How UPS trucks saved millions of dollars by eliminating left turns
gadgets.ndtv.com
gadgets.ndtv.com
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.
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.
> 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
I'm not sure how exactly the NYC exception works.
By the way, the map on the bottom right is for left turns on red, which isn't the topic here.
"So, I can go on a red light for a right turn, but sometimes I have to wait at a green light for a left turn?"
It was then I realised how peculiar the signals in the US can be.
(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.
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.
and now I'm once again angry about 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?".
They don't usually have to be that sharp, but they tend to be noticeably sharper than the turns in the route.
I get that it's more expensive, but then train spend a lot less time in stations for people to load/unload.
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)..
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.
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.
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.
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.
(I'm curious what other city you're talking about.)
Don't let assholes stress you. The honk shouldn't be used for that, plus you can take as much time as you need to make sure you're driving safely.
I believe Jeremy Clarkson once called it, "America's only useful contribution to Western civilization" :)
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.
https://www.statisticsdonewrong.com/power.html#the-wrong-tur...
("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."
http://www.mercurynews.com/2016/01/06/roadshow-right-on-red-...
Hm? I'm pretty sure that revenues from red light camera tickets generally go to municipalities, not the companies that make the cameras themselves.
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.
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.
http://www.aarp.org/money/budgeting-saving/info-05-2009/ask_...
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.
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.
I do agree that new stations should do this.
http://www.oregonlive.com/commuting/index.ssf/2015/10/turn_l...
(Incidentally, highway on-ramps are considered one way streets for the purpose of this law.)
[1] http://itd.idaho.gov/wp-content/uploads/2016/06/driver_manua...
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.
Popular expedience != sensible policies.
Curiously also, only California allows motorcycle lane-splitting.
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.
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):
https://algo2.iti.kit.edu/download/turn_ch.pdf
http://i11www.iti.uni-karlsruhe.de/extra/publications/dgpw-c...
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 :)
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.
Maybe it's not taking into account how fast can cars make each of the turns?
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.)
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.
See my other comment in this thread on the challenges associated with incorporating turn costs and restrictions in gerenal: https://news.ycombinator.com/item?id=13616676
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> 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?
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.
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!
Guys, you have a bug in your spreadsheet!
It would be an interesting experiment to see how different consumer grade satnav systems compare on this pure travelling salesman problem.
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.