Push to fix aging span

<p>Healdsburg's vintage, 1920s bridge over the Russian River, rated the worst in Sonoma County, may finally get fixed or replaced after years of delay.</p><p>The City Council on Tuesday voted unanimously to apply for $23 million in federal money to build a new bridge in its place, but left open the possibility of simply upgrading the existing span, a beloved landmark of history buffs and longtime residents.</p><p>Last month's collapse of a bridge in Minneapolis that killed at least a dozen people has provided new urgency to fixing or replacing the bridge in Healdsburg, which has an even worse rating than the bridge in the Midwest catastrophe.</p><p>Healdsburg Public Works officials are not willing to say their 1921 steel truss bridge is safe, particularly because trucks exceeding the weight limit frequently drive across it.</p><p>"If structural components are fatigued to the point they snap, if one or more critical members broke, there could be a chain reaction with catastrophic and devastating effects," Public Works Director Mike Kirn said Tuesday.</p><p>Consultants for the city said their primary concern is not that the bridge will collapse immediately, but that high water in winter could destroy it.</p><p>"Under high flows, it's very susceptible to being washed away," said Dennis Pecchia of HDR consultants. "A major earthquake could take that bridge now."</p><p>Mayor Gary Plass noted that fixing the Healdsburg Avenue bridge was one of the City Council's top priorities before the bridge collapse over the Mississippi River that drew national attention to the structural safety issue. But the fatal mishap brought renewed interest to bolstering, or replacing the obsolete span over the Russian River.</p><p>"We've got some concerns when bridges are falling," Plass said. "It obviously heightens our awareness."</p><p>On a scale of 1 to 100, with 1 being the worst, the 398-foot-long Healdsburg bridge has a sufficiency rating of 2. By comparison, the 600-foot span that collapsed in Minneapolis had a sufficiency rating of approximately 50.</p><p>Six of Sonoma County's 167 federally rated bridges have sufficiency ratings of 50 or less, which means the bridge may have to be replaced.</p><p>Consultants said there are a number of factors that are considered in a sufficiency rating, which include corrosion and cracking, as well as width, alignment and functionality.</p><p>Some who spoke in favor of preserving the bridge questioned the formula Caltrans uses to rate it. City officials said they will scrutinize the rating to ensure it is valid.</p><p>The low ranking does not reflect temporary structural reinforcements that were made three years ago. The bridge was closed for a week for emergency repairs to roller joints and bolts. Although it gave the bridge better flexibility to expand or contract in hot and cold weather, Plass said it was "a Band-Aid."</p><p>"It didn't materially make significant upgrades or improvement to the structure," Kirn said.</p><p>He said the bridge is vulnerable to earthquakes and its center concrete support has been "scoured" or undermined by the river.</p><p>Kirn said the bridge's pilings are apparently made of wood with a concrete cap over them. As the river eats away at the gravel and rock bottom around the center bridge pier, he said it could expose the pilings and concrete, undermining the structure.</p><p>Healdsburg officials have debated off and on since at least 1990 whether to replace the bridge because the cost of strengthening and refurbishing the landmark is so high.</p><p>The most practical solution, to simply replace the span with a new bridge, was opposed by history buffs and other residents who said it was part of the town's identity.</p><p>On Tuesday, they again came forward to implore the city to keep the historic structure.</p><p>The bridge served as the southern gateway into Healdsburg, part of the old Redwood Highway before Highway 101 was built to the west.</p><p>To simply rehabilitate the existing bridge, strengthen it for load capacity and retrofit it for earthquake and flood resistance would cost an estimated $13 million.</p><p>But that would still leave an overly narrow bridge with lanes less than 10-feet wide, as opposed to the current 12-foot standard. It also would provide no room for a bicycle lane.</p><p>Replacing the bridge with a modern one is estimated to cost $23 million.</p><p>In both instances, almost 90 percent of the cost would be paid with federal bridge replacement fund programs.</p><p>The most expensive alternative -- $40 million -- involves replacing the current bridge with a visually similar bridge. But city officials say less federal grant money may be available for that option and Healdsburg's local match may have to be much higher.</p><p>The estimated construction costs are adjusted for projected inflation between now and 2011, the probable date a project could begin after the city conducts environmental studies.</p><p>The City Council would then choose a preferred alternative.</p><p>Public Works officials said construction could take up two years. During that period, the bridge would be closed to traffic and motorists would be detoured to Highway 101.</p><p>You can reach Staff Writer</p><p>Clark Mason at 521-5214 or clark.mason@pressdemocrat.com.</p>