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Comment by gns24 | Hacker News Reader

Yeah, the potential loading is annoying. I remember wondering why predestrian/cycle bridges were always so annoyingly narrow despite having low loads. The issue is of course that they have to be strong enough to support being crammed with hundreds of people when everyone is there to watch the local fireworks/rowing race/anything else that's happening, even if that happens almost never.

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If you built a rope-bridge, I'm sure people would beware of cramming it. Maybe it's possible to build designs that discourage.

Where are you from? I haven't seen an "annoyingly narrow" ped/cycle bridge in Sweden or Belgium.

> “Where are you from? I haven't seen an "annoyingly narrow" ped/cycle bridge in Sweden or Belgium.”

I’d say most of London’s busy pedestrian/cycle bridges and tunnels are annoyingly narrow.

Even taking cyclists out of the equation, they can get congested at times, particularly with tourists stopping to take photos from the middle etc.

So a cyclist can either be polite and move at pedestrian speed, which is annoying for the cyclist. Or weave and dodge pedestrians at speed (typically Deliveroo/UberEats riders on e-bikes) which is annoying and dangerous for pedestrians…

>If you built a rope-bridge, I'm sure people would beware of cramming it.

You're not American or British, ehe? ;)

Or many other countries, I've seen enough video of bridge collapses to know that if people CAN cram on it, at some point they WILL cram on it.

This is interesting! But how does a dense crowd of people compare to a queue of lorries carrying cement or building materials in terms of mass per square metre?

Let's try to find some data ... ... ... A fully loaded Hanson cement lorry seems to be 32 tonnes / 2.55 m / 9.15 m, which is about 1.4 tonnes per square metre. That corresponds to 20 x 70 kg people per square metre, which would be a disaster whether or not the floor gives way, unless it's a very special kind of crowd (acrobats or something).

Lots of roads and bridges have a limit on axle load permitted on them. You can't do that with pedestrian bridges.

See also this story about the Golden Gate: https://www.sfgate.com/local-donotuse/article/golden-gate-br...

Love this quote: Friday marked the 32nd anniversary of the walk across the Golden Gate Bridge, an event The Chronicle's Peter Hartlaub once referred to as "the largest clusterf— in Bay Area history where no one actually died."

> "There were cheers as some people started to hurl bicycles over the railing," he wrote. "A stroller tumbled down and sank beneath the waves 220 feet below. 'Throw the baby, too,' people yelled, laughing.

I admit that I chuckled at this.

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