Jason Walsh: When it comes to rebuilding Watmaugh, Caltrans will cross that bridge when they come to it

At 6:05 p.m. on Aug. 1, 2007, the central span of the I-35 W. Mississippi Bridge in Minneapolis gave way, sending 111 rush-hour vehicles and 18 construction workers on a 115-foot drop into the Mississippi River.

Teetering precariously against the guardrail of the collapsed span was a school bus carrying 63 children, all of whom miraculously escaped by kicking their way out the back of the banana-yellow death trap.

In all, 13 were killed and 145 injured that day on the I-35 West.

Two years prior, the I-35 bridge had been given a federal inspection “sufficiency rating” of 50 out of 100; according to that rating system, out of more than 100,000 heavily used bridges only about 4 percent score below 50 – and that rating alone could imply “structural deficiency,” according to the federal inspection guidelines.

So how is a decade-old tragedy on the Big Muddy relevant to Sonoma? Because the Watmaugh Bridge has a sufficiency rating of 4. That’s right: four.

We’ll pause while readers en route GPS an alternate course across Sonoma Creek.

Let’s put that sufficiency rating in perspective. The Hussaini Hanging Bridge in Pakistan is suspended 2,600 feet above Lake Borit in the Hunza province and his held together by six thin cables and a dwindling number of wooden walking planks. Among bridges in regular use, it’s considered to be among the world’s most dangerous. While it hasn’t been given a sufficiency rating by U.S. federal bridge inspectors, let’s assume it’s a zero. That’s only four sufficiency points less than the Watmaugh Bridge.

That Watmaugh, built in 1929, is wobblier than the rubber-tire walk at your local children’s play structure is hardly news. The county has been planning on replacing it since 2003, when road officials reported that water had seeped through the concrete and rusted the rebar running along the underside of the bridge’s surface, causing chunks of concrete to break off and fall to the creek bed. The County has Watmaugh on is “mandatory seismic bridge replacement” list, with construction possibly starting three and a half years from now in the summer of 2020. Until then, any Billy Goats Gruff would be wise to avoid Watmaugh and its requisite troll, fol de rol.

As for the rest of us who sometimes need it to drive between Arnold Drive and Broadway, Caltrans is far more reassuring than the federal sufficiency numbers.

According to the state Department of Transportation website, “A low sufficiency rating number does not necessarily mean that the bridge is in need of immediate repair.” Nor does a “structurally deficient” designation mean a bridge is unsafe – it just sounds that way. According to DOT officials, 95 percent of the time that label is simply due to minor cracks in the concrete or the condition of the paint. Project timelines are set on a “bridge by bridge” basis and, at least in the eyes of California bridge inspectors, Watmaugh isn’t washing away into Sonoma Creek anytime soon.

Still, as is evidence by the rare, but occasional bridge failure the rating system isn’t air tight – and the very low ratings certainly suggest a far greater level of deterioration than the inspections seem to indicate.

Like Watmaugh, the 1957 movie, “The Bridge on the River Kwai,” was also about a debate over whether to build a bridge or let it collapse. Fans of the classic David Lean flick will recall that, in the end, no one could agree about the bridge - and it ultimately comes down, killing everyone on it and pretty much everyone around it (there was also a lot of shooting going on in this Japanese prisoner-of-war movie).

The Watmaugh Bridge sitting on a sufficiency rating of 4 for 17-plus years calls to mind the closing words of “Kwai.”

“Madness! Madness!”

Email Jason at Jason.walsh@sonomanews.com.