Assuming No Punking – Does Red Light Synchronization Help?

Background Reading


This article appeared in the NYTimes on April Fool’s Day 2013. Assuming it is “legit” it does bring up some interesting issues. The opening lines read:

By Ian Lovett
The New York Times
April 1, 2013

Monica Almeida/The New York Times Los Angeles has synchronized all of its 4,500 traffic lights in an attempt to keep vehicles moving.

Monica Almeida/The New York Times
Los Angeles has synchronized all of its 4,500 traffic lights in an attempt to keep vehicles moving.

LOS ANGELES — To combat its infamous traffic, Los Angeles has built subways and light rail lines. It has widened highways and added car pool, toll and bus-only lanes. But the roads have remained stubbornly clogged, creating a drag on commerce and the quality of life that has persisted here for generations.

Now, in the latest ambitious and costly assault on gridlock, Los Angeles has synchronized every one of its 4,500 traffic signals across 469 square miles — the first major metropolis in the world to do so, officials said — raising the almost fantastical prospect, in theory, of driving Western Avenue from the Hollywood Hills to the San Pedro waterfront without stopping once.

But with the number of cars on the road here continuing to rise (and almost seven million commuters already on the road each day during the rush in the metro area), even the system’s boosters admit that it may not be enough to prevent gridlock from growing worse.
Built up over 30 years at a cost of $400 million and completed only several weeks ago, the Automated Traffic Surveillance and Control system, as it is officially known, offers Los Angeles one of the world’s most comprehensive systems for mitigating traffic.

The system uses magnetic sensors in the road that measure the flow of traffic, hundreds of cameras and a centralized computer system that makes constant adjustments to keep cars moving as smoothly as possible. The city’s Transportation Department says the average speed of traffic across the city is 16 percent faster under the system, with delays at major intersections down 12 percent.

Without synchronization, it takes an average of 20 minutes to drive five miles on Los Angeles streets; with synchronization, it has fallen to 17.2 minutes, the city says. And the average speed on the city’s streets is now 17.3 miles per hour, up from 15 m.p.h. without synchronized lights.

So everyone in the Urban Cycling Community from riders to graphic artists seem to have a “Need for Speed“. This is interesting because all we ever hear about as a justification for “Road Diets” and the safety produced by “Protected Bike Lanes” is the term “traffic calming“. All of these measures have one thing in common, they slow down the rate of travel of motor vehicles, which is presumably a good thing. So it comes as a bit of a shock to hear bicyclists who are begging for “green waves” which is some ways seems to suggest that they prefer (at least for themselves) a chance to travel faster, not slower.

The BikeyFace graphic titled “Need for Speed” suggests that speed is preferable to safety when traveling around town. Remember again that “safety”  is the stated object of the increased bicycle infrastructure movement and its keep component involves “road diets” which by narrowing lanes increases the likelihood that automobile traffic will slow to a safer rate. So there is something of a mixed message thing going on here. But that is not uncommon in the Urban Cycling Community. We are often as confused on the “talking points” we use as the GOP and sometimes with equal success.

Forum Discussion On Red Light Synchronization

Let’s listen in on a forum where this very article is being discussed:

LASF writes:
its definitely noticeable, but there is no way to eliminate gridlock in any major world city. we just have to provide options (Rail) and thankfully we are doing so in a major way. Over a generation or so, peoples habits will change

MH writes:
Generally, the more they focus on throughput, the worse it is for pedestrians, particularly anyone crossing the high-volume streets.

JW writes:
In the short-term this is terrible, because faster traffic is worst for pedestrians and cyclists. It also does nothing to encourage transit use. In the long-term this is also terrible, because it just induces more traffic which will lead to more pollution. There is really no benefit.

FF writes:
What is worse for pollution, 3 cars traveling quickly all or most of the way without stopping, or 2 cars that travel more slowly because they must decelerate, idle, and accelerate again dozens of times along the same route?

D writes:
I don’t understand how it’s not safer for pedestrians. Pedestrians have to wait for a signal at crosswalks, just like cars wait for a signal at a stoplight. If you don’t cross when the signal is telling you not to, and you look both directions before crossing, you’re more than likely going to be just fine (this goes for vehicles and pedestrians).

WP writes:
Well, LA is a city built by the car, our rail and bus systems are pretty darn good by US standards, but the car is and will continue to be the primary means of transit for most residents. To say otherwise is living on another planet. That said, the signal synchronization generally stinks here. I just drove up Highland and EVERY light was red as the traffic was released from the previous red, despite there being a “synchronized” sign at every intersection. Saying things are synchronized is good, but not following through is another. (I am not talking just my 1 anecdotal example here, this is true all over LA, Valley is better for sure, but LA side is just god awful, total BS on the system)

Well, as much as we urbanites crap on Arizona, that is a state that GETS IT for traffic synchronization. Both Phoenix and Tucson do an excellent job of moving traffic along arteries. Simply the best in the nation IMO…this coming from someone who drove through 35 states last year and has driven in every state in the US save Maine and Alaska. LA has a lot to learn, some streets work well, most do not.

Phoenix and Tucson are at the forefront, and have been for a long time, lived and worked in Tucson in the 90s and saw how much better than LA it was back 20 years ago despite that state explosively growing. I was all over Arizona last week showed me that Phoenix and Tucson have this system down better at this than we in LA are, by a good margin, still to this day.

But for rail and bus, well, Phoenix can go suck it, LA wins hands down with our light, heavy and long distance rail, BRT and Metro Rapid system. we kick but in that department.

JW writes:

The former is far worse. And over the long-run with more traffic there’s going to be just as much decelerating, idling, and accelerating as there was before, only with higher traffic volumes.

How could it be safer for pedestrians? Higher traffic speeds are more dangerous for pedestrians. It is less likely that drivers can stop or swerve in time to avoid pedestrians at higher speeds, and if there is a collision the results are worse at higher speeds:You can see the risk of pedestrian deaths at different speeds on page 5 of this link: is illogical that speeding up traffic could possibly make pedestrians safer.


JW writes:

Re: safety of pedestrians and cyclists:

If pedestrian safety and the quality of the public realm are of any consideration, speeding up traffic has no positive effects, only negative ones.

D writes:

Obviously a vehicle traveling faster would cause more bodily harm, but, if pedestrians crossed when and where they were supposed to, and used common sense (like watching for traffic), then it shouldn’t be an issue.

BC writes:
Synchronization is kind of a misnomer for what the city has done with it’s traffic lights. Really all that’s happened is that every signal now runs through the same system. This allows for easy adjustments based on need, especially during the morning and evening rush hour. Basically, traffic will move more efficiently and overall travel times will decrease.

Don’t expect to be met with a constant stream of green lights at all hours of the day, though. Probably just for the street running portions of the Expo, Blue and Gold lines.

In regards to Phoenix/Tuscon, those are two cities with a fraction of LA’s population at substantially lower density. I’m not an expert, but it seems plausible that many traffic management strategies that work in Tuscon may not be as effective in Los Angeles.

JW writes:

Accidents happen all the time though. There are more than 30,000 automobile accident deaths in the United States alone every year. The faster the vehicular speed, the more difficult it is for a driver to stop or swerve in time to avoid a collision, and the worse the consequences when there is a collision. It is not more complicated than that. You can say it “shouldn’t be an issue”, but it is an issue with around 100 car accident deaths per day.

There is no optimal speed of traffic when it comes to pedestrian/cyclist safety (or even motor vehicle occupant safety). It is not like fuel economy with optimal speeds. The slower the moving traffic, the safer for pedestrians and cyclists. There are no safety gains for pedestrians with faster vehicular speeds. It doesn’t matter what the increase in speed is, or what the average speed was prior to the increase.

D writes:
I see where your point with speed, I’m just saying accidents can be avoided.

JL writes:
Umm it doesn’t say vehicles are driving faster…. it says their average speed is higher, that’s due to them being stuck at lights less, or for shorter periods of time. The speed limit was not increased, pedestrians aren’t at any more risk then they already are, it can even be argued they’d be at less risk as this might reduce the amount of people running lights are driving aggressively due to traffic rage.

JW writes:
It’s not just maximum speed that’s important though, it’s average speed too. If someone is only going 20MPH instead of 25MPH because they’re slowing down for a red light that they might not have to slow down for under a syncd traffic light scenario and a pedestrian jaywalks in front of them, they have a better chance of avoiding the pedestrian, and less severe consequences if they hit them.

D writes:
It would also be the jaywalker’s fault for being a dumbf***.

S writes:

Look at this Setup,

Two parallel sidewalks off a side street, CLEARLY created to cross, but with no crosswalk, so if you choose to follow the path that was created for foot traffic, YOU ARE BREAKING THE LAW!!! HOW DARE YOU JAYWALK ACROSS THAT!! DUMB ASS!! WHAT THE HELL IS WRONG WITH YOU!! You’re putting people in danger by following a logical action. The closest crosswalk is in two blocks either direction. Walk unnecessarily long in both directions like the rest of the smart people. FUCK YOU PEDESTRIAN! FUCK….YOU!!


TP writes:
Actually, there’s a dedicated crosswalk one block to the west on Stanley Avenue… roughly 300 feet away.

MH writes:

It probably is a crosswalk. In my city at least, paint is irrelevant except as a reminder. Anything unmarked is a crosswalk.

As to sucking in general, yes it probably does in that spot.

TP writes:
The picture in the OP looks west along Santa Monica Boulevard at La Brea Avenue. The picture highlights a concept known as simultaneous greens. Since Santa Monica Boulevard has 2-way traffic with traffic signals closely spaced it becomes impractical to try to favor one direction of travel. Instead, all the lights go green together and change back to red together. This type of setup encourages aggressive driving behavior since the faster a driver travels, the more lights they can make it through before all the green lights switch back to reds.

Having traffic signals all synced together does nothing to change the geometry of a road network. Along a high speed arterial (speed limit greater than 45 mph) with traffic signals spaced a half-mile apart it becomes next to impossible to achieve good 2-way signal progression. Drivers in LA shouldn’t assume they’ll be getting a platoon of green lights just because the signals are in sync.

DC writes:
San Francisco could REALLY use this. We must be the worst city in the nation with regards to traffic flow and light synchronization. It takes way too long to get around here by or bus, given this city is just 7×7 square miles.

KOH writes:

I just visited SF twice in the past month, staying in two different places: The Mission and Inner Richmond. Both times, I was appalled and quite literally horrified at how long seemingly mundane and not-far-at-all bus trips took. Like, they barely moved at all. Assuming SF doesn’t cheap out like the rest of the country, there are a number of bus routes there that can certainly benefit from HRT or LRT conversion. I think my friend told me that the average speed of MUNI buses is 8mph.

Also, what is up with the old school, wood-paneled interior on most of the buses? I haven’t come across such antiquated buses in any of my recent travels, save for a G train substitution in late night Brooklyn last spring. That was a pretty big exception, though. Still love The City, though!

JW writes:
Better for drivers = worse for pedestrians. The most pleasant streets to stroll are almost never the streets where traffic moves smoothly. They are the congested two-way streets that cause a headache for motorists.

Z writes:
Ugh, thanks for reminding me why I don’t live in California…

At least in my state (Oregon), any intersection is treated as having legally-defined pedestrian crosswalks anytime a path or sidewalk appears to continue into the intersection.


This wasn’t meant to start a flamewar, but as an example of the RIGHT WAY to set pedestrian safety into law.

FF writes:
I’d rather live in Portland nowadays than in SF, but let’s not let our pride of place make us fast and loose with the facts. California law defines a crosswalk as
“[T]hat portion of a roadway included within the prolongation or connection of the boundary lines of sidewalks at intersections where the intersecting roadways meet at approximately right angles…” Same thing as Oregon.

FF writes:
I’d rather live in Portland nowadays than in SF, but let’s not let our pride of place make us fast and loose with the facts. California law defines a crosswalk as
“[T]hat portion of a roadway included within the prolongation or connection of the boundary lines of sidewalks at intersections where the intersecting roadways meet at approximately right angles…” Same thing as Oregon.

A writes:
Actually… This kinda makes sense. If you go 20mph over 10 miles and spend 3 minutes at red lights, your average speed would be lower than if you went 20mph over 10 miles and spent 1 minutes at red lights.

Or is there something I’m missing?

Movements Are Frenetic By Design

Keeping folks on point in any discussion about traffic management is almost impossible. There is no single view or understanding that prevails amongst its members. If you think that being part of a movement is a confusing thing, just imagine what it feels like looking in from the outside. If you message is too jumbled you being to have GOP syndrome. Warring factions set in and before you know it the general public would rather memorize the comic section than read one more thing your supposed movement has to offer.

The folks that control the movements count on this sort of chaos as a way of controlling the workers who show up for photo ops and do the volunteering. Each small segment of the movement focuses in on a single point of emphasis and works its fingers to the bone for that one tidbit of change. It could be something like “Door Zone” collisions. Never mind that the collisions are totally preventable and avoidable by cyclists who travel slowly enough to avoid being surprised, and steer clear of the 3 foot space beside a stopped or parked automobile, it helps if the conversation can be directly solely at motorists because that brings cohesion to the workers.

The speed idea is nothing new in the Urban Cycling Community. Never mind that it directly contradicts the stated purpose of “traffic calming” messages. If you can allow most male fixed gear riders to move with “quickness” through the city you have won their vote. And if you can do this by making certain that they never have to stop at a light (thus losing their momentum) you have them in your pocket.

But as was pointed out in the forum discussion above the folks who lose out here are the ones on foot.

Here in Chicagoland area we have “Zebra Crosswalks” all over the place. Some of these are not at intersections but instead in the middle of the block! That makes for a nasty bit of eye-opening if you are cruising between intersections trying to maintain your green wave when suddenly someone steps out into a crosswalk and you being in either an automobile or aboard a bike have to slow and allow them the “right-of-way“, bummer!

Cyclists are going to have to determine whether they are part of the solution or the problem when it comes to increased rates of speed on city streets.