The long-awaited left-turn signal at Broadway and Leveroni Road is scheduled to be installed Wednesday.

Construction crews from San Leandro-based contractor Columbia Electric have been preparing the area for the signal arms over the last week. According to Dan Takasugi, Sonoma’s director of Public Works and City Engineer, the new signal mast arms and signal lights will be installed Feb. 19, with cutover from the old signals slated for later in the week.

The project comes after a September 2009 accident in which a 50,000-pound gravel truck crashed into three cars and the retaining wall at Broadway Market. While no one was killed or seriously injured in the multi-vehicle collision, the damage was sobering and Sonoma Police Chief Bret Sackett sent photos of the aftermath to Caltrans, urging safety improvements.

Nearly 75 percent of the project is funded under Caltrans Highway Safety Improvement Program and the rest by Measure J sales tax.

“These signal arms were on a very long lead time for delivery,” Takasugi said, “and thus delayed the start of construction.”

Takasugi expects “minimal impact” on traffic flow, although he noted there will likely be a flagger for traffic control. “I would expect some long delays right as each signal arm is raised.”

Columbia Electric, he said, will be grinding and paving the intersection the week of Feb. 24.