> In the US, and other countries where you drive on the right side of the road, right turns are free, but for a left turn you need to wait for a green light.
I don't know of any other country than the US where turning right on red is allowed, unless there's specific signage or additional traffic lights to allow it. Indeed, the turn-on-red rule in the US seems to work inverse to how I've seen it elsewhere – i.e. it's always allowed unless there's specific signage saying it isn't.
I was just in the US, and I love their turn-on-red rules, and I kept thinking that sometimes it's got to be smarter to turn right than go straight ahead, when there's a red light, even if it may be a longer drive. Glad to see someone took the time to figure this out.
Turning right on red is one of those idea that once you've been exposed to it you wonder why isn't everybody adopting it...
A similar idea is the train system in Munich where they built their platforms such that they can open doors on both sides, making one side of the train the exit, and the other side the entrance. Ever since I saw that, every single time I wait for people getting off a crowded train, I wonder "Why?".
> Turning right on red is one of those idea that once you've been exposed to it you wonder why isn't everybody adopting it...
It was first introduced in the 70s in the US in response to high oil prices, and only after road safety tests apparently demonstrated its safety. But since then there's been a fair amount of research indicating it increases accidents and pedestrian fatalities, amounting to somewhere under 100 deaths per year. The original studies were not large enough to detect the effect.
And now, turning right on a red light is just a cash cow for the slimy red light camera companies. Some areas report that upwards of 95% of the tickets issued by red light cameras were for not stopping for 6 seconds before turning right on a red light.
("In a two-month period in 2010 in South San Francisco, 98 percent of the 672 red-light violations recorded at El Camino Real and Westborough Boulevard were for right turns. Other cities say 4 in 5 tickets go to people turning right at intersections."
I thought California DMV rules only said you had to treat a red-light right like a stop sign. Make a complete stop then move. I don't recall reading anything about 6 seconds and the article doesn't mention that either.
NB: you should always make a complete stop when turning right on red (even if state regs don't require it). And slow down a LOT when turning right in general. There's always a risk of hitting a pedestrian or bicyclist coming up from behind you.
Sure, but the vast majority of the funds from tickets go to the city - that's who it's really a "cash cow" for. And the municipalities are the ones actually making the rules that govern the tickets themselves. Why "slimy companies", and not "slimy City Halls"?
But yes, city hall is slimy as well. Citizens do not get any say in the matter. Citizens do not get to vote to add red light cameras. You just see them going up, and fighting them is a long, hard road. Some cities in Texas have finally banned them, fortunately.
Redflex/etc are definitely profiting plenty off of the devices. No question about that.
If modern fuel-injected cars had automagic engine running management a-la hybrids, mucho idling gas could be saved. Modern engines apparently can save gas by shutting off if expected to stop for any more than 10 seconds.
It's not as commonly done because it's considerably more expensive to build triple platforms, and the bends required to make it work slow the train down and cause wear. It's good for high-capacity stations though.
When trains run in tunnels, or even when on aboveground rights-of-way, the rails are generally spaced very close together. A 3-platform station therefore requires the tracks to turn away from each other to make room for the central platform.
They don't usually have to be that sharp, but they tend to be noticeably sharper than the turns in the route.
NYC has no right on red. After getting used to I loved it. Now I live in another city with right on red and a fair amount of bike and pedestrian traffic.
Turning right on red means looking out for cars, people, bikes and having the pressure of a car behind you - perhaps honking because it wants you to go.
> Turning right on red is one of those idea that once you've been exposed to it you wonder why isn't everybody adopting it...
Because someone who comes from your left may go forward, or someone who comes from your front mau turn left?
Where I live, we do not assume that we can turn right on red lights. Where and when that's possible, we have a blinking yellow light (basically meaning proceed with caution)..
Turning right on a red light is only permitted after establishing that it is safe to do so. Obviously you can't just assume that it'll be fine to go. The difference between your country and the US is the default value: do you have a blinking light permitting it in some places, or a sign prohibiting it where it would be unsafe?
when the idea is baked into how your whole traffic system operates, you don't have these issues. People turning right have the same right-of-way as people going straight through an intersection. People turning left must wait for all traffic to clear from the opposing lane before turning.
As for someone to your left going straight thru the intersection... you, turning right, must yield to those going straight. However, there is not always traffic coming straight through the light. If someone on the perpendicular street turns right instead of going straight thru, you may turn right from your lane into their lane because there is a pause in traffic flow coming through the intersection.
That probably doesn't make much sense but the bottom line is that when everyone knows the rules and everyone observes them, right on red is mostly painless.
People turning right have the same right-of-way as people going straight through an intersection.
No they don't, They must come to a complete stop and yield to all traffic, including people turning left. At least in NJ, I don't know about other states.
or someone who comes from your front mau turn left?
so I guess you're right in the scenario that one direction has a green light with no green arrow and the opposite direction has a red light, but how often does that scenario exist?
If both directions have a green light, left-turners yield to right-turners because of traffic behind the right-turners and stop signs are always turn based.
I believe the GP is saying that they have the same right-of-way as if they were going straight. Admittedly, the difficulty in talking about this stuff precisely does leave me wondering if some people ITT are total menaces on the roads.
There's an elevator in one of the London tube stations like this (Everyone uses the elevator, like 150 stairs). Just makes so much sense, moves so many more people that way.
You're a pedestrian at an intersection and patiently waiting for the crosswalk signal to flash walk because you want to be safe and not jaywalk. As soon as it flashes walk, a "right turner" comes zooming in and proceeds to take their right. Either they abruptly stop when they finally notice me or they don't and just roll on through and I have to jump back on the sidewalk to avoid them. I try to intentionally wait in a position that is very visible to the right turners and it still happens.
I don't feel safe legally crossing the street. It sucks.
I have only been to the USA once and I noticed this. It didn't help that I was in Florida in the late summer (very hot) so none of the locals expected there to be pedestrians!
I guess the train thing isn't done everywhere because it basically requires that you rebuild every single train station for it to work (plus, you have to re-do all the railing to have space for an additional platform in between).
> Ever since I saw that, every single time I wait for people getting off a crowded train, I wonder "Why?".
Cost reasons. Wherever you adopt this, you need two platforms to serve a train instead of one. Not saying it doesn't make sense to do, just that someone probably sat down and did a cost/benefit calculation.
> Indeed, the turn-on-red rule in the US seems to work inverse to how I've seen it elsewhere – i.e. it's always allowed unless there's specific signage saying it isn't.
Driving laws vary widely by state. You cannot say "$x is [il]legal in the US" because it's likely there's at least one state where the inverse is true. That being said, my state does allow turning on red unless it's explicitly prohibited, including left turns if you are on a one-way street turning onto a one-way street.
> I kept thinking that sometimes it's got to be smarter to turn right than go straight ahead, when there's a red light, even if it may be a longer drive.
The city I live in actually times the light cycles to prevent this, you will end up exactly where you would have been had you not turned, or behind.
Having been across the US, I would say that the right-on-red rule is so consistent that you can say it's legal in the US. It's just a rule with an exception.
According to Wikipedia [1], "as of 1992, right turn on red is governed federally by 42 U.S.C. § 6322(c)", which reads [2]:
> Each proposed State energy conservation plan to be eligible
> for Federal assistance under this part shall include [...]
> a traffic law or regulation which, to the maximum extent
> practicable consistent with safety, permits the operator of a
> motor vehicle to turn such vehicle right at a red stop light
> after stopping and to turn such vehicle left from a one-way
> street onto a one-way street at a red light after stopping
This is not "governed federally". Making a state eligible for Federal assistance is not the same as being a legal requirement. How you confuse these things is an example a simple comprehension failure or possibly someone who doesn't understand US law to any degree. https://en.wikipedia.org/wiki/Turn_on_red shows a handy little map in the bottom right highlighting the differences between states.
The portion you take issue with is a quote from the same article that you're referring to, and clearly marked as such. I'm sorry that your "comprehension failure" insult backfired.
By the way, the map on the bottom right is for left turns on red, which isn't the topic here.
And in Quebec, you still see people turning right on red lights while looking solely to the right, instead of looking for oncoming traffic from the left.
In Milwaukee there are a few spots you can turn left on red technically "after stopping". The locations I know are freeway off-ramps onto one way streets, and simple left turns onto one way streets.
It's legal to turn right at a red light in parts of Germany (if there s a sign saying so at the traffic light). One of the few things that were adopted from East Germany after the reunification. https://de.wikipedia.org/wiki/Grünpfeil
Flip side, having driven in England 20+ years ago. In England, when stopped at a red they politely blink a yellow light when your stop light is about to turn green. In the US not only do we not do that, but many localities put extended shields around the lights, polarized lenses, etc. To prevent you from knowing when your light is about to turn by observing the lights for the perpendicular street.
In other words...
England provides more information to the driver expecting the driver to use that information to make good driving decisions.
The US hides information from drivers in an attempt to control their behavior because they don't trust the driver to make good driving decisions.
The majority of cars in the UK are manual (ie not automatic) gears. Consequently that forewarning gives the driver something to do as it does take a second or two to get into gear.
It's apocryphal but my history professor stated US stoplights used to actually have the red to green warning in order to assist large trucks which need a few seconds to build momentum. It caused more wrecks because of red light runners not clearing the intersection in time and people with a fresh green light trying to immediately enter the same intersection.
If you have to cross lanes of traffic, you have to wait for a light. If you are merely "changing lanes" you just have to wait for right of way.
(in my state at least) you're allowed to turn left from a one way to a one way on red, because you're not crossing any other lanes.
So do the math... how many lanes are involved. If it's just "current lane" and "target lane", you can go when the coast is clear. If there are ANY other lanes involved, wait for a light.
Keep in mind everywhere in NYC unless noted does not allow right on red. however on Long Island and in Upstate New York it is typically allowed unless noted. laws not only vary by state but also by locality [pardon if this is not the correct usage of the term]
> I don't know of any other country than the US where turning right on red is allowed
The DDR (East Germany) had this law and IIRC it was one of the two things they tried to preserve in the unification agreement (the other was abortion rights). Neither survived.
It's not just about turning on red. Even where that's not allowed, when the light is green the right turning traffic is less impeded and more cars pass through in a cycle. Those turning left have to wait longer for gaps in the oncoming traffic, in general at least.
> eliminating left turns wherever possible after it found that drivers have to sit idly in the trucks while waiting to take the left turn to pass through traffic. So, it created an algorithm that eliminated left turns from drivers’ routes even if meant a longer journey.
Sounds reasonable.
> In 2005 ... the total distance covered by its 96,000 trucks was reduced by 747,000km. In 2011, ... the company had reduced distance travelled by trucks by 20.4 million miles. A recent report by The Independent says that the total reduction in distance travelled by UPS trucks now stands at 45.8 million miles.
But how does eliminating left turns even it means a longer journey reduce the total distance travelled?
Edit:
The Independent article referenced here explains:
> The efficiency of planning routes with its navigation software this way has even helped the firm cut the number of trucks it uses by 1,100, bringing down the company’s total distance travelled by 28.5m miles – despite the longer routes.
I think "created an algorithm" is probably overselling it a bit. Clearly they already had a route planner, didn't they just modify it to add extra cost to a left turn?
Incorporating turn costs into route planning is actually not that easy! For one it increases the amount of data you need (street layout, type of intersection, etc) and a lookup to add the appropriate penalty. But more importantly, it doesn't play well with many speed-up techniques.
Two papers on the subject, applying turn costs to the two most popular speed-up techniques (I don't know if UPS uses either of these, though):
The first author of the first paper now works at Google, and the authors of the second paper used to work at Microsoft Research and now are at Apple and Amazon. Make of that what you will :)
It also tends to reduce distance travelled because left turns are often done to get onto faster roads - if you right-turn it all the way, you're often on slower roads, so you're not going as fast, but you're saving actual travel distance.
It's funny because occasionally my wife will tell me to take a certain route to a destination because that is what her traffic app told her was the fastest route. I'll disagree on the basis of this experiment; that the "fastest route" has too many left turns and that my route is better because it has fewer. Needless to say, she is never amused. Maybe after this news I'll be vindicated!
Wasn't Waze known to prefer routes that consisted of an incredible amount of left turns and small roads? Haven't checked if they changed the algorithm. Found that Google Maps is hard to beat on their preferred route usually.
At least in NJ, Google Maps typically does a terrible job. When I go from my home to Costco, I take one small road to the highway, take the highway, get off, and take one small road to Costco. It's very fast and easy. Makes a big L on the map, basically.
Google Maps ignores the highway and has me make twenty alternating left and right turns on tiny backroads. It's grueling, a lot of work, and you can't even go fast on them. All because Google Maps is trying to cut the diagonal from one end of the L to the other for a shorter distance. In terms of trip duration, it fails horribly, though.
This is an impressive result, but not exactly a UPS exclusive. Pretty much any vehicle routing software worth using has offside-turn-minimization options, usually as one of several 'weighting factors'. For example, almost every garbage collection service of any size minimizes its offside turns.
Since you need turn restrictions if you want to compute routes that users can actually follow, adding different costs for different kinds of turns (left, right, U-turn) is easy.
> Incorporating turn costs into route planning is actually not that easy! [I]t doesn't play well with many speed-up techniques.
+
> Since you need turn restrictions if you want to compute routes that users can actually follow, adding different costs for different kinds of turns (left, right, U-turn) is easy.
Does this mean all those speed-up techniques don't produce routes that are actually allowed? What's the point of developing them?
Nah, it's just that it took work to integrate turn restrictions, and that that results in a bit of a slowdown.
It's easier to do research on a more limited version of the problem (shortest path in a road graph with a suitably chosen edge weight function) and then generalise than start out with the most general formulation. The results are wild: these techniques are millions of times faster than Dijkstra's algorithms and provably produce the exact same result. It's what makes Google Maps possible.
I believe that Telogis does, from what one of the engineers was saying to me.
Most software will weight on rules like how long it will take to turn left rather than right at an intersection, and other average case rules at decision points.
If your navigation software doesn't permit weighting different turns, it's not really worth using for a business/organization of any substantial size. Usually there's also cost assignment/weighting for things like traffic time, stoplights-vs-all-way-stops, effective speed limits, time-vs-distance balancing, and all the zonal assignments that come up when breaking up a bunch of stops into different vehicles' routes for the day.
Okay, I assumed the implication was software "typical" for commercial/delivery/collection vehicle routing. Even a business with a dozen vehicles would generally have this sort of software.
Google Maps does not, the last time I checked, preferentially weight left turns beyond expected stoplight delay time. However, Waze does, apparently. (But this is just a comparative observation, the algorithms are not public.)
i talked to my friend, a UPS driver, about this last year when this same story surfaced on HN. He said it's not really true and that they turn left all the time -- but he was aware of some training about it.
> In 2005, a year after it announced that it will minimise left turns, the company said that the total distance covered by its 96,000 trucks was reduced by 747,000km, and 190,000 litres of fuel had been saved.
Er... I understand that you may reduce your fuel consumption by not waiting at red lights, but that the total distance driven has been reduced is clearly wrong!
Maybe they also implemented a better navigation algorithm as part of this? The media likes to reduce everything down to soundbites, but IIRC, this is a rather large effort within UPS to improve routes in general. The left hand turn optimization was just one of the outcomes of this.
Yes they may save money doing this, but when you do that follow your driver for your delivery thing they just came out with, It looks like your driver is on crack the travel patterns make no sense. No order. They are all over the place, similar to how Delta does connecting flights.
Worth mentioning that many drivers will be self-employed and have no such software. UPS seems to give all drivers a software with a route to follow, many others won't bother (as they pay the driver by delivery).
This optimisation must exist at a basic level in all satnav software because journey time must be longer for the route with more left turns, as fed back into the system from previous journeys by other users.
It would be an interesting experiment to see how different consumer grade satnav systems compare on this pure travelling salesman problem.
It's not TSP. In TSP, you have a graph and want to visit every node exactly once. Here you have a (road) graph and want to visit some set of nodes (the delivery addresses) at least once (it's okay to drive past a house where you dropped off a parcel earlier if that somehow makes the journey shorter).
Also, consumer satnav systems don't support this kind of query. You can't plug in a list of dozens of destinations and ask for the shortest path to get you to all of them, in any order.
It reduces to a special case called the metric TSP. If going through node C is shorter than going from A to B directly, then just replace the A-to-B distance with the length of A-to-C-to-B. It's just as hard to solve as regular TSP, but easier to approximate.
Well yeah it's clearly still NP-complete. But the TSP (or variant thereof) isn't related to the routing engine at all, as the routing engine only defines the edge weights. They're fairly orthogonal problems. Logistics software needs to solve both, but consumer satnav doesn't.
I don't know of any other country than the US where turning right on red is allowed, unless there's specific signage or additional traffic lights to allow it. Indeed, the turn-on-red rule in the US seems to work inverse to how I've seen it elsewhere – i.e. it's always allowed unless there's specific signage saying it isn't.
I was just in the US, and I love their turn-on-red rules, and I kept thinking that sometimes it's got to be smarter to turn right than go straight ahead, when there's a red light, even if it may be a longer drive. Glad to see someone took the time to figure this out.