Switching off Traffic Lights

September 10, 2008 8:21 AM

I'd like to ask a relatively simple question – what would happen if we switched of traffic lights when we didn't really need them? I'd like to know from an environmental aspect what effect turning off the nations traffic lights would have towards saving electricity and reducing emissions. From a social point of view could the nation's road users manage with such a change? And from a technical innovation view point – could it and should it happen and if so how?
posted by SarahM to travel & transportation (22 comments total)

??? and have no driving on city street between the hours of 1:00 am and 5:00 am ?
Or are you suggesting a system wherein the devices "sense" the approaching traffic and then respond activate and hope to do so within time to regulate traffic flow ?

We could save gas that way as well. Not being snarky , but this could only work in a martial law /curfew based system.
We could also turn out the street lights. Like London during the WWII Blitz bombing raids.
posted by Agamenticus at 8:27 AM on September 10, 2008

In my town, many traffic lights switch to flashing red / flashing yellow at 10 p.m., when the sidewalks get rolled up. Also during some storms. It doesn't save on electricity, but does save on gas; during low traffic, people don't have to idle at the light.
posted by theora55 at 8:31 AM on September 10, 2008

1. People would report them as broken, since intentionally 'off' lights blink yellow (or red).
2. Not much, compared to, say, leaving streetlamps off or converting existing lights to CF/LED bulbs.
3. At night, when lights are in blink mode, everyone defaults to "bigger road has right of way" and I suspect it would still work if there were no blinky lights to remind people. Unless no one could tell they'd arrived at an intersection.
4. No and no.
posted by cowbellemoo at 8:32 AM on September 10, 2008

Maybe not feasible for fast moving cars relying on traffic lights, but what a dim/sleep mode for billboards, walk signs, and other energy dependent public/commercial works?
posted by iamkimiam at 8:34 AM on September 10, 2008

Timers on controllers would activate lights during peak flows periods or on-demand (by pedestrian push buttons at crossings or by above or ground vehicle detection)
posted by SarahM at 8:53 AM on September 10, 2008

They already do something like this in Hobart. Not turning the lights off, that's an awful idea - but replacing the 35 watt halogen globes with ~10 watt LEDs. The LEDs also last for years and years, compared to about half a year for a globe. I read an estimate that if all of Australia's traffic lights were changed over, we'd reduce greenhouse gas emissions by about 100000T year.
posted by nicolas léonard sadi carnot at 8:57 AM on September 10, 2008

Googling "traffic signal watt" brings up this PDF as the first link. It's a cost/benefit analysis of switching Little Rock from incandescent traffic lights to LED lights. It notes that a single incandescent lamp is 135 W, an LED is 10-22 W (depending on color). The report estimates that with 263 traffic signals, the city would reduce its power consumption by 3.45 million kWh per year, which worked out to an annual savings of about $111,000. That's pretty good. LEDs cost a lot more to install, but are brighter and don't burn out all at once

Now, there would be a much smaller benefit to turning off those LEDs, because they're consuming much less wattage to start with. The savings would be roughly 1/10th that of switching from incandescent to LED, and you'd need to factor in the costs of added confusion, increased accidents, installing sensors to activate the LEDs (and the consequences of sensor malfunctions), etc. In the end, you'd probably come out behind.

Now, Little Rock has a population of ~185,000 people, or about 1/1620th the US population. If we do a straight-line extrapolation based on that, we'd see that replacing every incandescent traffic signal with an LED would save the US about 5.5 billion kWh/year worth about $180 million; turning off all those LEDs in the wee hours, about 1/10th that.
posted by adamrice at 9:01 AM on September 10, 2008 [1 favorite]

In the UK we have part-time traffic lights (they get pro-rata pay, but under new employment law rights to the same benefits as full time signals). I've mostly seen them on major junctions, such as motorway slip roads and roundabouts (why yes, we have junctions that are both lights and a roundabout), and they are used during rush hour, but off at other times. No idea about the environmental benefits, but technically and socially, it's possible here.
posted by Helga-woo at 9:06 AM on September 10, 2008

From a social point of view could the nation's road users manage with such a change?

Have you driven lately? People are dicks. Absolutely not. Expect casualties from both accidents and road rage to increase exponentially.
posted by Inspector.Gadget at 9:07 AM on September 10, 2008 [1 favorite]

At least a couple of medium-sized European cities have taken it one step further: no traffic signals at all. It seems to work OK.

BTW, I grew up in a small midwest town where the traffic lights went to a blinking yellow/red late at night until about 6:00 a.m. or so. Not sure if that saved much energy, but it does go to show that constant red/yellow/green not necessary 24/7.
posted by webhund at 9:08 AM on September 10, 2008

God damn anarchists!

I am with the Inspector on this one. While the intentions being good and all, you have to remember the most basic rule of the road. It is WAR out there!
posted by a3matrix at 9:10 AM on September 10, 2008

Webhund brings up one approach: scrap the traffic lights in favor of other ways of controlling intersections. Roundabouts, clear indications of right of way, and a whole panoply of traffic calming measures can work quite nicely.

But to see what your scheme (turning off the traffic lights without adding other sorts of intersection controls) would be like, try driving around during a power outage, when all the traffic lights go out. Small intersections with little traffic are no problem — people treat them as four-way stops and it works ok. Major intersections with heavier traffic are hell. It's sort of a four-way traffic, but with three lanes of traffic in each direction, criss-crossing turn lanes, and never mind the poor pedestrians, it gets chaotic very quickly.

Tom Vanderbilt's book has been getting a lot of positive attention (link is to a Times review), and may contain some of the answers you are looking for in a very readable form.
posted by Forktine at 9:19 AM on September 10, 2008

Read Traffic, by Tom Vanderbilt for much more on the social aspect.
posted by fixedgear at 9:19 AM on September 10, 2008 [2 favorites]

* It's sort of a four-way traffic stop
posted by Forktine at 9:20 AM on September 10, 2008

Have you driven lately? People are dicks.

Or people are encouraged to be dicks, because they've been allowed/required to absolve personal responsibility.

remove traffic lights and other controls, such as stop signs and the white and yellow lines dividing streets into lanes. Without any clear right-of-way, he says, motorists are forced to slow down to safer speeds, make eye contact with pedestrians, cyclists and other drivers, and decide among themselves when it is safe to proceed.

"The more you post the evidence of legislative control, such as traffic signs, the less the driver is trying to use his or her own senses," says Hamilton-Baillie, noting he has a habit of walking randomly across roads -- much to his wife's consternation. "So the less you can advertise the presence of the state in terms of authority, the more effective this approach can be."

And as has been already noted, some smaller cities do turn off traffic lights after a certain hour. Halifax, NS is another.
posted by regicide is good for you at 9:25 AM on September 10, 2008

The philosophy behind removing traffic signs (credited chiefly to Dutch traffic engineer Hans Monderman) is that you make people feel less safe so they act more carefully. See here for another good discussion of how this works, including some observations about why it will probably never happen in the U.S.:

- Americans haven't even really accepted even traditional traffic-calming methods such as roundabouts, despite their being safer and more efficient.
- Americans like to drive fast at all costs.
- Americans drivers don't like to share the road with other vehicles (like bicycles) and must be forced to do so.
- The American traffic system is built on an ideology of an "illusion of safety" created by traffic lights, signals, etc., rather than safety itself, which depends more on conscientious drivers.

But the author of the linked article points out that a lot has to do with the context of where we drive--improvised parking lots at county fairs, for example, are safe without having any traffic signs, but that's because people have a different attitude about a fair parking lot than they do about a city street.
posted by bokinney at 9:34 AM on September 10, 2008

Driving fast and recklessly isn't a uniquely American thing. We're little old ladies driving 40 mph in the fast lane compared to the drivers in South America and southern Europe.
posted by electroboy at 10:14 AM on September 10, 2008

Driving fast and recklessly isn't a uniquely American thing. We're little old ladies driving 40 mph in the fast lane compared to the drivers in South America and southern Europe.

And China. Everybody in Beijing bought a car about 2 hours ago and none of them has any idea how to drive on the same road with others. I got back to NYC(!) from China and was amazed at how orderly everything suddenly looked to me.
posted by JimN2TAW at 10:31 AM on September 10, 2008

Any energy-saving scheme that would have the effect of slowing down traffic flow and increasing congestion would end up being a net nagative for the environment due to more emissions from the slow, stopped, or otherwise idling vehicles.
posted by rocket88 at 11:29 AM on September 10, 2008

Americans haven't even really accepted even traditional traffic-calming methods such as roundabouts, despite their being safer and more efficient.

There's been a lot of bitching, but they are becoming a standard part of the traffic engineer toolkit here. So that is changing. In general, roundabouts have the great convenience of eliminating traffic conflicts wholly passively, so they are certainly a way to reduce accidents, and if they permit non-stop traffic when there is no one else using them, all the better for gas mileage.

Still, thinking "traffic calming" and passive instead of active measures is just a way to tweak the energy-use problem (which isn't really the responsibility of traffic engineers to solve). What we should be doing is encouraging walkable neigbhorhoods and transit-friendly (i.e. higher-density corridors) development, so people do less driving in the first place, as well as making sure that urban centers exist so that more people can live closer to work so they don't have as far to go. That's how you solve the problem in the long run.
posted by dhartung at 11:47 AM on September 10, 2008

I was in Ho Chi Minh City (Saigon) last year, and was amazed at how well traffic worked with what I estimated to be <10% of the signs and signals you'd expect in an American City. It's a very organic-looking phenomenon; streams of traffic (some cars but overwhelmingly scooters) joining and separating like branches of a river. People seem to maintain a constant awareness of their immediate space and constantly adjust as needed. Crossing a street as a pedestrian is a trip. You're told to move at a steady pace, absolutely NO stopping or jumping around. Stay calm and predictable and the traffic just flows around you. I also wondered if it could work in the US. It would require a major shift in motorist mindset, which I believe is possible, though not without a rough transition period. It's also worth thinking about the huge number of people such a shift would put out of work. All that infrastructure requires a lot of manufacturing and maintenance.
posted by sapere aude at 1:20 PM on September 10, 2008

In France they have something of a tradition of letting traffic lights go to a flashing amber phase during the night. As best as I can wwork out it turns the junction into a very Gallic "do what the hell you want, just don't blame me if it goes wrong."

In the UK we go the other way and have all our lights on 24/7 unless they are designated 'peak hours' lights which only operate during rush hours and the like. When they're off they're completely dark. You only get these (as far as I know) on roundabouts and sliproads, never on major 4 way type junctions.

In the UK we have Stevenage 'new town'. If anyone wants it, please take it. Until about 1992 it had no traffic lights. At all.

All traffic flow was controlled by give way signs and roundabouts. All pedestrian flow as controlled by bridges, underpasses and occasional zebra crossings. In general it worked pretty well.

Then it fell apart.

As best I can tell someone decided to put in an access road on a dual carriageway - which no-one could get out of because there was a constant stream of traffic on the dual. They added lights to control it purely because they hadn't thought far enough ahead to put a roundabout in. Within a few years the damned things were everywhere and the traffic flow was horrible.

It's worth noting that (in the UK at least) it's commonly believed that traffic flow is better when a power failure takes out the lights. Maybe this is because traffic lights knacker traffic flow. Maybe it's because people have no idea what it going on so stop playing stilly bastards.

From an ecological perspective (since that's what you've asked about) I'd say that killing traffic lights at night would reduce polution and noise. As far as power is concerned I suppose you could replace the night-time operation of the microprocessor controls with a 555-timer and a fistfull of amber LEDS. This would save power, but how much is a question for someone who remembers their electronics theory better than I do.

Could it happen? Judging by the rest of the world (you don't say where you are, so I automatically assume USA) it already does. Should it happen? Yes. Dear lord, yes...

For the record, the UK and France have a mutual friendly loathing for each other. Neither of us can learn anything from the other that would benefit our lives. That said, the French really seem to have worked out this concept of traffic lights. They routinely use this flashing amber at night lark. They also tie their lights to speed cameras so that if you speed, the next set of lights turn red for you. Finally they have this marvellous concept of repeater lights - little tiny light sets about 3 foot off the ground attached to the pole the main lights are mounted on. They point at the first car in the queue, so instead of using bright, confusing repeaters on the opposite side of the junction, the first car knows what is happening by turning his head 45^O to the left...
posted by twine42 at 3:15 PM on September 10, 2008