The word "bridge" is so synonymous with good that it's used in multiple positive phrases, such as "bridging gaps" and "building bridges". But some bridges are terrifying, even for people who don't suffer from Gephyrophobia — the fear of bridges. Let's take a look at the world's scariest bridges and why you might want to think twice should you ever need to cross one of them.

What Makes a Bridge Terrifying?

All terrifying bridges have one thing in common — they somehow make us feel vulnerable. It could be their vertigo-inducing height, what they're constructed from (think rope and wood), or the weather conditions when we cross them. Drivers concerned about crossing Michigan's ice-prone Mackinac Bridge can pay staff to drive them across its 5-mile length. Some people experience nausea when they cross Japan's Eshima Ohashi Bridge . This is because the bridge appears to disappear in midair when you're coming from one direction, while the descent is so steep from the other that you brake more than you drive.

The World's Top 5 Scariest Bridges

• Hussaini Bridge: Made with rope, wooden planks (some missing), and thin steel rods, it hangs precariously 100 feet above the Borit River.
• Zhangjiajie Grand Canyon Glass Bridge: Imagine a 1,230-foot-long walk over a glass floor that's 1,180 feet high (and often devoured by fog and clouds).
• Storseisundet Bridge: Sometimes likened to being on a rollercoaster lashed by Norway's Atlantic winds and waves.
• Royal Gorge Bridge: Suspended 956 feet above the Arkansas River, you'll need to tread 1257 wooden planks to get across.
• Millau Viaduct: At 1,125 feet above France's Tarn Valley, drivers often find that the clouds are underneath them.