It’s been a long time coming, but when the new eastern span of the Bay Bridge finally opens to the public, it will be packed with innovative features. The new bridge is composed of two very different structures—a gracefully curving 1.2-mile skyway, which will afford motorists sweeping views of the Bay, and a soaring 2,047-foot suspension span.
With its striking asymmetrical design, the single-tower, self-anchored suspension span will be the longest such structure in the world. But many of the bridge’s most important innovations are related to its seismic defenses and won’t be visible to the unschooled eye. Unlike earlier bridges, which were designed to resist earthquakes by their sheer size and strength, the new bridge is engineered to be flexible so that it can absorb a seismic punch without a catastrophic failure—much like the bumper of your car. To that end, the tower is composed of four steel shafts that are designed to sway up to five feet at the top during a major earthquake. Similarly, the skyway is divided into segments joined by giant steel tubes that are engineered to slide during a seismic event. Even the bridge’s concrete piers are designed to shift during a quake, limiting the damage to areas with extra reinforcing.
The final price tag of the new bridge is an earth-shaking $6.4 billion, making it one of the most expensive bridges in U.S. history and one of the costliest public works project ever in California. Here are some other noteworthy numbers:
1) Number of vehicles that cross bridge on average day: 280,000
1) Length of new span: 2.2 miles
2) Height of tower: 525 feet
3) Amount of steel: 250,000 metric tons (enough to build 10 Eiffel Towers or 33 Statues of Liberty)
4) Amount of concrete: 432,000 cubic meters
5) Diameter of main suspension cable: 2.6 feet
6) Length of steel wire in main cable: 14,800 miles
7) Diameter of steel piles: 8.5 feet
8) Depth of deepest pile: 300 feet
9) Number of LED lights: 48,000
10) Number of construction days: 4,235
11) Number of years bridge is designed to last: 150
12) Projected time to disassemble old span: 3 to 5 years