This One Weird Trick Could Double the Capacity of our Freeways

[kernals12]

Excuse the clickbait headline, but this is pretty damn cool.

The biggest source of congestion is phantom jams. Here's a video showing what they are

The reason for this is that we humans are very slow to react. If we see a car's brake lights in front of us, we'll take a few seconds to react and then slam on our brakes, and because of that, we have to brake harder than if we could react instantly, and that delay builds up with each driver who slows until you get bumper to bumper traffic.

But we can fix this with science. Many cars now have adaptive cruise control, which uses sensors to keep a set distance from the car in front of you. If your car could know that the one in front of it was braking, it could react instantly, and slow down more gradually, thereby maintaining a smoother flow of traffic, dissipating the shock wave. And they're working on it, it's called cooperative adaptive cruise control.

All it requires is adaptive cruise control and V2V communication. The former is common and the latter is beginning to emerge, with the VW Golf, one of the best selling cars in the world, getting it this year.

Studies have found that if every single car on the road had it, then freeway lane capacity would soar from 2,000 vehicles per hour to 4,000, because they could have shorter following distances. Could you imagine what would happen if the great congestion problem were finally solved? It would save us hundreds of billions of dollars in delays, it would mean far less need for freeway widenings, far fewer excuses for heinously expensive massive transit systems, and best of all, it would make driving way more enjoyable.

[interstatefan990]

This seems like it would be a cool technology, but in reality it seems a little too far-fetched for the foreseeable future. It doesn't solve, for example, people's desire to go faster or do what they want to. What if one driver decided that they didn't like the speed their lane was moving and and decided to resume manual control of their car? Also, this would only work if every car on the road had it, which would take about 20 years (the average time it takes for a feature to be equipped on all vehicles in use once it becomes mandatory). So that would mean we would have to put technology into cars that can't even be used yet, and I'm willing to bet manufacturers aren't going to front that unnecessary added cost. There could also be cybersecurity concerns with computers controlling the car based on external wireless input.

Perhaps one day. But I don't see something like this being implemented in the real world anytime soon.

[kernals12]

This seems like it would be a cool technology, but in reality it seems a little too far-fetched for the foreseeable future. It doesn't solve, for example, people's desire to go faster or do what they want to. What if one driver decided that they didn't like the speed their lane was moving and and decided to resume manual control of their car? Also, this would only work if every car on the road had it, which would take about 20 years (the average time it takes for a feature to be equipped on all vehicles in use once it becomes mandatory). So that would mean we would have to put technology into cars that can't even be used yet, and I'm willing to bet manufacturers aren't going to front that unnecessary added cost. There could also be cybersecurity concerns with computers controlling the car based on external wireless input.

Perhaps one day. But I don't see something like this being implemented in the real world anytime soon.

If the freeway is running at full capacity, then he won't be able to go any faster. And from what I've read, it would start showing benefits once the market penetration rate reaches 40%. And even a 10% increase in capacity will make the difference between free flow and bumper to bumper and unlike a traditional widening, the capacity increase grows over time and it applies to every single mile of freeway.

[kalvado]

Video shows 3 second intervals between those cars. Human drivers can do a bit better than 2 seconds with some truck traffic mixed in.
Add some disturbances, like entering and existing 5raffuc, deer on a shoulder, worn out tyres - and automatic system will do worse than humans

[Scott5114]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

[kernals12]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

Why is it irritating?

[kphoger]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

Why is it irritating?

Allow me to quote his previously stated position on the subject:

My first experience with it came on the Kansas Turnpike through the Flint Hills. There were a lot of frustrating games of catch up to a truck going slowly up a hill, have the cruise kill my speed, and then try to get over and get pinned in the right lane by people doing the speed limit passing both of us because my car decided it knows better than me what speed I want to be going. With normal cruise control this situation would have been fine because I could join the traffic at-speed and pass along with them, but I'm not about to step out in front of a line of cars doing 75 mph unless I'm doing something approximating that speed.

[SectorZ]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

I'm not enamored with it myself. I don't have a car with it but have driven my mother's Acura with it and I'm not sure if I would prefer it over regular cruise control.

Of course, 90% of people don't use cruise control anyways. I bet this forum produces an outlier population.

[CtrlAltDel]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

I'm not enamored with it myself. I don't have a car with it but have driven my mother's Acura with it and I'm not sure if I would prefer it over regular cruise control.

Of course, 90% of people don't use cruise control anyways. I bet this forum produces an outlier population.

Do you have a cite for that? The number seems very surprising to me.

[NWI_Irish96]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

Why is it irritating?

Allow me to quote his previously stated position on the subject:

My first experience with it came on the Kansas Turnpike through the Flint Hills. There were a lot of frustrating games of catch up to a truck going slowly up a hill, have the cruise kill my speed, and then try to get over and get pinned in the right lane by people doing the speed limit passing both of us because my car decided it knows better than me what speed I want to be going. With normal cruise control this situation would have been fine because I could join the traffic at-speed and pass along with them, but I'm not about to step out in front of a line of cars doing 75 mph unless I'm doing something approximating that speed.

In traffic that heavy I'm probably not using cruise control to begin with.

[kernals12]

One idea would be to allow these cars to use HOT lanes. You could have a device at the on ramps that tells the cars to automatically turn on their adaptive cruise control. This would incentivize take up.

[Scott5114]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

Why is it irritating?

Allow me to quote his previously stated position on the subject:

My first experience with it came on the Kansas Turnpike through the Flint Hills. There were a lot of frustrating games of catch up to a truck going slowly up a hill, have the cruise kill my speed, and then try to get over and get pinned in the right lane by people doing the speed limit passing both of us because my car decided it knows better than me what speed I want to be going. With normal cruise control this situation would have been fine because I could join the traffic at-speed and pass along with them, but I'm not about to step out in front of a line of cars doing 75 mph unless I'm doing something approximating that speed.

In traffic that heavy I'm probably not using cruise control to begin with.

The instance that I described didn't happen in heavy traffic conditions at all, just typical rural interstate conditions with the usual platooning behavior.

[jamess]

The biggest source of congestion is phantom jams.

Is there a source for this? Im pretty sure the largest source of congestion is more vehicles than the carry capacity of a road.

[kernals12]

The biggest source of congestion is phantom jams.

Is there a source for this? Im pretty sure the largest source of congestion is more vehicles than the carry capacity of a road.

Phantom jams are the reason why our freeways have low carrying capacity.

[oscar]

You could have a device at the on ramps that tells the cars to automatically turn on their adaptive cruise control. This would incentivize take up.

Are there cars on the market today that will accept instructions to turn on their adaptive cruise control (even if the driver has turned it off)? Or that will let the device know that it's been turned on?

[kernals12]

You could have a device at the on ramps that tells the cars to automatically turn on their adaptive cruise control. This would incentivize take up.

Are there cars on the market today that will accept instructions to turn on their adaptive cruise control (even if the driver has turned it off)? Or that will let the device know that it's been turned on?

I think that's a simple software fix if cars were equipped with V2X

[skluth]

One idea would be to allow these cars to use HOT lanes. You could have a device at the on ramps that tells the cars to automatically turn on their adaptive cruise control. This would incentivize take up.

I expect at some point in the future some urban freeways will be entirely self-driving with traffic density being controlled by computers controlling the cars. I'd be fine getting in my car, driving to the onramp, and entering my destination then taking a nap, reading a book, or sightseeing until I reached my destination. With almost nobody paying a gas tax, your trip would be metered and car owners will be charged a mileage tax monthly much like FasTrak does for HOT lanes. Drivers would get points or possibly even lose their license for turning off the autopilot before exiting the highway.

[kernals12]

One idea would be to allow these cars to use HOT lanes. You could have a device at the on ramps that tells the cars to automatically turn on their adaptive cruise control. This would incentivize take up.

I expect at some point in the future some urban freeways will be entirely self-driving with traffic density being controlled by computers controlling the cars. I'd be fine getting in my car, driving to the onramp, and entering my destination then taking a nap, reading a book, or sightseeing until I reached my destination. With almost nobody paying a gas tax, your trip would be metered and car owners will be charged a mileage tax monthly much like FasTrak does for HOT lanes. Drivers would get points or possibly even lose their license for turning off the autopilot before exiting the highway.

Toyota is working on a system that aims to seamlessly blend human and AI driving, they compare it to the blended envelope control on aircraft. That means you could still drive in manual mode with the car taking over only in emergencies.

[vdeane]

One idea would be to allow these cars to use HOT lanes. You could have a device at the on ramps that tells the cars to automatically turn on their adaptive cruise control. This would incentivize take up.

I expect at some point in the future some urban freeways will be entirely self-driving with traffic density being controlled by computers controlling the cars. I'd be fine getting in my car, driving to the onramp, and entering my destination then taking a nap, reading a book, or sightseeing until I reached my destination. With almost nobody paying a gas tax, your trip would be metered and car owners will be charged a mileage tax monthly much like FasTrak does for HOT lanes. Drivers would get points or possibly even lose their license for turning off the autopilot before exiting the highway.

Yuck.  I don't want the car navigating for me.  I want to drive myself, select my route myself, get around slowpokes if I so wish, etc.

Also yuck on mileage taxes.  I prefer how it's mostly invisible now.  I don't want to get big bills for my car usage.

[kernals12]

One idea would be to allow these cars to use HOT lanes. You could have a device at the on ramps that tells the cars to automatically turn on their adaptive cruise control. This would incentivize take up.

I expect at some point in the future some urban freeways will be entirely self-driving with traffic density being controlled by computers controlling the cars. I'd be fine getting in my car, driving to the onramp, and entering my destination then taking a nap, reading a book, or sightseeing until I reached my destination. With almost nobody paying a gas tax, your trip would be metered and car owners will be charged a mileage tax monthly much like FasTrak does for HOT lanes. Drivers would get points or possibly even lose their license for turning off the autopilot before exiting the highway.

Yuck.  I don't want the car navigating for me.  I want to drive myself, select my route myself, get around slowpokes if I so wish, etc.

Also yuck on mileage taxes.  I prefer how it's mostly invisible now.  I don't want to get big bills for my car usage.

With electric cars, mileage taxes are the only option to keep our roads funded.

And I suspect tomorrow's cars will offer a manual mode (with the AI stepping in as necessary)

[vdeane]

With electric cars, mileage taxes are the only option to keep our roads funded.

And I suspect tomorrow's cars will offer a manual mode (with the AI stepping in as necessary)

Easy: just slap a per kwh tax on everyone's electric bill and at chargers.  Or push hydrogen fuel cell cars instead of electric, as they work just like gas cars, except cleaner.

I'd rather not deal with the AI at all.  Things like Scott's story of adaptive cruise make me want absolutely nothing to do with it.

[jeffandnicole]

With electric cars, mileage taxes are the only option to keep our roads funded.

And I suspect tomorrow's cars will offer a manual mode (with the AI stepping in as necessary)

Easy: just slap a per kwh tax on everyone's electric bill and at chargers.  Or push hydrogen fuel cell cars instead of electric, as they work just like gas cars, except cleaner.

I'd rather not deal with the AI at all.  Things like Scott's story of adaptive cruise make me want absolutely nothing to do with it.

And yet, Scott's example also highlighted with us being in control of our vehicles, we don't think about the hazards we create.  If his car started slowing him down automatically, it sensed that it was too close to the car in front of him.  He could've easily have moved over into that line of traffic seconds earlier, but chose to remain in his lane.

We often get irritated when a car behind us gets too close to us - we have no control of that car, and it's invading that space which makes us uncomfortable if we need to slam on the brakes.  Yet, if we're the ones driving that vehicle, we are in control, and we know (or really, think we know) that we have enough room to slow down.

And that goes back to kernals' opening remarks...we as humans are slow to react, and when we do we need to slam on the brakes, which gets repeated by those behind us, a traffic jam forms.  Or, someone eventually hits someone else.  And when that happens, even if they were to move to the side of the road, that temporary stoppage when both drivers quickly realized what happened, creates an even bigger jam behind them as those motorists are forced to stop as well.

[SectorZ]

A great idea that wouldn't work because I would turn adaptive cruise off because it's so irritating.

I'm not enamored with it myself. I don't have a car with it but have driven my mother's Acura with it and I'm not sure if I would prefer it over regular cruise control.

Of course, 90% of people don't use cruise control anyways. I bet this forum produces an outlier population.

Do you have a cite for that? The number seems very surprising to me.

I don't, but just among the population I personally know those numbers are sound. Maybe my circle of friends and families are outliers.

I did try looking up any data about usage, and I can't find a thing.

[Dirt Roads]

The biggest flaw of adaptive cruise control (ACC) is it's inability to allow gaps for vehicles to enter from on-ramps.  From what I can tell, there are no plans from any manufacturer to equip autonomous mode with that ability either.  Whenever someone sets the ACC for 85 mph operation and pulls into the right lane during rush hour, it is impossible to merge in front of them (then the string of following traffic gets into a speed accordion).  I'm amazed how many times a week that I see 10 car-length gaps disappear at on-ramp merges (and I'm not driving near as much these days).

[kernals12]

The biggest flaw of adaptive cruise control (ACC) is it's inability to allow gaps for vehicles to enter from on-ramps.  From what I can tell, there are no plans from any manufacturer to equip autonomous mode with that ability either.  Whenever someone sets the ACC for 85 mph operation and pulls into the right lane during rush hour, it is impossible to merge in front of them (then the string of following traffic gets into a speed accordion).  I'm amazed how many times a week that I see 10 car-length gaps disappear at on-ramp merges (and I'm not driving near as much these days).

This is where V2X comes in. If your car is on the on ramp, it can send a signal to the car going 85 mph to either slow down or even change lanes.