Roundabouts suck ass at peak traffic times because you can get stuck behind an endless convoy if you're coming from the wrong direction.

Green waves mean the people on the main road don't all have to slow down and waste a bunch of fuel (and cause more emissions), but the people on adjoining streets still have a chance to get onto the road they need to get on.

And of course if you don't do proper green wave planning, people get the choice of speeding or waiting at every red. The worst possible option. But if you already have the lights, it's much cheaper to adjust the cycles properly than it is to install tons of roundabouts.

USA has an increasing number of roundabouts.

In the Netherlands they have electronic "green wave" signs on some main streets. They show the speed you need to get all green traffic lights on that street (and turn off when you won't catch a green wave, e.g. because you entered from another street).

It's amazing.

Yep. My hometown went to speed limit timed lights over 20 years ago. It was fantastic if you could catch the “Green Wave” and make ot all the way through a busy part of town without stopping.

there's a similar street that they're recently changed like that in my small city. it's a 25 street. my bike only does 20 until fix the front derailleur. if i catch the front of the wave and don't have anything heavy in my basket i can usually make 4 or 5 lights in a row before i hit a red and it's glorious.

Please dont put anymore roundabouts in the US until its included in the drivers license test. Every trip to work is a gamble and I have to slam my breaks while in the circle at least once a day, people will even use the right turn only lane to go fully around...

The DOT planning department I worked for (in the 80s) had studies showing that synchronizing the lights 10-15mph ABOVE the speed limit kept traffic flowing "optimally" to minimize congestion without having to expand the infrastructure (mostly: lanes). Even today I see city traffic lights synchronized mostly +10mph over the posted limit in the direction of highest flow on major arteries - you can tell when you "make" one yellow light, then lock in cruise control at limit+10 and "make" the next 3+ lights at exactly the same flash of yellow as you approach.

They do this to delay improvement projects like additional lanes, straightening curves, etc. by showing a higher "level of service" for the roadway than they would have with the lights synchronized at, say: speed limit -10mph. If you're talking about a 45mph roadway, moving the cars at 55mph instead of 35mph means 157% as many vehicles per hour at the same spacing, and we all know that people don't actually increase following distances at higher speeds, so... it's a real, and significant difference. Not as significant as getting people to carpool, or take public transit, but that's about as likely to happen as increasing following distances.

"Essentially, rather than encouraging drivers to speed up by presenting an endless succession of green lights, this strategy makes red the default state for lights on a busy road. When traffic approaches the red light, the cycle triggers. Traffic moving faster than the limit will approach the light while it’s still red, forcing it to slow or stop for the light before it changes, while traffic moving at the limit will be met with a perfectly-timed green.

Drive the limit, in other words, and you’re rewarded with a constant rhythm of green lights."

That's why the title makes sense

Never been a fan of the "we shouldn't make the smaller, easier improvements because we need to do the bigger, harder things instead" argument...

Yes, we need more and better public transit, but that is going to take a whole lot of time, money, and effort to work towards. Yes, it's worthwhile, and we shouldn't STOP working towards it because of this, but I don't think that's a reason to balk at a smaller, easier incremental change that encourages safer driving while also simply being more efficient.

engineers who set up the timing cycles

The engineers who set up the timing cycles in my DOT planning department set the cycles to run over the speed limit intentionally to get more cars per hour through the same roadway compared with moving them slower. Accident statistics were equivocal - similar accident rates at or +10 above the speed limit, but that is a politically charged statement, so you don't say it loudly.