To help pay for tuition, one summer I drove a university shuttle in the evenings after finishing my work-study job. At that time, the lights on Walnut and Chestnut streets in West Philly were set up with green waves. The best place to ride the wave was obviously at its tail, entering each intersection a little before the light would turn yellow. Traffic there was light-to-none, and its flow far smoother and safer than at the front, where there were usually drivers pointlessly fighting to maintain their positions. I would watch them all just up ahead of me, wastefully approaching each red light far too fast, braking hard until it turned green, then rapidly accelerating to the next, repeating this insane processes intersection after intersection for a dozen blocks at a time, like some sort of mobile psychology experiment gone wrong. Because I was naive, I thought poorly of Pennsylvania drivers.

Later I moved to SF and experienced the same thing on Franklin and Gough, and realized the phenomenon was probably fairly universal.

Green Waves could be a great thing, but there's still the unsolved problem of human beings behind the wheel.

The town where I live (in the Netherlands) has green waves for cyclists. It's lovely to experience and also a good way for the council to encourage this sustainable, healthy mode of transport.

This is why I always took W Passyunk Ave coming home from work when I lived in South Philly. If you travelled at around 20-23mph, you'd hit green lights from the moment you got off the highway to the street you had to turn on. It was great, but since nobody knew about the concept you'd have a lot of people frequently stopped in the middle of the street or not moving at the right speed. I wish this was more common so it would be taught in driver's tests or something, that way people would drive slower in these areas and also get to where they need to go quickly.

Great Highway [0] in San Francisco is my favorite example of this. If you drive precisely 35 mph, you'll hit green lights for about two miles. This works in both directions. I think it's possible because the lights are to allow pedestrians to cross the road, so there are no intersections with cars for the full two mile stretch. Still, I think it's a lot of fun.

[0] https://en.wikipedia.org/wiki/Great_Highway

This one sent me quite down the memory lane. Back in 2009, I realized a fake-iphone app pitch where the goal was to sync your music so that you can ride the green wave as a pedestrian. The music will slow down or accelerate so that by walking to the beat it guarantees you that you will go with the flow.

As it was just for a pitch, I realized a video (with the help of a friend checking for my safety) to showcase the usage : Two long-sequence shots of walking between two places in Paris and being sure to have only green lights, like 15 green lights total to be nailed when they are clearly not synchronized for you and there is people and traffic around.

It was an experience in the spiritual line of Claude Lelouch "C'était un rendez-vous".

Taking Portland Ave and Park Ave are great in Minneapolis, but I agree about cars in the front speeding, slamming on their breaks for the red, the going again. I wonder if there should be a new sign for green waves, or maybe we could just make them more popular.

It used to be that an MPH or two under the speed limit would get one halfway across Denver without stopping for a light. That was a long time ago, though.

I don't drive much these days. In Washington the traffic levels can be such that the best timing in the world won't set up a green wave. On the other hand, I do manage now an then to make it half a mile or so as a pedestrian without stopping for a light. (On 16th St. NW from U to Scott Circle, a saunter will hit all the lights green; a fast walk might do the same, but I seldom bother to try that.)

NYC has a bunch of these on most of the avenues that break down at rush hour but work pretty well at other times, especially on weekends when you can do miles at a time.

You can actually watch the downtown wave approach and pass when you're going uptown on Park Ave starting around 60th St (and you'll get to watch it many times as you constantly hit red lights since you're fighting the wave).

On my previous commute home, the green wave seemed to only work if you travelled 85 or 30 mph (posted limit 55), everyone else got hit with every red

I always appreciated this on the University of Pittsburgh's campus, and was really happy when they did it in my current hometown.

I used to take back roads and take my chances with speeding and stop signs, but now I find myself taking the main road way more now because I know I'll probably only stop at one light maximum, and I know how to time my driving.

Two green wave examples I value in San Francisco:

1) the Valencia bike commute green wave (named as such with posted speed)

When it's broken for some reason it's very noticeable and unfortunate.

2) the various coordinated designated auto throughways which make up for the lack of in-city access freeways

Except when you're going against the direction, like when my wife was in labor. :|

I live in a city where the traffic engineers are too stupid the understand the value of this...about 50% of the time I get a green light, only to immediately see the next light go red about 100 meters away. It's infuriating.

Folsom street in the Mission District of SF has one at 15mph. Perfect if you are on a bike. Keeps the average speed of drivers down in the residential areas, and if you know the timing is at 15mph, you might as well just cruise.

My city has posted signs indicating the "green wave speed" in a few spots and it actually seems like a more effective form of traffic calming than speed bumps or forced turn obstacles.

Best green wave I have ever experienced is going north on 10th ave in NYC. You can drive for 100 blocks without stopping if there isn't too much traffic and you time the lights correctly.

These don't work in my city because everyone just rushes to get to the lights first and come to a full stop. Then those stopped cars take their time to speed up again.

Sadly, our green wave is synchronized with a 50 mph speed, but the posted (and reasonable) limit is 35 mph.

My city has lights timed to ensure that signals turn red just before the wave of traffic reaches it. You can see the signals have antenna on them pointed at the next intersection.

It is infuriating on a level I can't describe. My guess is they are trying to reduce accidents or they are trying to make more tax money by getting people to burn more gasoline.

I only ever experience red waves.

Love when I get these. Give me more!

Obligatory XKCD Reference

https://xkcd.com/277/

Remember folks: lights timed for 40 are also timed for 80. /s

> In the UK, in 2009, it was revealed that the Department for Transport had previously discouraged green waves as they reduced fuel usage, and thus less revenue was raised from fuel taxes. Despite this government Webtag documents were only updated in 2011. It is still unclear if the economic appraisal software used to apply these guidelines has also been updated and if the new guidelines are being applied to new projects.

Lovely.

Right? Every fiber of my body screams "JUST INCREASE THE TAX!". Figure out the fuel usage drop, if any, and adjust the tax accordingly. Hell, I'd pay double fuel taxes if I didn't have to fight red lights anymore.

I wonder what would be the better pay-off on aggregate: more tax revenue from extra fuel use or -- presuming people get to where they need to be more efficiently -- more tax revenue from the increased productivity/consumerism? I wonder which is better in terms of pollution and other potential negatives? So, which is net cheapest? (My money's on green waves.)

I am all for government taxes, government bodies that oversee food production and commerce, social welfare programs or lay down ground rules for various social activities.

It doesn't mean that I think the government totally altruistic, and working solely common good. There is often (or always) a relatively hidden agenda which is conflated with the by all means honorable motives, like covering the costs of public services, saving the climate, or protecting us from a foreign adversary.

Seldom does the ulterior motive reveal itself so clearly as in this case however. Instead thinking this is a one-off, we should really be inspired to produce or look for a service where all policy decisions were inspected not only on the aspects that the politicians or public servant say but all relevant aspects, to find out the other reasons (not necessary more "real", but relevant too).

Somewhere deep among those other reasons there may be an effect that is actually not for the common good.

As policies move toward taxing fossil-carbon use aggressively enough to drive reductions, this unintended consequence could prove very troublesome.

Competently handled green waves will save transport energy from all sources. And, this kind of thing cries out to be integrated with adaptive cruise control (yeah, Elon, the thing you call "autopilot").