Workers from Kanzaa Construction tighten the last of 23,000 bolts that hold together the new tunnel at the site of the bridge at Washington and Clark streets Monday. Project Manager Felipe Bobadilla said the next step is to build the foundations for the retaining walls, on each side of the tunnel, that will hold 30,000 square yards of dirt fill, bringing the base to street level. If weather permits, he said, the job, which is not to exceed $8.6 million, should be completed by July 29. The 80-year-old bridge was demolished in August 2010 after having been closed since January 2009. It is the lone span along Vicksburg’s main north-south corridor connecting downtown and Interstate 20.