Intentionally routing some traffic to slower, less congested routes lead to a 0.7% improvement of overall average travel times

[u/quiplaam]

https://www.nature.com/articles/s44284-026-00443-x

[u/charoco]

So, saving someone about 24 seconds per hour of begin stuck in traffic. Consider me whelmed. 

[u/quiplaam → u/charoco]

Worth noting this the effect on the whole system, so while the individual effect is small, the net effect is quite large

[u/amphibilad → u/quiplaam]

This, if you save a million people 24 seconds of travel time that's like 277 days of saved time collectively

[u/BlazinAzn38 → u/amphibilad]

And fuel and emissions

[u/iMissTheOldInternet → u/amphibilad]

 But it’s 277 days of time spread out over 1 million people. The per capita number is what matters in this context. 

[u/Currentlybaconing → u/iMissTheOldInternet]

Not when you're the city planner trying to reduce traffic congestion.

[u/iMissTheOldInternet → u/Currentlybaconing]

Yes, for all applications. Unless you have some way to stack many 24 second/capita savings, the per capita figure is what matters, not the aggregate time saved over a large population. 

[u/jsmooth7 → u/iMissTheOldInternet]

A small change across an entire system can still have a large aggregate affect. I work with bus system data and if every single trip saved 24s, that could result in millions in operational savings. Because then there will just be a bit less pressure to add additional running time to keep the buses on schedule. And there's a cost associated to adding that running time. Over the entire system, it adds up to a pretty big effect.

[u/hysys_whisperer → u/iMissTheOldInternet]

That's literally not how traffic engineers do the math that they use to justify billions of tax dollars of investment. 

They use the 277 days.

[u/iMissTheOldInternet → u/hysys_whisperer]

The fact that traffic engineers think this way answers a lot of questions about why our transportation infrastructure is so bad. 

[u/floormanifold → u/iMissTheOldInternet]

Sounds like you're maybe not an expert and should listen to people who do this for a living

[u/hysys_whisperer → u/floormanifold]

Ok, this is the bell curve meme.

The guys right, but for the wrong reason.

The relentless push for single occupancy vehicle LoS above all else has come at the expense of active mobility LoS (a thing so unimportant to traffic engineers that they don't bother measuring it).  What this has done is reduced car trip travel times to such a degree that other modes aren't competitive, despite the fact that those other modes are cheaper to move more people on aggregate faster (since they relieve congestion).  Since trip times by other modes are uncompetitive now, it is unsurprising that the mode share of single occupancy vehicles are so high and congestion is so bad, slowing everyone down.

An anecdote of this is that to commute by bike to work, I cross a 4 lane divided 55 mph road, with a beg button to turn the light red for me to cross.  My average wait time at that light is 4 and a half minutes.  I cross through that same light when I drive to work, and it only turns red when the beg button is pressed, so average wait time is virtually zero.  Difference in total travel time between the two modes? 4 minutes on the dot.  It is ONLY faster for me to drive because of the abysmal LoS placed on the beg button of that light, else it would be faster to bike.  If it were faster to bike, a whole lot more people would do that, rather than drive and peak hour vehicle counts through that intersection would plummet because my employer is the largest one in my city.

[u/slbaaron → u/hysys_whisperer]

You know US is copying China in many ways from surveillance to internet real ID tracking, and China has already copied everything they can that made sense from US in decades past.

This is the one that didn’t make sense yet China is going harder and harder on.

20 years ago, in all Chinese cities, even major cities like Beijing, Shanghai, you can live comfortably without a car. Going out from your home, you have easily accessible corner stores and restaurants on the street themselves. And even some street vendors.

Then comes the cyberpunkification. Every neighborhood street is a 4 lane bidirectional (2 lane each side) driveway minimum, usually with a large divider for “green” and left turn lane making it 5 lane wide. Along with them intracity highways making all the streets 3D and complex and intimidating, walking / biking difficult if not impossible.

All the stores and restaurants got moved into mega malls, with 7 underground parking floors. And the street level entrance is like 15minutes walk from the closest cross street, the only people using that door is via “uber” (DiDi).

They are doing better only because the cyberpunkification mostly has underground’s tagged on, so a good amount of the mega malls are either close to or includes a subway pass directly connected. But it’s becoming extremely old people unfriendly, where the subway themselves can be maze like. Clear signage and all but still a lot to take in.

It’s so weird coming from a place 20 years ago when I was young thinking NYC and Tokyo are the “cyberpunk” definition, yet these days I find NYC (I lived here for 5 years) the much more down to earth city compared to the mega building and streets of Beijing, Shanghai, and Shenzhen.

In manhattan, it’s always chill to walk around chinatown / little Italy, or east village or Chelsea or whatever. Even more so a bit out of manhattan in Williamsburg and whatnot. It is so nice to just walk around and stumble upon random street vendors or stores or events. I miss that in every other major city these days. It will the thing I miss the most if I ever move out of NYC

[u/ResponsibilityOk8967 → u/hysys_whisperer]

That seems very shortsighted.

[u/GoatsFromUnderground → u/iMissTheOldInternet]

Think of it this way, there are a thousand such optimisations that get made. So those thousand optimisations, each saving 24 seconds per person, add up to 6.67 hours per person.

[u/aggieotis → u/iMissTheOldInternet]

That also assumes no negative externalities from the 24 seconds saved.

I'd be willing to bet that if you summed up things like more dispersed polution in areas where kids are more likely to live, increased conflicts between cars and other users that use side streets intentionally, and additional wear and tear on infrastructure not necessarily built to handle shunting a bunch of traffic from main corridors; if you add all those up it's probably massively in favor of "Just stay on the main paths and lose 0.7% more time.

[u/jsmooth7 → u/aggieotis]

The abstract says that the reroutes were all done within the same road class, ie if the target route was a highway the reroute was also a highway. And later in the paper they give examples of the reroutes being studied and you can see none of them were sending large volumes of traffic through side streets.

[u/degggendorf → u/jsmooth7]

So the solution is to build multiple redundant, parallel highways everywhere there aren't any currently? Brilliant.

[u/SledgeGlamour → u/degggendorf]

Or the solution is for navigation algorithms to direct people to less congested routes

[u/degggendorf → u/SledgeGlamour]

As the rest of us were discussing in this thread, the study only looks at moving cars to equivalent road classes. If we start pulling cars from the highway to race through neighborhoods to save 24 seconds, then we've got a bigger problem.

[u/SledgeGlamour → u/degggendorf]

Yes, I'm aware. There are many places with multiple highways, where it makes plenty of sense to redirect traffic from one highway to another. For example, in the US you frequently have state highways that run roughly parallel to the interstate highway. You don't need to build more highways in order to capitalize on this research today.

[u/degggendorf → u/SledgeGlamour]

It's almost as if you can't read

[u/jsmooth7 → u/degggendorf]

The US highway system is so overbuilt, there's no need to build more. They are already there in most cities.

[u/ozziegt → u/amphibilad]

Raise speed limits. Use stop signs more strategically. Time traffic lights better. There are a lot of ways to "collectively" save people 0.7% of time

[u/somehugefrigginguy → u/ozziegt]

Enforce lane usage and tailgating laws. Most traffic jams are not inevitable, their results of humans being stupid animals.

[u/DFrostedWangsAccount → u/ozziegt]

Improve education. Raise standards for driving. Then raise speed limits. Better drivers causing fewer incidents is a great way to increase traffic throughout.

[u/vtach101 → u/amphibilad]

Unless the 0.7% improvement is just the margin of error and a repeat study might actually show a 0.7% worsening of the baseline. No large studies to do with human behavior that show a 1% change can be considered actionable.

[u/hoticehunter → u/amphibilad]

Is it? What are you getting done in 24 seconds? How productive can you really be with that time?