 moved quite well as work continued on the two-month project.

CBS13 talked to Ed Yarbrough, the Caltrans safety manager on this project, and asked if workers have enough room to maneuver.

“They’ve got space to work,” he said. “It’s a matter of controlling the work, and ensuring people know who’s working where and what they’re doing.”

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He says there are daily safety briefings for every worker on the massive job.

Two workers from contractor Myers and Sons and a Caltrans inspector were injured on Wednesday. All three were transported with non-life-threatening injuries, and at last check, two have already been released.

As for what will change?

“It’s just a matter now of us having increased vigilance and watching out for each other and continuing to do so in the future,” he said.

On crucial question remains: Who was the driver? The big rig didn’t stop.

In a noisy construction zone, officers say it’s possible the driver didn’t realize he or she hit something.

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Caltrans currently has no video of the incident. The live traffic cameras set up are only used for live streaming and don’t record. Those cameras weren’t working on Wednesday.