Elon's Tunnels

danmanjones's picture

Elon Musk LITERALLY reinvents the tunnel!

The crucial part is at 14:00

The throughput just doesn't make sense compared to trains or even regular roads.

 

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sato's picture

watched this before and it makes a lot of mistaken assumptions.

the design adds the equivalent of 3 additional lanes of traffic, all without any traffic lights. it's the same concept as raised bypasses which already work well, just instead of having more lanes to increase capacity, the same is achieved through higher speeds.

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danmanjones's picture

the design adds the equivalent of 3 additional lanes of traffic

according to the loose calculations in the video it's a magnitude less than 1 lane of traffic when you consider the throughput. The first few cars to book the lane would get to the destination faster but after that it's downhill.

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sato's picture

the throughput is one of the mistaken assumptions. the promotional video shows a single access point, but that's only one of many. just as with a raised bypass there are many on and off ramps.

because the cars in the tunnel are going triple the speed, their journey is completed in one-third of the time, and thus it can handle three times the volume of a single lane. at worst it'll halve traffic on the surface roads, that's without even taking into account the reduced stoplight time, which further decreases traffic density.

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danmanjones's picture

cars in the tunnel are going triple the speed, their journey is completed in one-third of the time, and thus it can handle three times the volume of a single lane

You're still not getting it. Speed is just one variable. You have to measure how many people can move from A to B over an extended period of time. Volume would be measured by the number of people who arrive, not how quickly the first person gets there. Just for example, the car could carry 1 person or 5 people. It's the same speed but 5 times the volume.

 

Did you watch the video from around 14:00?

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daftcunt's picture

The whole idea is idiotic and it does by no means add 3 lanes of traffic. You will just end up with a system for the privileged that ends in the same queue a little further ahead and and the plebs have to wait even longer. And even this can only be achieved when introducing a traffic light system extemely favouring these "fast lanes" otherwise they will soon clog up worse than other roads.

 

The only way to cater for efficient suburb to downtown transport is a mass transport on dedicated lanes, for example a metro system.

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sato's picture

even longer? how? even if it's only for the priviledged, all those cars that would normally be on the surface roads, making traffic light queues longer, would no longer be there because they'd be underground instead. that's good for everyone else using those roads. just as buses benefit the people who don't take buses the most, by removing cars from the road. here where i live we have a main rail line and also a high-speed freeway (toll road) going the same direction. i don't use either, but when the freeway gets closed because of a crash, and once the trains were out because of flooding, my route suddenly experiences "normal" traffic and it takes me 1:30 to get to work instead of 30 minutes.

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danmanjones's picture

all those cars

you make it sound like a lot of cars when the number of cars is relative to how much it costs compared to alternatives. Eg. if it's 1,000 passengers per day per tunnel but costs the same as an underground train that can handle 50,000 passengers per day per tunnel then it's an inferior system. If it's a private venture then whatever but no doubt Elon will be wanting public funding - the concept kinda falls over at that point.

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daftcunt's picture

The cars using the fast lane tunnels have to return into traffic at the end of the tunnel, hence they overtake whoever is not in the tunnel (at least untill the tunnel itself clogs up at the exits) and thus the overtakees have to wait even longer. The cars overtaking them have originally been in the queue behind them after all.

 

The comparison "just as buses benefit the people who don't take buses the most" is flawed as people on public transport left their cars at home or at a P&R and, unlike the "tunnel travellers" don't need any space for them at the destination.

 

Regarding the "triple speed": this is a complete red herring (especially if many on and off ramps are included in the system) as the tunnel is single lane and thus cars exiting will slow everybody else down considerably.

 

Sorry, I must say again this idea is complete and utter bullshit. And I am most definitely not a "Tesla hater" like fullauto.

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