DarkRange55
🎂
- Oct 15, 2023
- 2,421
Washington State is home to 4 of the world's top 5 longest floating bridges 
Washington has the most frequently opened draw bridge in the world. The Fremont bridge gets opened on average of 35 times a day.
Washington has an extensive network of drive-on/drive-off ferryboats, the biggest in the US and second biggest in the world (BC & Istanbul are up there)... and they're part of the state highway system, so driving "state highway 104" for example involves driving onto a boat, waiting half an hour, then driving off on the other side)
Lake Washington is connected to Lake Union, which connects to the Puget Sound (and thus the Pacific Ocean) through a lock. Because of the floating bridges, the level of Lake Washington has to be maintained at 22 to 26 feet at all times, otherwise the bridges would be damaged. I think at times when the lake level is low, they have to suspend pleasure craft from using the lock to avoid losing too much water. The lowering of Lake Washington also destroyed the vast majority of the wetlands that used to be around the lake. It also made Seward Park into a peninsula instead of an island.
Hood Canal Bridge is over tidal water, so a 10-12 ft vertical change daily. The 3 bridges on Lake Washington are not subject to long-cycle wave action. The hood canal bridge can get some big waves, and IIRC they stop traffic and pull the drawspan open during high winds to relieve pressure. Something like 20% of the world's nuclear weapons float through that bridge.
During planning, they ran a convoy of semi trucks full of concrete slabs across to check how it behaved under load.
The geological / engineering reasons why they're floating is really cool. You might like this video that describes the geology around Seattle and why we have the floating bridges. Nick Zenter is great.
The nice thing about them is they are low on the water compared to a truss or suspension bridge and do not kill the view from land, and give a sense of skimming the lake when driving them
Washington has the most frequently opened draw bridge in the world. The Fremont bridge gets opened on average of 35 times a day.
Washington has an extensive network of drive-on/drive-off ferryboats, the biggest in the US and second biggest in the world (BC & Istanbul are up there)... and they're part of the state highway system, so driving "state highway 104" for example involves driving onto a boat, waiting half an hour, then driving off on the other side)
Lake Washington is connected to Lake Union, which connects to the Puget Sound (and thus the Pacific Ocean) through a lock. Because of the floating bridges, the level of Lake Washington has to be maintained at 22 to 26 feet at all times, otherwise the bridges would be damaged. I think at times when the lake level is low, they have to suspend pleasure craft from using the lock to avoid losing too much water. The lowering of Lake Washington also destroyed the vast majority of the wetlands that used to be around the lake. It also made Seward Park into a peninsula instead of an island.
Hood Canal Bridge is over tidal water, so a 10-12 ft vertical change daily. The 3 bridges on Lake Washington are not subject to long-cycle wave action. The hood canal bridge can get some big waves, and IIRC they stop traffic and pull the drawspan open during high winds to relieve pressure. Something like 20% of the world's nuclear weapons float through that bridge.
During planning, they ran a convoy of semi trucks full of concrete slabs across to check how it behaved under load.
The geological / engineering reasons why they're floating is really cool. You might like this video that describes the geology around Seattle and why we have the floating bridges. Nick Zenter is great.
The nice thing about them is they are low on the water compared to a truss or suspension bridge and do not kill the view from land, and give a sense of skimming the lake when driving them
