Why is Caltrans closing Tower Bridge? It’s sagging and needs new suspenders

Sacramento’s iconic Tower Bridge is 82 years old. With age, there’s sagging.

Bridge inspectors last year noticed the cables that help lift the main span for tall ships have stretched 14 inches longer than they once were – a sign that time, weather, and stress have taken a toll.

So the golden span is getting fitted with new suspenders.

The $6 million project, which includes a handful of other upgrades, continues through December and is requiring daily traffic-lane reductions and several full-bridge nighttime closures.

Officials said they think they will have all lanes fully open again by Dec. 1, although overhead work will continue beyond then.

The work focuses on cutting and replacing, one at a time, 96 steel cables that connect the lift deck to two 1 million-pound counterweight blocks that are suspended high inside each of the span’s twin towers.

Those counter-weight blocks slowly lower, via a second cable system, as the bridge deck rises, providing a weight balancing role.

The bridge deck budges only occasionally now, about 10 times week, officials say, and inspectors were concerned about the aging cable system’s capacity for handling the load.

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Standing on an upper-level catwalk among pigeon roosts, Caltrans engineer Mike White said the state could have let the cables remain as is, but took action partly because officials feared potential deterioration inside the nearly 2-inch-thick cables.

“They’ve never been replaced before, as far as we can tell,” White said. “They’re actually in pretty good shape. But it’s good to be prudent.

”Nothing lasts forever.”

The project work includes redoing electrical cables and lights, and upgrading security and communications systems.

The bridge is owned by Caltrans and sits on State Route 275, the shortest highway in California, running from one end of the bridge to the other. The state relinquished the rest of that highway more than a decade ago to West Sacramento on one side and Sacramento on the other.

Caltrans, meanwhile, is alerting drivers that it will be closing another local lift bridge, the Rio Vista Bridge on Highway 12, for inspections of the lift system’s counter-weight chains. The closures will take place overnight on Thursday, Nov. 8 and Friday, Nov. 9.